JP6475603B2 - Movie data reproducing apparatus and program - Google Patents

Description

  The present invention relates to a moving image data reproducing apparatus and a program.

For frames that have received base layer data and enhancement layer data, use both of these to generate high-quality frames, and for frames that have received only base layer data, use only base layer data In addition, there has been known a moving image data reproducing apparatus that generates low-quality frames and reproduces moving image data (see, for example, Patent Document 1).
[Prior art documents]
[Patent Literature]
[Patent Document 1] JP-A-2015-0505599

  It is desirable to be able to improve the quality of moving images experienced by the viewer.

  According to the first aspect of the present invention, there is provided a moving image data reproducing device for decoding moving image data encoded so as to include a plurality of hierarchies, the buffer temporarily storing the moving image data, and the moving image data. A playback unit that decodes the layer data included in each of the plurality of frames of the moving image data included in the buffer, and the layer data of layer ID = 1 and the layer ID = 2 in the first frame In the case where both layer data are stored and only the layer data of layer ID = 1 is stored in the second frame subsequent to the first frame, the predetermined first data after the second frame are stored. Even if both layer data of layer ID = 1 and layer data of layer ID = 2 are stored for frames of the number of hierarchy maintaining frames, layer ID = The first layer-maintaining frame number after the second frame is decoded using only the layer data of the second frame, and both the layer data of layer ID = 1 and the layer data of layer ID = 2 are stored in the first frame. And when the layer data of layer ID = 1 and the layer data of layer ID = 2 are stored in the second frame, the second frame is decoded using both of the layer data, and the layer ID in the first frame When only the layer data of = 1 is stored, a moving image data reproducing apparatus that decodes the second frame so as to reproduce a moving image of the highest layer that can be reproduced using the stored layer data. Provided.

  The moving image data reproduction device may further include a moving image data display unit that displays a moving image obtained by decoding the moving image data. The moving image data reproducing apparatus may change the first hierarchy maintaining frame number according to the moving image data. The playback unit stores the layer data of the layer ID = 1 and the layer data of the layer ID = 2 for the third frame in which more layer data is stored than the previous frame, and When both the layer data of the layer ID = 1 and the layer data of the layer ID = 2 are stored for all the frames of the predetermined first layer guaranteed frame number after the third frame, The third frame is decoded using both the layer data of the layer ID = 1 and the layer data of the layer ID = 2 of the third frame, and the frames having the number of first hierarchical guaranteed frames after the third frame are decoded. When only layer data of the layer ID = 1 is stored for at least one of the above, the above-mentioned third frame It may decode the third frame using only layer data of ear ID = 1. The moving image data reproducing device may change the first hierarchical guaranteed frame number according to moving image data.

  In the case where the moving image data is encoded so as to include a plurality of hierarchies of three or more layers, the reproducing unit includes at least one of all stored layer data for each of the plurality of frames of the moving image data. The frame may be decoded using one layer data. In the case where the moving image data is encoded so as to include a plurality of hierarchies of three or more hierarchies, the playback unit performs the above-described processing on the fourth frame in which less layer data is stored than the previous frame. Layers stored for the fourth frame, even if more layer data than the fourth frame is stored for a predetermined number of second layer maintenance frames after the fourth frame The same number of layer data as the number of data may be used to decode the second layer-maintaining frame number after the fourth frame. In the case where the moving image data is encoded so as to include a plurality of hierarchies of three or more hierarchies, the playback unit performs the above processing on the fifth frame in which more layer data is stored than the previous frame. When more layer data than the layer data stored in the frame immediately before the fifth frame is stored for all the frames of the predetermined second layer guaranteed frame number after the fifth frame, Using the same number of layer data as the smallest number of layer data among the number of layer data of the fifth frame and the predetermined number of second layer guaranteed frames after the fifth frame, the fifth frame is used. The fifth frame is decoded and at least one of the frames of the second hierarchy guaranteed number of frames after the fifth frame is decoded. If less layer data than the previous frame is stored, the same number of layer data as the number of layer data stored for the previous frame of the fifth frame is stored for the fifth frame. It may be used to decode the fifth frame.

  In the case where the moving image data is encoded so as to include a plurality of hierarchies of three or more hierarchies, the playback unit has a predetermined reduction limit on the number of layer data stored after the next frame. The sixth frame may be decoded using only a part of the plurality of stored layer data for the sixth frame that is greater than the number of layers. In the case where the moving image data is encoded so as to include a plurality of hierarchies of three or more hierarchies, the playback unit has a predetermined increase limit on the number of layer data stored before the previous frame. For the seventh frame that is greater than the number of layers, the seventh frame may be decoded using only a part of the plurality of stored layer data.

  According to the second aspect of the present invention, there is provided a moving image data reproducing apparatus for decoding moving image data having a plurality of frame groups each encoded with a plurality of layers and each including a plurality of frames. A buffer that temporarily stores data; and a playback unit that decodes the video data, wherein the playback unit confirms the layer data included in each of the plurality of frame groups of the video data included in the buffer, Layer ID = 1 and layer ID = 2 are stored for all the frames in the frame group, and all the second frame groups subsequent to the first frame group are stored. If only layer data of layer ID = 1 is stored for at least one of the frames, the second This is a case where both the layer data of layer ID = 1 and the layer data of layer ID = 2 are stored for all the frames for the frame group of the first number of first layer maintaining frame groups after the frame group. Even so, the second frame group is decoded using only the layer data of all layer IDs = 1 of the second frame group, and the layer data and layers of layer ID = 1 for all the frames of the first frame group When both layer data of ID = 2 are stored and both layer data of layer ID = 1 and layer data of layer ID = 2 are stored for all frames of the second frame group, All layer data of layer ID = 1 in the second frame group And the second frame group is decoded using the layer data of layer ID = 2, and for the first frame group, only the layer data of layer ID = 1 is stored for at least one of all the frames. In this case, a moving image data reproducing apparatus is provided that decodes the second frame group so as to reproduce the highest layer moving image that can be reproduced using the stored layer data.

  The moving image data reproduction device may further include a moving image data display unit that displays a moving image obtained by decoding the moving image data. The reproducing unit performs the above-described layer processing for all the frames in the third frame group next to the frame group in which only the layer data of layer ID = 1 is stored for at least one of the frames included in the frame group. Layer data of ID = 1 and layer data of the layer ID = 2 are stored, and all of the frame groups of the predetermined number of first hierarchical guaranteed frame groups after the third frame group are as follows: When the layer data of the layer ID = 1 and the layer data of the layer ID = 2 are stored for all the frames, all the layer data of the layer ID = 1 of the third frame group and the layer ID = The third frame is used for the first frame data. Only the layer data of layer ID = 1 for at least one of all the frames for at least one of the first hierarchical guaranteed frame group number after the third frame group. Is stored, the third frame group may be decoded using only the layer data of all the layer IDs = 1 of the third frame group.

  In the case where the moving image data is encoded so as to include a plurality of hierarchies of three or more layers, the reproducing unit performs all the frames for all the frames for each of the plurality of frame groups of the moving image data. The frame group may be decoded using layer data equal to or less than the group minimum layer data number, which is the number of layer data of the frame having the smallest number of stored layer data. In the case where the moving image data is encoded so as to include a plurality of hierarchies of three or more hierarchies, the reproducing unit performs the fourth frame group having a smaller group minimum layer data number than the previous frame group. This is a case where the number of group minimum layer data is greater than the number of group minimum layer data of the fourth frame group for the frame groups having the predetermined number of second layer maintenance frame groups after the fourth frame group. However, the same number of layer data as the number of group minimum layer data of the fourth frame group may be used to decode the frame groups of the second layer-maintaining frame group number after the fourth frame group. . In the case where the moving image data is encoded so as to include a plurality of hierarchies of three or more hierarchies, the reproducing unit has a fifth frame group in which the number of group minimum layer data is larger than the previous frame group. For all the frame groups having the predetermined second layer guaranteed frame number after the fifth frame group, the group minimum layer data number is the group minimum layer of the frame group immediately before the fifth frame group. When the number of data is greater than the number of data, it is the same as the number of group minimum layer data that is the smallest among all the frame groups of the fifth frame group and the predetermined number of second layer guaranteed frame groups after the fifth frame group. Decode the fifth frame group using a number of layer data When at least one of the second hierarchically guaranteed frame group number after the fifth frame group is smaller than the group minimum layer data number of the frame group immediately before the fifth frame group, For the fifth frame group, the fifth frame group may be decoded using the same number of layer data as the number of group minimum layer data of the previous frame group of the fifth frame group.

  In the case where the moving image data is encoded so as to include a plurality of hierarchies of three or more hierarchies, the playback unit has a reduction limiting hierarchy in which the number of group minimum layer data is predetermined as compared to the next frame group For the sixth frame group that is greater than or equal to the number, the sixth frame group may be decoded using only a smaller number of layer data than the group minimum layer data number of the sixth frame group for all frames. . In the case where the moving image data is encoded so as to include a plurality of hierarchies of three or more hierarchies, the playback unit has an ascending restriction hierarchy in which the number of group minimum layer data is determined in advance than the previous frame group For the seventh frame group that is greater than or equal to the number, the seventh frame group may be decoded by using only the number of layer data that is smaller than the group minimum layer data number of the seventh frame group for all frames.

