JP4148673B2 - Video distribution system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention comprises a camera device that delivers captured video information to a network and a receiver that displays video information obtained from the network.For video distribution systemRelated.
[0002]
[Prior art]
Conventionally, a system that receives video information obtained from a plurality of cameras via a network and displays it on a display screen of a receiver, such as a surveillance camera system, is known. As video information compression technology advances and network infrastructure speeds up, it is also possible to build a video distribution system in which the camera unit of such a system is a broadcasting station and the screen display unit is a home terminal. .
[0003]
FIG. 15 is a block diagram showing a conventional example of such a video distribution system, where 10 is a camera terminal, 11 is a camera, 12 is an encoder, 20 is a receiving terminal, 21 is a decoder, 22 is a display, and 23 is a system controller. , 24 is a changeover switch, 25 is a recording medium (recording / reproducing apparatus), and 30 is a network.
[0004]
In the figure, in this conventional video distribution system, a camera terminal 10 and a receiving terminal 20 are connected via a network 30. The camera terminal 10 includes a camera 11 and an encoder 12, and the reception terminal 20 includes a decoder 21, a display 22, a system controller 23, a changeover switch 24, and a recording medium 25.
[0005]
Next, the operation of this conventional example will be described.
[0006]
In the camera terminal 10, the camera 11 takes a picture and generates a video signal. This video signal is subjected to information compression processing by the encoder 12 to generate a bit stream, and this bit stream is supplied to the receiving terminal 20 via the network 30. As described above, the camera terminal 10 is a minimum unit for distributing a bit stream, and one or more camera terminals 10 are connected to the network 30 and a bit stream is distributed from each of them.
[0007]
In the receiving terminal 20, each part is controlled by the system controller 23. Under this control, a bit stream from a predetermined camera terminal 10 transmitted via the network 30 is selected and decoded by the decoder 21 into a video signal. The decoded video signal is recorded and stored in the recording medium 25 and is supplied to the display 22 by the system controller 23 via the changeover switch 24 closed to the a contact side, where video display is performed.
[0008]
When the viewer of the receiving terminal 20 wants to view the distributed video again, the system controller 23 switches the changeover switch 24 to the b-contact side and the recording medium by the viewer performing a predetermined operation for that purpose. The video signal is read by operating 25 and supplied to the display 22 via the changeover switch 24. As a result, past video signals stored in the recording medium 25 can be reproduced on the display 22.
[0009]
[Problems to be solved by the invention]
In the above-described conventional example, the viewer needs rewind playback because the video displayed on the display 22 is alerted, and he wants to see the video of the part that has been alerted in detail. Because it is. For this purpose, it is necessary to distribute a detailed video from the camera terminal 10. However, for this purpose, it is necessary to decrease the compression rate and increase the bit amount on the encoder 12 side.
[0010]
By the way, in a video distribution system using a surveillance camera system as a representative example, it is necessary to constantly distribute video, and a large number of camera terminals 10 are connected to the network 30 and video signals from them are connected. The bitstream is always transmitted. For this reason, when the bit amount of the bit stream output from each camera terminal 10 is increased, the bit amount transmitted through the network 30 is increased according to the number of camera terminals 10 connected thereto.
[0011]
On the other hand, the network 30 also has a transmittable capacity, and the amount of bits that can be transmitted is limited. For this reason, if a detailed (high-quality) video bitstream compressed at a low compression rate is constantly transmitted from each camera terminal 10 via the network 30, the camera terminal 10 connected to the network 30 is naturally connected. The number of units is limited, and if a large number of camera terminals 10 are to be connected to the same network 30, the video signal compression rate of each camera terminal 10 must be increased, and a portion for monitoring cautions. You can't watch it again with high-quality video.
[0012]
  The present invention has been made in view of such a problem, and an object of the present invention is to obtain a high-quality image of the same portion to be viewed again without constantly increasing the transmission bit amount in the network. MadeVideo distribution systemIt is to provide.
[0013]
[Means for Solving the Problems]
  In order to achieve the above object, the present invention provides a video distribution system in which a camera terminal and a receiving terminal are connected via a network, and a bit stream generated from a captured video by the camera terminal is distributed to the receiving terminal. The terminal encodes the captured video signal, and uses the first bit stream and the first bit stream.Encoded at a high frame rate and used for slow playbackAnd a second bit stream that forms a high-quality video, and normally distributes the first bit stream to the receiving terminal.Generated by viewer's slow playback operationIn response to the retransmission request, the second bit stream from the video a predetermined time before the time when the retransmission request is made is distributed.
[0015]
  Furthermore, the present invention providesThe camera terminal is configured to include a processor that performs time-division encoding processing of the first bit stream and the second bit stream.
[0016]
  Furthermore, the present invention providesA plurality of camera terminals are connected to the network, and a viewer can view videos from the plurality of camera terminals by a receiving terminal.
[0017]
  Furthermore, according to the present invention, the first and second bit streams are encoded by a method compliant with MPEG.
[0018]
  further,The present inventionThe second bit stream is subjected to lossless data compression.
[0019]
  Furthermore, the present invention providesThe camera terminal includes an image / speech recognition circuit that extracts a specific image or sound from the camera output of the camera terminal and a recording unit, and a specific image or sound set in advance in the image / speech recognition circuit by a viewer. When it appears, the recording means writes the specific image or sound on the recording medium.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, embodiments of the present invention will be described with reference to the drawings.
  FIG. 1 is according to the invention.Video distribution system1 is a block diagram illustrating a first embodiment, where 10 is a camera terminal, 11 is a camera, 12a and 12b are encoders, and 13 is a recording medium (or a recording / reproducing apparatus; 14 is a changeover switch, 20 is a receiving terminal, 21 is a decoder, 22 is a display, 23 is a system controller, and 30 is a network.
[0025]
In the figure, a camera terminal 10 and a receiving terminal 20 are connected via a network 30 to constitute a video distribution system. Here, one camera terminal 10 and one reception terminal 20 are shown, but two or more camera terminals 10 and two reception terminals 20 may be connected to the network 30. The camera terminal 10 includes a camera 11, encoders 12 a and 12 b, a changeover switch 14, and a recording medium 13, and the reception terminal 20 includes a decoder 21, a system controller 23, and a display 22.
