JPH0227887A - Picture transmitter - Google Patents

Abstract

PURPOSE:To cope easily with even the case with a change in a delay time of a picture data by counting an average sheet number of a sent video frame rate, calculating the processing delay quantity of a picture data and setting the voice delay corresponding thereto. CONSTITUTION:A video frame pulse representing the head of the video frame is detected by a picture decoding section 5, a video frame pulse count section 21 counts the pulses, a video frame rate calculation section 22 calculates the video frame number per unit time. A delay time is given to an address of a ROM 11 and the data of the ROM 11 is outputted to the initial value of a write address generation counter 10 setting the delay time of voice. A selector 13 selects the initial value set in the write address generation counter 10 and the initial value of a read address generation counter. 12, the result is written in the address of a RAM 14 and a proper voice delay time is set corresponding to the picture quality mode depending on the difference between the initial value of the counter 10 and the initial value of the counter 12. Thus, the voice delay is easily set.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is used for TV (television) conference equipment, etc.
The present invention relates to an image transmission device that uses an audio delay circuit to delay audio data to match the processing time of image data and outputs the delayed audio data to a receiving side.

[Conventional technology]

Figure 3 shows, for example, the technical report IC866-
4 is a simplified block diagram of the configuration of the conventional image transmission device shown on page 26. In the figure, 1 is an image encoding unit that digitizes image data on the transmitting side and outputs it to the multiplexing circuit 3; 2 is an audio encoding unit that digitizes audio data on the transmitting side and outputs it to the multiplexing circuit 3)
The multiplexing circuit 3 multiplexes the output of the image encoding section 1 and the output of the audio encoding section 2, and transmits the multiplexed output to the receiving side through the same transmission path.

4 is a separating circuit on the receiving side that separates image data and audio data transmitted from the multiplexing circuit 3 on the transmitting side via a transmission path; 5 is a separating circuit that decodes the image data separated by the separating circuit 4; An image decoding unit outputs the image signal as an image signal; 6 is an audio decoding unit that decodes the audio data separated by the separation circuit 4 and outputs audio; 7 is an audio delay circuit; When outputting, the processing time required to decode image data and audio data in the image decoding section 5 and audio decoding section 6, respectively, is different.If these data are received as they are, the audio data will be faster, and the image data will be faster. To prevent data from being output with a delay, it is provided between the demultiplexing circuit 4 and the audio decoding section 6.

Next, the operation will be explained. On the transmitting side, image data and audio data are respectively digitized by an image encoding unit 1 and an audio encoding unit 2, then multiplexed by a multiplexing circuit 3, and sent to the receiving side via the same transmission path.

On the receiving side, a separation circuit 4 separates image data and audio data, the image data is decoded by an image decoding unit 5 to output an image, and the audio data is delayed for a predetermined time by an audio delay circuit 1. After that, the audio decoding section 6 decodes the audio and outputs the audio.

At this time, when the image data is decoded by the image decoding unit 5, the audio data is delayed by the audio delay circuit 7 to avoid the delay in decoding the audio data by the audio decoding unit 6. Match the time of the data and image data.

Conventionally, the audio delay circuit 7 is provided with, for example, three delay modes.The receiving side compares the TV screen and the audio output and takes into account the priority level of image quality and motion, and selects an appropriate delay mode. It was selected.

That is, for example, the first mode is a mode that prioritizes image quality, the second mode is a mode that prioritizes motion and reduces the number of pixels, and the third mode is a mode that prioritizes motion by reducing the number of pixels. The amount of delay for each of these modes was fixed at a specific value.

FIG. 4 is a block diagram of the conventional audio delay circuit 7 described above. In the figure, 8 is a manual setting switch. When the manual setting switch 8 is turned on, the audio delay setting switch 9 is used to set the The binary coded data is sent to a write address (Write Addr) via a read-only memory (hereinafter referred to as ROM) 11.
ess) is set to the initial value of the generation counter 10.

Also, if the manual setting switch 8 is turned off,
The audio delay amount corresponding to each image quality mode is input to the initial value of the write address generation counter 10.

12 is a read address generation counter that sets 0, and 13 is a selector), which selects the output of the write address generation counter 10 and the output of the read address generation counter 12 in response to a write pulse.
The address of the RAM 14 is designated by the output of step 3, and the audio data is input.

