JP4480971B2 - Optical disk playback device - Google Patents

Description

  The present invention relates to an optical disc reproducing apparatus that reads and reproduces video information recorded on an optical disc recording medium such as a DVD (digital versatile disc).

  Conventionally, when recording video information such as a video shot by a video camera or a TV program received by a TV tuner on an optical disc such as a DVD, the video information is compressed (encoded) in accordance with the MPEG standard. Yes. In addition, when reproducing video information recorded on an optical disc, the compressed video information read from the optical disc is decoded (decoded) in accordance with the MPEG standard.

  When reading video information from the optical disc, the video signal (video signal) is decoded in accordance with the MPEG2 standard, and the audio signal (audio signal) is decoded in accordance with the MP3 standard. Since these video signal and audio signal are decoded by different decoding circuits or elements, respectively, in order to reproduce the video information on the screen of the monitor device, the video signal and the audio signal are converted based on a predetermined AV synchronization signal. The data must be output while being synchronized (AV synchronization processing).

  For example, the configuration of the conventional example shown in Patent Document 1 is shown in FIG. This conventional example relates to an apparatus that essentially converts a frame rate. For example, when a video code recorded at a frame rate of 25 frames / second is displayed at a frame rate of 30 frames / second, a video for 5 pictures is displayed. When displaying 6 pictures by repeating 1 picture for each code data, and conversely displaying a video code recorded at a frame rate of 30 frames / second at a frame rate of 25 frames / second, 5 pictures worth The video code data for one picture is discarded (skip) without decoding for each display period.

  The conventional apparatus shown in FIG. 4 includes an AV synchronization control unit 101 having an AV synchronization check function for synchronizing a video signal and an audio signal, and a picture repeat request signal RP or RP in response to the supply of the decode timing signal TD. A frame rate conversion control unit 102 that outputs a picture skip request signal RS, a video timing generation unit 103 that generates a display timing signal TH and a decode timing signal TD in response to supply of the video synchronization signal SY, and a decode timing signal TD A decoding control unit 104 that outputs a decoding start signal DS in response to the supply of video, a video code buffer 105 that temporarily stores the input video code data DV and sequentially supplies it to the picture decoding unit 106, and a decoding start signal Video code for one picture in response to DS supply Decodes over data DV, comprising a picture decoding unit 106 in response to the supply of the skip request signal skipped without decoding the one picture of the video encoded data DV.

  The frame rate conversion control unit 102 includes a check signal generation circuit 108 that generates a synchronization check timing signal TC indicating an original decoding timing when frame conversion is not performed in response to supply of the system clock SC. The AV synchronization control unit 101 includes a check circuit 107 that performs AV synchronization check in response to the supply of the synchronization check timing signal TC. With such a configuration, AV synchronization processing can be performed regardless of whether or not the frame rate is being converted.

  On the other hand, in Patent Document 2, when a synchronization error occurs between a video signal and an audio signal, if the video signal precedes the audio signal, the video signal is decoded on a screen (frame) basis. There is shown a synchronization shift control device that stops and conversely skips the decoding process of the video signal by a predetermined time when the video signal is behind the audio signal.

Patent Document 3 discloses a method for obtaining a reference time for synchronization processing when playback switching is performed in an audio / video synchronized playback apparatus. Further, Patent Document 4 discloses a method for determining the playback timing when the video playback pause is canceled.
JP-A-8-322043 (FIG. 1) JP-A-10-262208 (Claims 2 and 3, FIG. 4) JP 2000-125265 A JP 2002-197794 A

  By the way, in the conventional optical disk reproducing apparatus disclosed in Patent Document 1, the AV synchronization processing functions such as the AV synchronization control unit 101, the check circuit 107, and the check signal generation circuit 108 are achieved by hardware, and the decoder An AV synchronization processing function has been incorporated into an element (chip) having a function. When the AV synchronization processing function is incorporated in the decoder element, it is necessary to store image signals and audio signals for a predetermined time, so that it is necessary to increase the memory capacity of the decoder element accordingly.

  On the other hand, along with the increase in the operation speed of the CPU, there is a tendency to achieve hardware simplification and cost reduction by achieving functions that have been processed by hardware in software. In response to this demand, decoder elements that do not include an AV synchronization processing function are being put into practical use in response to demands for reducing the cost of optical disc playback apparatuses.