[0026]
Next, the operation of the first embodiment will be described.
[0027]
In the camera terminal 10, the camera 11 shoots and generates a video signal A. This video signal A is subjected to information compression (encoding) processing based on a high compression rate, for example, a method conforming to the international standard MPEG (Moving Picture Expert Group), and the like, and the video signal A has a low bit rate and therefore low image quality. Bitstream (hereinafter referred to as low quality bitstream) B_LIs generated. The video signal A generated by the camera 11 is subjected to information compression processing by an encoder 12b based on a low compression rate, for example, a method compliant with MPEG, and the like. B)_HIs generated. The changeover switch 14 is controlled to be switched by the system controller 23 of the receiving terminal 20, but is normally closed to the a contact side. Therefore, the low-quality bit stream B output from the normal encoder 12a_L Are transmitted over the network 30 via the changeover switch 14.
[0028]
Also, the high-quality bit stream B output from the encoder 12b_HIs always supplied to the recording medium 13 and recorded. The recording medium 13 is, for example, a semiconductor memory, and can be reproduced simultaneously with recording. That is, this high-quality bit stream B supplied from the encoder 12b_HAre sequentially recorded, and a portion recorded a predetermined time T before the recording time is reproduced. Therefore, the high-quality bit stream B is output from the recording medium 13._HIs reproduced with a delay of a predetermined time T. Playback high-quality bitstream B from the recording medium 13_H'Is supplied to the contact b of the changeover switch 14, but the normal changeover switch 14 is closed to the contact a side._H'Is not supplied to the network 30.
[0029]
In the case where the recording medium 13 is a semiconductor memory, recording is performed from the head address. However, when recording for a predetermined time T is performed, recording for the recording capacity is performed, and the head address is recorded. Recording will be performed again, and the already recorded content will be rewritten. Further, reproduction is performed with a delay of a predetermined time T from this recording. In this way, recording and reproduction are performed at the same time, whereby a high-quality bit stream that is always recorded and delayed by a predetermined time T is reproduced. In this case, the recording medium 13 may be a memory having a capacity capable of recording a high-quality bit stream for a time slightly longer than the predetermined time T. The predetermined time T can be arbitrarily set as appropriate. However, when this embodiment is applied to a surveillance camera system, a high-quality image is obtained from a scene that goes back to some extent before a scene that calls attention. It needs to be time that can be seen. The same applies to other embodiments described later.
[0030]
Bitstream B_L, B_HIs encoded in a format compliant with MPEG, a high-quality bitstream B for a retransmission request_HThe distribution of 'is encoded from within the frame and started from the frame or immediately before.
[0031]
In this way, the video signal A output from the camera 11 is a low-quality bit stream B._L Is distributed from the network 30 to the receiving terminal 20.
[0032]
In the receiving terminal 20, a bit stream distributed via the network 30 is received, decoded into an original video signal by the decoder 21, and supplied to the display 22. As a result, the distributed video is displayed on the display 22.
[0033]
In such a display state, a scene that alerts the viewer is displayed, and when the viewer wants to view this scene again, the viewer performs a predetermined operation (hereinafter referred to as retransmission) with the remote control or operation unit on the receiving terminal 20 side. The system controller 23 generates a switching control signal C and transmits it to the camera terminal 10 via the network 30. In the camera terminal 10 that has received this, the changeover switch 14 is controlled by this changeover control signal C, and the contact is switched from the a contact to the b contact. Thereby, the reproduction high-quality bit stream B of the recording medium 13_H'Is distributed (retransmitted) to the receiving terminal 20 via the changeover switch 14 and the network 30. As a result, this playback high-quality bitstream B_H'Is decoded into a high-quality video signal by the decoder 21 and supplied to the display 22 to display a high-quality video.
[0034]
Here, the reproduction high-quality bit stream B of the recording medium 13_H'Is a low-quality bitstream B output from the encoder 12a and distributed._LSince the bit stream is delayed by the predetermined time T, the display 22 at the receiving terminal 20 starts to display a high-quality video from the time point that is a predetermined time T ahead of the current time. That is, the same effect as the rewind reproduction from the recording / reproducing apparatus can be obtained with the high-quality video, so that the above-mentioned scene that has attracted the viewer's attention can be seen again with the high quality. . At this time, since the changeover switch 14 is switched to the b-contact side, the low-quality bit stream B from the encoder 12a._LAre not transmitted over the network 30.
[0035]
(1) Bitstream B_HWhen 'is delivered to the receiving terminal 20 for a certain set time T' that is equal to or greater than the predetermined time T, the changeover switch 14 automatically switches to the a contact side, and the low-quality bitstream B_LOr (2) a low-quality bitstream B on the receiving terminal 20 side._LUnless a switch control signal is transmitted from the system controller 23, the high-quality bitstream B is used as it is._H'May continue to deliver.
[0036]
Low quality bitstream B_LWhen a scene (scene) that calls attention is displayed, the viewer usually wants to see this scene again after viewing the scene. In such a case, the camera terminal is requested to retransmit after viewing this scene. In response to such a retransmission request, in both cases (1) and (2), the retransmitted high-quality bitstream B_HThe display of high-quality video by 'must start at least from the beginning of the above-mentioned scene as seen at least, and the predetermined time T must be set to a time that goes back to the beginning of this scene. Don't be. For example, if the time for which the viewer recognizes such a scene as a whole is about 2 to 3 minutes, the predetermined time T may be set longer than the time required.
[0037]
Also, the high-quality bit stream B in the case of (1) above_HThe high-quality video display period (the set time T ') can be appropriately set to an arbitrary time required by the normal viewer. In the case of (2) above, the viewer can continue to watch high-quality video until they are satisfied.
[0038]
The same applies to the embodiments described later.
