JP2007221421A - Video audio reproducing system, av center constituting same, and monitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a video audio reproducing system capable of obtaining and setting an exact delay time of a synchronized audio signal to a video signal so that videos to be reproduced can be synchronized with audios. <P>SOLUTION: In the video audio reproducing system, an AV center has a control circuit, and a delay synchronizing circuit for delaying an audio signal to execute synchronization processing between the video signal and the audio signal. The delay synchronization circuit includes an audio delay circuit for delaying the audio signal; a video detecting circuit to be connected to a light receiver; and a test signal output circuit for reproducing a test video signal alternately including white and black video signals. The control circuit calculates a delay time of a test video image reproduced from a monitor corresponding to the test video signal detected by the video detecting circuit, and sets it at a delay time of the audio delay circuit of the delay synchronization circuit. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention comprises a monitor that reproduces a video signal as a video, an AV center and a speaker that reproduces an audio signal synchronized with the video signal as audio, and reproduces the video and audio synchronized with each other. About the system.

  When playing back content including a video signal synchronized with an audio signal such as a movie, it is played back from an AV center (equipment such as an AV amplifier, AV selector, controller, etc. that reproduces the video signal and audio signal) and a speaker. For example, an image reproduced on a monitor with a built-in liquid crystal display may be delayed due to a delay due to an image conversion process on the monitor or an image signal transmission process. Depending on the configuration of the video / audio playback system, the delay of the playback video with respect to the playback audio may be about 30 to 100 msec. As a result, the viewer may feel uncomfortable that the playback timing of the video and the audio does not match. is there.

  Conventionally, in order to solve this problem, signal processing for delaying an audio signal synchronized with a video signal is performed. For example, a video / audio reproduction system includes a DVD player that reproduces a synchronized MPEG-2 video signal and an ATSC audio signal, an AV center that receives a reproduction signal from the DVD player, a monitor that is connected to the AV center, and an AV center. The AV center performs signal processing for delaying the audio signal, so-called “lip sync” or “AV Sync”, for about 0 to 300 msec. There is one that can set the delay time in the range. In addition, when a video / audio reproduction system is connected via a network such as HDMI (High-Definition Multimedia Interface) or IEEE1394 (i-Link) standard, a transmission time delay in the network may occur. In some cases, lip sync processing including this is performed (Patent Document 1).

  Conventionally, using a light source and a sound source that emit light at equal time intervals, the light emission state and the sound generation state are picked up and picked up by a television camera and a microphone, respectively, to detect the time difference between video and sound. There is a configuration in which a video signal and an audio signal are generated to obtain a delay time difference, and synchronization between reproduced video and audio is realized (Patent Document 2).

JP 2002-344898 A (FIG. 1) Japanese Patent Laid-Open No. 10-145645 (FIG. 3)

  However, with the conventional method, it has been difficult to achieve accurate video and audio synchronization. For example, the propagation speed of sound in the air is about 340 m / sec, and it is an order that requires only about 3 msec for propagation at a distance of 1 m. Therefore, in the AV center, the sound signal is represented by a representative sampling frequency of 44.1 kHz. In this case, fine delay processing can be performed in units of about 22.68 μsec. On the other hand, the video signal typically has a wide width of about 1/30 second, that is, about 30 msec in one frame in the NTSC system, so it may be difficult to set the delay time of the synchronized audio signal accurately. There is a problem that an accurate audio delay time cannot be set.

  The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention relates to a video / audio reproduction system and an AV center and a monitor constituting the same, so that reproduced video and audio are synchronized. Another object of the present invention is to provide a video / audio reproduction system capable of obtaining and setting an accurate delay time for a synchronized audio signal with respect to a video signal.

  The video / audio reproduction system of the present invention includes a monitor that reproduces a video signal as a video, an AV center and a speaker that reproduces an audio signal synchronized with the video signal as audio, a light receiver that detects a video reproduced from the monitor, The AV center includes a control circuit that controls the operation of the AV center, and a delay synchronization circuit that delays the audio signal to perform synchronization processing of the video signal and the audio signal. An audio delay circuit for delaying, a video detection circuit connected to the optical receiver, and a test signal output circuit for reproducing a test video signal including alternating white and black video signals, the control circuit including the video detection circuit The delay time of the test video corresponding to the detected test video signal is calculated, and the delay time is set to the delay time of the audio delay circuit of the delay synchronization circuit.

  Preferably, in the video / audio reproduction system of the present invention, the video detection circuit of the delay synchronization circuit amplifies the output signal of the light receiver, the video level detection circuit to which the output signal from the video amplification circuit is input, The video level detection circuit detects a change from white to black or a change from black to white in the test video reproduced from the monitor.