  If the audio signal is recorded for the same time corresponding to the video signal, even if the video information is reproduced without performing the AV synchronization check using a decoder element that does not include the AV synchronization processing function, the image and the audio are particularly There is no deviation. However, the synchronization error between the video signal and the audio signal may occur due to an error in reading the video information due to scratches or dirt on the optical disc as well as due to an audio gap in which no audio signal is recorded corresponding to the video signal. In addition to the case where the audio signal precedes the video signal, the video signal may precede the audio signal.

  In the conventional example shown in Patent Document 2, the timing of video signal decoding processing is operated in order to synchronize the video signal and the audio signal, so that a predetermined number of video signals are stored. Buffer memory is required. However, since the video signal has a very large data capacity, in order to synchronize the video signal with the audio signal, the buffer memory capacity must be very large, which increases the cost.

  According to the present invention, in an optical disk reproducing apparatus using a decoder element that does not include an AV synchronization processing function, a synchronization deviation correction process (AV) between a video signal and an audio signal is achieved without increasing the capacity of a buffer memory for storing the video signal. An object of the present invention is to provide an optical disc reproducing apparatus capable of performing synchronization processing.

In order to achieve the above object, the invention of claim 1 is directed to a video information reading means for reading video information from an optical disc, and a video information read by the video information reading means to separate a video signal and an audio signal. Separating means, video signal decoding means for decoding the video signal separated by the separating means in conformity with the MPEG2 standard, and MP3 standard for the audio signal separated by the separating means An optical disk playback device using a decoder element that includes an audio signal decoding means for performing decoding processing in accordance with the video signal and the audio signal synchronization processing function,
Time information acquisition means for acquiring information about the time of video and audio during reproduction from the video signal decoded by the video signal decoding means and the audio signal decoded by the audio signal decoding means;
The information about the time of the video and audio acquired by the time information acquisition means is compared every time a predetermined time elapses, and when there is a synchronization shift between the video signal and the audio signal for a predetermined time or more, Determine which of the audio signals is ahead, and determine whether the synchronization deviation time of the video signal and the audio signal after the synchronization deviation correction is corrected by the synchronization deviation correction means described below has become a predetermined reference time or less. A synchronization deviation determining means,
When it is determined by the synchronization deviation determination means that a synchronization deviation of a predetermined time or more has occurred, an audio signal is output for a certain period of time when switching from fast-forward mode to playback mode or switching from pause mode to playback mode. Audio signal is output, but the level is almost zero, or waits for a time period below a certain level where the viewer cannot hear audio. When the audio signal is ahead of the video signal, the output of the audio signal is stopped for a predetermined time that is equal to or less than the time difference between the video signal and the audio signal, and the audio signal is delayed from the video signal. by fast-forward predetermined time period the output of the audio signal when you are, correct the synchronization error of the audio signal to the video signal, the time synchronization deviation of the video signal and the audio signal, the audio If longer than the time period that has not been output, multiple runs of synchronization processing of the audio signal to the video signal, when the synchronization deviation time after correction is equal to or less than the reference time, the audio signal to the video signal sync And a synchronization deviation correcting means for ending the deviation correction.

According to such a configuration, when the video signal and the audio signal are not synchronized, for example, when switching from the fast-forward mode to the playback mode or when switching from the pause mode to the playback mode, for a certain period of time. When the audio signal image video signal precedes the audio signal image video signal during a time period when the audio is not output, the audio signal is output for the predetermined time. Since fast-forwarding is performed, the synchronization deviation of the audio signal relative to the video signal can be corrected without causing the viewer to feel uncomfortable. In particular, when the output time of the audio signal is short between the video signal and the audio signal, the synchronization error of the audio signal with respect to the video signal can be corrected by a single process. In addition, when the synchronization deviation time between the video signal and the audio signal is longer than the time zone during which no audio is output, the AV signal may be executed multiple times to synchronize the video signal and the audio signal. .