[0039]
FIG. 2 is a timing chart showing the above operation. FIG. 2A shows a low-quality bit stream B in the camera terminal 10._LAnd high-quality bitstream B_LFIG. 4B shows the low-quality bit stream B at the receiving terminal 20._LDisplay timing of low-quality video and high-quality bitstream B_HShows the display timing of high-quality video by.
[0040]
  In the figure, the time at which the receiving terminal 20 is operated to receive distribution from the camera terminal 10 is t.₁Then, in the receiving terminal 20, the low-quality stream B_LIs received and decoded into a video signal by the decoder 21, and the time t₂The low-quality video starts to be displayed on the display 22. After that, there is a scene in which the viewer is alerted at time t ′ in this video, and the viewer has time t_ThreeWhen an operation for reproducing high-quality video is performed, a switching control signal is sent from the system controller 23 to the camera terminal 10 via the network 30. In the camera terminal 10, the changeover switch 14 is switched to the b contact side, and the recording medium 13 to time t₁High-quality bitstream B recorded from_HIs reproduced and distributed to the receiving terminal 20 via the changeover switch 14 and the network 30. In the receiving terminal 20, thishigh resolutionBitstream B_HIs decoded by the decoder 21 into a high-quality video signal, and the time t_FourTo display 22 at time t₁A high-quality video signal is supplied from and the video is reproduced.
[0041]
Note that the time t from the encoder 12b₁The portion that is output to and recorded on the recording medium 13 is reproduced from the recording medium 13 later than the predetermined time T. Therefore, the high-quality bit stream B shown in FIG._HIs a high-quality bit stream B output from the encoder 12b._H And the time t₁This portion is delivered to the receiving terminal 20 after a predetermined time T.
[0042]
In addition, low-quality bitstream B_LTime t₁The time t until the part starts to be displayed on the display 22₁₂(= T₂-T₁) Is a high-quality bitstream B_HTime t₁Is the start of distribution (time t_Three) Display on display 22 (time t)_Four) Time t₃₄(= T_Four-T_Three) Is longer than the low quality bitstream B_L This is because it takes more time to decode the original video signal because the information is more compressed.
[0043]
As described above, according to the first embodiment, the camera terminal 10 delivers a high-quality video only when the viewer is alerted to the delivered video and wants to review it again. Normally, a low-quality bitstream B with a bit rate of the minimum required image quality_LThe high-quality bitstream B is transmitted only when requested by the system controller 23._HIt is possible to reduce the amount of bits transmitted by the network 30 on a regular basis. In addition, high-quality bitstream B_HIs retransmitted, it is possible to obtain a detailed (that is, high-quality) video signal as compared to the conventional technique shown in FIG.
[0044]
In the first embodiment, for simplicity of explanation, one camera terminal is connected to the network 30. However, the number of camera terminals is increased within a range in which the network 30 can transmit a bit stream, and a plurality of receiving terminals are used. You may be able to view the screen. For example, for the purpose of monitoring with a large number of cameras, the bit rate transmitted by the network 30 is suppressed by connecting a large number of camera terminals and reducing the image quality output by each camera terminal during normal times. However, in the event of an anomaly that alerts the viewer, the low-quality bitstreams of other camera terminals are suppressed or eliminated, and only the video of the camera terminal of interest is delivered as a high-quality bitstream. It becomes possible to view the details again. In normal times, the minimum necessary low image quality bit rate is sufficient, so it is possible to increase the number of camera terminals without changing the maximum transmission capacity of the network 30, and when an abnormality occurs, more camera terminals are generated. Detailed video can be obtained by viewing the video only.
[0045]
Further, for example, when the first embodiment is intended for television broadcasting, the amount of data per unit time that can be transmitted through the network 30 is finite, so the broadcasting station charges according to the amount of data viewed. It is envisaged to insert a CM or insert a CM. A viewer can normally view a television broadcast by performing viewing with a low-quality bitstream and requesting a high-quality bitstream as necessary during viewing.
[0046]
  In the above description, the high-quality video reproduced and distributed from the recording medium 13 can be viewed only once on the display 22, but the conventional receiving terminal 20 shown in FIG. As shown, the recording medium controlled by the system controller 2325And a changeover switch 24 for displaying a high-quality video signal decoded by the decoder 21 on the display 22, and the recording medium.25Record on this recording medium when necessary25Thus, the high-quality video signal may be reproduced and supplied to the display 22 via the changeover switch 24. The same applies to other embodiments described later.
[0047]
Further, although the recording medium 13 in FIG. 1 is a semiconductor memory, it may be a recording medium such as a recordable / reproducible disk or a magnetic tape. In this case, when the switching control signal C is supplied from the system controller 23, the recording medium is also controlled to switch from the recording mode to the reproduction mode, and the recording is performed a predetermined time T before the switching point. To high-quality bitstream B_H Start playing. The same applies to other embodiments described later.
[0048]
  FIG. 3 is according to the invention.Video distribution systemFIG. 9 is a block diagram illustrating a second embodiment, wherein 10a and 10b are camera terminals, 20a, 20b, and 20c are receiving terminals, 30 to 32 are networks, and 40 and 41 are local servers. The same reference numerals are assigned to the components, and duplicate descriptions are omitted.
[0049]
In this figure, in this embodiment, the network 30 is hierarchically configured with the network 30 as an upper layer and the networks 31 and 32 as lower layers, and the network 30 is a high-capacity network of the upper layer. The plurality of camera terminals 10 a and 10 b are connected to a plurality of local servers 40 and 41 via the upper layer network 30. The lower layer network 31 connects the local server 40 and the receiving terminal 20a, and the lower layer network 32 connects the local server 41 and the receiving terminals 20b and 20c.
[0050]
The camera terminals 10 a and 10 b are different from the camera terminal 10 in FIG. 1 only in that the changeover switch 14 is not provided. Therefore, any of the camera terminals 10 a and 10 b is output from the encoder 12. Low quality bitstream B_LAnd high-quality bitstream B delayed by the recording medium 13_H'Is always transmitted to the local servers 40 and 41 via the network 30. Therefore, the local servers 40 and 41 store the low image quality bit streams and the delayed high image quality bit streams from all the camera terminals connected to the network 30.