  Preferably, in the video / audio reproduction system of the present invention, the video level detection circuit has a reference white level value corresponding to the white color of the test video and a reference black level value corresponding to the black color of the test video. A change from white to black or a change from black to white in the test video is detected using an intermediate value between the level value and the reference black level value as a threshold value.

  More preferably, in the video / audio reproduction system according to the present invention, the light receiving element of the light receiver is located at a position where the ((N / 2) +1) th scanning line scans among all scanning lines N scanning the monitor screen. It arrange | positions so that the image | video of the screen center vicinity may be detected.

  The video / audio reproduction system of the present invention further includes a microphone for detecting audio reproduced from a speaker, the AV center delay synchronization circuit further includes an audio detection circuit connected to the microphone, and a test signal output circuit is provided. Output a test audio signal that changes in synchronization with the change of the test video signal from white to black, or from black to white, and the control circuit outputs a video detection circuit for the test audio detected by the audio detection circuit. The delay time of the detected test video is calculated, and the delay time is set to the delay time of the audio delay circuit of the delay synchronization circuit.

  Preferably, in the video / audio reproduction system of the present invention, the audio detection circuit of the delay synchronization circuit includes a microphone amplification circuit that amplifies the output signal of the microphone, and an audio level detection circuit that receives the output signal of the microphone amplification circuit. In addition, the audio level detection circuit detects a change in the test video signal reproduced from the speaker corresponding to a change from white to black in the test video signal or a change from black to white.

  Preferably, in the video / audio reproduction system of the present invention, the test audio signal is burst white noise including a white noise interval corresponding to white of the test video signal and a silent interval corresponding to black of the test video signal, The sound level detection circuit has a reference sound level value corresponding to the white noise interval of the test sound and a reference sound level value corresponding to the sound interval of the test sound. The reference sound level value and the reference sound level value The change in the white noise section and the silent section of the test voice is detected using the intermediate value between and as a threshold value.

  More preferably, the time obtained by subtracting the delay associated with the time constant of the filter for smoothing the output from the light receiving element of the light receiver from the delay time of the test signal detected by the delay synchronizing circuit is added to the audio signal of the delay synchronizing circuit. Delay time.

  The AV center of the present invention includes a delay synchronization circuit and an amplifier circuit that constitute a video / audio reproduction system.

  The monitor of the present invention includes a light receiver that constitutes a video / audio reproduction system.

  The operation of the present invention will be described below.

  The video / audio reproduction system of the present invention includes at least a monitor for reproducing a video signal as video, an AV center for reproducing an audio signal synchronized with the video signal as audio, a speaker connected to an amplifier circuit of the AV center, and a monitor. And a light receiver for detecting the reproduced image. In addition to the amplifier circuit, the AV center includes a control circuit that controls the operation of the AV center, and a delay synchronization circuit that delays the audio signal to perform synchronization processing between the video signal and the audio signal. An audio delay circuit that delays the audio signal, an image detection circuit connected to the optical receiver, and a test signal output circuit that reproduces a test video signal that alternately includes white and black video signals.

  Here, since the optical receiver for receiving the test video reproduced from the monitor is connected to the video detection circuit of the delay synchronization circuit of the AV center, the control circuit of the AV center detects the test video signal detected by the video detection circuit. It is possible to calculate the delay time of the test video reproduced from the monitor corresponding to. Therefore, the calculated delay time can be set as the delay time of the audio delay circuit of the delay synchronization circuit, and the video delay caused by the video conversion on the monitor with respect to the reproduced audio is eliminated. Can be synchronized.

  Specifically, the video detection circuit of the delay synchronization circuit of the AV center includes a video amplification circuit that amplifies the output signal of the light receiver, and a video level detection circuit that receives the output signal from the video amplification circuit, The video level detection circuit detects a change from white to black or a change from black to white in the test video reproduced from the monitor. The video level detection circuit has a reference white level value corresponding to white of the test video and a reference black level value corresponding to black of the test video, and an intermediate value between the reference white level value and the reference black level value is obtained. As the threshold value, a change from white to black or a change from black to white in the test video is detected. In addition, the light receiving element of the light receiver detects an image near the center of the screen corresponding to the position scanned by the ((N / 2) +1) th scanning line among all the scanning lines N that scan the monitor screen. Placed in.

  For example, it takes about 30 (?) Msec for all the scanning lines to scan the monitor screen. Therefore, for the viewer's vision, the time when the image is recognized as changing from white to black, for example, is the most. The appropriate timing is not the timing at which the first scanning line of all scanning lines N starts scanning, nor is the timing at which the last scanning line of all scanning lines N finishes scanning. This is the timing when the scanning line near the center of the screen changes from white to black. The light receiving element of the light receiver arranged so as to detect the image near the center of the screen of the monitor accurately detects the timing when the test image changes to white and black visually. , More accurate voice delay time can be set.

