JPH07123301B2 - Multiplex transmission system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] When a digital audio signal and a digital video signal in which a unique word asynchronous with the digital audio signal is provided are multiplexed and transmitted, the period of the unique word is unique. When the audio signal bit is inserted during the unique word period with an integral multiple of the word width, the bit position information of the audio signal bit should be inserted at a predetermined position of the unique word for transmission. In this way, multiplexed transmission is possible with a small circuit scale.

[Industrial application field]

The present invention relates to an improvement of a multiplexing transmission system for multiplexing and transmitting a digital audio signal and a digital video signal asynchronous with the digital audio signal.

When digitizing the video signal and transmitting it, it is shown in Fig. 7 in order to know where the MSB is and where the LSB is when detecting the horizontal synchronizing signal on the receiving side and converting the received serial signal into a parallel signal. As described above, a unique word is provided in the horizontal synchronizing signal, and a special code which does not appear in a normal signal within this period, for example, ten consecutive 0s is inserted so that it starts with MSB and ends with LSB and is transmitted.

In the case of FIG. 7, since 10 consecutive 0s are inserted,
1s are inserted on both sides in order to eliminate 0 consecutive numbers.

Further, when the horizontal synchronizing signal is digitized by comparing it with a threshold value, the period of the digitized horizontal synchronizing signal is not always constant due to the distortion generated on both sides of the horizontal synchronizing signal, and therefore the period of the unique word is also constant. However, it is not always possible to use this as a synchronization signal.

As described above, it is desired that the circuit scale is small in the multiplex transmission system in which the digital video signal in which the unique word is inserted in the horizontal synchronization signal and the asynchronous digital audio signal are multiplexed and transmitted.

[Problems to be solved by conventional technology and invention]

When a digital audio signal and a digital video signal asynchronous with the digital audio signal are multiplexed and transmitted, conventionally, a buffer memory for storing data is provided in order to match the bit rates of the digital video signal and the digital audio signal. The occupancy of the buffer memory is stored by storing, and the detection result indicates that the code length of the digital video signal is changed by the variable length encoder and multiplexed so that a shorter code length is used if the occupancy is large. It was transmitting. (At this time, of course, a signal indicating the code length was also inserted in the data for transmission.) Therefore, a buffer memory and a variable length encoder with a large circuit scale are required, and the circuit scale increases and power consumption increases. There is a problem.

[Means for solving problems]

The above problem is caused by inputting a horizontal synchronizing signal and a signal indicating a unique word width as shown in FIG. 1 and setting the cycle to an integral multiple of the unique word width. Output pulse width and select
A pulse output means 1 for inputting as a selection signal of 11, and a signal obtained by branching the least significant bit of parallel image data, audio data, bit position information of audio data, and audio data for inserting audio data into the least significant bit of the parallel image data. A data insertion signal and a signal indicating the unique word width are input, and from the output, an audio signal inserted by the audio data insertion signal into the least significant bit of parallel image data is output, and the least significant bit is branched into parallel image data. In addition, if the voice data is inserted by the voice data insertion signal during the unique word period by inputting to the selector 11 or from the output, it means that the voice data has been inserted at the predetermined position of the unique word. Is output to the selector 11 with the same number of bits as the parallel image data, in which the bit position information of the code and the audio data is inserted. The selector 11 selects parallel data from the processing means 8 when a pulse is input from the pulse output means 1 and inserts an audio signal into the least significant bit when the pulse is not input. This is solved by the multiplex transmission system of the present invention which selects and outputs the parallel image data.

[Action]

According to the present invention, in the selector 11, the parallel image data in which the audio signal is inserted in the least significant bit and the audio data in the unique word period output from the processing means 8 are inserted by the audio data insertion signal. In this case, parallel data with the same number of bits as the parallel image data, in which the code indicating that the audio data has been inserted and the bit position information of the audio data have been inserted at the predetermined position of the unique word, and pulse output When the pulse from the means 1 is input, the parallel data from the processing means 8 is selected, and when the pulse is not input, the parallel image data with the audio signal inserted in the least significant bit is selected and output. With this, bit synchronization of audio data becomes possible, and multiplexed transmission of a digital audio signal and a digital video signal asynchronous with this becomes possible, resulting in a large circuit scale. Ffuamemori and variable-length coder is unnecessary, it is possible to reduce the circuit scale.