  According to the third aspect of the present invention, there is provided a moving image data reproducing device for decoding moving image data encoded so as to include a plurality of hierarchies, the buffer temporarily storing the moving image data, and the moving image data. A playback unit for decoding, the playback unit confirms the layer data included in each of the plurality of frames of the moving image data included in the buffer, and the first layer data of the first hierarchy and the second layer are included in the first frame. When both of the second layer data of the hierarchy are stored and only the first layer data is stored for the second frame subsequent to the first frame, the second and subsequent frames are predetermined. Even if both the first layer data and the second layer data are stored for the first number of frames, only the first layer data is used for the second and subsequent frames. The first frame data and the second layer data are both stored in the first frame, and both the first layer data and the second layer data are stored in the second frame. Is stored, the second frame is decoded using both the first layer data and the second layer data of the second frame, and only the first layer data is stored in the first frame. There is provided a moving image data reproducing device that decodes the second frame so as to reproduce the moving image of the highest layer that can be reproduced using the stored layer data.

  According to a fourth aspect of the present invention, there is provided a moving image data reproduction device for decoding moving image data having a plurality of frame groups each encoded with a plurality of layers and each including a plurality of frames. A buffer that temporarily stores data; and a playback unit that decodes the video data, wherein the playback unit confirms the layer data included in each of the plurality of frame groups of the video data included in the buffer, The first layer data of the first layer and the second layer data of the second layer are stored for all the frames of the first frame group, and the second frame group next to the first frame group If only the first layer data is stored for at least one of all the frames, the second frame Even if both the first layer data and the second layer data are stored for all the frames for the predetermined first number of frame groups after the loop, the second frame group Decoding the second frame group using only all the first layer data, storing both the first layer data and the second layer data for all the frames of the first frame group; and When both the first layer data and the second layer data are stored for all the frames in the second frame group, all the first layer data and the second layer data in the second frame group are stored. Is used to decode the second frame group and all frames for the first frame group are decoded. When only the first layer data is stored for at least one of the frames, the second frame group is decoded so as to play back the highest layer video that can be played using the stored layer data. A moving image data reproducing apparatus is provided.

  According to the fifth aspect of the present invention, there is provided a program for causing a computer to function as the moving image data reproducing device.

  The above summary of the invention does not enumerate all necessary features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

An example of the moving image data 150 is shown. 3 is an example of hierarchically encoded moving image data 160. It is an example of the moving image data 170 in which some layer data of the enhancement layer is missing in the hierarchically encoded moving image data. 1 schematically shows an example of a moving image data reproducing apparatus 100. An example of the moving image data 150 stored in the buffer 102 is schematically shown. An example of decoding control by the reproduction unit 108 is schematically shown. An example of the flow of processing by the moving image data reproducing apparatus 100 is schematically shown. A specific example of the flow of processing by the moving image data reproducing apparatus 100 is schematically shown. An example of decoding control by the reproduction unit 108 is schematically shown. An example of the flow of processing by the moving image data reproducing apparatus 100 is schematically shown. An example of the flow of processing by the moving image data reproducing apparatus 100 is schematically shown. An example of the moving image data 150 stored in the buffer 102 is schematically shown. An example of decoding control by the reproduction unit 108 is schematically shown. An example of the flow of processing by the moving image data reproducing apparatus 100 is schematically shown. A specific example of the flow of processing by the moving image data reproducing apparatus 100 is schematically shown. An example of the flow of processing by the moving image data reproducing apparatus 100 is schematically shown. A specific example of the flow of processing by the moving image data reproducing apparatus 100 is schematically shown. An example of decoding control by the reproduction unit 108 is schematically shown. An example of the flow of processing by the moving image data reproducing apparatus 100 is schematically shown. A specific example of the flow of processing by the moving image data reproducing apparatus 100 is schematically shown. An example of the flow of processing by the moving image data reproducing apparatus 100 is schematically shown. A specific example of the flow of processing by the moving image data reproducing apparatus 100 is schematically shown. It is an example of moving image data 180 that is hierarchically encoded so as to form a frame group with a plurality of frames. This is an example of reproducing a high-quality moving image using the frame group 182 encoded by the hierarchical encoding method. This is an example of reproducing a low-quality moving image using the frame group 182 encoded by the hierarchical encoding method. In this example, decoding is performed using the frame group 200 encoded by the hierarchical encoding method. An example of the moving image data 150 stored in the buffer 102 is schematically shown. An example of the moving image data 150 stored in the buffer 102 is schematically shown. 1 schematically shows an example of a moving image data reproducing apparatus 100 capable of receiving moving image data from the outside.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. Moreover, not all the combinations of features described in the embodiments are essential for the solution means of the invention.

  FIG. 1 is an example of the moving image data 150. The moving image data 150 is composed of a plurality of frames 151. Each frame 151 is identified by a sequence ID indicating the playback order (hereinafter, the sequence ID may be abbreviated as SID). The moving image data 150 can reproduce a moving image by sequentially displaying each frame according to the SID.

  FIG. 2 is an example of hierarchically encoded moving image data 160. The moving image data 160 includes a plurality of frames 161, and each frame 161 includes two layer data 162 and 163. The layer data 162 is called a base layer, and the layer data 163 is called an enhancement layer. Each layer data can be identified by a sequence ID indicating the reproduction order and a layer ID indicating the layer (hereinafter, the layer ID may be abbreviated as LID). The basic layer is, for example, layer data that has a low image quality but is necessary for reproduction. On the other hand, the enhancement layer is layer data that can improve image quality by being added to the basic layer. Accordingly, in moving image data that has been hierarchically encoded, a low-quality moving image can be reproduced by sequentially displaying only the layer data of the base layer according to the SID. It is also possible to reproduce high-quality moving image data by combining the layer data of the base layer and the extension layer and sequentially displaying them according to the SID. In this embodiment, it is assumed that the layer ID of the base layer is 1, and the layer ID of the enhancement layer is 2 or more.

  The layer data constituting the hierarchically encoded moving image data may be lost due to various factors. For example, when streaming playback of moving image data via a network, layer data may be lost in the transmission path. In addition, layer data may be lost when moving image data is read from an optical disk or a magnetic disk.

  FIG. 3 is an example of moving image data 170 in which part of the layer data of the enhancement layer is missing from the hierarchically encoded moving image data. The moving image data 170 is composed of a plurality of frames 171, and each frame is composed of two layer data 172 and 173. In the video data 170, SID = 1, 2, 6, and 7 frames include both basic layer and enhancement layer data, but SID = 3, 4, and 5 frames lack enhancement layer data. Only the base layer data is included.

  When the moving image data 170 is reproduced, a high-quality moving image can be reproduced using the layer data of both the basic layer and the extended layer in each frame of SID = 1,2. However, since each frame of SID = 3, 4, and 5 has only layer data of the basic layer, the moving image is reproduced by switching to low image quality. In each frame of SID = 6 and 7, playback is performed again by switching to high image quality using layer data of both the basic layer and the enhancement layer. As described above, the hierarchically encoded moving image data can be reproduced by switching the image quality even if the layer data of the enhancement layer is missing.

  However, if a high-quality video and a low-quality video are switched suddenly and frequently during viewing, the change in the image quality at the time of switching may be obstructive to human eyes, which may degrade the viewer's quality of experience. Therefore, a playback device that smoothly switches between high-quality video and low-quality video is required when playing back hierarchically encoded moving image data.

  FIG. 4 schematically shows an example of a moving image data reproducing apparatus 100 that can reproduce hierarchically encoded moving image data. The moving image data reproducing device 100 reproduces, for example, scalable encoded moving image data. The moving image data reproducing apparatus 100 may reproduce moving image data that has been hierarchically encoded by another encoding method.

  The moving image data playback device 100 includes a buffer 102 and a playback unit 108. The buffer 102 can temporarily store moving image data to be reproduced. For example, moving image data transmitted from a communication network and moving image data read from an optical disk or a magnetic disk are stored. Accordingly, in the moving image data stored in the buffer 102, a part of the enhancement layer may be missing.

  The reproduction unit 108 decodes the moving image data stored in the buffer 102 and reproduces the moving image. For example, when both the base layer data and the enhancement layer layer data are stored for each of a plurality of frames of moving image data encoded to include two layers, the playback unit 108 If the frame is decoded using both the layer data of the enhancement layer and the layer data of the enhancement layer, or only the layer data of the base layer, and only the layer data of the base layer is stored, the frame is formed using only the layer data of the base layer. The moving image data reproducing apparatus 100 reproduces each decoded frame in the order of the SID.

  In addition, for example, the playback unit 108 obtains at least one layer data of all the layer data stored in the buffer 102 for each of a plurality of frames of moving image data encoded to include three or more layers. To decode the frame. As a specific example, when the moving image data is encoded so as to include four layers, the playback unit 108 uses only the layer data of the base layer or the layer data of the base layer and the layer of the extension layer of the first layer. The video data is decoded by using the data, the layer data of the base layer, the layer data of the extension layer of the first layer and the layer data of the extension layer of the second layer, or using all the layer data. The playback device 100 plays back each decoded frame in the order of the SID.

  Further, the reproduction unit 108 may decode moving image data that is encoded so as to include a plurality of hierarchies and each includes a plurality of frame groups each including a plurality of frames. For example, the reproduction unit 108 is encoded so as to include two layers, and for each of a plurality of frame groups of video data having a plurality of frame groups each including a plurality of frames, all frames included in the frame group If both the base layer layer data and the enhancement layer layer data are stored, the frame group is decoded using all the base layer layer data and the enhancement layer layer data of the frame group, and the frame group If only the base layer layer data is stored for at least one of the frames included in the frame group, the frame group is decoded using only the layer data of all the base layers of the frame group, and the video data Raw device 100 reproduces each frame decoded in the order of SID.