  The video / audio reproduction system according to the present invention further includes a microphone installed at a viewer's position, and an audio detection circuit connected to the delay synchronization circuit of the AV center. The test signal output circuit includes a test video output circuit. You may output the test audio | voice signal which changes synchronizing with the change from white to black of a signal, or the change from black to white. The audio detection circuit of the delay synchronization circuit includes a microphone amplification circuit that amplifies the output signal of the microphone, and an audio level detection circuit to which the output signal of the microphone amplification circuit is input. A change in the test sound reproduced from the speaker corresponding to the change from white to black or the change from black to white is detected. The test audio signal is burst white noise including a white noise interval corresponding to white of the test video signal and a silence interval corresponding to black of the test video signal.

  Therefore, the delay time of the test video detected by the video detection circuit via the optical receiver for the test audio detected by the voice detection circuit via the microphone can be set as the delay time of the audio delay circuit of the delay synchronization circuit. As a result, the video and audio can be synchronized, including the audio delay time associated with the propagation distance from the speaker to the viewer. The time obtained by subtracting the delay associated with the time constant of the filter that smoothes the output from the light receiving element of the light receiver from the delay time of the test signal detected by the delay synchronization circuit is defined as the delay time for the audio signal of the delay synchronization circuit. Thus, a more accurate voice delay time can be set.

  The video / audio reproduction system of the present invention and the AV center and the monitor constituting the video / audio reproduction system seek an accurate delay time from the video signal to the synchronized audio signal so that the video and audio reproduced better for the viewer are synchronized. Can be set.

  In the video / audio reproduction system of the present invention, the AV center performs the operation of the AV center for the purpose of obtaining and setting an accurate delay time for the synchronized audio signal with respect to the video signal so that the reproduced video and audio are synchronized. A control circuit for controlling, a delay synchronization circuit for delaying the audio signal and performing a synchronization process between the video signal and the audio signal, and the delay synchronization circuit is connected to the audio delay circuit for delaying the audio signal and the optical receiver Including a video detection circuit and a test signal output circuit for reproducing a test video signal including alternating white and black video signals, and a control circuit delays a test video corresponding to the test video signal detected by the video detection circuit This was realized by calculating the time and setting the delay time to the delay time of the audio delay circuit of the delay synchronization circuit.

  Hereinafter, a video / audio reproduction system and an AV center and a monitor constituting the same according to preferred embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

  FIG. 1 is a diagram illustrating a video / audio reproduction system 100 according to a preferred embodiment of the present invention. The video / audio reproduction system 100 includes a DVD player 1, an AV center 2 to which a reproduction signal from the DVD player 1 is input, a monitor device 3 connected to the AV center 2, and a plurality of amplifier circuits connected to the AV center 2. It comprises speakers 41 to 45, a light receiver 5 and a microphone 6 connected to the AV center 2. The video / audio reproduction system 100 reproduces the video V from the monitor device 3 and the audio described later from the speakers 41 to 45 arranged around the viewer (not shown) at the viewing position 10, The video / audio content recorded on the recording medium (DVD disc) played back by the DVD player 1 is played back.

  Here, the plurality of speakers 41 to 45 are center speaker 41 in the front direction, left speaker 42 in the left front direction, and right speaker in the right front direction, with the direction in which monitor device 3 is arranged from viewing position 10 as the front. 43, a left surround speaker 44 in the left rear direction, and a right surround speaker 45 in the right rear direction, and reproduces a so-called 5-channel surround sound field. Center channel sound C is reproduced from the center speaker 41 in the front direction, and left channel sound, right channel sound, left surround channel sound and right surround channel sound are also reproduced from the other speakers 42 to 45, respectively. In FIG. 1, connection lines between the AV center 2 and the other speakers 42 to 45 are omitted for simplification of the drawing except for the connection lines between the AV center 2 and the center speaker 41 which are clearly shown. ing. In the following description, unless otherwise specified, the description of the audio reproduction will be made in the case where the center channel audio C is representatively reproduced, and the reproduction of the other channel audio follows the center channel audio C.

  The DVD player 1 reads and reproduces a synchronized video signal and audio bit stream recorded from a recording medium (DVD disc), and a video signal and audio bit stream multiplexed by HDMI at the input terminal of the AV center 2. Enter. Of course, the playback data of the synchronized video / audio content input to the AV center 2 is not limited to that played back by the DVD player 1, but is received by a receiver that receives other broadcasts or a data communication device connected to the Internet. There may be.