[0051]
On the other hand, the receiving terminal 20a connected to the local server 31 and the receiving terminals 20b and 20c connected to the local server 32 have the same configuration as the receiving terminal 20 shown in FIG. The low-quality bitstream is distributed from the local servers 40 and 41 via the networks 31 and 32, and there is a scene that draws attention to the viewer by watching the video by the low-quality bitstream displayed on the display 22, When a predetermined operation for requesting retransmission of a scene is performed by the viewer, a retransmission request signal is formed and output from the system controller 23 and transmitted to the local servers 40 and 41 via the networks 31 and 32. When receiving the retransmission request signal, the local servers 40 and 41 replace the delayed high-quality bit stream corresponding to the low-quality bit stream that has been transmitted so far with the low-quality bit stream, and send the networks 31 and 32. To the receiving terminal 20a and the receiving terminals 20b and 20c.
[0052]
As described above, in the network 30 of the upper layer, the low-quality bit stream B from each camera terminal_LAnd high-quality bitstream B_HAre transmitted at the same time, but in the lower layer networks 31 and 32, the low-quality bit stream B_LAnd high-quality bitstream B_HOnly one of 'is transmitted.
[0053]
In this way, in each of the receiving terminals 20a to 20c, when a re-transmission request is made, a scene to call attention can be seen again with a high-quality video, and the local servers 40 and 41 each have the same camera. Since the low-quality bit stream and the delayed high-quality bit stream from the terminals 10a and 10b are stored, when the respective receiving terminals 20a to 20c can acquire the video from the camera terminals 10a and 10b, In addition, images from the same camera terminal 10a or 10b can be acquired simultaneously.
[0054]
As described above, in the second embodiment, similarly to the first embodiment shown in FIG. 1, the low-quality bit stream with a low bit rate is normally transmitted and the same video distributed by the viewer is displayed. When viewing again, a high-quality bit stream with a high bit rate is retransmitted, so that a high-quality video can be obtained.
[0055]
In addition, even if a retransmission request for a high-quality bitstream is issued from all receiving terminals to one camera terminal, the camera terminal only needs to transmit this to each local server. The maximum transmission capacity is not exceeded.
[0056]
Also, for example, when the second embodiment is intended for television broadcasting, it is expected that viewers concentrate on one camera terminal and request a high-quality bitstream. By layering the network 30 and the lower-layer networks 31 and 32, it is possible to reduce the transmission load on the recording medium 13 in the camera terminal and to continuously transmit a high-quality bit stream to the receiving terminal. Become.
[0057]
  FIG. 4 is according to the invention.Video distribution systemFIG. 14 is a block diagram showing a third embodiment, in which 15 is a processor, 16 is a memory, 16a is an encoding program, and 16b is an encoding program. Omitted.
[0058]
In the figure, the processor 15 executes encoding programs 16 a and 16 b stored in the memory 16 to encode the video signal A output from the camera terminal 10. Here, the encoding program 16a causes the processor 15 to perform processing equivalent to the encoder 12a in FIG. 1, and the encoding program 16b causes the processor 15 to perform processing equivalent to the encoder 12b in FIG. It is. As a result, the processor 15 uses the low-quality bitstream B._LAnd high-quality bitstream B_HAnd a low-quality bitstream B_L Is supplied to the changeover switch 14 and the high-quality bitstream B_HIs supplied to the recording medium 13 and recorded.
[0059]
FIG. 5 is a timing diagram showing a specific example of the processing operation of the processor 15 in FIG. 4, where the horizontal axis is the time axis and the time ta + tb is one frame period of the camera 11.
[0060]
For each period (one frame period) in which the camera 11 outputs one frame of the video signal A (FIG. 4), the processor 15 executes the encoding programs 16a and 16b in a time-sharing manner. The encoding program 16a is executed during the period ta before the low-quality bitstream B_LAnd the encoding program 16b is executed in the subsequent period tb after this same frame period to generate the high-quality bit stream B_H Is generated.
[0061]
Here, the processor 15 is provided with a frame memory, and the video signal A supplied from the camera 11 is temporarily stored in the frame memory, and is first read out from the frame memory at a high speed, and then the period ta Encoded low-quality bitstream B_LIs then read out again from the frame memory at a high speed, encoded by the encoding program 16b within the period tb, and the high-quality bitstream B_HIs generated. These generated low-quality bitstreams B_LAnd high-quality bitstream B_HAre once recorded in a separate frame memory, read out from these so as to have a time length of one frame period, and output from the processor 15.
[0062]
As described above, in the third embodiment, the processor 15 performs the encoding process in a time division manner, so that the encoding process with different compression rates can be performed without increasing the number of parts constituting the camera terminal 10. In addition, a high-quality bitstream can be retransmitted in response to a request from the receiving terminal 20. Further, by reducing the number of parts, it is possible to reduce the weight of the camera terminal 10 and the manufacturing process.
[0063]
Needless to say, this third embodiment can also be applied to the second embodiment shown in FIG.
[0064]
  Next, according to the present inventionVideo distribution systemA fourth embodiment will be described.
  The configuration of the fourth embodiment is the same as that of the previous embodiment, but will be described below with the configuration of the first embodiment shown in FIG.
[0065]
In FIG. 1, the fourth embodiment also enables retransmission of a still image from the recording device 13. For this reason, the encoder 12b performs reversible compression (for example, intraframe coding) for each frame of the video signal A from the camera 11.
[0066]
When the viewer performs a retransmission operation on the receiving terminal 20 side, the changeover switch 14 is set to the b contact side on the camera terminal 10 by the switching control signal from the system controller 23, as in the first embodiment shown in FIG. To the high-quality bit stream B from the recording medium 13_H'Is retransmitted to the receiving terminal 20 and a high-quality video is displayed on the display 22, but when the viewer performs a still image playback instruction operation, the instruction control signal is supplied from the system controller 23 to the camera terminal 10, The recording medium 13 is controlled, and the high-quality bit stream of one frame at that time is repeatedly read and distributed to the receiving terminal 20. As a result, a still image is displayed on the display 22 of the receiving terminal 20 by repeating the high-quality bit stream of one frame.
