JPH05328321A - Receiver for digital multi-channel transmission system - Google Patents

Abstract

PURPOSE:To enable a user to conveniently select a program by simultaneously displaying the images of plural channels on a screen in the case of selecting a required channel from TV signals obtained by multi-channel transmission. CONSTITUTION:A demultiplexing circuit 401 separates signals from plural channels and an image decoding circuit 407 decodes a signal obtained from one channel CH1. On the other hand, a refresh data multiplexing circuit 402 separates only refresh signals from respective channels and time-dividedly multiplexes the refresh signals and an image decoding circuit 404 decodes the multiplexed signal. The decoded signals for many channels are temporarily inputted to a memory 405, sent to an output mode selecting circuit 406 and inserted into the decoded signal for the main channel and a multi-picture signal is outputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiver for a digital multi-channel system for receiving multi-channel television signals transmitted using digital high efficiency coding (compression coding).

[0002]

2. Description of the Related Art In a system for transmitting and receiving a television signal as digital data as it is, it is possible to receive a television signal of the same high quality as that of the transmitting side without deterioration due to noise, interference or interference of the transmission system. It is a next-generation transmission and reception system that has been researched and developed in various fields such as broadcasting, communication, and so on.

The technology of this transmission and reception system is a so-called compression technology for compressing a huge amount of data generated when a television is digitized by high-efficiency coding, but in recent years, there has been a great progress in this field. Systems have become realistic. There are various techniques for highly efficient encoding of television signals, but the one that has become mainstream in recent years is DCT (discrete cosine transform).
It is based on a combination of coding, motion compensation interframe predictive coding and variable length coding. The basics of such a video high-efficiency coding method are already known in many documents and the like, and will be described in detail in, for example, the video coding method for TV conference / telephone (H.261 standard) standardized by CCIR. Has been.

FIG. 6 shows a block diagram as a basic configuration of the video high efficiency decoding apparatus. Where the input signal is
It is assumed that high efficiency coding has already been performed. The input signal is first input to the buffer memory 203 to absorb the temporal fluctuation of the variable length coded signal. That is, since the amount of generated information per unit time of the variable length coded signal is not constant, in order to decode a video signal with a certain number of pixels per unit time so as to continue decoding, it is Buffering is required. Next, the variable length coded signal is decoded by the decoder 204. After this, it is processed as a video signal having a fixed number of pixels per unit time.

Next, the inverse quantizer 206 restores the quantized representative value, and the inverse DCT unit 207 further transforms the DCT transform coefficient into the original signal in the time domain. The inverse DCT output is input to the adder 208. If the inverse DCT output is a motion-compensated inter-frame prediction signal, the inverse DCT output is added with the signal of the previous frame that has been motion-compensated using the motion vector simultaneously output from the variable length decoder 204 and output. It In order to prevent the decoded video signal from being corrupted due to a transmission error or the like, the transmitter side is forced to perform the inverse DCT.
If the output is transmitted so as not to be a motion-compensated inter-frame prediction signal, that is, if it is an intra-frame coded signal (hereinafter this is referred to as refresh), it is output without performing the addition. The signal of the previous frame is the adder 20
The output of No. 8 is delayed by the frame memory 209 for one frame period, and the motion compensation circuit 210 compensates the motion amount according to the motion vector.

[0006] By further advancing such a technique, it has been proposed to simultaneously transmit a plurality of digital high-efficiency coded television signals to a transmission line where only one television signal can be transmitted by an analog signal in the related art. ing.
In such a transmission system, for example, the digital television signal can be simultaneously transmitted on four or ten channels on a transmission path for one channel of the analog television signal (hereinafter, referred to as multi-channel transmission).

FIG. 7 shows a block diagram of a receiver for receiving signals sent by multi-channel transmission. The received signal is input to the channel selection unit 103 via the antenna 101 and the radio frequency (RF) amplifier 102, and the desired RF channel is selected. The selection here is the selection of the transmission RF channel, in which a plurality of TV channels are further time-division multiplexed as digital data.
After channel selection, automatic gain control (AGC) amplifier 104 performs automatic gain control, demodulation and error correction circuit 105 performs error correction, and then input to demultiplexing circuit 106. The demultiplexing circuit 106 is a circuit for demultiplexing the time-division multiplexed signal of the TV channel, which is also selected by the viewer. The signals of the separated and selected TV channels are, for example, coded video signals, coded audio signals and auxiliary data signals such as teletext. Each signal is decoded and processed by each video decoding circuit 107, audio decoding circuit 108 and auxiliary data processing circuit 109, and is output to each output terminal.