  The AV center 2 has a CPU 20 that controls the operation of the AV center 2 and a separation circuit 21 that separates the input video signal and audio bitstream multiplexed by HDMI into video data Vd and audio data Ad, respectively. A delay synchronization circuit 22 for delay-synchronizing the video V and the center channel audio C to be reproduced by receiving the output of the separation circuit 21, and a plurality of amplifiers 23 (shown in FIG. 1) connected to the speakers 41 to 45. Center channel audio C only). Under the control of the CPU 20, the delay synchronization circuit 22 outputs the video data Vd to the monitor device 3 by HDMI, and as a result, the video V is reproduced from the monitor device 3. The delay synchronization circuit 22 decodes the audio data Ad into a 5-channel audio signal, outputs the center channel audio signal Cs to the center speaker 41 via the amplifier 23, and the center channel audio C is reproduced from the center speaker 41. Is done.

  The monitor device 3 includes a CPU 30 that controls the operation of the monitor device 3, a video conversion circuit 31 to which the video data Vd is input, and a liquid crystal display 32 that receives the output of the video conversion circuit 31 and reproduces the video V. Including. In the video conversion circuit 31, it may take a long time to convert the video data Vd into a video signal that can be displayed on the liquid crystal display 32. For example, when the video data Vd is a video signal and the liquid crystal display 32 is D1 standard (525i) scanning 525 lines per frame, it may take about 30 to 100 msec.

  The light receiver 5 includes a lens (not shown), a CCD (semiconductor light receiving element), and a CCD output circuit that outputs the output of the CCD to the AV center 2. The CCD converts light input to the pixel through a lens into an electrical signal. The light receiver 5 installed at the viewing position 10 and having the lens directed toward the monitor device 3 receives the video V reproduced from the liquid crystal display 32 of the monitor device 3 and converts the light of the video V into an electrical signal. . The CCD output circuit outputs an electrical signal from the CCD to the delay synchronization circuit 22 of the AV center 2.

  The microphone 6 includes a capacitor microphone unit (not shown) and a preamplifier circuit that amplifies the output of the capacitor microphone unit and outputs the output to the AV center 2 that connects the output. For example, when the audio data Ad includes only the center channel audio data Cd, the microphone 6 installed at the viewing position 10 receives the center channel audio C reproduced from the center speaker 41 and outputs the center channel audio C. Convert to electrical signal. The preamplifier circuit outputs the electrical signal from the microphone 6 to the delay synchronization circuit 22 of the AV center 2.

  The center speaker 41 is installed in the vicinity of the monitor device 3 in the front direction in which the monitor device 3 is arranged from the viewing position 10, that is, at a distance Y from the viewing position 10. Specifically, since the distance Y is generally about 1 m to 6 m, the center channel sound C reproduced by the center speaker 41 reaches the viewing position 10 with a transmission time of about 1 to 18 msec.

  The liquid crystal display 32 of the monitor device 3 is arranged in the front direction at a distance X from the viewing position 10. Specifically, when the video / audio reproduction system 100 is used in a general home, the distance X is also substantially equal to the distance Y, and is generally about 1 m to 6 m. The light receiver 5 installed at the viewing position 10 detects the video V reproduced from the monitor device 3, and the time during which the light is transmitted through the distance X is so short that it can be ignored. It has almost nothing to do with synchronized playback. On the other hand, the processing time (about 30 to 100 msec) associated with the video conversion in the video conversion circuit 31 of the monitor device 3 described above is synchronized with the video V and the audio C even when compared with the transmission time of the center channel audio C described above. It has the greatest impact on playback. Therefore, the delay synchronization circuit 22 of the AV center 2 performs a process of delaying an audio signal that is reproduced earlier than the video in order to realize synchronized reproduction of the video and audio at the viewing position 10.

  FIG. 2 is a diagram for explaining the configuration of the delay synchronization circuit 22 of the AV center 2. The delay synchronization circuit 22 includes an audio delay circuit 24 to which the audio data Ad from the separation circuit 21 is input, a video detection circuit 25 connected to the light receiver 5, an audio detection circuit 26 connected to the microphone 6, and a test signal output. A circuit 27 and a switch circuit 28 are included. The operation of the delay synchronization circuit 22 is controlled by the CPU 20, and specifically includes a DSP (Digital Signal Processor), a delay delay circuit having a memory, a digital / analog conversion circuit, an operational amplifier, and the like.

  The audio delay circuit 24 receives the audio data Ad and decodes it into 5-channel surround signal data C0, L0, R0, LS0, and RS0, a delay circuit 24b that delays the surround signal data, and a delay And a digital / analog converter 24c for converting the surround signal data delayed from the circuit 24b into surround signals Cs, Ls, Rs, LSs and RSs of analog signals. The surround signals Cs, Ls, Rs, LSs, and RSs output from the digital / analog converter 24c are input to a plurality of amplifiers 23 of the AV center 2, respectively.

  The video detection circuit 25 includes a video amplification circuit 25a that amplifies the output signal of the light receiver 5, and a video level detection circuit 25b that receives the output signal from the video amplification circuit 25a. The video level detection circuit 25b detects a change from white to black or a change from black to white in the test video, and the detection result is notified to the CPU 20.