[0067]
Alternatively, the receiving terminal 20 is provided with a recording medium 25 or a recording medium such as a frame memory as shown in FIG._H'May be sequentially recorded, and together with the above-described still image reproduction instruction, the high-quality bit stream of one frame recorded at this time may be repeatedly reproduced from the recording medium and supplied to the display 22.
[0068]
By the way, since the video compression system represented by the MPEG system has a high correlation between frames before and after the video signal, interframe coding by motion compensation is performed in most frames. In general, a frame subjected to interframe coding by motion compensation has a lower image quality than a frame subjected to intraframe coding in order to improve the compression rate. For this reason, when a pause is made at a frame that has been subjected to interframe coding by motion compensation and a still image is requested, a video with poor image quality is stopped and displayed on the display 22 as it is.
[0069]
However, in the fourth embodiment, since the high-quality bitstream is subjected to a reversible compression process, even when the viewer temporarily displays the delivered high-quality image, High-quality bit stream B at the decoder 21_HSince 'is decoded into a video signal while maintaining high image quality, a high-quality still image without image quality degradation can be obtained.
[0070]
  Next, according to the present inventionVideo distribution systemA fifth embodiment will be described.
  The configuration of the fifth embodiment is the same as that of the previous embodiment. However, a high-quality slow motion image (hereinafter referred to as a slow image) is also obtained. The configuration shown in FIG. Will be described as an example.
[0071]
Hereinafter, the operation of the fifth embodiment will be described with reference to FIG. 6. FIG. 6A shows a frame to be encoded by the encoder 12a in FIG. 1, and FIG. 6B shows the encoder in FIG. Reference numeral 12b denotes a frame to be encoded, and FIG. 10C shows a video frame displayed on the display 22 in the receiving terminal 20.
[0072]
In FIG. 1, the encoder 12a, as shown in FIG. 6 (a), has a low-quality bit stream B for each frame period in the order of frame 1, frame 2, frame 3,._LIs output.
[0073]
Further, as shown in FIG. 6B, the encoder 12b encodes a video signal with a high frame rate received from the camera so that a slow image is possible. Here, in FIG. 6B, frame 1.5 is a frame at a time intermediate between frames 1 and 2, and frame 2.5 is a frame at a time intermediate between frames 2 and 3. The same applies hereinafter. Here, each frame 1, frame 1.5, frame 2, frame 2.5,... Is a frame that is time-compressed to 1/2 frame time length so that a double slow image can be obtained. High-quality bitstream B_HThis is output from the encoder 12b and recorded on the recording medium 13.
[0074]
In general, in order to obtain n (where n is an integer of 2 or more) slow images, (n−1) one of the frames in the video signal A from the camera 11 is obtained. Frames whose contents sequentially change from one frame to the other are inserted.
[0075]
From the recording medium 13, the high-quality bit stream B of each frame in the frame period._H'Is played. In the receiving terminal 20, as a retransmission from the recording medium 13, a slow image (high-quality bit stream B of FIG._HIn this case, it is also possible to request the reproduction of a double slow image).
[0076]
Therefore, as shown in FIG. 6C, the low-quality bit stream B shown in FIG._LIn the state of “(1) normal playback” in which the video is distributed and displayed, if there is a request for slow playback on the receiving terminal 20 side, the changeover switch 14 switches to the b contact side as described above. As shown in FIG. 6 (b), each frame is recorded on the recording medium 13 at a ½ frame period._LIs a high-quality bitstream B in which each frame is one frame period_H'And is retransmitted from the changeover switch 14 to the receiving terminal 20 via the network 30. Thereby, on the display 22, as shown in FIG. 6C, a frame having a length of one frame time from the time ts is frame 0._.5, frame 1, frame 1_.5, frames 2,... Are displayed in this order, and the state becomes “(2) Slow playback” with double high-quality slow playback.
[0077]
Note that the receiving terminal 20 can also request retransmission of a normal high-quality bitstream. In this case, in response to this request, the high-quality bit stream of every other frame is read from the recording medium 13 in the order of frame 1, frame 2, frame 3,. be delivered.
[0078]
As described above, in the fifth embodiment, it is possible to increase the frame rate and observe the video only when the slow reproduction is selected for the distributed image. The viewer needs slow playback when the video changes quickly. Since the encoder 12b always encodes at a high frame rate, it cannot be seen from the output from the encoder 12a (frames 0.5, 1... Shown as d, e, and f in FIG. 6C). 5, the movement of the frame 2.5) can be seen in detail, and the detailed movement can be observed.
[0079]
In the fifth embodiment, the high-quality bit stream B for slow playback is used._HAs described above, the frame is inserted between the frames of the input video signal A before recording on the recording medium 13, but in the same manner as in the first embodiment shown in FIG. High Quality Bitstream B from_HMay be recorded on the recording medium 13 and reproduced from the recording medium 13 by repeatedly reproducing the high-quality bit stream of each frame a plurality of times to perform high-quality slow reproduction.
[0080]
  Next, according to the present inventionVideo distribution systemA sixth embodiment will be described.
  In the sixth embodiment, images are distributed simultaneously from a plurality of camera terminals, and the distributed images can be simultaneously displayed on the display of the same receiving terminal. FIG. 7 is a block diagram for explaining the sixth embodiment in the case where video is simultaneously distributed from two camera terminals to the same receiving terminal. Reference numerals 10a and 10b denote camera terminals 10 in the previous embodiment. However, here, assuming that the camera terminal 10 has the same configuration as that of the camera terminal 10 shown in FIG. 1, parts corresponding to those in FIG.
[0081]
In the figure, the receiving terminal 20 can control the change-over switches 14 a and 14 b of the camera terminals 10 a and 10 b by the switching control signal C from the system controller 23, and the system controller 23 can control the receiving terminal 20. A receiving unit (not shown) can be controlled. As a result, the receiving terminal 20 can receive a video (low-quality video or high-quality video) from either one of the camera terminals 10 a and 10 b and display the received video on the display 22. It is also possible to simultaneously receive video from both the camera terminals 10a and 10b and display these videos on the display 22 at the same time.