  In addition, when the time difference between the video signal and the audio signal becomes less than the reference time, for example, a time when the synchronization error is hardly recognized, the correction of the audio signal synchronization error with respect to the video signal is stopped. It is possible to prevent reversal of the progress of the video signal and audio signal due to processing.

  Furthermore, video signals with a large data capacity are subjected to normal playback processing, and the output of audio signals with a relatively small data capacity is stopped for a predetermined time or fast-forwarded by a predetermined time in order to correct the synchronization error between the video signal and the audio signal. Therefore, it is only necessary to store the audio signal for a predetermined time in the audio signal buffer (firmware memory) in the normal reproduction state, and the increase in the capacity of the entire buffer memory can be reduced. . Furthermore, in the process of correcting the synchronization deviation of the audio signal with respect to the video signal, the output of the audio signal is paused (paused) for a predetermined time, or the audio signal for a predetermined time is discarded and the audio signal is fast-forwarded (discarded). And no special software processing is required.

According to a second aspect of the present invention, there is provided a video information reading unit for reading video information from an optical disc, a separation unit for separating the video information read by the video information reading unit into a video signal and an audio signal, and the separation. Video signal decoding means for performing predetermined decoding processing on the video signal separated by the means, and audio signal decoding means for performing predetermined decoding processing on the audio signal separated by the separation means An optical disc playback apparatus using a decoder element that does not include a synchronization processing function of the video signal and the audio signal,
Information about the time of video and audio during playback is obtained from the video signal decoded by the video signal decoding unit and the audio signal decoded by the audio signal decoding unit, respectively, and the time of the acquired video and audio is obtained. When information is compared every time a certain time elapses and it is determined that the video signal and audio signal are not synchronized, when switching from fast-forward mode to playback mode or switching from pause mode to playback mode When the audio signal is ahead of the video signal in the time period when the audio is not output for a certain period of time, the output of the audio signal is stopped for a predetermined time that is equal to or less than the time difference between the video signal and the audio signal. When the audio signal is delayed from the video signal, the audio signal is sent to the audio signal by fast-forwarding the output of the audio signal by a predetermined time. No. of Correct synchronization deviation, the video signal in the case of time synchronization deviation is longer than the time period which is not output audio voice signal, a video signal until the synchronization deviation time after correction is equal to or lower than a predetermined reference time The synchronization processing of the audio signal with respect to is executed a plurality of times .

  According to such a configuration, when the video signal and the audio signal are not synchronized, for example, when switching from the fast-forward mode to the playback mode or when switching from the pause mode to the playback mode, for a certain period of time. In the time zone when the audio is not output, if it precedes the audio signal image video signal, it pauses for a predetermined time, and if the audio signal is delayed from the video signal, the output of the audio signal is set for the predetermined time. Since fast-forwarding is performed, the synchronization deviation of the audio signal with respect to the video signal can be corrected without causing the viewer to feel uncomfortable.

  Further, when the output of the video signal is stopped for a predetermined time or forwarded by a predetermined time, the audio signal for a predetermined time may be stored in an audio signal buffer (firmware memory) in a normal reproduction state. There is no need to increase the memory capacity. Further, the correction process of the synchronization deviation of the audio signal with respect to the video signal may be performed only by stopping the output of the audio signal for a predetermined time or discarding the audio signal for a predetermined time, and no special software processing is required.

  As described above, according to the first aspect of the present invention, since the output of the audio signal is stopped for a predetermined time or the output of the audio signal is fast-forwarded for the predetermined time in the time zone where the audio is not output for a certain period of time, It is possible to correct the synchronization deviation of the audio signal with respect to the video signal without giving a strange feeling to the user. In addition, when the time difference between the video signal and the audio signal becomes equal to or less than the reference time at which the synchronization error is hardly recognized, the correction of the audio signal synchronization error with respect to the video signal is stopped. It is possible to prevent reversal of the progress of the video signal and the audio signal. Furthermore, it is possible to perform the correction process of the synchronization deviation of the audio signal with respect to the video signal without increasing the buffer memory capacity and without performing complicated software processing.