  The sound detection circuit 26 includes a microphone amplification circuit 26a that amplifies the output signal of the microphone 6, and a sound level detection circuit 26b that receives the output signal of the microphone amplification circuit 26a. The sound level detection circuit 26b performs white noise of the test sound in the test sound to be described later that is reproduced from the speakers 41 to 45 corresponding to the change of the test video signal to be described later from white to black or from black to white. Changes in sections and silent sections are detected. The CPU 20 is also notified of the detection result in the audio level detection circuit 26b.

  The test signal output circuit 27 is a test video signal output circuit 27a that reproduces the test video signal data Tvd that alternately includes video signals that are white and black in one frame and are continuous for a predetermined time, and the test video signal data Tvd from white to black. White noise corresponding to the white color of the test video signal data Tvd and the silent period corresponding to the black color of the test video signal data Tvd in synchronization with the change in color or the change from black to white A test audio signal output circuit 27b for reproducing the test audio signal data Tad. For example, the test video signal data Tvd is an image in which white and black are alternately switched at intervals of about 10 seconds, and the test audio signal data Tad has the same white noise and silent period corresponding to white and black. This is a test signal that is reproduced as voice alternately at intervals of about 10 seconds. Test video signal data Tvd and test audio signal data Tad output from the test signal output circuit 27 are output by a control command from the CPU 20 and input to a switch circuit 28 described later.

  The switch circuit 28 outputs the video data Vd and the audio data Ad input from the DVD player 1 to the monitor device 3 and the speakers 41 to 45 from the delay synchronization circuit 22 according to a control command from the CPU 20, or a test signal output circuit. The test video signal data Tvd and the test audio signal data Tad output from 27 are switched. Here, the switch circuit 28 is a set of at least two switches 28a and 28b corresponding to the test video signal and the test audio signal, and when the audio delay time of the audio delay circuit 24 of the delay synchronization circuit 22 is adjusted. The CPU 20 issues a command to switch to the switch circuit 28a, and outputs the test video signal data Tvd to the video conversion circuit 31 of the monitor device 3. Further, the CPU 20 issues a command to switch to the switch circuit 28 b and outputs the test sound signal data Tad to the delay circuit 24 b of the sound delay circuit 24. For example, the switch circuit 28b may be set inside the audio delay circuit 24 as shown, and the test audio signal data Tad is switched to the audio data C0 and output to the center speaker 41. Of course, when adjusting the audio delay time of the audio delay circuit 24 of the surround audio channel corresponding to the other speakers 42 to 45, the switch circuit 28b provided in each surround audio channel operates to test the audio signal data. Tad is output to each speaker.

  FIG. 3 is a diagram for explaining the operation of setting the audio delay time Tx of the audio delay circuit 24 of the delay synchronization circuit 22, that is, the operation of setting “AV Sync”. FIG. 3A schematically shows a setting operation of the CPU 20 of the AV center 2 including a time flow. When the operation of “AV Sync” is started for the first time, the CPU 20 gives a control command to the switch circuit 28 so as to switch the switch to output the test video signal data Tvd and the test audio signal data Tad. (S301).

  The CPU 20 gives a control command to the test signal output circuit 27 of the audio delay circuit 24, and the test signal output circuit 27 outputs test video signal data Tvd and test audio signal data Tad (S302). First, the test video signal data Tvd is all black video signal data (S302a), and the test audio signal data Tad is “silenced” in synchronization with the test video signal data Tvd while the test video signal data Tvd is black. In other words, zero audio signal data is output (S302b). The state where the test video is black and the test sound is silent (S302) may be continuous for at least several tens of milliseconds to 1 second.

  Next, the test signal output circuit 27 changes and outputs the test video signal and the test audio signal in synchronization (S303). That is, the signal output circuit 27 changes the test video signal data Tvd to all white video signal data and outputs it (S303a), and the test audio signal data Tad is displayed while the test video signal data Tvd is white. In synchronization with the “sound”, that is, the sound signal data of white noise is changed and output (S303b). The state where the test video is white and the test sound is white noise (S303) may be continuous for at least about 1 second to about 10 seconds (continuous time of about 30 to 300 frames). Note that the test signal output circuit 27 may repeat the state (S302) and the state (S303) a plurality of times. Then, the test signal output circuit 27 stops outputting the test signal after continuing the output of the test video signal data Tvd in which the test video is white and the test audio signal data Tad in which the test audio is white noise.