  In addition, for example, the playback unit 108 is encoded so as to include three or more hierarchies, and each of a plurality of frame groups of moving image data having a plurality of frame groups each including a plurality of frames, for all frames. The moving picture data reproducing apparatus 100 decodes the frame group using layer data equal to or less than the group minimum layer data number, which is the number of layer data of the frame having the smallest number of layer data stored among all the frames. Each decoded frame is reproduced in the order of SID.

  The moving image data display unit 110 displays moving images decoded and reproduced by the reproducing unit 108 for moving image data encoded to include a plurality of layers. The moving image data display unit 110 displays the moving image decoded by the reproducing unit 108 for moving image data that is encoded to include a plurality of hierarchies and has a plurality of frame groups each including a plurality of frames.

  The moving image data display unit 110 may be a display included in the moving image data playback device 100. Further, the moving image data display unit 110 may be a display provided in another device. The moving image data display unit 110 may be connected via, for example, an arbitrary network.

  The moving image data reproduction device 100 may receive moving image data encoded so as to include a plurality of hierarchies from the outside. The playback unit 108 may decode the video data received from the outside, and the video data display unit 110 may display the video data received from the outside that is decoded and played back by the playback unit 108.

  FIG. 5 schematically shows an example of the moving image data 150 stored in the buffer 102. Here, moving image data 150 encoded to include two layers of a base layer and an enhancement layer is shown. Each of the base layer and the enhancement layer includes a plurality of layer data 152. The missing layer data 154 indicates that the layer data 152 is not stored. For example, in the moving image data 150 illustrated in FIG. 5, the layer data of the base layer and the layer data of the enhancement layer are stored for the first, second, fourth, sixth, eighth, 10th to 12th, and 14th to 16th frames. For the third, fifth, seventh, ninth and thirteenth frames, only the base layer data is stored.

  Here, when only the base layer data is stored, the frame is decoded using only the base layer data, and both the base layer data and the enhancement layer data are stored. In the case of decoding using both of them, in the moving image data 150 shown in FIG. 5, the high image quality and the low image quality are switched for each frame from the second frame to the ninth frame. In some cases, the quality of the moving image experienced by the viewer is low.

  On the other hand, the moving image data reproducing device 100 according to the present embodiment executes a process for improving the quality of the moving image experienced by the viewer. The playback unit 108 included in the moving image data playback apparatus 100 stores, for example, only the base layer data for the next frame of one frame in which both base layer data and enhancement layer data are stored. If the basic layer layer data and the enhancement layer layer data are both stored for the predetermined number of first hierarchy maintaining frames after the next frame, Only the layer data of the layer is used to decode the first layer-maintaining frame number after the next frame. The number of first layer maintenance frames may be an example of the first number.

  FIG. 6 schematically shows an example of decoding by the playback unit 108. Here, a case where the number of first layer maintenance frames is three is illustrated. Since the reproduction unit 108 stores only the base layer layer data for the third frame next to the second frame in which both the base layer layer data and the enhancement layer layer data are stored, Even if both the base layer data and the enhancement layer layer data are stored for the third to fifth frames, the third to fifth frames are decoded using only the base layer data. To do.

  Discarded layer data 156 indicates layer data discarded by the reproducing unit 108. In the example illustrated in FIG. 6, the layer data of the fourth, eighth, fourteenth, and fifteenth enhancement layers is discard layer data 156. Thus, according to the moving image data reproducing apparatus 100 according to the present embodiment, frequent switching between high image quality and low image quality can be suppressed, and the quality of moving images experienced by the viewer can be improved.

  FIG. 7 schematically shows an example of the flow of processing by the moving image data playback apparatus 100. The processing shown in FIG. 7 will be described assuming that the moving image data reproducing apparatus 100 has received a reproduction instruction for moving image data encoded to include two layers. Each process shown in FIG. 7 may be executed entirely within the playback unit 108 of the moving image data playback apparatus 100. Here, the first frame will be described on the premise that the first frame is reproduced in the highest reproducible layer. Playing back at the highest layer that can be played back means that the frame is decoded and played back using all the layer data stored for the frame.

  In step 502 (step may be abbreviated as S) 502, the first frame and the next second frame stored in the buffer 102 are confirmed.

  In S504, it is determined whether or not the layer of the second frame is lowered with respect to the first frame. When the layer of the second frame is lowered with respect to the first frame, the number of layer data stored for the second frame is greater than the number of layer data stored for the first frame. Indicates less. If it is determined that the layer is not lowered, the process proceeds to S506, and if it is determined that the layer is lowered, the process proceeds to S508.

  In S506, it is determined to reproduce the second frame in the highest reproducible layer. In S508, it is determined to reproduce the next N frames in the base layer. “Playback in the base layer” means that even if a plurality of layer data is stored for the target frame, the frame is decoded and played back using only the layer data of the base layer. N may be an example of the number of first layer maintenance frames. N may be a predetermined number or may be changeable.

  In S510, it is determined whether or not processing has been completed up to the final frame of the moving image data. If it is determined that the processing has not been completed up to the final frame, the process returns to S502 to confirm the next frame. If it is determined that the process has been completed up to the last frame, the process ends.

  When the decoding policy is determined in steps S506 and S508, sequential decoding may be executed to display a moving image using the frames that have been decoded on the moving image data display unit 110. In addition, the processing of S502 to S512 is repeated to determine the decoding policy for a plurality of frames or all the frames included in the moving image data, and then decoding is performed, and the moving image data display unit 110 uses the decoded frame. Video may be displayed.

  FIG. 8 schematically shows a specific example of the flow of processing by the moving image data playback apparatus 100. The process shown in FIG. 8 will be described assuming that the moving image data reproducing apparatus 100 has received a reproduction instruction for moving image data encoded to include two layers. Each process illustrated in FIG. 8 may be executed entirely within the reproduction unit 108 included in the moving image data reproduction apparatus 100. Here, the first frame will be described on the premise that the first frame is reproduced in the highest reproducible layer.

  In the figure, X indicates a frame number. Y represents the maximum value of X. The initial value of X is 0, and Y is the number of frames included in the moving image data. B [X] indicates the number of layer data stored in the buffer 102 for the Xth frame. Here, a case where the moving image data is encoded so as to include two layers is illustrated, so the minimum value of B [X] is 1, and the maximum value of B [X] is 2.

  In S602, the first frame and the next second frame stored in the buffer 102 are confirmed. In S604, it is determined whether B [X + 1] is smaller than B [X]. If it is determined that B [X + 1] is not smaller than B [X], the process proceeds to S606. If it is determined that B [X + 1] is not smaller than B [X], the process proceeds to S610.

  In S606, it is determined to play back the X + 1th frame according to B [X + 1]. Reproduction according to B [X + 1] may indicate that a frame is decoded and reproduced using the number of layer data indicated by B [X + 1]. In S608, 1 is added to X.

  In S610, 1 is substituted for n. In S612, it is determined that the X + n-th frame is to be reproduced in the base layer. In S614, 1 is added to n. In S616, it is determined whether n = N. If it is determined that n = N, the process returns to S612. If it is determined that n = N, the process proceeds to S618. In S618, N is added to X.

  In S620, it is determined whether X = Y. If it is determined that X = Y is not satisfied, the process returns to S602, and if it is determined that X = Y, the process is terminated.

  As described above, when reproducing moving image data that is hierarchically encoded so as to include two layers as in the example illustrated in FIG. 5, frequent image quality switching due to lack of layer data occurs, and the quality of experience deteriorates. Sometimes. Therefore, as a method to prevent this, as shown in FIG. 6, after the layer is lowered, the quality of the video that the viewer feels is improved by playing the frames for the number of hierarchy maintaining frames without raising the layer. Can be made. A specific implementation method can be realized by executing each process shown in FIGS. 7 and 8 by the playback unit 108 in the moving image data playback apparatus 100 shown in FIG.

  FIG. 9 schematically shows an example of decoding control by the playback unit 108. Here, when the high image quality cannot be maintained continuously for M frames after switching from the low image quality to the high image quality, the playback unit 108 performs processing that discards the layer data of the enhancement layer and does not switch to the high image quality. The case will be described. M may be an example of the number of first hierarchical guaranteed frames. M may be a predetermined number or may be changeable. Here, a case where M is 2 will be described as an example.

  In the example shown in FIG. 9, the layer data of the fourth, eighth, fourteenth, and fifteenth enhancement layers are discarded by the processing described in FIG. 6, and the third to fifth, seventh to ninth, and thirteenth to fifteenth frames are discarded. The frame is decoded using only the base layer data. Here, for the sixth frame, both the base layer data and the enhancement layer data are stored. However, since only the layer data of the base layer is stored for the seventh frame, it is not possible to maintain high image quality for two consecutive frames. Therefore, the playback unit 108 uses the sixth and seventh frames. Decide to decode using only the layer data of the base layer. Discarded layer data 158 indicates layer data discarded by the reproducing unit 108. As described above, the playback unit 108 stores both the base layer data and the enhancement layer layer data for a frame that contains more layer data than the previous frame, such as the sixth frame. If both the basic layer layer data and the enhancement layer layer data are stored for all the frames of the first hierarchy guaranteed frame number after the frame, the base layer data for the frame is stored. When the base layer data is stored for at least one of the frames of the first hierarchical guaranteed number of frames after the frame, the base layer of the base layer is decoded. Decoding may be performed using only layer data. As described above, according to the moving image data reproducing apparatus 100 according to the present embodiment, frequent switching between high image quality and low image quality can be further suppressed, and the quality of moving images experienced by the viewer can be improved. .