As described above, in a system in which a TV signal can be transmitted on a plurality of channels through one transmission path, one of the transmitted TV signals is selected and decoded. By the way, in receiving a signal transmitted through multi-channels, an operation for selecting one TV signal from many TV signals is required, which is very troublesome as compared with the case where multi-channel transmission is not performed. That is, in multi-channel transmission, the number of channels of a TV signal is increased several times, and the viewer has to select a desired program from among a large number of channels.

Referring to FIG. 7, after selecting the RF channel, the viewer must further select the multiple channels. If the number of TV channels is relatively small, it is easy to select an appropriate one from the program guide, etc. However, if the number of channels becomes several times, such selection becomes troublesome for general viewers. .. Further, if the viewer cannot easily select a favorite program, the spread of the program is hindered, which is not preferable in the industry.

Of course, if a plurality of decoders are prepared,
A plurality of TV signals can be decoded at the same time, and a plurality of channels can be selected at a time, but at this time, the cost of the receiver is increased by the number of decoders. This also hinders widespread use and is not desirable in industry.

[0011]

As described above, in the receiver of the multi-channel transmission system, the number of TV signal channels that the viewer has to select is extremely large, which is inconvenient in use. There is.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a digital multi-channel receiver which can easily select a desired channel from among TV channels increased by multiplexing.

[0013]

According to the present invention, there is provided means for simultaneously separating a coded signal which is not interframe predictive coded, that is, an intraframe coded signal (refresh signal) from a multiplexed signal for a plurality of channels, Means for decoding the time-division multiplexed separated refresh signal,
It has a memory means for storing the decoded signal and a means for reading out the video signal of each channel which is the output of the memory means so as to be displayed on the same screen.

[0014]

According to the above means, from the multiplexed signal,
By the demultiplexing means, only refresh signals for a plurality of arbitrary TV channels are simultaneously demultiplexed and time-division multiplexed. Further, since only the refresh signal is used in the decoding means, the above-mentioned plural channels can be decoded by one decoding means by the time-division multiplexing processing, and even if the addition processing between frames is not performed, At least it is possible to perform frame-dropping video decoding. Further, this output is input to the memory means, and at the time of output, it acts so as to be continuously displayed as a still image or a frame-dropped moving image. Also, depending on the input and output method to the memory means, like a small screen,
It is possible to simultaneously display the signals of the plurality of channels on the screen. It is useful for the user to select a program. To

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. In the figure, the multiplexed coded signal is separated by the demultiplexing circuit 401 as follows. That is, the signal separated here is a complete TV signal 1 including the inter-frame prediction signal.
Channel (probably CH1) and other T
The V signal (probably CH2 to CHn), the audio signal of CH1, and the auxiliary data signal of CH1.

Here, in a multi-channel transmission system for a plurality of TV signals, it is obvious that each TV channel can be completely separated by demultiplexing, and therefore each CH can be separated. Also, CH1
The same applies to the voice and auxiliary data. next,
In the separated CH2 to CHn TV signals, only their refresh signals are further separated. Hereinafter, this separation method will be described.

The refresh signal is time-division multiplexed in the variable length coded signal, and its multiplexing position cannot be known unless variable length decoding is performed. Therefore, here, it is assumed that before the variable-length decoding, for example, the processing as shown in FIG. 2 is performed on the transmitting side in advance so that the refresh signal can be partially separated. That is, a specific sync word (refresh sync word) is placed in front of the refresh data, and its start position is clarified, and at the same time, following the sync word, the length of the refresh signal (refresh data length) is indicated. A codeword is inserted. The method of indicating the refresh period is not particularly limited to this example,
A method of sandwiching the front and rear of the refresh signal with a specific synchronization word may be used. If a sync word or a code word for clarifying the position of such refresh data is prepared, only the refresh signal can be easily separated by detecting the sync word or the code word.

The refresh signals of CH2 to CHn demultiplexed by the demultiplexing circuit 401 according to this rule are clarified in the period and then re-multiplexed by the refresh data multiplexing circuit 402. At the time of multiplexing, the inter-frame coded signal is naturally removed, and only the intra-frame processed signal of each channel is multiplexed.

