JP4336879B2 - Video / audio delay confirmation circuit and video / audio delay confirmation method used therefor - Google Patents

Description

  The present invention relates to a video / audio delay confirmation circuit and a video / audio delay confirmation method used therefor, and more particularly, to a video / audio delay confirmation method in a video codec.

  Conventionally, in a video encoder constituting a video codec, when measuring a video / audio delay, as shown in FIG. 4, a video signal and an audio signal from a dedicated external test signal generator (video signal source) 4 are converted into video. The signals are input to the video input unit 31 and the audio input unit 32 of the encoder 3, encoded by the video encoding unit 34 and the audio encoding unit 35, multiplexed by the multiplexing unit 36, and output as a TS (Transport Stream) stream. The

  The TS stream output from the video encoder is input to a video decoder (not shown), and the video / audio delay difference is measured by the video decoder. In FIG. 4, when an encoding start signal is input, the encoding start control unit 33 outputs a video encoded signal to the video encoding unit 34 and outputs an audio encoded signal to the audio encoding unit 35. ing.

Japanese Patent Laid-Open No. 11-252058

  However, in the above-described conventional video codec, since the video / audio test signal generator is outside the video encoder, a dedicated test signal generator is prepared to check the video / audio delay difference of the video codec. It is necessary to input as an input signal.

  In other words, the conventional video codec has a problem that the video / audio delay cannot be measured unless a video / audio delay measurement signal is prepared and input to the video encoder.

  Accordingly, an object of the present invention is to eliminate the above-mentioned problems and to use a video / audio delay confirmation circuit capable of measuring a video / audio delay without requiring an external signal generator for measuring the video / audio delay, and to use the same. It is to provide a video / audio delay confirmation method.

A video / audio delay confirmation circuit according to the present invention includes a video encoder including a video encoding unit that encodes a video signal, and an audio encoding unit that encodes the audio signal, and decodes the video signal and the audio signal. A video / audio delay confirmation circuit for confirming a delay between the video signal and the audio signal in a video codec comprising a video decoder,
Video test signal generating means for generating a video test signal;
Audio test signal generating means for generating an audio test signal synchronized with the video video test signal;
The video test signal generating means and the audio test signal generating means are controlled to output different signals in units of video frames, and the encoding start points of the video encoding means and the audio encoding means are the video frames. The video encoder includes a coding start control means for controlling to synchronize,
The relative delay difference between the video signal and the audio signal is measured by observing change points of the video signal and the audio signal decoded by the video decoder.

A video / audio delay confirmation method according to the present invention includes a video encoder including a video encoding unit that encodes a video signal, and an audio encoding unit that encodes the audio signal, and decodes the video signal and the audio signal. A video / audio delay confirmation method for confirming a delay between the video signal and the audio signal in a video codec comprising a video decoder,
Video test signal generating means for generating a video test signal and audio test signal generating means for generating an audio test signal synchronized with the video video test signal are incorporated in the video encoder,
The video test signal generating means and the audio test signal generating means are controlled to output different signals in units of video frames, and the encoding start points of the video encoding means and the audio encoding means are the video frames. Control to synchronize with
The relative delay difference between the video signal and the audio signal is measured by observing change points of the video signal and the audio signal decoded by the video decoder.

  In other words, the video / audio delay confirmation circuit of the present invention has a built-in means for measuring the relative delay difference between the video signal and the audio signal that have passed through the codec in a video codec that encodes and decodes each of the video signal and the audio signal. is doing.

  More specifically, in the video / audio delay confirmation circuit according to the present invention, a video test signal generator and an audio test signal generator for generating synchronized video / audio test signals in the video encoder constituting the video codec, respectively. Is arranged.

  The video test signal generator and the audio test signal generator are controlled by the encoding start controller to output different signals for each video frame. Further, when the encoding start control unit encodes the signals output from the video test signal generation unit and the audio test signal generation unit respectively by the video encoding unit and the audio encoding unit, their encoding start points are It is controlled to synchronize with the video frame.

  In the video / audio delay confirmation circuit of the present invention, by this control, the same time information is attached to the video encoded data and the audio encoded data at the start of encoding, and is output from the respective encoding units. The video / audio delay confirmation circuit of the present invention can generate video / audio encoded data having the same time information about once every about 20 seconds, depending on the audio encoding method. .

  A TS (Transport Stream) stream sent to the video decoder is decoded and output as a video / audio signal. By observing the change point between the output video and audio signal, the relative delay difference between the video and audio can be accurately measured.

  With the configuration and operation described below, the present invention provides an effect that the video / audio delay can be measured without requiring an external signal generator for measuring the video / audio delay.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a video encoder according to an embodiment of the present invention. In FIG. 1, a video encoder 1 includes a video input unit 11, an audio input unit 12, a video test signal generation unit 13, an audio test signal generation unit 14, an encoding start control unit 15, and signal switching units 16 and 17. A video encoding unit 18, an audio encoding unit 19, and a multiplexing unit 20.