[0082]
FIG. 8 is a timing chart showing the operation of the sixth embodiment. FIG. 8A shows a low-quality bit stream B in the camera terminal 10a._LAnd high-quality bitstream B_H(B) shows a low-quality bit stream B at the camera terminal 10b._LAnd high-quality bitstream B_H(C) shows the low-quality bit stream B on the display 22 of the receiving terminal 20._LDisplay timing of low-quality video and high-quality bitstream B_HShows the display timing of high-quality video by.
[0083]
In the figure, when the viewer performs an operation for requesting simultaneous video distribution from the camera terminals 10a and 10b on the receiving terminal 20 side (time t1), the low-quality bit stream B from these camera terminals 10a and 10b._LAre simultaneously received, and these are simultaneously supplied to the display 22 decoded by the decoder 21 into a video signal. At this time, a screen reduction process is performed on these video signals by a processing unit (not shown). As a result, on the display 22, as shown in FIG. Thumbnails that are displayed at the same time are reduced (time t2).
[0084]
Thereafter, for example, there is a scene that alerts the viewer to the video from the camera terminal 10b, and when the viewer performs an operation for requesting retransmission of the high-quality video 2 (time t3). The system controller 23 causes the receiving unit (not shown) to receive only the bit stream from the camera terminal 10b, and closes the changeover switch 14 in the camera terminal 10b to the b contact side by the change control signal C. As a result, the high-quality bitstream B from the camera terminal 10b_H'Is distributed and received by the receiving terminal 20, which is decoded and supplied to the display 22. At this time, that is, when only the bit stream distributed from one camera terminal is received, the received video (in this case, the camera terminal 10b) is controlled by the system controller 23 as shown in FIG. 9B. (High-quality video from) is displayed on the entire screen of the display 22 (time t4).
[0085]
Here, two camera terminals are targeted, but the same applies to a case where three or more arbitrary number of camera terminals are targeted.
[0086]
As described above, in the sixth embodiment, after the viewer previews the videos of the plurality of camera terminals, the viewer can view the desired video of the predetermined camera terminal again from the beginning.
[0087]
In addition, when the sixth embodiment is applied to television broadcasting, if the capacity of the recording medium 13 is a predetermined time T, the viewer can simultaneously watch the beginning portion of the program broadcast at the same time. If an interesting program is selected within the time T, it can be viewed from the broadcast start time. In this case, the recording medium 13 records the program from the start address when the program starts broadcasting. When a program for a predetermined time T is recorded, the recording capacity is recorded. Recording is performed again from the head address, and the already recorded content is rewritten. Further, when there is a read request from the recording medium 13 from the system controller 23 of the receiving terminal 20, the recording medium 13 starts reading from the head address. Thus, if there is a read request from the recording medium 13 from the system controller 23 of the receiving terminal 20 before the predetermined time T has elapsed since the start of the program reception, the program is read out and received from the beginning. It is distributed to the terminal 20. Therefore, the predetermined time T is a time that allows the viewer to sufficiently select one desired program from the plurality of thumbnail-always programs shown in FIG. 9A, for example, 1 to several minutes. Any degree is acceptable.
[0088]
In this way, the viewer can select the program after actually watching the program, and can easily and efficiently select the program as compared with a program guide such as EPG (Electoronic Program Guide). .
[0089]
  FIG. 10 is according to the invention.Video distribution systemIt is a block diagram which shows 7th Embodiment, Comprising: 17 is a signal processing part, The same code | symbol is attached | subjected to the part corresponding to FIG. 1, and the overlapping description is abbreviate | omitted.
[0090]
In the figure, the camera terminal 10 is provided with a signal processing unit 17, and the video signal A output from the camera 11 is processed by the signal processing unit 17 and then supplied to the encoder 12 a and encoded. Low quality bitstream B_L Is generated. Other than this, the second embodiment is the same as the first embodiment shown in FIG. 1. Therefore, the encoder 12b encodes the video signal A from the camera 11 as it is and performs a high-quality bit stream B._H Is generated.
[0091]
The signal processing unit 17 extracts a part of the video signal A output from the camera 11 so that a part of the image captured by the camera 11 is extracted, and the extracted part becomes the size of one screen. The image is enlarged and supplied to the encoder 12a.
[0092]
This will be described with reference to FIG. 11. In FIG. 11A, a range 50 is a shooting range of the camera 11, and a video signal A in the shooting range 50 is output from the camera 11. The signal processing unit 17 extracts a part of a range (hereinafter referred to as an extraction range) 51 of the shooting range 50 from the video signal A of the shooting range, and the video of the extraction range 51 is extracted from the receiving terminal 20. Expansion processing is performed so that the entire screen of the display 22 is displayed. In this extension processing, line interpolation processing is performed so that one frame line matches the number of lines of the video signal A.
[0093]
In this manner, the video signal A ′ obtained by extending the video of the extraction range 51 of a part of the shooting range 50 of the camera 11 is output from the signal processing unit 17 and supplied to the encoder 12a to be encoded. Here, for example, by setting the extraction range 51 to about 1 / several times to 1/10 times the shooting range 50, the video signal A ′ is sufficiently narrower than the original video signal A. Therefore, the encoder 12a can encode at a higher information compression rate than the original video signal A is encoded.
[0094]
Low quality bit stream B output from the encoder 12a_LIs supplied from the changeover switch 14 to the receiving terminal 20 via the network 30, the display 22 displays the image of the extraction range 51 shown in FIG. 11A over the entire screen as shown in FIG. It will be enlarged.
[0095]
Here, in FIG. 11A, the position of the extraction range 51 is changed so that the extraction range 51 moves within the photographing range 50 as indicated by an arrow for each frame. For this reason, the image displayed on the display 22 also changes. Then, when an image that calls attention to the viewer such as the person 52 enters the extraction range 51, the person 52 is displayed on the display screen 22 as shown in FIG. The image begins to appear. When the viewer performs a retransmission request operation on the receiving terminal 20 side after seeing this to some extent, the changeover switch 14 is closed to the b-contact side and the image quality from the recording medium 13 is the same as in the first embodiment shown in FIG. Bitstream B_H'Is distributed, and a high-quality image in the shooting range 50 shown in FIG.