  On the other hand, the CPU 20 waits several msec to several hundreds msec after the test signal output is stopped for the respective detection results to be notified from the video detection circuit 25 and the audio detection circuit 26 of the delay synchronization circuit 22 (S304). That is, as a result of changing the output of the test audio signal data Tad in synchronization with the test video signal, the audio detection circuit 26 detects the change and notifies the CPU 20 when the test audio is switched from the silent period to the white noise period. (S304b). In addition, as a result of the change to the test video signal data Tvd of white that makes the test video white in synchronism with the change of the output of the test audio signal data Tad, the video detection circuit 25 determines that the black color of the liquid crystal display 32 is tested. It detects that the video has changed to white and notifies the CPU 20 (S304a).

  When the output of the white test video signal data Tvd from the test signal output circuit 27 is stopped, the CPU 20 starts counting the first timer, and until the detection result is notified from the video detection circuit 25, the CPU 20 Continue counting. The CPU 20 calculates the delay time Tx of the test video associated with the processing time associated with the video conversion in the video conversion circuit 31 of the monitor device 3 from the count result of the first timer, and uses this to calculate the audio delay circuit 24 of the delay synchronization circuit 22. The delay circuit 24b is set as a delay time Tx for delaying the input audio data (S305). When the setting of the delay time Tx is completed, the CPU 20 gives a control command to the switch circuit 28 so as to output the video signal data Vd and the audio signal data Ad, and the setting operation of “AV Sync” is ended. As a result, the delay synchronization circuit 22 delays the audio signal data Ad and realizes synchronous reproduction of the video V and the audio C.

  Alternatively, the CPU 20 starts counting the second timer after the detection result is notified from the audio detection circuit 26, and continues counting the second timer until the detection result is notified from the video detection circuit 25. The CPU 20 calculates the delay time Tx of the test video with respect to the test audio from the result of the count of the second timer, and delays the audio data to which the delay circuit 24b of the audio delay circuit 24 of the delay synchronization circuit 22 is input. Time Tx is set (S305). When the setting of the delay time Tx is completed, the CPU 20 gives a control command to the switch circuit 28 so as to output the video signal data Vd and the audio signal data Ad, and the setting operation of “AV Sync” is ended. As a result, the delay synchronization circuit 22 delays the audio signal data Ad after incorporating the delay time associated with the transmission time of the distance Y from the speaker to the viewing position 10, and performs synchronous reproduction of the video V and the audio C. Realize.

  FIG. 3B schematically illustrates an operation (S304) in which the video detection circuit 25 and the audio detection circuit 26 of the delay synchronization circuit 22 detect the sound noise interval of the white test video and the white of the test audio. It is a figure to do. The audio level detection circuit 26b of the audio detection circuit 26 is a test audio white in the test audio reproduced from the speakers 41 to 45 corresponding to the change of the test video signal from white to black or the change from black to white. A reference sound level value Lao corresponding to the noise interval and a reference silence level value Lan corresponding to the silence interval of the test voice are included, and the reference sound level value Lao and the reference silence level value Lan are provided. A change in the white noise interval and the silent interval of the test voice is detected using an intermediate value Las (for example, Lav = 0.5 * (Lao + Lan)) as a threshold value. For example, in FIG. 3B, the sound level detection circuit 26b notifies the CPU 20 of the detection result on the assumption that the silent section of the test sound changes to the white noise section at the time ta when the sound level reaches the intermediate value Las. . At a typical sampling frequency of 44.1 kHz, the test voice is instantaneously switched from a silent period to a white noise period.

  The video detection circuit 25 includes a video amplification circuit 25a and a video level detection circuit 25b that amplify the output signal of the light receiver 5, and the video level detection circuit 25b includes a reference white level value Lvw corresponding to the white color of the test video described later. And a reference level circuit for holding a reference black level value Lvb corresponding to the black color of the test video. The video level detection circuit 25b uses the intermediate value Lvs (for example, Lsv = 0.5 * (Lvw + Lvb)) between the reference white level value Lvw and the reference black level value Lvb as a threshold, and changes the test video from white to black. Alternatively, a change from black to white is detected. Even if the black frame is switched to the white frame, it takes about 30 msec to scan one frame of the liquid crystal display 32 of the monitor device 3, so that the video level in the video level detection circuit 25b is one frame. While the time corresponding to the operation time elapses, the reference black level value Lvb increases to the reference white level value Lvw. Therefore, in FIG. 3B, the video level detection circuit 25b notifies the CPU 20 of the detection result, assuming that the black color of the test video changes to white at the time tv when the video level reaches the intermediate value Lvs.