  FIG. 10 schematically shows an example of the flow of processing by the moving image data playback apparatus 100. The processing shown in FIG. 10 will be described assuming that the moving image data reproducing apparatus 100 has received a reproduction instruction for moving image data encoded to include two layers. Each process shown in FIG. 10 may be executed entirely within the playback unit 108 of the moving image data playback apparatus 100. Here, the first frame will be described on the premise that the first frame is reproduced in the highest reproducible layer.

  In S802, the first frame and the next second frame stored in the buffer 102 are confirmed. In S804, it is determined whether or not the layer of the second frame goes up with respect to the first frame. When the layer of the second frame goes up with respect to the first frame, the number of layer data stored for the second frame is greater than the number of layer data stored for the first frame. Indicates many.

  If it is determined that the layer does not rise, the process proceeds to S806, and if it is determined that the layer goes up, the process proceeds to S808. In S806, it is determined to play back the second frame in the highest layer that can be played back.

  In S808, it is determined whether or not the next M frames can be reproduced in the enhancement layer continuously. When the base layer layer data and the enhancement layer layer data are stored for all of the next M frames, the playback unit 108 determines that playback is possible in the enhancement layer continuously for M frames, and otherwise plays back. You may judge it impossible. If it is determined that playback is possible, the process proceeds to S810. If it is determined that playback is not possible, the process proceeds to S812.

  In S810, it is determined that the next M frame is to be reproduced in the enhancement layer. In S812, it is determined that the next frame is to be reproduced in the base layer.

  In S814, it is determined whether or not the processing has been completed up to the final frame of the moving image data. If it is determined that the processing has not been completed up to the final frame, the process returns to S802, and the reproducing unit 108 further confirms the next frame. If it is determined that the process has been completed up to the last frame, the process ends.

  FIG. 11 schematically shows a specific example of the flow of processing by the moving image data reproducing apparatus 100. The process shown in FIG. 11 will be described assuming that the moving image data reproducing apparatus 100 has received an instruction to reproduce moving image data encoded to include two layers. Each process shown in FIG. 11 may be executed entirely within the playback unit 108 of the moving image data playback apparatus 100. Here, the first frame will be described on the premise that the first frame is reproduced in the highest reproducible layer.

  In the figure, X indicates a frame number. Y represents the maximum value of X. The initial value of X is 0, and Y indicates the number of frames included in the moving image data. B [X] indicates the number of layer data stored in the buffer 102 for the Xth frame. Here, a case where the moving image data is encoded so as to include two layers is illustrated, so the minimum value of B [X] is 1, and the maximum value of B [X] is 2.

  In S902, the first frame and the next second frame stored in the buffer 102 are confirmed. In S904, it is determined whether B [X + 1] is larger than B [X]. When it is determined that B [X + 1] is not larger than B [X], the process proceeds to S906, and when it is determined that B [X + 1] is larger than S [B], the process proceeds to S910.

  In S906, it is determined to play back the X + 1th frame according to B [X + 1]. In S908, 1 is added to X.

  In S910, it is determined whether or not frames from the (X + 1) th frame to the (X + M) th frame can be reproduced in the enhancement layer. If it is determined that playback is possible, the process proceeds to S912. If it is determined that playback is not possible, the process proceeds to S924.

  In S912, 1 is substituted for n. In S914, it is determined that the X + nth frame is to be reproduced in the enhancement layer. In S916, 1 is added to n. In S918, it is determined whether n = M. If it is not determined that n = M, the process returns to S914. If it is determined that n = M, the process proceeds to S920. In S920, 2 is substituted into B [X + n]. In S922, N is added to X.

  In S924, it is determined that the X + 1-th frame is to be reproduced in the base layer. In S926, 1 is substituted into B [X + 1]. In S928, 1 is added to X.

  In S934, it is determined whether X = Y. If it is determined that X = Y is not true, the process returns to S902 to confirm the next frame. If it is determined that X = Y, the process ends.

  FIG. 12 schematically shows an example of the moving image data 150 stored in the buffer 102. Here, moving image data 150 encoded so as to include four layers of a base layer and enhancement layers 1 to 3 is shown. In the example shown in FIG. 12, the layer data of the enhancement layers 2 to 3 in the third frame, the layer data of the enhancement layer 3 in the sixth frame, and the enhancement layer 3 in the eighth frame Layer data of the enhancement layer, layer data of the enhancement layers 1 to 3 in the 11th frame, and layer data of the enhancement layers 2 to 3 in the 13th frame are the missing layer data 154. An example is given.

  Here, when a frame is decoded using all the stored layer data for each frame, the image quality is frequently switched in the moving image data 150 shown in FIG. The quality may be low.

  On the other hand, the moving image data reproducing device 100 according to the present embodiment executes a process for improving the quality of the moving image experienced by the viewer. The playback unit 108 included in the moving image data playback apparatus 100, for example, for a frame with less layer data stored than the previous frame, a predetermined second layer maintenance frame after the one frame Even if a larger number of layer data than the one frame is stored for a number of frames, the same number of layer data as the number of layer data stored for the one frame is used. The frames of the second layer maintenance frame number after the first frame are decoded.

  FIG. 13 schematically shows an example of decoding control by the playback unit 108. Here, a case where the number of second layer maintenance frames is three is illustrated. Since the playback unit 108 stores less layer data for the third frame than the second frame immediately before, the playback unit 108 has more layer data for the third to fifth frames than the second frame. Are stored, the third to fifth frames are decoded using the same number of layer data as the number of layer data stored for the second frame. Similarly, the playback unit 108 decodes the seventh frame using the same number of layer data as 3, which is the number of layer data stored for the sixth frame. Similarly, the reproduction unit 108 decodes the twelfth and thirteenth frames using the same number of layer data as the number of layer data stored for the eleventh frame.

  As described above, in the example illustrated in FIG. 13, the layer data of the enhancement layers 2 to 3 in the fourth frame, the layer data of the enhancement layers 2 to 3 in the fifth frame, and the seventh layer The enhancement layer 3 layer data in the frame, the enhancement layer 1 to 3 enhancement layer data in the 12th frame, and the enhancement layer 1 enhancement layer data in the 13th frame are discarded layer data. 156. Thus, according to the moving image data reproducing apparatus 100 according to the present embodiment, frequent switching of image quality can be suppressed, and the quality of moving images experienced by the viewer can be improved.

  FIG. 14 schematically shows an example of the flow of processing by the moving image data playback apparatus 100. The processing shown in FIG. 14 will be described assuming that the moving image data reproducing apparatus 100 has received a moving image data reproduction instruction as a start state. Each process shown in FIG. 14 may be executed entirely within the playback unit 108 of the moving image data playback apparatus 100. Here, the first frame will be described on the premise that the first frame is reproduced in the highest reproducible layer.

  In S1202, the first frame and the next second frame stored in the buffer 102 are confirmed. In step S1204, it is determined whether the layer of the second frame is lowered with respect to the first frame. If it is determined that the layer is not lowered, the process proceeds to S1206. If it is determined that the layer is lowered, the process proceeds to S1208.

  In S1206, it is determined to play back the second frame in the highest reproducible layer. In S1208, the highest layer L that can be reproduced continuously in the next N frames is specified. In S1210, it is determined that the next N frames are to be reproduced in layer L. Here, N may be an example of the number of second layer maintenance frames. N may be a predetermined number or may be changeable.

  In S1212, it is determined whether or not the processing has been completed up to the final frame of the moving image data. If it is determined that the processing has not been completed up to the final frame, the process returns to S1202 to confirm the next frame. If it is determined that the process has been completed up to the last frame, the process ends.

  FIG. 15 schematically shows a specific example of the flow of processing by the moving image data reproducing apparatus 100. The process shown in FIG. 15 will be described assuming that the moving image data reproducing apparatus 100 has received a moving image data reproduction instruction as a start state. Each process shown in FIG. 15 may be performed entirely within the playback unit 108 of the moving image data playback apparatus 100. Here, the first frame will be described on the premise that the first frame is reproduced in the highest reproducible layer.

  In the figure, X indicates a frame number. Y represents the maximum value of X. The initial value of X is 0, and Y indicates the number of frames included in the moving image data. B [X] indicates the number of layer data stored in the buffer 102 for the Xth frame. J indicates the maximum number of layers, that is, the number of encoding layers of moving image data.

  In S1302, the first frame and the next second frame stored in the buffer 102 are confirmed. In S1304, it is determined whether B [X + 1] is smaller than B [X]. If it is determined that B [X + 1] is not smaller than B [X], the process proceeds to S1306. If it is determined that B [X + 1] is smaller than B [X], the process proceeds to S1310.

  In S1306, it is determined to reproduce the X + 1th frame according to B [X + 1]. In S608, 1 is added to X.

  In S1310, J is substituted for L. In S1312, it is determined whether or not the X + Nth frame to the X + Nth frame can be reproduced in the layer L. If it is determined that reproduction is not possible, the process proceeds to S1314. If it is determined that reproduction is possible, the process proceeds to S1316. In S1314, 1 is subtracted from L, and the process returns to S1312.

  In S1316, 1 is substituted for n. In S1318, it is determined that the X + n-th frame is to be reproduced in the layer L. In S1320, 1 is added to n. In S1322, it is determined whether n = N. If it is determined that n is not N, the process returns to S1318, and if it is determined that n is N, the process proceeds to S1324. In S1324, N is added to X.

  In S1326, it is determined whether X = Y. If it is determined that X = Y is not true, the process returns to S1302 to confirm the next frame. If it is determined that X = Y, the process ends.