〔Example〕

FIG. 2 is a block diagram showing the structure of the main part of the multiplexing circuit of the embodiment of the present invention, and FIG. 3 is a time chart of the input / output data of the ROM of FIG. It corresponds to points a to h in FIG. FIG. 4 is a block diagram of a circuit for outputting a pulse having a unique word period that is an integral multiple of the unique word width, and FIG. 5 is a time chart of waveforms of respective parts in FIG. It corresponds to points a to f in the figure.
Note that (a), (e), and (f) are reduced views of (A), (E), and (F). FIG. 6 shows the output of the selector 12 of FIG.
It is a figure which shows the multiplexed data.

In the figure, 6 is a coder, 7 is a counter, 9, 10, 17, 19, 20 are flip-flops, 8 is ROM, 11 and 12 are selectors, 13 is a parallel-serial conversion circuit, 14 is a NOR circuit, 15 is a clamper, 16 Is a knot circuit, 18 is an AND circuit, and 21 is a NAND circuit.

As the input signal of the multiplexing circuit of FIG. 2, the audio data shown in FIG.
In the circuit shown in FIG. 4, which will be described later, the audio data insertion signal at the substantially center of the audio data for inserting the audio data shown in FIG. The generated reset signal indicating the unique word period shown in FIG. 3 (D), and the audio bit position information indicating the number of the audio data of, for example, 32-bit structure shown in FIG. 3 (F) from the counter 7. , A signal from the image counter divided by the unique word width shown in FIG. 3 (G),
In the embodiment, image data having a 5-bit structure is input.

These input signals are input to the flip-flop 9 as reset signals, and the LSB 1 bit of image data is stored in the ROM8.
The remaining 4 bits are input to the flip-flop 10, and the voice data insertion signal, voice data, and voice bit position information are input to the ROM 8.

In the ROM8, from these input signals, the audio data D1, D2, ... Are inserted in 1 bit of the LSB of the image data according to the audio data insertion signal shown in FIG. Flip-flop 10 with 5 bits superimposed on data
I am trying to type in.

In the ROM8, as shown in FIG. 3 (H), a special code indicating the MSB and LSB of the image data having a unique word width divided into a certain width by the signal from the image counter shown in FIG. 3 (G) is inserted. A 5-bit signal having a code of 1 is formed on both sides of the position to be input and is input to the flip-flop 10. When voice data is inserted into this unique word width, FIG. With the voice data insertion signal shown in
As shown in C and D, the voice data D1, D2, ...
Insert the audio bit position information indicating the second, second ...
Further, the code 1 indicating that the voice data has been inserted is inserted at a predetermined position and input to the flip-flop 10. The audio data is the image data outside the unique word.
Of course, it may be inserted in the LSB.

5 bits of image data input to this flip-flop 10 with audio data inserted in the LSB and FIG. 3 (H)
The 5-bit constant 6-bit wide unique word signals shown in FIG.

The selector 11 normally selects the image data side indicated by A, and when the reset signal is input through the flip-flop 9, selects the signal on the unique word side indicated by B,
It is sent to the selector 12.

The selector 12 is based on the signal from the reset signal shown in FIG. 3 (D) through the flip-flop 9 and the signal from the image counter shown in FIG. 3 (G) shown in FIG. 3 (C). The signal from the produced ROM 8 is input to the NOR circuit 14, and the special code insertion pulse shown in FIG. 3 (E) that is output is input. When this pulse is input, the selector 12 Selects the ground side, inserts ten 0-series special codes at predetermined positions of the signal of the unique word width selected by the selector 11, and sends them to the parallel-serial conversion circuit 13.

As shown in FIG. 6, the output of the selector 12 is a signal in which audio data, for example, D2 is superimposed on the LSB of the image data, and a unique word signal provided in the horizontal synchronizing signal. When data such as D1 is inserted, the code 1 indicating that the data has been inserted and the position information such as 00001 indicating the order are both inserted.

The data obtained by multiplexing the image data and the audio data as shown in FIG. 6 is sent to the parallel-serial conversion circuit 13 and sent to the transmission line as a serial signal.