  FIG. 4 is a diagram for schematically explaining the relationship between the scanning line for scanning one frame of the liquid crystal display 32 of the monitor device 3 and the output of the video detection circuit 25 that has received the output signal of the light receiver 5. FIG. 4A shows the moment when the test video signal for switching from black to white is inputted to the liquid crystal display 32 and the scanning line scans one frame. The scanning lines sequentially scanned up to the th are scanned over the entire scanning lines N scanning the liquid crystal display 32 (N / 2), and the screen of the liquid crystal display 32 is sequentially black from top to bottom. Changing to a white image. Here, the light receiver 5 is installed at the viewing position 10 so that the lens is directed toward the monitor device 3 and is arranged to detect an image near the center 32x of the screen. That is, the light receiving element of the light receiver 5 is a screen corresponding to the position scanned by the (N / 2) th or ((N / 2) +1) th scanning line among all scanning lines N scanning the liquid crystal display 32. It arrange | positions so that the image | video of the center 32x vicinity may be detected. The light receiver 5 arranged in this manner can accurately detect the timing at which the test image visually changes from black to white.

  FIG. 4B is a diagram for explaining the video level in the video level detection circuit 25 b of the video detection circuit 25. Since the light receiver 5 is arranged to detect an image near the center 32x of the screen, a test image for switching black to a white image in the process of scanning one frame from the first to the Nth in sequence. In this case, the video level starts to rise from the reference black level value Lvb and reaches the reference white level value Lvw near the (N / 2) th of all the scanning lines N. Therefore, the time when the (N / 2) th scanning line is scanned, that is, the timing at which the test image is visually changed from black to white, is that the image level is the reference white level value Lvw and the reference black level value Lvb. It is detected as the time tv when it reaches the intermediate value Lvs. Therefore, the delay synchronization circuit 22 of the AV center 2 can set a more accurate audio delay time Tx.

  The video level detection circuit 25b only needs to have a reference level circuit that holds a reference white level value Lvw corresponding to the white color of the test video and a reference black level value Lvb corresponding to the black color of the test video. The white level value Lvw and the reference black level value Lvb may be adjusted and held after the light receiver 5 is connected to the video detection circuit 25. For example, the reference white level value Lvw may be obtained by measuring and holding the level of the output signal output from the light receiver 5 when the front surface of the liquid crystal display 32 reproduces a white video signal. The level value Lvb may include the brightness of the periphery of the liquid crystal display 32 when the monitor device 3 is not reproducing video, and may hold the level of the output signal output from the light receiver 5.

  The image near the screen center 32x detected by the light receiver 5 may be an image near the (N / 2) th of all the scanning lines N that scan the liquid crystal display 32 of the monitor device 3. For example, Even if the light receiver 5 is not installed at the viewing position 10, the light receiver 5 in FIG. 4A is positioned at the left end of the liquid crystal display 32 at the center position 32y or at the right end at the center position of the height. It may be attached in the vicinity of 32z. In such a case, of course, the light receiver 5 may be built in the monitor device 3 or may be integrally formed. When the light receiver 5 is about (N / 2) th of all the scanning lines N of the liquid crystal display 32, the reference white level value Lvw corresponding to the white color of the test image and the reference black level value Lvb corresponding to the black color of the test image. Therefore, the time tv when the intermediate value Lvs is reached can be accurately detected.

  Further, even if the light receiver 5 is not arranged to detect the image near the center 32x of the screen, the light receiver 5 is capable of mainly detecting at least the image of the entire liquid crystal display 32 of the monitor device 3. It only has to be arranged. If the light receiver 5 can mainly detect the image of the entire liquid crystal display 32, the image level in the image level detection circuit 25b is about the (N / 2) th of all the scanning lines N, and the test is performed. It is possible to detect a time tv that has reached an intermediate value Lvs between the reference white level value Lvw corresponding to the white color of the image and the reference black level value Lvb corresponding to the black color of the test image.

  The CCD output circuit of the light receiver 5 may include a filter that smoothes an electrical signal obtained by converting light input to the CCD pixel. When the delay time Ty associated with the time constant of such a filter occurs, the CPU 20 of the AV center 2 changes the sound delay time in the delay synchronization circuit 22 to (Tx−Ty), and the sound delay circuit 24. The delay circuit 24b may be set. Therefore, a more accurate audio delay time can be set, and synchronized reproduction of the video V and the audio C is realized.

  Further, the signal transmission method or command control method of the DVD player 1, AV center 2, monitor device 3, and light receiver 5 is not limited to wired or wireless connection, but also transmission of IEEE 1394, etc. It may be a method. Therefore, if the transmission time delay time Tz inherent in the transmission method between the optical receiver 5 and the AV center 2 is expected, the CPU 20 of the AV center 2 sets the audio delay time in the delay synchronization circuit 22 ( The delay circuit 24b of the audio delay circuit 24 may be set instead of (Tx−Tz).

  In the above embodiment, the case where the center channel sound C is reproduced from the center speaker 41 in the front direction has been described. However, the left channel sound, right channel sound, left surround channel sound, right sound reproduced from the other speakers 42 to 45 are described. Similarly, the sound delay time of each sound channel in the delay synchronization circuit 22 may be set for surround channel sound. Of course, even when the multi-channel surround sound has a larger number of channels than the five channels of the present embodiment, an accurate sound delay time may be set for each.