  FIG. 16 schematically shows an example of the flow of processing by the moving image data playback apparatus 100. The process shown in FIG. 16 will be described assuming that the moving image data reproducing apparatus 100 has received a moving image data reproduction instruction as a start state. Each process illustrated in FIG. 16 may be executed entirely within the reproduction unit 108 of the moving image data reproduction apparatus 100. Here, the first frame will be described on the premise that the first frame is reproduced in the highest reproducible layer.

  In S1402, the first frame and the next second frame stored in the buffer 102 are confirmed. In S1404, it is determined whether or not the layer of the second frame is raised with respect to the first frame. If it is determined that the layer does not rise, the process proceeds to S1406. If it is determined that the layer is raised, the process proceeds to S1408.

  In S1406, it is determined to reproduce the second frame in the highest reproducible layer. In S1408, the highest layer L that can be reproduced continuously in the next M frame is specified. In S1410, it is determined whether or not the layer L determined in S1408 is higher than the layer of the previous frame. If it is not determined that the layer L is higher than the layer of the previous frame, the process proceeds to S1412. If it is determined, the process proceeds to S1414. In S1412, it is determined that the next frame is to be reproduced in the same layer as the previous frame. Here, M may be an example of the number of second layer guaranteed frames. M may be a predetermined number or may be changeable. In S1414, it is determined to reproduce the next frame in layer L.

  In step S1416, it is determined whether the processing has been completed up to the final frame of the moving image data. If it is determined that the processing has not been completed up to the final frame, the process returns to S1402 to confirm the next frame. If it is determined that the process has been completed up to the last frame, the process ends.

  FIG. 17 schematically shows a specific example of the flow of processing by the moving image data playback apparatus 100. The processing shown in FIG. 17 will be described assuming that the moving image data reproducing apparatus 100 has received a moving image data reproduction instruction as a start state. Each process shown in FIG. 17 may be executed entirely within the playback unit 108 of the moving image data playback apparatus 100. Here, the first frame will be described on the premise that the first frame is reproduced in the highest reproducible layer.

  In the figure, X indicates a frame number. Y represents the maximum value of X. The initial value of X is 0, and Y indicates the number of frames included in the moving image data. B [X] indicates the number of layer data stored in the buffer 102 for the Xth frame. J indicates the maximum number of layers, that is, the number of encoding layers of moving image data.

  In S1502, the first frame and the next second frame stored in the buffer 102 are confirmed. In S1504, it is determined whether B [X + 1] is larger than B [X]. If it is determined that B [X + 1] is not greater than B [X], the process proceeds to S1506. If it is determined that B [X + 1] is greater than B [X], the process proceeds to S1510.

  In S1506, it is determined to play back the X + 1-th frame according to B [X + 1]. In S1508, 1 is added to X.

  In S1510, it is determined whether the X + Mth frame from the X + 1th frame can be reproduced in a layer higher than B [X]. If it is determined that reproduction is not possible, the process proceeds to S1512. If it is determined that reproduction is possible, the process proceeds to S1514. In S1512, it is determined to play back the X + 1th frame according to B [X].

  In S1514, 0 is substituted into L. In step S1516, it is determined whether the X + Mth frame to the X + Mth frame can be reproduced in the layer L. If it is determined that playback is possible, the process proceeds to S1518. If it is determined that playback is not possible, the process proceeds to S1526. In S1518, 1 is added to L. In S1520, it is determined whether L = J. If it is determined that L = J is not established, the process returns to S1516. If it is determined that L = J is established, the process proceeds to S1522.

  In S1522, it is determined that the X + 1th frame is to be reproduced in layer L. In S1524, L is substituted into B [X + 1]. In S1526, it is determined that the X + 1-th frame is to be reproduced in the layer L-1. In S1528, L−1 is substituted into B [X + 1]. In S1530, 1 is added to X.

  In S1532, it is determined whether X = Y. If it is determined that X = Y is not true, the process returns to S1502 to confirm the next frame. If it is determined that X = Y, the process ends.

  FIG. 18 schematically shows an example of decoding control by the playback unit 108. Here, a process of suppressing switching of layers across a plurality of layers by the moving image data reproduction device 100 will be described. For example, with respect to moving image data encoded to include four layers, a base layer data and layer data of enhancement layers 1 to 3 are added to a frame decoded using only base layer data. When a frame decoded using the reproduction is reproduced, there is a case where the difference in image quality is large and the quality of the moving image experienced by the viewer is low. FIG. 18 shows a state in which the discard layer data 156 is discarded. For example, the difference in the number of layer data stored for each of the 10th frame and the 11th frame is 3. Further, the difference in the number of layer data stored for each of the 13th frame and the 14th frame is 3.

  On the other hand, the playback unit 108 included in the moving image data playback apparatus 100 according to the present embodiment gradually increases the image quality when the difference in the number of layer data stored for each adjacent frame is 2 or more. You may control to switch. In the example shown in FIG. 18, since the difference in the number of layer data stored for each of the 10th frame and the 11th frame is 3, the playback unit 108 switches the image quality in stages. Accordingly, the layer data of the enhancement layer 3 in the ninth frame and the layer data of the enhancement layers 2 and 3 in the tenth frame are set as discard layer data 159. In addition, since the difference in the number of layer data stored for each of the 13th frame and the 14th frame is 3, the reproduction unit 108 changes the image quality in steps so that the image quality is switched in stages. The layer data of the enhancement layers 2 and 3 in the frame and the layer data of the enhancement layer 3 in the 15th frame are set as discard layer data 159.

  Further, since the difference in the number of layer data stored for each of the 10th frame and the 11th frame is 3, the playback unit 108 makes the difference in the number of layer data smaller than 3. At least one layer data of the 10th frame may be discarded. For example, the playback unit 108 discards the layer data of the enhancement layer 3, the layer data of the enhancement layer 2 and the enhancement layer 3, or the layer data of the enhancement layers 1 to 3 stored for the 10th frame.

  As described above, when the moving image data is encoded so as to include a plurality of hierarchies of three or more hierarchies, the playback unit 108 determines the number of layer data stored in advance of the next frame. For one frame that is greater than the number of lower limit layers, the one frame may be decoded using only a part of the plurality of stored layer data.

  In addition, when the moving image data is encoded to include a plurality of hierarchies of three or more hierarchies, the reproduction unit 108 increases the number of layer data stored in advance of the previous frame. For one frame that is more than the limit number of layers, the one frame may be decoded using only a part of the plurality of stored layer data.

  FIG. 19 schematically shows an example of the flow of processing by the moving image data playback apparatus 100. The process shown in FIG. 19 will be described assuming that the moving image data reproducing apparatus 100 has received a moving image data reproduction instruction as a start state. Each process shown in FIG. 19 may be executed entirely within the playback unit 108 of the moving image data playback apparatus 100. Here, the first frame will be described on the premise that the first frame is reproduced in the highest reproducible layer.

  In S1702, the first frame and the next second frame stored in the buffer 102 are confirmed. In S1704, it is determined whether or not the layer of the second frame is lowered by K layers or more with respect to the first frame. When the layer of the second frame falls by K layers or more with respect to the first frame, the number of layer data stored for the first frame is equal to the number of layer data stored for the second frame. It may indicate that the value is equal to or greater than the value obtained by adding K. K may be an example of the number of lower limit layers. K may be a predetermined number or may be changeable. If it is not determined that the K layer will be lowered, the process proceeds to S1706, and if it is determined that the K layer is lowered, the process proceeds to S1708.

  In S1706, it is determined to play back the first frame in the highest playable layer. In S1708, it is determined to play back the first frame in a layer one lower than the highest playable layer.

  In S1710, it is determined whether or not the processing has been completed up to the last frame of the moving image data. If it is determined that the process has not been completed up to the final frame, the process returns to S1702 to confirm the next frame. If it is determined that the process has been completed up to the last frame, the process ends.

  FIG. 20 schematically shows a specific example of the flow of processing by the moving image data playback apparatus 100. The processing shown in FIG. 20 will be described assuming that the moving image data reproducing apparatus 100 has received a moving image data reproduction instruction as a start state. Each process illustrated in FIG. 20 may be executed entirely within the reproduction unit 108 of the moving image data reproduction apparatus 100. Here, the first frame will be described on the premise that the first frame is reproduced in the highest reproducible layer.

  In the figure, X indicates a frame number. Y represents the maximum value of X. The initial value of X is 0, and Y indicates the number of frames included in the moving image data. B [X] indicates the number of layer data stored in the buffer 102 for the Xth frame. K indicates the number of layers that should not be lowered across.

  In S1802, the first frame and the next second frame stored in the buffer 102 are confirmed. In S1804, it is determined whether B [X] is equal to or greater than (B [X + 1] + K). If it is not determined that B [X] is equal to or greater than (B [X + 1] + K), the process proceeds to S1806. If it is determined, the process proceeds to S1808.

  In S1806, it is determined to play back the Xth frame according to B [X]. In step S1808, it is determined that the Xth frame is to be reproduced in the layer B [X] -1.

  In S1810, it is determined whether X = Y. If it is determined that X = Y is not satisfied, the process proceeds to S1812. If it is determined that X = Y, the process is terminated. In S1812, 1 is added to X, and the process returns to S1802. In S1802, the next frame is further confirmed.

  FIG. 21 schematically shows an example of the flow of processing by the moving image data playback apparatus 100. The process shown in FIG. 21 will be described assuming that the moving image data reproducing apparatus 100 has received a moving image data reproduction instruction as a start state. Each process shown in FIG. 21 may be executed entirely within the playback unit 108 of the moving image data playback apparatus 100. Here, the first frame will be described on the premise that the first frame is reproduced in the highest reproducible layer.