  According to the second aspect of the present invention, since the output of the audio signal is stopped for a predetermined time or the output of the audio signal is fast-forwarded for the predetermined time in a time zone where the audio is not output for a certain period of time, the viewer feels uncomfortable. Without being applied, the synchronization deviation of the audio signal with respect to the video signal can be corrected. Furthermore, it is possible to perform the correction process of the synchronization deviation of the audio signal with respect to the video signal without increasing the memory capacity of the decoder element and without performing complicated software processing.

According to the second aspect of the present invention, when the deviation time between the video signal and the audio signal is short in the output of the audio signal, the synchronization deviation of the audio signal with respect to the video signal can be corrected by a single process. In addition, when the synchronization deviation time between the video signal and the audio signal is longer than the time zone during which no audio is output, the AV signal may be executed multiple times to synchronize the video signal and the audio signal. .

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The present invention relates to an optical signal reproducing apparatus using a decoder element that does not include an AV synchronization processing function, using a time zone in which no audio is output when the video signal and the audio signal are not synchronized, Is paused or fast-forwarded for a predetermined time to enable a correction process for synchronization between the video signal and the audio signal (hereinafter referred to as “AV synchronization process”).

  FIG. 1 shows an electrical block configuration of the optical disk reproducing apparatus according to the present embodiment. The optical disk reproducing apparatus 1 includes a disk insertion detection unit 2 for detecting whether or not an optical disk 70 such as a DVD is inserted at a predetermined position, a spindle motor 3 for rotating the optical disk 70 at a predetermined speed, and the optical disk 70. The optical pickup 4 for reading data recorded on the optical disk 4, the moving motor 5 for moving the optical pickup 4 in the radial direction of the optical disk 70, and the laser driving unit 6 for controlling the semiconductor laser 41 of the optical pickup 4. Output from the signal processing unit 7 for processing the signal from the photodetector 46 of the optical pickup 4, the servo control unit 8 for controlling the position of the objective lens 44 of the optical pickup 4, and the signal processing unit 7. A decoder 9 that performs a predetermined decoding process on the recorded data to generate a video signal and an audio signal; 1 is a general control unit 10 that performs overall control, a remote control device 11 that is operated by a user to input various instructions, a remote control reception unit 12 that receives signals from the remote control device 11, and an optical disc playback device 1 The display unit 13 displays necessary information according to each function. The video signal and audio signal generated by the decoder 9 are output to the monitor device 50, and the video is reproduced on the screen.

  The optical pickup 4 includes a semiconductor laser 41, a collimator lens 42, a beam splitter 43, an objective lens 44, a condenser lens 45, a light detector 46, and the like. The light emission of the semiconductor laser 41 is controlled by the laser driving unit 6 based on a signal output from the overall control unit 10. Laser light output from the semiconductor laser 41 is condensed on the optical disc 70 via the collimator lens 42, the beam splitter 43, and the objective lens 44. Reflected light from the optical disk 70 is incident on the beam splitter 43 via the objective lens 44, and the optical axis is bent by 90 degrees, and then condensed on the photodetector 46 by the condenser lens 45.

  The objective lens 44 is held by a lens holder 47. In the vicinity of the lens holder 47, a focusing coil 48 for moving the lens holder 47 in the optical axis direction of the objective lens 44 by magnetic action and a tracking for moving the lens holder 47 in the radial direction of the optical disk 70 by magnetic action. A coil 49 is provided. The focusing coil 48 and the tracking coil 49 are respectively controlled by the servo control unit 8 to finely adjust the positions of the lens holder 47 and the objective lens 44 held thereon. The servo control unit 8 adjusts the position of the objective lens 44, that is, the condensing position of the laser beam, based on a focusing error signal and a tracking error signal, which will be described later, while monitoring the signal output from the signal processing unit 7.

  The light detector 46 is a photoelectric conversion element such as a divided photodiode in which the attendance surface is divided into a plurality of regions, for example, and the intensity of the reflected light from the collected optical disk 70 is determined for each light receiving region of the light receiving surface. Convert to electrical signal and output. The entire optical pickup 4 is moved in the radial direction of the optical disk 70 by a moving motor 5 constituted by a linear motor or the like.

