JP3229992B2 - Audio mute method in image coding device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image encoding apparatus for encoding moving picture signals with high efficiency, and more particularly to a transmission line error or the like when a receiving section separates and reproduces an audio signal multiplexed with an image signal. The present invention relates to a sound mute method for eliminating noise caused by the sound.

[0002]

2. Description of the Related Art In a conventional image encoding apparatus, a method of delaying and outputting an audio signal by a delay circuit including a memory in order to adjust the audio signal to a time consumed for processing the image signal (lip sync) is employed. I am taking. At this time, if an error occurs in the transmission path, the output audio signal is muted, and the mute is released after the transmission path error is recovered, and an erroneous audio signal written to the memory of the delay circuit during the transmission path error occurrence period is output. Will be output.

In order to prevent this, the time from the restoration to the release of the mute is fixedly set in advance to a time sufficient to completely output all erroneous audio signals.

[0004]

In the conventional method, the time until the mute is released after the restoration of the transmission path error is fixedly set in advance to a time sufficient to completely output all the erroneous audio signals. As a result, the time until the mute is released becomes longer, and the sound is muted for a while even though the image is normally displayed.

[0005]

According to the present invention, there is provided an audio mute system in an image encoding apparatus according to the present invention, which comprises a high efficiency buffer having a buffer for smoothing an image signal obtained by performing high efficiency encoding on an input moving image signal. An encoding circuit, an audio delay circuit for giving the same delay to the time spent for the high-efficiency encoding processing of the moving image signal to the input audio signal, and a transmission line frame are assembled, and the image signal and the audio signal are A transmitting unit having a multiplexing circuit for multiplexing and transmitting, a separating circuit for establishing a transmission path frame, separating the multiplexed image signal and audio signal, and outputting first transmission path error information, when spent decoding of image signals by entering the high efficiency decoding circuit for obtaining a video signal by performing decoding processing on the image signal, the audio signal and the said first transmission path error information A reception delay circuit that outputs the audio signal and the second transmission line error information by respectively giving the same delay, obtains the first transmission line error information, and mutes the audio signal when an error occurs It is characterized by having a receiving unit comprising an audio mute means and an audio mute release means for obtaining the second transmission path error information and releasing the mute of the audio mute means after error recovery.

[0006]

Next, embodiments of the present invention will be described with reference to the drawings.

Referring to FIG. 1, in a transmission section according to an embodiment of the present invention, moving image data from an input terminal 1 is input to a high efficiency coding circuit 3. High efficiency coding circuit 3
Performs a high-efficiency encoding process on moving image data, and then stores it in an internal buffer memory. The high-efficiency coded image signal is read out at the transmission line speed, and
Output to

The audio data from the input terminal 2 is input to a transmission audio delay circuit 5. The transmission audio delay circuit 5 delays the audio data in order to match the time spent in the high-efficiency encoding processing of the moving image data, and outputs it to the multiplexing circuit 4.

The multiplexing circuit 4 assembles the transmission line frame and multiplexes the image signal output from the high efficiency coding circuit 3 and the audio data output from the transmission audio delay circuit 5. The multiplexed signal is transmitted to the transmission path 7 via the output terminal 6.

In the receiving section, transmission line data from the transmission line 7 is received at an input terminal 8 and input to a separation circuit 9. After establishing the frame synchronization, the separation circuit 9 separates the multiplexed image signal and audio data. The image signal is input to the high-efficiency decoding circuit 10, and the audio data is input to the reception audio delay circuit 12. Further, the separation circuit 9 outputs the transmission line error information a generated due to a transmission line error or the like to the reception voice delay circuit 12 and the mute control circuit 14.

The high-efficiency decoding circuit 10 receives the image signal from the separation circuit 9, performs a high-efficiency decoding circuit, reproduces the image data, and sends it to the output terminal 11.

The reception audio delay circuit 12 receives the audio data from the separation circuit 9 and the transmission path error a, and delays the audio data in order to match the processing time spent for the high-efficiency decoding of the image signal. At the same time, the transmission path error information a is delayed to give the transmission path error information b. The delayed audio data is sent to the switch 13 for transmission path error information b.
Is output to the mute control circuit 14.

The mute control circuit 14 receives the transmission line error information a and b, goes to the TTL “H” level at the falling edge of the transmission line error a, and sets the transmission line error information b.
Is output to the switch 13 at the rising edge of the TTL "L" level.

The switch 13 has a normal mute control circuit 14
Receives the TTL “L” level of the switching signal c, switches to the audio data from the reception audio delay circuit 12 and
Send to 6. However, when an error or the like occurs in the transmission path, the transmission path error information a is sent to the mute control circuit 14. In response, the mute control circuit 14 sets the level of the switching signal c to the TTL “H” level. Switch 1
3 receives the TTL “H” level and sends the mute signal from the mute signal generator 15 to the output terminal 16. That is, the audio signal is muted.