  In S1902, the first frame and the next second frame stored in the buffer 102 are confirmed. In step S1904, it is determined whether the layer of the second frame is higher than the K layer by the first frame. When the layer of the second frame rises by K layers or more with respect to the first frame, the number of layer data stored for the second frame is equal to the number of layer data stored for the first frame. It may indicate that the value is equal to or greater than the value obtained by adding K. K may be an example of the number of rise restriction levels. If it is not determined that the level is higher than the K layer, the process proceeds to S1906. If it is determined that the level is higher than the K layer, the process proceeds to S1908.

  In S1906, it is determined to play back the second frame in the highest playable layer. In S1908, it is determined to play back the second frame in a layer one lower than the highest playable layer.

  In S1910, it is determined whether or not processing has been completed up to the final frame of the moving image data. If it is determined that the process has not been completed up to the final frame, the process returns to S1902 to confirm the next frame. If it is determined that the process has been completed up to the last frame, the process ends.

  FIG. 22 schematically shows a specific example of the flow of processing by the moving image data reproducing apparatus 100. The process shown in FIG. 22 will be described assuming that the moving image data reproducing apparatus 100 has received a moving image data reproduction instruction as a start state. Each process illustrated in FIG. 22 may be executed entirely within the reproduction unit 108 of the moving image data reproduction apparatus 100. Here, the first frame will be described on the premise that the first frame is reproduced in the highest reproducible layer.

  In the figure, X indicates a frame number. Y represents the maximum value of X. The initial value of X is 0, and Y indicates the number of frames included in the moving image data. B [X] indicates the number of layer data stored in the buffer 102 for the Xth frame. K indicates the number of layers that should not rise across.

  In S2002, the first frame and the next second frame stored in the buffer 102 are confirmed. In S2004, it is determined whether B [X + 1] is equal to or greater than (B [X] + K). If it is not determined that B [X + 1] is equal to or greater than (B [X] + K), the process proceeds to S2006. If it is determined, the process proceeds to S2008.

  In S2006, it is determined to reproduce the X + 1th frame according to B [X + 1]. In S2008, it is determined that the X + 1th frame is to be reproduced in the layer of B [X + 1] -1.

  In S2010, it is determined whether X = Y. If it is determined that X = Y is not satisfied, the process proceeds to S2012. If it is determined that X = Y, the process is terminated. In S2012, 1 is added to X, and the process returns to S2002. In S2002, the next frame is confirmed.

  In the hierarchical encoding method, there are cases where a group is formed by a plurality of consecutive frames and encoding is performed using a reference relationship between frames in the same group. A set of a plurality of frames having a reference relationship is referred to as a frame group (note that the frame group described here may be referred to as a GOP (group of picture)). In encoding that constitutes a frame group, higher compression efficiency can be realized compared to encoding that does not constitute a frame group.

  FIG. 23 is an example of moving image data 180 that is hierarchically encoded so as to form a frame group with a plurality of frames. The moving image data 180 is composed of a plurality of frame groups 182 and 184. Each frame group includes a plurality of frames 186 and 188, and each frame includes a plurality of layer data that can be identified by LID and SID.

  When decoding video data that has been hierarchically encoded to form a frame group, it is possible to decode high-quality video by decoding using both layer data of the base layer and the enhancement layer. In addition, it is possible to decode a low-quality moving image by decoding using only the layer data of the base layer. FIG. 24 shows an example in which a high-quality moving image is reproduced using the frame group 182 encoded by the hierarchical encoding method. In frame group 190, decoding is performed using both base layer data 192 and enhancement layer data 193 in the frame group. On the other hand, FIG. 25 is an example in which a low-quality moving image is reproduced using the frame group 182 encoded by the hierarchical encoding method. In the frame group 194, decoding is performed using only the layer data 196 of the base layer.

  FIG. 26 is an example in which decoding is performed using the frame group 200 encoded by the hierarchical encoding method. In the frame group 200, the layer data 202 of the enhancement layer included in the frame of SID2 is missing, and all other layer data is available. In this case, in the frame group 206, decoding is performed using only the layer data 204 of the base layer. This is because there is a reference relationship between the layer data of the enhancement layer in the frame group, and the enhancement layer cannot be decoded due to the lack of the layer data 202 in the frame group 206.

  As described in paragraph 0020, layer data may be lost due to various factors in moving image data that is hierarchically encoded so as to form the frame group shown in FIG. Therefore, when decoding moving image data that has been hierarchically encoded so as to form a frame group, by applying the same processing as in the embodiments described in paragraphs 0024 to 0117, the quality of the viewer's experience can be improved. Is possible. Examples thereof will be described below.

  FIG. 27 schematically shows an example of the moving image data 150 stored in the buffer 102. Here, moving image data 150 that is encoded so as to include two layers and has a plurality of frame groups each including four frames is shown. In the example shown in FIG. 27, the layer data of the enhancement layer in the 6th and 8th frames belonging to the second frame group and the 14th frame belonging to the fourth frame group is the missing layer data 154. An example is given.

  Here, for each of the plurality of frame groups of the video data 150, when the layer data of the base layer and the layer data of the enhancement layer are stored for all the frames included in the frame group, all the base layers of the frame group are stored. When the frame data is decoded using the layer data and the layer data of the enhancement layer, and only the base layer data is stored for at least one frame among all the frames included in the frame group, all of the frame groups When a frame group is decoded using only the layer data of the base layer, the high image quality and the low image quality are switched for each frame group, and the quality of the video experienced by the viewer viewing the video becomes low. May end up .

  On the other hand, the moving image data reproducing device 100 according to the present embodiment executes a process for improving the quality of the moving image experienced by the viewer. The playback unit 108 included in the moving image data playback apparatus 100 is, for example, for the second frame group next to the first frame group in which both the layer data of the base layer and the layer data of the enhancement layer are stored for all frames. When only layer data of the base layer is stored for at least one frame among all the frames, all the frame groups of the first number of first layer maintaining frame groups after the second frame group are all Even when both base layer data and enhancement layer layer data are stored for a frame, the second frame group is decoded using only the base layer data of all base layers of the second frame group. Turn into. Thereby, frequent switching between high image quality and low image quality can be suppressed, and the quality of moving images experienced by the viewer can be improved. The number of first layer maintenance frame groups may be an example of the first number.

  Also, the playback unit 108, for example, for the third frame group following the number of first hierarchically maintained frame groups after the second frame group, for the base layer layer data and the enhancement layer for all frames. Layer data is stored, and for all the frame groups of the first number of first guaranteed layer groups after the third frame group, the basic layer layer data and the enhancement layer layer for all frames When data is stored, the third frame group is decoded using the layer data of all the basic layers and the layer data of the enhancement layer of the third frame group, and the first hierarchical guaranteed frame after the third frame group Small number of frame groups In the case where only the base layer layer data is stored for at least one of all the frames, only the base layer data of all the base layer of the third frame group is used for the third frame group. Decrypt. As described above, the playback unit 108 uses the basic layer for all frames in the next frame group after the frame group in which only the layer data of the basic layer is stored for at least one of the frames included in the frame group. Layer data and enhancement layer layer data are stored, and the base layer layer data and extension for all the frames of the first hierarchy guaranteed frame group number after the one frame group are stored. When layer data of a layer is stored, the one frame group is decoded using the layer data of all the basic layers and the enhancement layer of the one frame group, and after the one frame group First If only layer data of the base layer is stored for at least one of all frames for at least one frame group of the number of layer guaranteed frame groups, only layer data of all base layers of the one frame group May be used to decode the one frame group. Thereby, frequent switching between high image quality and low image quality can be further suppressed, and the quality of moving images experienced by the viewer can be improved.

  FIG. 28 schematically shows an example of the moving image data 150 stored in the buffer 102. Here, the moving image data 150 is encoded to include four layers and each has a plurality of frame groups each including four frames. In the example shown in FIG. 28, the layer data of the enhancement layer in the sixth and eighth frames belonging to the second frame group and the fifteenth frame belonging to the fourth frame group is the missing layer data 154. An example is given.

  Here, for each of the plurality of frame groups of the moving image data 150, for all the frames, the number of layer data of the group having the smallest number of layer data stored in all the frames is the minimum number of layer data. When the frame group is decoded using the layer data, the highest image quality is used for the first and third frame groups, and only the base layer data and the enhancement layer 1 layer data are used for the second and fourth frame groups. The image quality is changed, and the high image quality and the low image quality are switched for each frame group, and the quality of the moving image experienced by the viewer viewing the moving image may be low.

  On the other hand, the moving image data reproducing device 100 according to the present embodiment executes a process for improving the quality of the moving image experienced by the viewer. The playback unit 108 included in the moving image data playback apparatus 100, for example, with respect to one frame group having a group minimum layer data number smaller than that of the previous frame group, a predetermined second after the one frame group. For a frame group with the number of hierarchically maintained frame groups, even if the number of group minimum layer data is larger than the number of group minimum layer data of the one frame group, the group minimum layer data of the one frame group of all frames The same number of layer data is used to decode the frame groups of the number of second layer maintenance frame groups after the one frame group, thereby suppressing frequent switching between high image quality and low image quality. And improve the quality of videos that viewers can experience It can be.

  In addition, the playback unit 108 has a group minimum layer data number greater than that of the one frame group for the frame group next to the second hierarchy maintaining frame group number after the one frame group, and When the number of group minimum layer data is equal to or greater than the number of group minimum layer data of the next frame group for all of the frame groups of the predetermined second layer guaranteed frame group number after the next frame group, Using the same number of layer data as the group minimum layer data number of the next frame group of all the frames, the next frame group is decoded, and the number of second hierarchical guaranteed frame groups after the next frame group For at least one of the frame groups, If the minimum group data number is less than the group minimum layer data number of the next frame group, the same number of layer data as the group minimum layer data number of the one frame group of all frames for the next frame group Is used to decode the next frame group. Thereby, frequent switching between high image quality and low image quality can be further suppressed, and the quality of moving images experienced by the viewer can be improved.