[0096]
In this way, in the seventh embodiment, since a limited area within the shooting range of the camera is normally viewed and the entire screen is viewed as necessary, the received bit amount in the normal state It is also possible to display an image capable of recognizing an image that needs to be retransmitted while drastically reducing. Further, since only a limited area (video in the extraction range 51) is distributed during normal times, the amount of bits that the network 30 regularly transmits can be greatly reduced.
[0097]
  Next, according to FIG.Video distribution systemAn eighth embodiment will be described.
  The configuration of the eighth embodiment is the same as that of the first embodiment shown in FIG.
[0098]
FIG. 12A shows a bit stream B output from the encoder 12a in FIG._LFIG. 12B shows the bit stream B output from the encoder 12b in FIG._HIt shows the resolution of the video obtained from. A grid surrounded by a dotted line in FIGS. 12A and 12B represents a pixel.
[0099]
As is clear from FIGS. 12A and 12B, the bit stream B output from the encoder 12a._LThe video by the video stream has sufficient resolution to view it, but the bit stream B output from the encoder 12b_HTherefore, the bit stream B reproduced from the recording medium 13_H'Is a bit stream B output from the encoder 12a_LCompared with the video by, it is a higher resolution video. For this reason, the viewer normally receives the bit stream B from the encoder 12a._L Watching the video by is enough.
[0100]
Such bitstream B_L When a scene that alerts the user during viewing of the video appears and the viewer requests the retransmission, the bit stream B is recorded from the recording medium 13 as in the previous embodiment._H'Is reproduced and distributed to the receiving terminal 20, and a high-resolution video is displayed on the display 22. The details of the part that has attracted attention from this video, for example, if this part is the face part of the person 53, the facial part has a large number of pixels, so that the facial expression can be clearly recognized.
[0101]
In the eighth embodiment, when the high-resolution video is retransmitted in this way, the video signal decoded by the decoder 21 is supplied to the display 22 via the frame memory in the receiving terminal 20. By configuring in this way, it is possible to enlarge and display the part that has received attention.
[0102]
Now, there is a scene that draws attention to the viewer in the video display state shown in FIG. 12A, and when the viewer requests retransmission, the recording medium 13 in the camera terminal 10 as described above. Bitstream B of high-resolution video reproduced from_H'Is distributed to the receiving terminal 20, decoded by the decoder 21, and supplied to the display 22 through the frame memory. As a result, a high-resolution video as shown in FIG. 12B is displayed on the display 22. Here, when a predetermined portion is indicated by a cursor operation or the like on the high-resolution video screen, this indication portion is displayed. An area having a predetermined size is enlarged and displayed by reading control of the frame memory. The enlarged display area is displayed so as to overlap the video shown in FIG.
[0103]
Here, by setting the enlargement ratio of the video in the enlarged display area to a value in which, for example, the resolution of the video in the enlarged display area is equal to or less than the resolution of the video shown in FIG. Can be enlarged and displayed at a high resolution. Therefore, even if a part of the video is enlarged and displayed, a clear video can be obtained, and the viewer can clearly recognize the part of the video to be confirmed.
[0104]
  FIG. 13 is according to the invention.Video distribution systemFIG. 14 is a block diagram showing the ninth embodiment, in which 18 is an image / speech recognition circuit, and parts corresponding to those in FIG.
[0105]
In the figure, the camera terminal 11 is provided with an image / sound recognition circuit 18, and a specific video is obtained from a video signal obtained from the camera 11, or alternatively, from a microphone (not shown) provided in the camera 11. When specific sound is detected by the image / speech recognition circuit 18 from the output sound signal, the image / sound recognition circuit 18 controls the recording medium 13 in response to this detection, and the high-quality bit stream from the encoder 12b. B_HIs written to the recording medium 13.
[0106]
Here, the specific video is, for example, a video of a moving object, and when this embodiment is applied to a monitoring system, when a person or the like enters a shooting scene, this is converted into an image / voice recognition circuit. 18 recognizes this, controls the recording medium 13 during the period in which it recognizes it, and outputs the high-quality bit stream B from the encoder 12b._HTo record. Also, some specific videos are stored in the image / sound recognition circuit 18, and when a video other than the stored specific video is recognized from the video signal A from the camera 11, or this specific video is recognized. When the video is recognized, the recording medium 13 may be recorded. The same applies to sound, and when sound is output from the above microphone, the image / sound recognition circuit 18 may recognize this and cause the recording medium 13 to perform recording operation, or some specific sound. The pattern is stored, and when the sound of the pattern other than the specific sound pattern is output from the microphone or when the specific sound pattern is output from the microphone, the image / speech recognition circuit 18 recognizes this. Thus, the recording medium 13 may be operated for recording.
[0107]
In this way, in the ninth embodiment, since the recording medium 13 is written according to the recognition result of the image / speech recognition circuit 18, the storage capacity required for the recording medium 13 can be reduced, and A long-time video can be stored in the recording medium 13.
[0108]
Information stored in the recording medium 13 in this way is read out by a control signal from the system controller 23 and distributed to the receiving terminal 20. Therefore, the viewer can obtain information stored in the recording medium 13 and display it on the display 22 by making a distribution request when necessary.
[0109]
  FIG. 14 is according to the invention.Video distribution systemFIG. 14 is a block diagram illustrating a tenth embodiment, in which 12c is an encoder and 13a is a recording medium. The same reference numerals are given to portions corresponding to those in FIG.
[0110]
In the figure, the tenth embodiment is obtained by adding an encoder 12c and a recording medium 13a to the first embodiment shown in FIG. One of the output and the output of the recording medium 13, 13a is selected.