  The signal processing unit 7 generates an RF signal (reflection intensity) corresponding to data recorded on the optical disc 70, a focusing error signal, and a tracking error signal from the signal output from the photodetector 46. The RF signal is output to the decoder 9, and the focusing error signal and tracking error signal are output to the servo control unit 8. The decoder 9 performs a predetermined decoding process on the RF signal from the signal processing unit 7 to generate a video signal and an audio signal. Details of the decoder 9 will be described later.

  The remote control device 11 is operated by the user when playing back the video recorded on the optical disc 70 or selecting various functions provided in the optical disc apparatus 1, and the operation keys corresponding to the various functions. Is provided. When the operation keys are operated, a code signal corresponding to each operation key is transmitted as an infrared signal. The remote control receiving unit 12 receives an infrared signal from the remote control device 11, converts it into a predetermined electrical signal, and inputs it to the overall control unit 10.

  The overall control unit 10 includes a ROM that stores a control program, a CPU that performs arithmetic processing in accordance with the control program, a RAM that temporarily stores a control program and data, and the like. The entire optical disc playback apparatus 1 is controlled in accordance with a user instruction input via the control.

  Next, FIG. 2 shows a block configuration of the decoder 9 in the present embodiment. The decoder 9 includes a video / audio separation unit 91 for separating the RF signal from the signal processing unit 7 from the video signal and the audio signal unit, a video signal buffer 92 for temporarily storing the separated video signal, The audio signal buffer 93 for temporarily storing the separated audio signal, and the video signal for each image (one frame) output from the video signal buffer 92 are sequentially decoded according to the MPEG2 standard. The audio signal decoder 94 for decoding the audio signal output from the audio signal buffer 93 in accordance with the MP3 standard, and the currently reproduced video signal and audio signal from the decoded video signal and audio signal. A time information acquisition unit 96 that acquires (extracts) information (time information) related to the current time regarding video and audio, time information of the video signal, and time information of the audio signal. In comparison, it is determined whether the video signal and the audio signal are synchronized, and when the video signal and the audio signal are not synchronized, which of the video signal and the audio signal is preceded and the deviation time thereof are determined. And a synchronization deviation correction unit 98 that corrects the synchronization deviation under a certain condition when a synchronization deviation occurs between the video signal and the audio signal.

  In this embodiment, the video signal decoder 94 and the audio signal decoder 95 are composed of MPEG decoder elements or the like that do not have an AV synchronization processor function, and are synchronized when the video signal and the audio signal are out of synchronization. The shift correction unit 98 corrects the synchronization shift between the video signal and the audio signal by firmware processing.

  Next, correction of the synchronization deviation between the video signal and the audio signal in the present embodiment will be described. As described above, the synchronization error between the video signal and the audio signal is caused by an audio gap in which no audio signal is recorded corresponding to the video signal, or by an error in reading video information due to scratches or dirt on the optical disc 70. Can also happen. In addition to the case where the audio signal precedes the video signal, the video signal may precede the audio signal.

  By the way, like the well-known afterimage phenomenon, the response speed of human vision is slow, and it cannot cope with a rapid change in brightness or a rapid change in image. Comparing visual characteristics and auditory characteristics, auditory characteristics are more sensitive. Therefore, when the video signal and the audio signal are not synchronized, changing the video signal to synchronize with the audio signal is more effective than changing the audio signal to synchronize with the video signal. It is hard to notice. In addition, when the audio signal precedes the video signal, the viewer tends to notice the synchronization deviation more than when the audio signal precedes the audio signal.

  However, since the video signal has a very large data capacity, in order to synchronize the video signal with the audio signal, the memory capacity of the video signal buffer 92 for storing the video signal for a predetermined time is very large. Must be bigger. On the other hand, the data capacity of the audio signal is relatively small, and the memory capacity of the audio signal buffer 93 for storing the audio signal for a predetermined time need not be so large.

  Therefore, in this embodiment, when the video signal and the audio signal are not synchronized, for example, when switching from the fast-forward mode to the playback mode or when switching from the pause mode to the playback mode, the audio signal is output for a certain period of time. If the audio signal is ahead of the video signal during the time period when the video signal is not output, the output of the audio signal is stopped for a predetermined time less than or equal to the time difference between the video signal and the audio signal. When the signal is behind the video signal, the audio signal output is fast-forwarded by a predetermined time to correct the synchronization deviation of the audio signal with respect to the video signal.