When the transmission line error or the like is recovered, the transmission line error information b is sent to the mute control circuit 14. Thereby, the mute control circuit 14 sets the level of the switching signal c to T
Set to TL “L” level. The switch 13 is a TTL “L”
Upon receiving the level, switch to the normal state. That is, switching to the audio data from the reception audio delay circuit 12 cancels the mute of the audio.

Next, the mute control circuit 14 will be described with reference to FIG. When a transmission line error occurs, the transmission line error information a from the shunt circuit 9 changes from the TTL “H” level to the TTL “L” level, and is input to the differentiator 141 of the mute control circuit 14. The differentiator 141 differentiates the falling edge of the transmission path error information a and outputs the result to the set terminal of the flip-flop circuit 143. At this time, the output of the flip-flop circuit 143 changes from the normal TTL “L” level to the TTL “H” level and outputs.

When the transmission path error is recovered, the transmission path error information b from the receiving voice delay circuit 12 changes from the TTL "L" level to the TTL "H" level, and is input to the differentiator 142 of the mute control circuit 14. You. The differentiator 142 differentiates the rising edge of the transmission path error information b and outputs the result to the reset terminal of the flip-flop circuit 143.
At this time, the output of the flip-flop circuit 143 changes from the TTL “H” level in the transmission line error occurrence state to the normal TT
The signal changes to L level and is output.

FIG. 3 shows the timing of the audio mute and mute release method based on the switching signal c obtained by the transmission line error information a and b when an error occurs in the audio due to the transmission line error.

[0019]

As described above, according to the present invention, when the mute of the audio data is released, the transmission path error information is set to the release signal by giving the same delay amount as the delay of the audio. Can be realized in a relatively short period of time from the restoration to the release of the mute. For this reason,
When the image is normally displayed, it can be reproduced almost simultaneously.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a detailed block diagram of a mute control circuit in the embodiment shown in FIG.

FIG. 3 is a timing chart for explaining the operation of the embodiment shown in FIG. 1;

[Explanation of symbols]

 1, 2 input terminal 3 high efficiency encoding circuit 4 multiplexing circuit 5 transmission audio delay circuit 6 output terminal 7 transmission line 8 input terminal 9 separation circuit 10 high efficiency decoding circuit 11 output terminal 12 reception audio delay circuit 13 switch 14 Mute control circuit 15 Mute signal generator 16 Output terminal 141, 142 Differentiator 143 Flip-flop circuit

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N ^5/ 50-5/63 H04N ^7/ 00-7/088 H04N ^7/ 14-7/173 H04N ^7/ 24-7 / 68 H04B 14/00-14/08

Claims (3)

(57) [Claims] 1. A high-efficiency coding circuit having a buffer for smoothing an image signal obtained by performing high-efficiency coding on an input moving image signal, and a high-efficiency coding of a moving image signal on an input audio signal. A transmission unit comprising: an audio delay circuit for giving the same delay to the time spent for the multiplexing process; and a multiplexing circuit for assembling a transmission line frame and multiplexing and transmitting the image signal and the audio signal. A separation circuit for establishing a transmission path frame, separating a multiplexed image signal and an audio signal and outputting first transmission path error information, and a high efficiency decoding for performing a decoding process on the image signal to obtain a moving image signal Circuit, and the audio signal and the second transmission path error information are given the same delay for the time spent for decoding the image signal by inputting the audio signal and the first transmission path error information. information And a reception delay circuit that outputs the first transmission line error information, an audio muting unit that mutes an audio signal when an error occurs, and obtains the second transmission line error information, and after error recovery, A sound mute canceling means for canceling the mute of the sound mute means. 2. The audio mute means and the audio mute release means attain a TTL "H" level at a falling edge of the first transmission path error information, and a TTL "H" level at a rising edge of the second transmission path error information. A mute control circuit for outputting a switching signal having an L level; receiving a TTL “L” level of the switching signal, switching to audio data from the delay circuit;
2. The audio mute system according to claim 1, further comprising: a switching unit configured to switch to an audio mute state in response to the "H" level. 3. A mute control circuit comprising: a first differentiator for differentiating a falling edge of the first transmission path error information; and a second differentiator for differentiating a rising edge of the second transmission path error information. 3. The differential circuit according to claim 2, further comprising: a differentiator; and a flip-flop circuit that sets the output signal of the first differentiator and resets the output signal of the second differentiator to obtain the switching signal. An audio mute method in an image encoding device.