In order to synchronize the video signal, the reset signal for determining the unique word width for making the unique word period an integral multiple of the unique word width is as described below with reference to FIGS. Made

By inputting the video signal to the clamper 15, the horizontal synchronizing signal shown in FIG. 5 (A), this reduced view (a) is extracted and input to the flip-flop 19, and the output of the flip-flop 19 is input to the flip-flop 20. At the same time, it is input to the NAND circuit 21, and the output of the flip-flop 20 is input to the NAND circuit 21.

On the other hand, the flip-flop 17 receives the clock obtained by inverting the clock shown in FIG. 5 (B) by the knot circuit 16 and the signal from the ROM 8 showing the unique word width shown in FIG. 5 (C), A clock and the output signal of the flip-flop 17 shown in FIG. 5 (D) are input to the input of the AND circuit 18,
From the output, a pulse having the same phase as the clock and having a unique word width is obtained as shown in FIG. 5 (E), which is a reduced diagram (e), and is input to the flip-flops 19 and 20 as a clock.

By this clock, a reset signal as shown in FIG. 5 (F) and its reduced diagram (f) is obtained at the output of the NAND circuit 21 of the differentiating circuit composed of the flip-flops 19, 20 and the NAND circuit 21.

This reset signal is generated by the horizontal synchronizing signal shown in FIG. 5 (a) and the clock shown in FIG. 5 (e). Even if the cycle of the horizontal synchronizing signal changes as shown in FIG. A unique word is provided in the signal, the width of the unique word is constant, the unique word period is an integral multiple of the unique word width, and the video signal can be synchronized based on the unique word width.

According to the above, the digital audio signal and the digital video signal asynchronous with the digital audio signal can be multiplexed and transmitted. In this case, the buffer memory having a large circuit scale used in the conventional multiplex transmission system is used. Since a variable length encoder or the like is not used, the circuit scale can be made very small and power consumption can be made small.

[Effects of the Invention] As described in detail above, according to the present invention, the circuit scale of a multiplexing circuit for multiplexing and transmitting a digital audio signal and a digital video signal asynchronous with the digital audio signal can be made extremely small. Therefore, there is an effect that power consumption can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing the principle of the present invention, FIG. 2 is a block diagram showing a configuration of a main part of a multiplexing circuit according to an embodiment of the present invention, and FIG. A time chart, FIG. 4 is a block diagram of a circuit that outputs a pulse having a unique word period that is an integral multiple of the unique word width, FIG. 5 is a time chart of the waveforms of the respective parts in FIG. 4, and FIG. 6 is FIG. FIG. 7 is a diagram showing the multiplexed data output from the selector 12, and FIG. 7 is a diagram showing the contents of the unique word in the conventional example. In the figure, 1 is pulse output means, 6 is a coder, 7 is a counter, 8 is a processing means, ROM, 9,10,17,19,20 are flip-flops, 11,12 are selectors, 13 is a parallel-serial conversion circuit, 14 is a NOR circuit, 15 is a clamper, 16 is a knot circuit, 18 is an AND circuit, and 21 is a NAND circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiichi Matsuda 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor Toshitaka Tsuda 1015, Kamedotachu, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited

Claims (1)

[Claims] 1. A horizontal synchronizing signal and a signal indicating a unique word width are input when a digital audio signal and a digital image signal in which a unique word asynchronous with this is provided in a horizontal synchronizing signal are multiplexed and transmitted. And a pulse output means (1) for outputting a pulse having a unique word width of a unique word in the horizontal synchronizing signal whose cycle is an integer multiple of the unique word width and inputting it as a selection signal of a selector (11), Input a signal obtained by branching the least significant bit of image data, audio data, bit position information of audio data, an audio data insertion signal for inserting audio data into the least significant bit of the parallel image data, and a signal indicating the unique word width. , The output outputs the audio signal inserted by the audio data insertion signal to the least significant bit of the parallel image data, and branches the least significant bit. In addition to the parallel image data, it is input to the selector (11), and when the audio data is inserted from the output by the audio data insertion signal during the unique word period,
The code indicating that the audio data has been inserted and the bit position information of the audio data are inserted in the predetermined position of the unique word, and the parallel data having the same number of bits as the parallel image data is output to the selector (11). Processing means (8)
The selector (11) selects parallel data from the processing means (8) when a pulse is input from the pulse output means (1), and outputs an audio signal in the least significant bit when not input. A multiplex transmission method characterized in that the inserted parallel image data is selected and output.