  The video test signal generator 13 generates and outputs a test video signal, and the audio test signal generator 14 generates and outputs a test audio signal. The signal switcher 16 switches between an input video signal and a test video signal. The switched video signal is input to the video encoding unit 18 and converted into video encoded data by the video encoding unit 18. The signal switcher 17 switches between an input audio signal and a test audio signal. The audio signal after switching is input to the audio encoding unit 19 and converted into audio encoded data by the audio encoding unit 19.

  The video encoded data and the audio encoded data converted by the video encoding unit 18 and the audio encoding unit 19, respectively, are sent to the multiplexing unit 20, multiplexed by the multiplexing unit 20, and output as TS (Transport Stream) data. Is done. The encoding start control unit 15 performs switching between the test video signal and the test audio signal and encoding start control for the video encoding unit 18 and the audio encoding unit 19.

  FIG. 2 is a block diagram showing a configuration of the encoding start control unit 15 of FIG. In FIG. 2, the encoding start control unit 15 includes a counter 21, a decoding unit 22, an AND circuit 23, and an encoding start determination unit 24.

  The encoding start control unit 15 includes a frame synchronization signal and a video signal synchronization clock indicating the frame synchronization signal of the input video signal, and an encoding start corresponding to a flag signal indicating the start of encoding sent from the control unit (not shown). A signal and a test selection signal (a signal when no test is selected and a counter value “1” in FIG. 2) indicating whether video / audio input or a test signal is selected are input.

  Based on the above input signal, the encoding start control unit 15 performs a test switching signal (test video signal selection and test audio signal selection in FIG. 2) to the signal switchers 16 and 17, a video encoding unit 18 and an audio code. An encoding start signal (video encoding start signal and audio encoding start signal in FIG. 2) is output to each of the encoding units 19.

  When the test selection signal (counter value “1”) for selecting the test signal is input to the counter 21, the counter 21 starts counting the frame by the video signal synchronization clock and sends the frame count value to the decoding unit 22. Thereafter, the counter 21 counts from “1” to “80” based on the signal (dec_80) from the decoding unit 22, and receives a test selection signal (signal when the test is not selected) for selecting video / audio input. When this is done, the count value is reset.

  The decoding unit 22 decodes the frame count value from the counter 21, feeds back a signal (dec_80) to the counter 21, and outputs a test switching signal (test video signal selection and test audio signal selection) to the signal switches 16 and 17. To do.

  The AND circuit 23 performs an AND operation between the frame synchronization signal and the encoding start signal, and outputs the operation result to the counter 21. The encoding start determination unit 24 determines the encoding start from the frame synchronization signal, the encoding start signal, and the video signal synchronization clock, and the video encoding start unit 18 and the audio encoding start signal are converted into the video encoding start signal and the audio encoding start signal. To each of the units 19.

  The video input unit 1, the audio input unit 2, the video encoding unit 5, and the audio encoding unit 6 are each well known to those skilled in the art and are not directly related to the present invention. Description is omitted.

  FIG. 3 is a time chart showing the operation of the encoding start control unit 15 of FIG. The operation of the encoding start control unit 15 will be described with reference to FIGS.

  When the test signal is selected and the encoding start is selected, the encoding start control unit 15 operates the counter 21 according to the frame signal of the video signal input. The counter 21 is reset to “0” except when the test signal is selected and the encoding start is selected, and counts up according to the frame signal.

  The counter 21 changes cyclically from “1” to “80”. When the counter 21 is “1” to “5”, the video test signal generator 13 is designated to output a “color bar”, and the audio test signal generator 14 is set to “1 kHz sine wave”. Specify to output.

  When the counter 21 is “6” to “80”, the video test signal generator 13 is designated to output “black”, and the audio test signal generator 14 is set to “silence (level 0)”. Specify to output.

  The encoding start determination unit 24 selects the encoding start signal to the video encoding unit 15 and the audio encoding unit 16 immediately after the frame synchronization signal is input for the first time after the test signal is selected and the encoding start is selected. (Video encoding start signal and audio encoding start signal) are output.

  With this operation, in this embodiment, the time information attached to the video / audio encoded data can be matched at the start of encoding. In addition, by changing the video / audio test signal in units of 80 frames, the video / audio encoding units can be made to coincide with each other at the start of encoding.

  The reason why the video signal is switched in a period of 80 frames is that the video frame frequency is 29.97 Hz and the audio sampling frequency are 48 kHz that are widely used in the broadcasting field, and the audio encoding format is SMPTE (Society of Motion Picture and Television Engineers) 302M. In the case of MPEG1, (Moving Picture Experts Group 1) -Layer2, MPEG2-AAC (Advanced Audio Coding), the encoding unit of video and audio is made to coincide in the following cycle.