  In addition, as a timing for executing the AV synchronization processing, a time zone in which audio is not output for a certain period of time is used, such as switching from the fast-forward mode to the playback mode and switching from the pause mode to the playback mode. These mode switchings are not frequently performed. Therefore, in the normal playback mode, the viewer cannot hear the sound (silence mode), that is, the sound signal is output, but the level is almost 0 or the viewer can hear the sound. The AV synchronization process may be executed using a time zone below a certain level.

  The time information acquisition unit 96 reads the time information included in the video signal and the audio signal separately for the image signal and the video signal currently being reproduced. When the video signal and the audio signal are synchronized, the time information read out separately matches. However, when the video signal and the audio signal are not synchronized, both are slightly shifted. Therefore, the synchronization shift discriminating unit 97 compares the time information on the currently reproduced video signal and audio signal acquired by the time information acquiring unit 96, and the audio signal precedes or delays the video signal. And the time of the synchronization deviation between the video signal and the audio signal is obtained. Then, the determination result and the time of synchronization deviation are output to the synchronization deviation correction unit 98.

Based on the determination result output from the synchronization error determination unit 97 and the time of synchronization error, the synchronization error correction unit 98 uses a time zone during which audio is not output for a certain period of time before the audio signal image signal. synchronization error and stops the output of the audio signal by a predetermined time when being also by fast-forward predetermined time period the output of the audio signal when the audio signal is delayed from the video signal, the audio for the video signal signal To correct. More specifically, the audio signal buffer 93 is controlled to stop outputting the audio signal from the audio signal buffer 93 to the audio signal decoder 95 for a predetermined time, or discard the audio signal for a predetermined time.

  The predetermined time concerning the pause (pause) of the output of the audio signal or the fast-forwarding (discard) of the audio signal is basically a predetermined time that is shorter than or shorter than the time of synchronization between the video signal and the audio signal. That is, when the audio signal is ahead of the video signal, output of the audio signal is stopped for the preceding time, and output of the audio signal is resumed at the timing when the video signal and the audio signal are synchronized. That's fine. Further, when the audio signal is delayed with respect to the video signal, the output of the audio signal may be discarded for the delay time.

  When the AV synchronization processing of the video signal and the audio signal by stopping the output of the audio signal or discarding the audio signal is executed in the normal playback mode, the audio is interrupted for a predetermined time or the audio becomes discontinuous. Give an unnatural impression. Therefore, when the viewer operates the remote controller 11 to switch from the fast-forward mode to the playback mode or when the viewer switches from the pause mode to the playback mode, for example, a time zone in which no audio is output for a certain period of time is used. Then, AV synchronization processing of the video signal and the audio signal is executed. Alternatively, as described above, in a normal playback mode, the viewer cannot hear the sound, that is, the sound signal is output, but the level is almost 0 or the viewer can hear the sound. The AV synchronization processing is executed using a time zone below a certain level.

  If the synchronization time of the video signal and the audio signal is longer than the time period during which no audio is output, the video signal and the audio signal may not be synchronized in one AV synchronization process. In that case, the AV synchronization process may be executed a plurality of times to synchronize the video signal and the audio signal. In that case, a time shorter than the synchronization deviation time between the video signal and the audio signal may be selected as the predetermined time for the output pause or fast-forward of the audio signal in one AV synchronization process.

  On the contrary, the synchronization deviation time between the video signal and the audio signal is short and there is no particular problem even if the AV synchronization processing is not performed. As a result of performing the AV synchronization processing a plurality of times, the prior relationship between the video signal and the audio signal is reversed. There is also a case where it ends up. Therefore, the synchronization error correcting unit 98 does not execute the AV synchronization process from the beginning and executes the AV synchronization process when the synchronization error time of the video signal and the audio signal is equal to or shorter than a predetermined reference time (for example, 30 ms). When the time difference between the video signal and the audio signal becomes less than the reference time, the AV synchronization process is stopped.

  Next, the synchronization deviation correction process in this embodiment will be described with reference to the flowchart shown in FIG. This flow is executed every time a fixed time elapses.

