JP2884567B2 - Digital information transmission method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for digitally transmitting both an image signal and an audio signal.

[Conventional technology]

In the digital information transmission method, an error detection and correction code is added on the transmission side in order to cope with an error occurring on the transmission path, and the reception side detects and corrects a transmission error using the error detection and correction code.

In this specification, one information unit to which the error detection and correction code is added is referred to as an error correction block. Conventionally, when handling image signals and audio signals as information signals to be transmitted,
As shown in FIGS. 2 (a) and 2 (b), separate error correction blocks are formed for image data and audio data, and encoding and decoding are performed by different circuits. As shown in (c) and (c), a common method is to use the same data length for the error correction blocks of image data and audio data and to share a circuit. In FIG. 2, the ID
Is the block number and other additional data, V is the image data,
A indicates audio data, and P indicates an error detection and correction code.

[Problems to be solved by the invention]

However, in the former conventional example in which image data and audio data are processed by separate circuits, the circuit scale becomes large, and there is too much waste in commonable parts. Further, in the latter conventional example in which the data length of the error correction block is the same, the amount of information per unit time of image data and audio data is too different. Fatal errors can occur in the data, and the sound data tends to deteriorate significantly.

Therefore, an object of the present invention is to provide a digital information transmission method capable of simplifying a circuit for processing an image signal and an audio signal.

[Means for solving the problem]

A digital information transmission method according to the present invention is a method of digitally transmitting an image signal and audio signals of a plurality of channels, wherein a block serving as a unit of error correction includes a first portion to include a predetermined amount of image data; An error detection and correction code is generated and added to the data of the first and second parts, including the second part which should include a predetermined amount of audio data of each channel.

[Action]

Since one block includes an image and audio of a plurality of channels, an appropriate transmission unit amount can be set according to the information amount per unit time of the image and the audio. In addition, since image data and audio data of multiple channels are individually transmitted, even if a burst error occurs, there is little damage to the image data and audio data of each channel, and correction of uncorrectable data is compared. It is easy. Further, since an error detection and correction code is generated and added to the whole of a predetermined amount of image data and audio data of each channel, much of the transmission / reception circuit system can be shared between image processing and audio processing. Hardware can be simplified.

〔Example〕

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

FIG. 1 shows the format of an error correction block in one embodiment of the present invention. ID indicates a block number and other additional data, V indicates image data, A indicates audio data, and P indicates an error detection and correction code. In this format, the error detection and correction code P is added to the entirety of the image data V and the audio data A, and the transmission device sends out a transmission path by adding a synchronization signal and the like to this error correction block.

For example, if a high-definition image with an effective scanning line number of 1,050 lines / frame is treated as image data, and 1/3 line data is included in one error correction block, 3,150 error correction blocks are formed per frame. You. In this embodiment, audio data is dispersedly inserted into the 3,150 error correction blocks. Even if audio signals of four channels are sampled at 48 KHz each, the amount of audio data per error correction block is about 2 samples, and even if a burst error occurs, audio data is not lost altogether. .

Further, in consideration of interpolation at the time of error occurrence, as shown in FIG. 3, it is preferable that audio data composed of N channels are dispersedly arranged for each channel in one error correction block. As a result, the audio data of each channel that is temporally continuous is further dispersed. Therefore, when data that is determined to be uncorrectable during decoding is corrected, the data before and after the error correction block of interest is corrected. Can be interpolated using the data of the same channel in the block.

In the case of an audio signal of four channels, four samples of four channels at the same time are included in one error correction block, and
Assume that audio data per error correction block is 4 samples. Then, no audio data is inserted into about half of the error correction blocks per frame, but a space for four samples is provided, and the block length is kept the same.

4A and 4B show the transmission / reception system of the present embodiment, and FIG.
The figure shows a transmission system, and FIG. 4B shows a schematic block diagram of a reception system. The transmission / reception operation will be described with reference to these drawings.