  In addition, when the moving image data is encoded so as to include a plurality of hierarchies of three or more hierarchies, the playback unit 108 performs the following operation on one frame group in which the number of group minimum layer data is larger than the previous frame group. When the number of group minimum layer data is greater than the number of group minimum layer data of the previous frame group of the one frame group for all the frame groups of the second hierarchy guaranteed frame group number after the one frame group, Using the same number of layer data as the smallest group minimum layer data number of all the frame groups of the one frame group and the second layer guaranteed frame group number after the one frame group, the one frame Decode the group, and the second after the one frame group For at least one frame group of the number of layer guaranteed frame groups, when the number of group minimum layer data is less than the number of group minimum layer data of the previous frame group of the one frame group, The one frame group is decoded using the same number of layer data as the number of group minimum layer data of the previous frame group of one frame group.

  In addition, when the moving image data is encoded so as to include a plurality of hierarchies of three or more hierarchies, the playback unit 108 has a reduction restriction in which the number of group minimum layer data is predetermined as compared to the next frame group. For one frame group that is greater than or equal to the number of hierarchies, the one frame group may be decoded using only a smaller number of layer data than the group minimum layer data number of the one frame group for all frames. The number of lower limit layers may be a predetermined number or may be changeable.

  In addition, when the moving image data is encoded so as to include a plurality of hierarchies of three or more hierarchies, the playback unit 108 has an increase restriction in which the number of group minimum layer data is predetermined as compared to the previous frame group. For one frame group that is greater than or equal to the number of hierarchies, the one frame group may be decoded using only a smaller number of layer data than the group minimum layer data number of the one frame group for all frames. The number of rise limit layers may be a predetermined number or may be changeable.

  FIG. 29 schematically shows an example of a moving image data reproducing apparatus 100 that can receive moving image data from the outside. The moving image data reproducing apparatus 100 may receive moving image data encoded so as to include a plurality of layers distributed by the moving image server 310, and decode and reproduce the received moving image data. The moving image data reproducing device 100 may receive moving image data from the moving image server 310 via the network 300. The network 300 may include at least one of the Internet, a wired LAN (Local Area Network), a wireless LAN, a wired telephone network, and a wireless telephone network.

  The video server 310 may stream video data. The moving image data reproducing apparatus 100 may receive moving image data streaming from the moving image server 310, decode the image data while storing it in the buffer 102, and reproduce the moving image data. Further, the moving image data reproducing apparatus 100 accepts streaming of moving image data from the moving image server 310 and stores it in the buffer 102. After the entire moving image data is stored in the buffer 102, the moving image data is decoded and reproduced. Good.

  Further, the moving image server 310 may distribute moving image data in units of moving image files, for example, instead of streaming distribution. The moving image data reproducing apparatus 100 may store the moving image data received in units of moving image files in the buffer 102 and then decode and reproduce the moving image data.

  The moving image data reproducing device 100 may include a packet receiving unit 112. The packet receiving unit 112 may receive a packet that has been packetized and transmitted for each layer data by the moving image server 310. The packet may include an SID. The packet receiving unit 112 may store the layer data included in the packet in the buffer 102.

  In addition, the moving image data reproduction device 100 may receive moving image data captured by the camera 130 from the camera 130. The camera 130 may be a still camera, a video camera, a surveillance camera, or the like that can capture a moving image. The camera 130 may transmit the moving image data encoded so as to include a plurality of hierarchies to the moving image data reproduction device 100.

  The moving image data reproducing device 100 may include a video signal receiving unit 114. The video signal receiving unit 114 receives moving image data from the camera 130. The video signal receiving unit 114 may receive moving image data that the camera 130 sequentially transmits while taking an image. Further, the video signal receiving unit 114 may receive moving image data transmitted by the camera 130 after completion of imaging. The moving image data playback device 100 may receive moving image data from the camera 130 via the network 300. Note that the moving image data reproduction device 100 may include both the packet receiving unit 112 and the video signal receiving unit 114, or may include only one of them.

  In the above embodiment, it has been described that the number of first layer maintenance frames may be changeable. However, the moving image data playback device 100 changes the number of first layer maintenance frames according to the moving image data to be played back. Good. For example, the moving image data reproduction device 100 determines the first tier maintenance frame number based on at least one of the intensity of motion of the moving image data content and the length of the moving image data. As a specific example, the moving image data reproduction device 100 increases the number of first layer maintenance frames as the movement becomes more intense. Thereby, the frequency with which the image quality is switched can be reduced as the moving image data moves more rapidly. As a specific example, the moving image data reproducing device 100 increases the number of first layer maintenance frames as the moving image data becomes longer.

  In addition, when the moving image data reproducing apparatus 100 receives and reproduces moving image data from the moving image server 310, the moving image data reproducing device 100 may change the first tier maintenance frame number according to the communication environment. For example, the moving image data reproduction device 100 increases the number of first layer maintenance frames as the communication quality is higher. The higher the communication quality, the fewer frames are lost in the video data. Therefore, the higher the communication quality, the larger the number of first layer maintenance frames. The number of times of reproduction as a frame can be reduced. The moving picture data reproducing apparatus 100 includes a first layer guaranteed frame number, a second layer maintained frame number, a second layer guaranteed frame number, a first layer maintained frame group number, a first layer guaranteed frame group number, As for the number of hierarchy maintaining frame groups of 2, the number of second hierarchy guaranteed frame groups, the number of lower limit hierarchies, and the number of increase limit hierarchies, moving picture data and moving picture data are also recorded in the same manner as the first hierarchy maintaining frame number. You may change according to at least one of the communication environments to communicate. Note that the number of first layer maintenance frames, the number of second layer maintenance frames, the number of first layer maintenance frame groups, and the number of second layer maintenance frame groups may be different values or the same value. There may be. Also, the number of first layer guaranteed frames, the number of second layer guaranteed frames, the number of first layer guaranteed frame groups, and the number of second layer guaranteed frame groups may be different values. There may be.

  In the above description, each unit of the moving image data reproduction device 100 may be realized by hardware or may be realized by software. Further, it may be realized by a combination of hardware and software. Further, the computer may function as the moving image data reproducing apparatus 100 by executing the program. The program may be installed from a computer-readable medium or a storage device connected to a network to a computer that constitutes at least a part of the moving image data playback device 100.

  A program that is installed in a computer and causes the computer to function as the moving image data reproducing apparatus 100 according to the present embodiment works on a CPU or the like to cause the computer to function as each unit of the moving image data reproducing apparatus 100. Information processing described in these programs functions as a specific means in which software and hardware resources of the moving image data reproducing apparatus 100 cooperate with each other by being read by a computer.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The order of execution of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that it can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first,” “next,” etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

100 video data playback device, 102 buffer, 108 playback unit, 110 video data display unit, 112 packet reception unit, 114 video signal reception unit, 130 camera, 150 video data, 151 frames, 152 layer data, 154 missing layer data, 156 Discarded layer data, 158 Discarded layer data, 159 Discarded layer data, 160 video data, 161 frames, 162 layer data, 163 layer data, 170 video data, 171 frames, 172 layer data, 173 layer data, 180 video data, 182 Frame group, 184 frame group, 186 frame, 188 frame, 190 frame group, 192 layer data, 193 layer data, 194 frame group 196 layer data, 200 frame groups, 202 layer data, 204 layer data, 206 frame groups, 300 network, 310 video server

Claims (21)