  In SMPTE 302M, since the audio signal is encoded in units of one frame of video, it is encoded in units of “1602” or “1603” samples. In MPEG1-Layer2, encoding is performed in “1152” sample units, and in MPEG2-AAC, encoding is performed in “1024” sample units.

  In these encoding formats, the period in which the video frame and the audio encoding unit match is 1 frame (1601, 1602 audio samples) in the case of SMPTE302M, 720 frames (1151532 audio samples) in the case of MPEG1-Layer2, and MPEG2 -In the case of AAC, it becomes 640 frames (1025024 audio samples). Under this condition, the test signal generation period that can correspond to all coding formats is 80 frames corresponding to the greatest common divisor of 720 frames and 640 frames. According to this condition, in this embodiment, the test signal switching period is set to 80 frames.

  As described above, in this embodiment, since the video test signal generator 13 and the audio test signal generator 14 are built in the video encoder 1, a signal generator for measuring the video and audio delay is required outside the video encoder 1. The video / audio delay can be measured.

  In this embodiment, since the time data of the video data and the time data of the audio data match in the TS stream output from the video encoder 1, it can be used as a test signal for the video decoder.

  In the present invention, 29.97 Hz is described as the video frame period. However, the present invention can be applied to a signal sequence having a video frame period other than 29.97 Hz by changing the period for generating the test signal. .

  The present invention is also applicable to an MPEG2 video codec, SNG (Satellite News Gathering), and digital FPU (Field Pickup Unit).

It is a block diagram which shows the structure of the video encoder by one Example of this invention. It is a block diagram which shows the structure of the encoding start control part of FIG. It is a time chart which shows operation | movement of the encoding start control part of FIG. It is a block diagram which shows the structure of the video encoder by a prior art example.

Explanation of symbols

1 Video encoder 11 Video input unit 12 Audio input unit 13 Video test signal generation unit 14 Audio test signal generation unit 15 Encoding start control unit 16, 17 Signal switching unit 18 Video encoding unit 19 Audio encoding unit 20 Multiplexing unit 21 Counter 22 Decoding unit 23 AND circuit 24 Encoding start determination unit

Claims (6)

The video in a video codec comprising: a video encoder including a video encoding means for encoding a video signal; an audio encoding means for encoding an audio signal; and a video decoder for decoding the video signal and the audio signal. A video / audio delay confirmation circuit for confirming a delay between a signal and the audio signal,
Video test signal generating means for generating a video test signal;
Audio test signal generating means for generating an audio test signal synchronized with the video video test signal;
The video test signal generating means and the audio test signal generating means are controlled to output different signals in units of video frames, and the encoding start points of the video encoding means and the audio encoding means are the video frames. The video encoder includes a coding start control means for controlling to synchronize,
A video / audio delay confirmation circuit characterized by observing change points of the video signal and audio signal decoded by the video decoder and measuring a relative delay difference between the video signal and the audio signal.   2. The audio / video delay confirmation circuit according to claim 1, wherein said encoding start control means outputs the signal encoded by each of said video encoding means and said audio encoding means with the same time information added thereto. . The video encoder includes video switching means for switching between the input video signal and the video test signal, and audio switching means for switching between the input audio signal and the audio test signal,
The encoding start control unit controls the video switching unit and the audio switching unit to switch to the video test signal and the audio test signal when checking the video / audio delay. The video / audio delay confirmation circuit according to claim 1 or 2. The video in a video codec comprising: a video encoder including a video encoding means for encoding a video signal; an audio encoding means for encoding an audio signal; and a video decoder for decoding the video signal and the audio signal. A video / audio delay confirmation method for confirming a delay between a signal and the audio signal,
Video test signal generating means for generating a video test signal and audio test signal generating means for generating an audio test signal synchronized with the video video test signal are incorporated in the video encoder,
The video test signal generating means and the audio test signal generating means are controlled to output different signals in units of video frames, and the encoding start points of the video encoding means and the audio encoding means are the video frames. Control to synchronize with
A video / audio delay confirmation method comprising: measuring a relative delay difference between the video signal and the audio signal by observing a change point of each of the video signal and the audio signal decoded by the video decoder.   5. The video / audio delay confirmation method according to claim 4, wherein the same time information is added to the signals encoded by the video encoding means and the audio encoding means, respectively, and output. Video switching means for switching between the input video signal and the video test signal, and audio switching means for switching between the input audio signal and the audio test signal are incorporated in the video encoder,
6. The video switching unit and the audio switching unit are controlled to perform switching to the video test signal and the audio test signal when the video / audio delay is confirmed. To check the video and audio delay.

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