In this case, the audio delay amount corresponding to the image quality mode is set based on the difference between the initial value set for the write address generation counter IOK and the initial value of the read address generation counter 12, and after the set delay time elapses, the audio Output data.

[Problem that the invention attempts to solve]

Since conventional image transmission devices are configured as described above, the amount of audio delay for each image quality mode is fixed to a specific value, so if the image processing time changes due to differences in the installation conditions of the image transmission device. , problems arose, such as the need to replace the ROM 11 from the system and change the amount of audio delay each time.

This invention was made to solve the above-mentioned problems, and it provides an image transmission system in which the video frame rate of image data and the processing delay time of the image data are known, and the amount of audio delay can be easily set in accordance with the processing delay time of the image data. The purpose is to obtain equipment.

[Means to solve the problem]

The image transmission device according to the present invention calculates the average number of video frames of image data that multiplexes digitally encoded image data and audio data and transmits them from the transmitting side to the receiving side via the same transmission path, An audio delay circuit is provided that calculates the processing delay amount of image data and sets the audio delay amount in accordance with the processing delay amount.

[Operation] The audio delay circuit of the present invention calculates the video frame rate of image data, calculates the image data processing delay time based on the calculation, and even if the image data processing time changes depending on the environmental conditions of the device, To set an audio delay amount without replacing a ROM from a system.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, 21 is a video frame pulse count unit that counts video frame pulses representing the beginning of the received video frame when decoding and video output is performed from the image decoding unit 5 on the receiving side, and 22 is the count number of this video frame pulse. This is a video frame rate calculation unit that calculates the number of video frames per unit time after measuring for n seconds (n is an arbitrary value). The other parts indicated by numerals 11 to 14 are the same as those in FIG. 4.

Next, the operation will be explained. The image decoding unit 5 decodes the image data transmitted from the transmitting side as shown in FIG. 3, and when outputting the video, the image decoding unit 5 detects a video frame pulse indicating the beginning of the video frame. do.

A video frame pulse counting section 21 counts the video frame pulses, and a video frame rate calculation section 22 calculates the number of video frames per unit time.

Since the number of video frames per unit time is inversely proportional to the amount of motion of the video input to the image transmission device, it is greatly influenced by the environmental conditions of the input video. For example, 1
If 27 video frames are transmitted per second,
As shown in FIG. 2, the video decoded by the image decoding section 5 has a delay of 500 m5ec.

The total delay time of the image data is obtained by adding the processing time of the image encoding section 1 and the processing time of the image decoding section 5 (processing time specific to the apparatus) shown in FIG. 3 to this amount.

The image data delay time calculated in this way is
A write address generation counter 10 inputs to the address of 11 and sets the delay time of the data and audio of the ROM 11.
Output to the initial value of , and then do the same as in Figure 4,
The selector 13 selects the initial value set in the write address generation counter 10 and the initial value of the read address generation counter 12 and writes them to the address of the RAM 14. Set an appropriate audio delay time corresponding to the image quality mode based on the difference with the value.

In the above embodiment, the audio delay circuit 7 is located on the receiving side, but since the video frame rate is the same in the image encoding section 1 and the image decoding section 5, the image encoding section 1 Since the video frame rate can be calculated in the same way as the image decoding section 5, the audio delay circuit 7 may be provided on the transmitting side.

〔Effect of the invention〕

As described above, according to the present invention, the average number of transmitted video frame rates is counted, the processing delay amount of image data is calculated, and the audio delay amount is set correspondingly. Even if the delay time of image data changes due to differences in the environmental conditions of the apparatus, it can be easily handled.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an image transmission device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing the relationship between the number of video frames and the processing delay time of image data for explaining the same embodiment, and FIG. The figure is a block diagram showing the overall configuration of a conventional image transmission device, and FIG. 4 is a block diagram of an audio delay circuit in the conventional image transmission device. 5 is an image decoding section, T is an audio delay circuit, 10 is a write address generation counter, 11 is a ROM, 21 is a video frame pulse count section, and 22 is a video frame rate calculation section. In addition, the same symbols in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] When digitally encoded image data and audio data are multiplexed and transmitted over the same transmission path, and the receiving side separates and decodes the image data and audio data, the audio data is delayed. In the image transmission device that outputs,
An image transmission device comprising an audio delay circuit that calculates a video frame rate of the image data to be transmitted, determines a processing delay time of the image data from the rate, and sets an audio delay amount.