  First, the synchronization shift discriminating unit 97 waits for the fixed time to elapse (# 1), and obtains each time information from the decoded video signal and audio signal output from the video signal decoder 94 and the audio signal decoder 95. It acquires (# 2) and compares the acquired time information, and determines whether or not a synchronization shift of a predetermined time or more has occurred between the video signal and the audio signal (# 3). When the video signal and the audio signal are synchronized or when the time of the synchronization shift between the video signal and the audio signal is smaller than a predetermined time (for example, 30 ms) (NO in step # 3), the AV synchronization process is not performed. The synchronization error correcting unit 98 does not execute the AV synchronization process, and the synchronization error determining unit 97 returns to step # 1 and waits for a certain period of time to prepare for the next AV synchronization process.

  When a synchronization shift of a predetermined time or more has occurred between the video signal and the audio signal (YES in step # 3), the synchronization shift determination unit 97 indicates that the level of the audio signal is almost 0 or the audio is sent to the viewer. The sound muting mode is turned on (# 4) so as to wait for a period (silence period) during which the sound is not heard or below a predetermined level. Further, the synchronization deviation determination unit 97 determines whether the audio signal precedes the video signal (# 5). When the audio signal is ahead of the video signal (YES in step # 5), the synchronization deviation determination unit 97 outputs a pause signal to pause the synchronization deviation correction unit 98 for a predetermined time. To do. The synchronization shift correcting unit 98 waits for the timing of performing AV synchronization processing, that is, the time zone when no audio is output, and causes the audio signal buffer 93 to pause (pause) the output of the audio signal for a predetermined time. (# 6). Thereby, the advance of the audio signal with respect to the video signal is reduced by a predetermined time (for example, 20 ms).

  On the other hand, when the audio signal is delayed with respect to the video signal (NO in step # 5), the synchronization deviation determination unit 97 causes the synchronization deviation correction unit 98 to advance the output of the audio signal by a predetermined time. Output a fast-forward signal. The synchronization error correcting unit 98 waits for the time zone when no sound is output, and controls the audio signal buffer 93 to fast-forward (discard) the audio signal for a predetermined time (# 7). Thereby, the delay of the audio signal with respect to the video signal is reduced by a predetermined time.

  Next, the synchronization deviation determining unit 97 determines that the synchronization deviation time (time difference between video and audio) after the output of the audio signal is paused or fast-forwarded in step # 6 or # 7 is a predetermined reference value. It is determined whether or not the time is below (for example, 30 ms) (# 8). When the corrected synchronization deviation time is equal to or less than the reference value (YES in Step # 8), it is not necessary to perform AV synchronization processing any more, so the mute mode is turned off (# 9), and the synchronization deviation correction unit 98 performs AV End the synchronization process. Also, the synchronization deviation determination unit 97 returns to step # 1 and waits for a certain period of time to prepare for the next AV synchronization process. On the other hand, if the corrected synchronization time is longer than the reference value (NO in step # 8), the synchronization error between the video signal and the audio signal is not sufficiently corrected by one AV synchronization process. The above steps # 5 to # 8 are repeated until the time of synchronization loss becomes equal to or less than the reference luck time.

In the above embodiment, the AV synchronization processing is performed for both the case where the audio signal precedes the video signal and the case where the audio signal is delayed. It is not limited. As described above, since the human auditory characteristics are more sensitive than the visual characteristics, even if the audio signal is slightly ahead of the video signal, it is possible to enjoy the video without much discomfort. Therefore, the AV synchronization processing may be performed only when the audio signal precedes the video signal. Further, when the progress of the audio signal with respect to the video signal reaches about 100 ms, it is recognized that the video and the audio clearly do not match (so-called “mouth” state), and a sense of incongruity occurs. Therefore, the AV synchronization processing may be performed only when the audio signal precedes the video signal by a predetermined time (for example, 100 ms).
Further, in the silence mode in steps # 4 to # 9, the synchronization error correcting unit 98 is configured to wait for a silence period in which the level of the audio signal is almost 0 or less than a predetermined level at which no audio can be heard by the viewer. However, in order to correct the synchronization error in a short time, the level of the audio signal may be forcibly lowered so that the level of the audio signal is approximately 0 or below a predetermined level.