  The transmission signal processing apparatus according to the present invention can be applied not only to an AV center for multi-channel sound reproduction with a built-in amplifier, but also to a control amplifier without an amplifier.

1 is a diagram illustrating a video / audio reproduction system according to a preferred embodiment of the present invention. FIG. Example 1 It is a figure explaining the structure of the delay synchronizing circuit 22 of the AV center 2 of this invention. Example 1 It is a figure explaining the operation | movement which sets the audio | voice delay time of the audio | voice delay circuit 24 of the delay synchronizing circuit 22 of this invention. Example 1 It is a figure which illustrates typically the relationship between the scanning line which scans 1 frame of the liquid crystal display 32 of the monitor apparatus 3 of this invention, and the output of the image | video detection circuit 25 which received the output signal of the light receiver. Example 1

Explanation of symbols

1 DVD player 2 AV center 20 CPU
21 Separation circuit 22 Delay synchronization circuit 23 Amplifier 24 Audio delay circuit 25 Video detection circuit 26 Audio detection circuit 27 Test signal output circuit 28 Switch circuit 3 Monitor device 30 CPU
31 Video conversion circuit 32 Liquid crystal display 41 Center speaker 42 Left speaker 43 Right speaker 44 Surround left speaker 45 Surround right speaker 5 Light receiver 6 Microphone 100 Video / audio reproduction system

Claims (10)

A monitor for reproducing a video signal as a video, an AV center and a speaker for reproducing an audio signal synchronized with the video signal as audio, and a light receiver for detecting a video reproduced from the monitor,
The AV center has a control circuit that controls the operation of the AV center, and a delay synchronization circuit that delays the audio signal to perform synchronization processing between the video signal and the audio signal,
An audio delay circuit for delaying the audio signal; a video detection circuit connected to the optical receiver; a test signal output circuit for reproducing a test video signal including white and black video signals; Including
The control circuit calculates a delay time of a test video corresponding to the test video signal detected by the video detection circuit, and sets the delay time to a delay time of the audio delay circuit of the delay synchronization circuit. Playback system. The video detection circuit of the delay synchronization circuit includes a video amplification circuit that amplifies the output signal of the light receiver, and a video level detection circuit that receives an output signal from the video amplification circuit,
The video / audio reproduction system according to claim 1, wherein the video level detection circuit detects a change from white to black or a change from black to white in the test video reproduced from the monitor. The video level detection circuit includes a reference white level value corresponding to white of the test video and a reference black level value corresponding to black of the test video, and the reference white level value and the reference black level value Detecting a change from white to black in the test video or a change from black to white
The video / audio reproduction system according to claim 1 or 2. The light receiving element of the light receiver detects an image near the center of the screen corresponding to the position scanned by the ((N / 2) +1) th scanning line among all scanning lines N scanning the screen of the monitor. Placed in the
The video / audio reproduction system according to claim 1. A microphone for detecting sound reproduced from the speaker;
The delay synchronization circuit of the AV center further includes a sound detection circuit connected to the microphone,
The test signal output circuit outputs a test audio signal that changes in synchronization with a change from white to black of the test video signal or from black to white,
The control circuit calculates the delay time of the test video detected by the video detection circuit with respect to the test audio detected by the audio detection circuit, and sets the delay time to the delay time of the audio delay circuit of the delay synchronization circuit. The video / audio reproduction system according to any one of claims 1 to 4. The sound detection circuit of the delay synchronization circuit includes a microphone amplification circuit that amplifies the output signal of the microphone, and a sound level detection circuit that receives the output signal of the microphone amplification circuit,
The audio level detection circuit detects a change in the test video signal from white to black or a change in the test audio reproduced from the speaker corresponding to a change from black to white;
The video / audio reproduction system according to claim 1. The test audio signal is a burst white noise including a white noise interval corresponding to white of the test video signal and a silent interval corresponding to black of the test video signal,
The sound level detection circuit includes a reference sound level value corresponding to a white noise interval of the test sound and a reference sound level value corresponding to a sound interval of the test sound, and the reference sound level value Detecting a change in white noise interval and silence interval of the test voice with an intermediate value of the reference silence level value as a threshold value;
The video / audio reproduction system according to any one of claims 1 to 6. The time obtained by subtracting the delay associated with the time constant of the filter for smoothing the output from the light receiving element of the light receiver from the delay time of the test signal detected by the delay synchronization circuit is the audio signal of the delay synchronization circuit. Delay time,
The video / audio reproduction system according to claim 1.   9. An AV center including the delay synchronization circuit and the amplification circuit constituting the video / audio reproduction system according to claim 1. A monitor including the light receiver constituting the video / audio reproduction system according to claim 1.

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