[0111]
That is, as a method of displaying video on the display 22 of the receiving terminal 20 (image playback mode), not only normal playback (normal display) of low-quality video and high-quality video, but also slow playback as described above. Various modes such as still image playback and high-speed playback are conceivable, and in order to make these possible, the bit stream to be distributed must be encoded by a processing method suitable for such image playback mode. (For example, as described above, when a still image is reproduced from a bit stream encoded by a processing method compliant with MPEG, good still image reproduction is not always performed). In the sixth embodiment, therefore, a bit stream encoded by various processing methods can be obtained.
[0112]
The encoder 12c performs an encoding process different from that of the encoders 12a and 12b, and the high-quality bit stream B generated by the encoder 12c._hIs stored in the recording medium 13a. The changeover switch 14 is normally used for the low-quality bit stream B of the encoder 12a._LHowever, when a retransmission request is received from the system controller 23 of the receiving terminal 20, the bit stream that has been optimally encoded among the high-quality bit streams stored in the recording media 13 and 13a is selected. Select and output.
[0113]
Here, two encoders that perform different encoding processes other than the low image quality encoder 12a are provided, but three or more coarse encoders may be provided.
[0114]
Thus, in the tenth embodiment, by performing a plurality of encodings within the camera terminal 10, it is possible to select a bitstream that has been subjected to an optimal encoding process in response to a retransmission request. The optimum encoding method differs depending on the form of image reproduction, such as slow reproduction and enlargement reproduction. In the tenth embodiment, encoding processing is performed by an optimum method for each form of image reproduction. And a recording medium for storing the bit stream output from these encoders, and these encoders simultaneously encode video signals from the same camera 11 and store them in the recording medium. In response to a re-transmission request instructing the reproduction form from the video, it is possible to receive a bitstream that has been encoded by a method that is always optimal for the designated reproduction form, and the viewer is always clear regardless of the reproduction form It is possible to receive a playback image.
[0115]
【The invention's effect】
As described above, according to the video distribution system of the present invention, the camera terminal and the reception terminal are connected via the network, and the video distribution system distributes the bit stream generated from the captured video by the camera terminal to the reception terminal. The camera terminal encodes the captured video signal to generate a first bit stream and a second bit stream that forms a higher quality video than the first bit stream, and In general, the first bit stream is delivered to the receiving terminal, and the second bit stream from the video a predetermined time before the time when the retransmission request is made in response to the retransmission request from the receiving terminal. In normal times, it can be received with the minimum required image quality and the amount of bits can be suppressed, and when a retransmission is requested, the amount of bits is large. However, going back to the required point in time and rewinding playback, high-quality video is displayed and a clear image can be obtained. Therefore, a clear image can be obtained from a necessary portion without increasing the amount of bits to be obtained.
[Brief description of the drawings]
FIG. 1 is according to the invention.Video distribution systemIt is a block diagram which shows 1st and 4th embodiment.
FIG. 2 is a timing chart showing an operation in the first embodiment shown in FIG. 1;
FIG. 3 according to the inventionVideo distribution systemIt is a block diagram which shows 2nd Embodiment.
FIG. 4 according to the inventionVideo distribution systemIt is a block diagram which shows 3rd Embodiment.
FIG. 5 is a timing chart showing the processing operation of the processor in FIG. 4;
FIG. 6 is according to the present invention.Video distribution systemIt is a figure which shows operation | movement of 5th Embodiment.
FIG. 7 is according to the present invention.Video distribution systemIt is a block diagram which shows 6th Embodiment.
FIG. 8 is a timing chart showing the operation of the sixth embodiment shown in FIG.
9 is a diagram showing a specific example of a screen displayed on the display of the receiving terminal in FIG.
FIG. 10 is according to the present invention.Video distribution systemIt is a block diagram which shows 7th Embodiment.
11 is an explanatory diagram of a display image by a bit stream obtained by the low image quality encoder in the seventh embodiment shown in FIG.
FIG. 12 is according to the present invention.Video distribution systemIt is explanatory drawing of the image | video displayed in 8th Embodiment.
FIG. 13 is according to the present invention.Video distribution systemIt is a block diagram which shows 9th Embodiment.
FIG. 14 is according to the present invention.Video distribution systemIt is a block diagram which shows 10th Embodiment.
FIG. 15 is a block diagram illustrating an example of a conventional video distribution system.
[Explanation of symbols]
  10 Camera terminal
  11 Camera
  12a-12c encoder
  13, 13a Recording medium
  14 Bitstream selector switch
  15 processor
  16 memory
  16a, 16b encoding program
  17 Signal processor
  18 Image / voice recognition circuit
  20 Camera terminal
  21 Decoder
  22 display
  23 System controller
  30-32 network
  40, 41 Local bus
  50 shooting range
  51 Extraction range
  52,53 people

Claims (6)

A video distribution system in which a camera terminal and a receiving terminal are connected via a network, and a bit stream generated from a captured video by the camera terminal is distributed to the receiving terminal,
The camera terminal encodes the captured video signal, encodes the first bit stream and a higher bit rate than the first bit stream, and forms a high-quality video used for slow playback. And normally delivering the first bit stream to the receiving terminal and responding to the retransmission request generated by the viewer's slow playback operation from the receiving terminal. A video distribution system that distributes the second bit stream from a video a predetermined time before the point in time. In claim 1 ,
The video distribution system, wherein the camera terminal includes a processor that performs time-division encoding processing of the first bit stream and the second bit stream. In claim 1 ,
A video distribution system in which a plurality of the camera terminals are connected to the network, and a viewer can view videos from the plurality of camera terminals by the receiving terminal. In claim 1 ,
The video distribution system, wherein the first and second bitstreams are encoded by a method conforming to MPEG. In claim 1 ,
The video distribution system, wherein the second bit stream is subjected to reversible data compression. In claim 1 ,
The camera terminal comprises an image / speech recognition circuit and a recording means for extracting a specific image or sound from the camera output of the camera terminal,
A video distribution system, wherein when a specific image or sound preset by the viewer in the image / speech recognition circuit appears, the recording means writes the specific image or sound onto a recording medium.

Images