A moving image data reproducing device for decoding moving image data encoded to include a plurality of layers,
A buffer for temporarily storing the video data;
A playback unit for decoding the video data,
The playback unit
Check the layer data included in each of the plurality of frames of the video data included in the buffer,
Both the layer data of layer ID = 1 and the layer data of layer ID = 2 are stored in the first frame, and only the layer data of layer ID = 1 is stored in the second frame next to the first frame. When stored, both the layer data of the layer ID = 1 and the layer data of the layer ID = 2 are stored for the frames of the first number of first hierarchy maintaining frames after the second frame. Even if it is a case where only the layer data of said layer ID = 1 are used, the frame of the said 1st hierarchy maintenance frame number after the said 2nd frame is decoded,
Both the layer data of the layer ID = 1 and the layer data of the layer ID = 2 are stored in the first frame, and the layer data of the layer ID = 1 and the layer ID = 2 layer data is stored, the second frame is decoded using both the layer data of the layer ID = 1 and the layer data of the layer ID = 2 of the second frame,
When only the layer data of the layer ID = 1 is stored in the first frame, the second frame is decoded so as to play back the highest layer video that can be played back using the stored layer data. A moving image data reproducing device.   The moving image data reproduction device according to claim 1, further comprising a moving image data display unit that displays a moving image obtained by decoding the moving image data.   The moving image data reproduction device according to claim 1, wherein the first hierarchy maintaining frame number is changed according to the moving image data.   The playback unit stores the layer data of the layer ID = 1 and the layer data of the layer ID = 2 for the third frame in which more layer data is stored than the previous frame, and When both the layer data of the layer ID = 1 and the layer data of the layer ID = 2 are stored for all of the frames having the predetermined number of first hierarchical guaranteed frames after the third frame, The third frame is decoded using both the layer data of the layer ID = 1 and the layer data of the layer ID = 2 of the third frame, and the frames having the number of first hierarchical guaranteed frames after the third frame When only layer data of the layer ID = 1 is stored for at least one of the above, the third frame Decoding the third frame using only layer data of ear ID = 1, the moving picture data reproducing apparatus according to any one of claims 1 to 3.   The moving image data reproducing device according to claim 4, wherein the first hierarchical guaranteed frame number is changed according to the moving image data.   In the case where the moving image data is encoded so as to include a plurality of hierarchies of three or more layers, the reproducing unit includes at least one of all stored layer data for each of the plurality of frames of the moving image data. 6. The moving image data reproduction device according to claim 1, wherein the frame is decoded using one layer data.   In the case where the moving image data is encoded so as to include a plurality of hierarchies of three or more hierarchies, the playback unit performs the first frame on the fourth frame with less layer data stored than the previous frame. Layers stored for the fourth frame, even if more layer data than the fourth frame is stored for a predetermined number of second layer maintenance frames after the fourth frame 7. The moving image data reproducing apparatus according to claim 6, wherein the second frame maintaining frame number after the fourth frame is decoded using layer data equal to or less than the number of data. In the case where the moving image data is encoded so as to include a plurality of hierarchies of three or more hierarchies, the reproducing unit performs the above processing on the fifth frame having more layer data stored than the previous frame. When more layer data than the layer data stored in the frame immediately before the fifth frame is stored for all the frames of the predetermined second layer guaranteed frame number after the fifth frame, By using the same number of layer data as the smallest number of layer data among the number of layer data of the fifth frame and the predetermined number of second layer guaranteed frames after the fifth frame, the fifth frame is used. Decrypt the frame,
When at least one of the frames of the second hierarchy guaranteed frame number after the fifth frame is stored with less layer data than the frame immediately before the fifth frame, the fifth frame, The moving image data reproduction device according to claim 6 or 7, wherein the fifth frame is decoded by using the same number of layer data as the number of layer data stored for the frame immediately before the fifth frame.   In the case where the moving image data is encoded so as to include a plurality of hierarchies of three or more hierarchies, the playback unit has a predetermined lower limit on the number of layer data stored after the next frame. The moving image data reproduction according to any one of claims 6 to 8, wherein the sixth frame is decoded using only a part of the plurality of stored layer data for the sixth frame that is greater than the number of layers. apparatus.   In the case where the moving image data is encoded so as to include a plurality of hierarchies of three or more hierarchies, the playback unit has a predetermined increase limit on the number of layer data stored before the previous frame. The moving image data reproduction according to any one of claims 6 to 9, wherein the seventh frame is decoded by using only a part of the plurality of stored layer data for the seventh frame having a number greater than or equal to the number of layers. apparatus. A video data reproducing device that decodes video data that is encoded to include a plurality of layers and each has a plurality of frame groups each including a plurality of frames,
A buffer for temporarily storing the video data;
A playback unit for decoding the video data,
The playback unit
Check the layer data included in each of the plurality of frame groups of the video data included in the buffer,
And both all records about the frame unpleasant ID = 1 of the layer data and Layer ID = 2 of the layer data of the first frame group is stored, and, first of the next of said first frame group When only the layer data of the layer ID = 1 is stored for at least one of all the frames for the two frame groups, the first hierarchy maintaining frame determined in advance after the second frame group Even if both the layer data of the layer ID = 1 and the layer data of the layer ID = 2 are stored for all the frames of the number of groups, all the frames of the second frame group Decoding the second frame group using only the layer data of the layer ID = 1 And,
Both the layer data of the layer ID = 1 and the layer data of the layer ID = 2 are stored for all the frames of the first frame group, and the frame data of all the frames of the second frame group When both the layer data of layer ID = 1 and the layer data of layer ID = 2 are stored, all the layer data of layer ID = 1 and the layer of layer ID = 2 of the second frame group Decoding the second frame group using data;
For the first frame group, when only the layer data of the layer ID = 1 is stored for at least one frame among all the frames, the stored layer data is used for the second frame group Decoding to play the highest layer video that can be played,
Movie data playback device.   The moving image data reproducing device according to claim 11, further comprising a moving image data display unit that displays a moving image obtained by decoding the moving image data. The playback unit includes the layer ID for all frames in a third frame group next to a frame group in which only layer data of layer ID = 1 is stored for at least one frame included in the frame group. = 1 of the layer data and layer ID = 2 are layer data storage, and, for all the third first hierarchy guaranteed frame group number of frames groups of predetermined subsequent frame group of When the layer data of the layer ID = 1 and the layer data of the layer ID = 2 are stored for all the frames, all the layer data of the layer ID = 1 and the layer ID of the third frame group = 2 using the layer data of = 2 Only the layer data of the layer ID = 1 for at least one of all the frames for at least one of the first hierarchical guaranteed frame group number after the third frame group. The video data reproducing device according to claim 12, wherein the third frame group is decoded using only layer data of all the layer IDs = 1 of the third frame group.   In the case where the moving image data is encoded so as to include a plurality of hierarchies of three or more layers, the reproducing unit is configured to perform the operation for all the frames for each of the plurality of frame groups of the moving image data. 14. The moving image according to claim 12, wherein the frame group is decoded using layer data equal to or less than a group minimum layer data number, which is the number of layer data of a frame having the smallest number of layer data stored therein. Data playback device.   When the moving image data is encoded so as to include a plurality of hierarchies of three or more hierarchies, the reproducing unit performs the fourth frame group having a smaller group minimum layer data number than the previous frame group. This is a case where the number of group minimum layer data is greater than the number of group minimum layer data of the fourth frame group for the frame groups having the predetermined number of second layer maintenance frame groups after the fourth frame group. However, using the same number of layer data as the number of group minimum layer data of the fourth frame group, the frame groups of the second layer-maintaining frame group number after the fourth frame group are decoded. The moving image data reproducing device according to claim 14. In the case where the moving image data is encoded so as to include a plurality of hierarchies of three or more hierarchies, the playback unit, for a fifth frame group having a larger group minimum layer data number than the previous frame group, For all of the frame groups of the predetermined second layer guaranteed frame group number after the fifth frame group, the group minimum layer data number is the group minimum layer of the frame group immediately before the fifth frame group. When the number of data is greater than the number of data, it is the same as the number of group minimum layer data that is the smallest among all the frame groups of the fifth frame group and the predetermined number of second-layer guaranteed frame groups after the fifth frame group. Decode the fifth frame group using a number of layer data
For at least one of the second hierarchically guaranteed frame group number after the fifth frame group, the group minimum layer data of the frame group immediately before the fifth frame group is the group minimum layer data number. When the number is less than the number, the fifth frame group is decoded using the same number of layer data as the group minimum layer data number of the frame group immediately before the fifth frame group. The moving image data reproducing device according to claim 14 or 15,   In the case where the moving image data is encoded so as to include a plurality of hierarchies of three or more hierarchies, the playback unit has a lower limit hierarchies in which the number of group minimum layer data is determined in advance than the next frame group For the sixth frame group that is greater than or equal to the number, the sixth frame group is decoded using only the number of layer data that is less than the group minimum layer data number of the sixth frame group for all frames. The moving image data reproducing device according to any one of claims 14 to 16.   In the case where the moving image data is encoded so as to include a plurality of hierarchies of three or more hierarchies, the playback unit has an ascending restriction hierarchy in which the number of group minimum layer data is determined in advance than the previous frame group. For the seventh frame group that is greater than or equal to the number, the seventh frame group is decoded using only a smaller number of layer data than the group minimum layer data number of the seventh frame group for all frames. The moving image data reproducing device according to any one of claims 14 to 17. A moving image data reproducing device for decoding moving image data encoded to include a plurality of layers,
A buffer for temporarily storing the video data;
A playback unit for decoding the video data,
The playback unit
Check the layer data included in each of the plurality of frames of the video data included in the buffer,
Both the first layer data of the first hierarchy and the second layer data of the second hierarchy are stored in the first frame, and the first layer for the second frame next to the first frame The case where only the data is stored is the case where both the first layer data and the second layer data are stored for the first predetermined number of frames after the second frame. However, only the first layer data is used to decode the first number of frames after the second frame,
Both the first layer data and the second layer data are stored in the first frame, and both the first layer data and the second layer data are stored in the second frame. If so, the second frame is decoded using both the first layer data and the second layer data of the second frame,
When only the first layer data is stored in the first frame, the second frame is decoded so as to play back the highest layer video that can be played back using the stored layer data. ,
Movie data playback device. A video data reproducing device that decodes video data that is encoded to include a plurality of layers and each has a plurality of frame groups each including a plurality of frames,
A buffer for temporarily storing the video data;
A playback unit for decoding the video data,
The playback unit
Check the layer data included in each of the plurality of frame groups of the video data included in the buffer,
Both the first layer data of the first layer and the second layer data of the second layer are stored for all the frames of the first frame group, and the second second after the first frame group is stored. When only the first layer data is stored for at least one frame among all the frames, a predetermined first number of frame groups after the second frame group, Even if both the first layer data and the second layer data are stored for all the frames, the first layer data is used only for all the first layer data of the second frame group. Decoding the second frame group;
Both the first layer data and the second layer data are stored for all the frames of the first frame group, and the first layer for all the frames of the second frame group When both data and the second layer data are stored, the second frame group is decoded using all the first layer data and the second layer data of the second frame group And
For the first frame group, when only the first layer data is stored for at least one of all the frames, the second frame group is reproduced using the stored layer data. Decode to play the highest possible layer video,
Movie data playback device.   A program for causing a computer to function as the moving image data reproducing device according to any one of claims 1 to 20.