In the transmission system shown in FIG.4A, a signal obtained by digitizing a horizontal scanning image signal such as a television signal is input to an input terminal 10, and a digital audio signal encoded by, for example, PCM is input to an input terminal 12. You. The data compression circuit 14
The digital image signal at input terminal 10 is
Compress using the CM method. The time axis conversion / synthesis circuit 16
The image data from the data compression circuit 12 and the audio data at the input terminal 12 are time-axis-converted and synthesized as shown in FIG. FIG. 5 (a) shows that V is a digital image signal and A is
Indicates a digital audio signal. The ID addition circuit 18 inserts an ID signal into the output of the time axis conversion / synthesis circuit 16 for each error correction block as shown in FIG. 5B.

The error correction code circuit 20 outputs the ID
An error correction code is generated for each error correction block, and the fifth
A parity P is added as shown in FIG. Examples of the error correction code include a Reed-Solomon code. The synchronization adding circuit 22 adds a synchronization signal to form a synchronization block, and the modulation circuit 24 modulates the synchronization block in a form suitable for the characteristics of the transmission line and sends it out to the transmission line.

Next, the operation of the receiving side in FIG. 4B will be described. The transmission signal on the transmission path is demodulated by the demodulation circuit 26, and the synchronization separation circuit 28 separates the synchronization signal added by the synchronization addition circuit 22 (FIG. 4A). The sync signal separated here is not shown,
This is a reference for the operation timing of each circuit. Sync separation circuit 28
The digital information signal from which the synchronizing signal has been separated is applied to the error correction circuit 30. The error correction circuit 30 corrects a transmission error according to a predetermined algorithm. However, for a block for which it is determined that error correction cannot be performed, a correction flag indicating that correction is not possible is written to the correction flag memory 32.
The signal that has been subjected to the error correction operation in the error correction circuit 30 is applied to the ID separation circuit 34, where the ID signal is separated. Here, the separated ID signal is supplied to a system controller (not shown).

The image / audio separation circuit 36 separates a digital image signal and a digital audio signal from the signal from which the ID signal has been separated by the ID separation circuit 34, and applies them to the data decompression circuit 38 and the audio error correction circuit 40, respectively. The data decompression circuit 38 decompresses the separated digital image signal and applies it to the image error correction circuit 42. The audio error correction circuit 40 and the image error correction circuit 42 refer to the correction flag memory 32 and perform correction processing such as interpolation with adjacent data on data that could not be corrected by the error correction code.

〔The invention's effect〕

As can be easily understood from the above description, according to the present invention, it is possible to provide a transmission method in which the sound of each channel is hardly deteriorated even by a burst error or the like on a transmission path. Further, a considerable part of the hardware can be commonly used for the image and sound in the transmission / reception circuit system, and therefore, it can be realized with a small-scale circuit configuration.

[Brief description of the drawings]

FIG. 1 shows the format of an error correction block according to an embodiment of the present invention, FIG. 2 shows the format of an error correction block of a conventional example, FIG. 3 shows another error correction block format of the present invention, FIG. FIG. 4B is a configuration block diagram of a transmission / reception system of the digital information transmission system according to the present invention,
FIG. 5 is an explanatory diagram of an error correction block generation process in this embodiment. 10 image input terminal, 12 audio input terminal, 14 data compression circuit, 16 time axis conversion / synthesis circuit, 18 ID addition circuit, 20 error correction code circuit, 22 synchronization Additional circuit, 24: Modulation circuit, 28: Synchronization separation circuit, 30: Error correction circuit, 32: Correction flag memory, 34: ID separation circuit, 36: Image / voice separation circuit, 38: Data decompression circuit, 40 ... Audio error correction circuit, 42 ... Image error correction circuit

Claims (1)

(57) [Claims] 1. A method for digitally transmitting an image signal and audio signals of a plurality of channels, comprising: a first portion for including a predetermined amount of image data in a block serving as an error correction unit; And generating and adding an error detection / correction code to the data of the first and second parts, including a second part which should be included by a predetermined amount.