The electrical block block diagram of the optical disk reproducing | regenerating apparatus by one Embodiment of this invention. The block block diagram of the decoder in the said one Embodiment. The flowchart which shows the synchronization shift correction process in the said one Embodiment. The block diagram which shows the structure of a prior art example.

Explanation of symbols

1 optical disk playback device 4 optical pickup (image information reading means)
7 Signal Processing Unit 9 Decoder 10 Overall Control Unit 70 Optical Disc 91 Video / Audio Separation Unit (Separation Means)
92 Video signal buffer 93 Audio signal buffer 94 Video signal decoder (video signal decoding means)
95 Audio signal decoder (Audio signal decoding means)
96 Time information acquisition unit (time information acquisition means)
97 Synchronization deviation determination unit (Synchronization deviation determination means)
98 Synchronization deviation correction unit (Synchronization deviation correction means)

Claims (2)

Video information reading means for reading video information from an optical disc, separation means for separating video information read by the video information reading means into a video signal and an audio signal, and a video signal separated by the separation means Video signal decoding means for performing decoding processing in accordance with the MPEG2 standard, and audio signal decoding means for performing decoding processing in accordance with the MP3 standard on the audio signal separated by the separating means, An optical disk playback device using a decoder element that does not include a synchronization processing function of the video signal and the audio signal,
Time information acquisition means for acquiring information about the time of video and audio during reproduction from the video signal decoded by the video signal decoding means and the audio signal decoded by the audio signal decoding means;
The information about the time of the video and audio acquired by the time information acquisition means is compared every time a predetermined time elapses, and when there is a synchronization shift between the video signal and the audio signal for a predetermined time or more, Determine which of the audio signals is ahead, and determine whether the synchronization deviation time of the video signal and the audio signal after the synchronization deviation correction is corrected by the synchronization deviation correction means described below has become a predetermined reference time or less. A synchronization deviation determining means,
When it is determined by the synchronization deviation determination means that a synchronization deviation of a predetermined time or more has occurred, an audio signal is output for a certain period of time when switching from fast-forward mode to playback mode or switching from pause mode to playback mode. Audio signal is output, but the level is almost zero, or waits for a time period below a certain level where the viewer cannot hear audio. When the audio signal is ahead of the video signal, the output of the audio signal is stopped for a predetermined time that is equal to or less than the time difference between the video signal and the audio signal, and the audio signal is delayed from the video signal. by fast-forward predetermined time period the output of the audio signal when you are, correct the synchronization error of the audio signal to the video signal, the time synchronization deviation of the video signal and the audio signal, the audio If longer than the time period that has not been output, multiple runs of synchronization processing of the audio signal to the video signal, when the synchronization deviation time after correction is equal to or less than the reference time, the audio signal to the video signal sync An optical disc reproducing apparatus comprising synchronization deviation correction means for ending correction of deviation. Video information reading means for reading video information from an optical disc, separation means for separating video information read by the video information reading means into a video signal and an audio signal, and a video signal separated by the separation means Video signal decoding means for performing predetermined decoding processing on the audio signal, and audio signal decoding means for performing predetermined decoding processing on the audio signal separated by the separation means, An optical disk playback apparatus using a decoder element that does not include the audio signal synchronization processing function,
Information about the time of video and audio during playback is obtained from the video signal decoded by the video signal decoding unit and the audio signal decoded by the audio signal decoding unit, respectively, and the time of the acquired video and audio is obtained. When information is compared every time a certain time elapses and it is determined that the video signal and audio signal are not synchronized, when switching from fast-forward mode to playback mode or switching from pause mode to playback mode When the audio signal is ahead of the video signal in the time period when the audio is not output for a certain period of time, the output of the audio signal is stopped for a predetermined time that is equal to or less than the time difference between the video signal and the audio signal. When the audio signal is delayed from the video signal, the audio signal is sent to the audio signal by fast-forwarding the output of the audio signal by a predetermined time. No. of Correct synchronization deviation, the video signal in the case of time synchronization deviation is longer than the time period which is not output audio voice signal, a video signal until the synchronization deviation time after correction is equal to or lower than a predetermined reference time An optical disk reproducing apparatus, wherein a synchronization process of an audio signal is executed a plurality of times .

Images