The re-multiplexed refresh signal is decoded by the video signal decoding circuit 404. The video decoding circuit 404 is a decoding circuit that decodes an intra-frame decoded signal, and does not require the motion compensation circuit and frame addition as described above, and is a relatively simple circuit.

FIG. 3 shows a block diagram of the decoding circuit 404. The operation is almost the same as that of the decoder shown in FIG. 6, except that there is no frame addition and the inverse DCT output is output as it is. Therefore, the same parts as those of the circuit block shown in FIG.

Since the decoding circuit 404 time-division-multiplexes and decodes a plurality of TV channels in frame units, its output is also a time-division-multiplexed video signal. Generally, refresh is from several frames of video frame to several
Since the data is transmitted once per 0 frame, each channel is decoded according to this cycle.

Next, the decoded refresh signals of a plurality of TV channels are written in the memory 405. The memory 405 is a circuit for continuously outputting video signals input discontinuously by the same operation as that of the frame synchronizer. That is, the output of the decoding circuit 404, that is, the signal in which each channel has been subjected to the time division multiplexing processing is decoded as an image of one frame for each refresh cycle. Therefore, it is simply decoded as a so-called quasi-moving image on a frame skip, not a normal continuous moving image. As a result, the refresh signal is sent to the memory 405 like a frame drop.
Is output to. The memory 405 operates so that the non-decoded video frame repeatedly outputs the previous frame so that the quasi-moving image signal can be reproduced at a normal frame period. The memory 405 is prepared for the plurality of TV signals, but in order to save the memory, the pixels are thinned out in advance and divided into one frame of memory to be written, and the plurality of TV signals are divided into screens. It can also be used to reproduce. Next, the memory output is selected by the output mode selection circuit 406 with the output of the video decoding circuit 407 or is screen-multiplexed and displayed.

In the demultiplexing circuit 401, the audio signal of the channel CH1 and the auxiliary data signal of CH1 are also separated, and are input to the audio decoding circuit 408 and the auxiliary data processing circuit 409 to be decoded.

FIG. 4 shows an example of the display mode of the signal output from the output mode selection circuit 406. FIG. 10A shows an example in which an image for three channels of the refresh signal is inserted into the image of the main channel of CH1 and displayed as a small screen. Further, FIG. 9B is an example in which images for four channels are simultaneously displayed on the split screens of the same size. Various other examples of display are conceivable, but the present invention is not limited to such a display method. A display control signal is supplied to the output mode selection circuit 406, and the above multi-screen is obtained at the time of channel selection. For example, a high frequency selection operation is performed,
Until a channel is finally determined, a display control signal is generated with predetermined data and a multi-screen is displayed.

As described above, in the above embodiment, a plurality of TV channels can be simultaneously and simply viewed by adding only one relatively simple intraframe decoder. Since it is possible to view even the frame-dropped video signals at the same time, it is very convenient as a channel selection means. Next, another embodiment of the present invention will be described.

In FIG. 5, the decoder for the refresh signal does not have a dedicated intra-frame decoder, but the main channel C is used.
This is an embodiment shared with an H1 decoder. The same parts as those in the previous embodiment are designated by the same reference numerals.

In sharing the decoder, the period between the remultiplexing circuit output of the refresh signal and the CH1 separated output is clarified, and the multiplexing circuit 501 further remultiplexes. That is, the output of the refresh multiplexing circuit 402 and the CH1 signal demultiplexed by the demultiplexing circuit 401 are supplied to the main channel / subchannel multiplexing circuit 501 to be multiplexed. Next, the multiplexed output is decoded by a decoding circuit 502 having a complete inter-frame and intra-frame decoding function according to each coding mode. At this time, the decoding speed is increased as much as it is multiplexed, and a circuit capable of time-division multiplexing and decoding the refresh signal is used. That is, a decoding circuit that can operate at a faster speed than a decoding circuit for only one channel is used. This processing speed is determined based on the amount of refresh signals to be processed at the same time, but even if the refresh signals momentarily increase and decoding in time division becomes impossible, CH1 decoding is performed. Since this is prioritized, this decoded output will not fail.

On the other hand, the refresh signal is originally a frame-dropped video signal, and even if the decoding is partially stopped, it has no great influence, and at the same time, the decoding can be restarted immediately. Therefore, the decoding circuit 502
Even if the processing speed of 1 is insufficient, the processing can be continued without significant performance degradation.

The output of the decoding circuit 502 is written into the respective memories 503 and 504 for CH1 and the remaining channels. The memory 503 is a memory for returning the CH1 signal to the original continuous signal because the CH1 signal is output in bursts by the time division multiplexing process. Note that this signal is a complete moving image signal. On the other hand, the memory 504 is a memory for writing the decoded output of the remaining refresh signal and outputting the same as in the previous embodiment.

As described above, in this embodiment, by using a high-speed decoding circuit, a plurality of TV channels can be simultaneously simplified without using a dedicated circuit for decoding a multiplexed signal of refresh signals for a plurality of channels. You can see Similar to the above example, even if the remaining reproduced image except one channel is a frame-dropped video signal, they can be viewed at the same time, so the user can select the channel while watching this multi-screen. It can be used as a reference and is very convenient.

The notations such as CH1 in the above description are used for simplifying the description, and particularly C
It does not specify the H number. Further, it is easy for the viewer to display an arbitrary channel as the main channel of CH1 in the complete moving image in the above-mentioned embodiment,
It does not depart from the spirit of this invention. Further, the same is true for the designation of TV channels that are simply reproduced in the form of time-lapse frames, and the number of designated channels does not limit the present invention.

In addition, the T selected by the simultaneous display can be easily selected.
The V channel information is stored together with the RF channel selection information described with reference to FIG. 7, and it becomes more convenient for the user if both channels are automatically selected without performing the same operation when selecting again.

Further, in the above description, the video high efficiency coding including the DCT coding is used as an example, but the present invention is not limited to this coding system, and all the interframe coding using the interframe coding. The coding method can be generally applied.

[0035]

As described above, according to the present invention, it is possible to easily decode multiple channels and display them for a plurality of channels simultaneously on one screen. As a result,
It is easy for a user to select a desired channel from multi-channel transmitted TV signals, and at the same time, it has an industrial effect that the problem of channel selection in multi-channel transmission is alleviated and its spread is promoted. large.

[Brief description of drawings]

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

2 is an explanatory diagram showing an example of a transmission format of an encoded signal in the system of FIG.

FIG. 3 is a diagram showing an example of a decoding circuit in FIG.

FIG. 4 is an explanatory diagram showing a display example of the device according to the present invention.

FIG. 5 is a diagram showing another embodiment of the present invention.

FIG. 6 is a block diagram of a video high efficiency decoder.

FIG. 7 is a block diagram of a digital multi-channel transmission receiver.

[Explanation of symbols]

401 ... Demultiplexing circuit, 402 ... Refresh signal re-multiplexing circuit, 404 ... Video decoding circuit, 405 ... Memory,
406 ... Output mode selection circuit, 501 ... Main channel / sub channel multiplexing circuit, 502 ... Video decoding circuit, 50
3, 504 ... Memory.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location H04N 5/45 7/137 Z

Claims (4)

[Claims] 1. The video signals of a plurality of channels are respectively
In a receiver of a multi-channel transmission system, which receives high-efficiency video coding using inter-frame coding, is further multiplexed, and is transmitted as a multi-coded signal on the same transmission path, A means for guiding a signal, separating a coded signal which has not been coded between frames of each channel, that is, an intra-frame coded signal (refresh signal) and time-division-multiplexing and outputting the signal; And a decoding unit that decodes each refresh signal, a memory unit that stores the decoded signal, and a unit that reads the output of the memory unit so that the output of the memory unit is displayed on the same screen. Receiver for multi-channel transmission system. 2. The receiver of a digital multi-channel transmission system according to claim 1, wherein the decoding means for the refresh signal is a decoding circuit for an intra-frame coded signal having no frame addition. .. 3. The refresh signal decoding means comprises:
2. The receiver of the digital multi-channel transmission system according to claim 1, wherein the decoding circuit having a high coding speed is circuit-shared with the interframe decoding processing by time division multiplexing processing. 4. The receiver of a digital multi-channel transmission system according to claim 1, wherein the multiple encoded signal includes a refresh synchronization word for identifying the refresh signal period.