CN1051193C - A system for transmitting high-definition television using existing digital broadcasting equipment - Google Patents

Abstract

A system for transmitting high-definition television using existing digital video broadcasting (DVB) equipment, wherein the transmitting end includes a plurality of ordinary digital television encoders (3), a multiplexer (4), a channel coding and modulation circuit (5), a transmitting system (6), etc., and the receiving end includes an integrated receiving decoder (7), which includes a demodulation circuit (71), a demultiplexer (72), an ordinary digital television video decoder (73) and an audio decoder (74), etc., and an A/D converter (1), an image segmenter (2) and a controller (9) are added to the transmitting end; an image splicing circuit (75) and a D/A conversion and post-processing circuit (76) are added to the integrated receiving decoder of the receiving end; thus, the high-definition television signal can be transmitted using the existing digital video broadcasting (DVB) equipment through segmentation at the transmitting end and splicing at the receiving end.

Description

The present invention relates to high-definition television (HDTV) systems, and more particularly to systems for transmitting high-definition television using existing digital video broadcast (DVB) equipment.

Video broadcasting is information broadcasting at a high data rate, and HDTV has a greater information content due to its high resolution. For example, a digital high-definition television interface signal format proposed in the 1TU-R BT.1120 proposal is: the full-frame image format is 1728*1250/50/2:1, and the effective image pixel is 1440*1152. The bandwidth of each analog component signal is 27MHz. For this wideband video signal, it is currently agreed that it should be digitally compressed so that it can be transmitted with a narrower bandwidth in order to fully utilize the frequency space. If the signal is sampled at a sampling rate of 54MHz, and the sampling rate ratio of the chrominance signal is 4:2:0, the total data rate after digitization is about 650Mbps. At present, the commonly used compression method is the video compression method in MPEG2, in which the processing includes motion estimation, motion compensation, DCT transformation, quantization, variable length coding, etc., and these complicated processing should be performed on the huge amount of data of high-definition television , the processing capability of the device is required to be very powerful. However, the current device level cannot realize low-cost and practical high-definition television coding equipment. In addition, although the processing of the decoding part is simpler than that of encoding, due to the large amount of data and the level of devices of high-definition television, it is still impossible to obtain receiving equipment that can meet consumption capabilities.

At present, ordinary digital video broadcasting (DVB) has been pushed to the market, its related technologies and devices have matured, and transmission standards (DVB satellite, cable, etc.) have been formulated. Lower-cost receiving equipment scales consumption, and scaled consumption further reduces the cost of equipment.

In DVB broadcasting, the current compression and modulation technology has realized the transmission of four common digital TV programs in one common analog TV channel. Its system structure is shown in Figure 1.

In the DVB broadcasting system shown in Figure 1, the four common TV signals are digitally coded by four common digital TV encoders 3, and the coded data is sent to the multiplexer 4, and then channel coded by the channel coding and modulation circuit 5 and modulation, and finally sent to the launch system 6 for launch. Channels can be satellite, cable, or terrestrial broadcast, among others. At the receiving end, it is received by an integrated reception decoder (IRD) 7, which includes a demodulation circuit 71 for demodulation of channel coding; a demultiplexer 72 for separating multiplexed four-way digital television signals into four an independent digital television signal; a common digital television video decoder 73, which is used to decode the encoded digital television signal into an original common television signal; an audio decoder 74, which performs audio decoding. The video signal and audio signal decoded by the above-mentioned ordinary digital TV video decoder 73 and audio decoder 74 are sent to the display device 8 for display.

For a more detailed description of the above-mentioned background technology, please refer to the document "Full Digital High-Definition Television and DVB" (edited by Zheng Zhihang, Beijing: China Radio and Television Press, first edition in 1997).

Since the consumer market for high-definition TV has not yet started, and low-cost and practical high-definition TV codec equipment has not yet been realized, broadcasters are now required to take a greater risk to purchase high-priced high-definition TV broadcasting equipment to start A consumer market for HDTV is unrealistic.

The purpose of the present invention is to use the image segmentation technology to realize the broadcast transmission of high-definition television at low cost by utilizing the existing common digital television broadcasting equipment.

Considering that the video compression technology adopted in DVB broadcasting is also MPEG2 technology, and the digital multiplexing technology is adopted in digital video broadcasting. Therefore, the present invention adopts the image segmentation at the sending end and the image splicing at the receiving end to realize high-definition television broadcast transmission on the basis of the existing DVB broadcasting equipment. Utilizing the system can realize high-definition television broadcasting quickly and at low cost, and promote the development of high-definition television broadcasting services and the development of consumer markets.

According to the system of utilizing existing digital video broadcasting (DVB) equipment to transmit high-definition television according to the invention, its transmitting end includes a plurality of common digital television encoders, multiplexers, channel coding and modulation circuits, and a transmitting system; its receiving end includes Comprehensive receiving decoder, it comprises demodulation circuit, demultiplexer, common digital TV video decoder and audio decoder etc., it is characterized in that:

Its transmitter also includes: A/D converter, image divider and controller, etc.

The high-definition TV video signal is first processed by the high-definition TV A/D converter and then becomes a digital signal. Several sub-video data streams are formed, and these sub-video data streams are sent to multiple common digital TV encoders for compression and encoding processing. The operating parameters of each encoder (such as quantization matrix, data rate, etc.) are configured and controlled by the system controller, so that each encoder has the same program clock reference (PCB), and each sub-picture originally belonging to the same frame Like having the same presentation time scale (PTS) and decoding time scale (DTS),

The coded sub-video streams are sent to the multiplexer as independent program video compression streams for multiplexing, and the system controller controls the parameter settings of the multiplexer to meet the requirements of image segmentation and splicing;

The integrated receiving decoder at the receiving end also includes image splicing circuit, D/A conversion and post-processing circuit. The video decompresses the code stream and stitches the images according to the segmentation information in it. The spliced video code stream is processed by A/D conversion and post-processing circuit for A/D conversion and filtering, and then sent to the high-definition TV display device to display.

According to the system of utilizing existing digital video broadcasting equipment to transmit high-definition television according to the present invention, it is characterized in that said image divider divides the high-definition television image into four frames suitable for ordinary A sub-picture processed by a digital television encoder.

Utilize existing digital video broadcasting equipment to transmit the system of high-definition television according to the present invention, it is characterized in that said image splitter divides high-definition television image into every field two suitable common digital A sub-picture processed by a teleccoder.

According to the system of utilizing existing digital video broadcasting equipment to transmit high-definition television according to the present invention, it is characterized in that said image divider begins to extract several pixels from the origin of the original high-definition television image to form a common digital television code Then change the sampling start phase (that is, shift the horizontal or vertical start point of sub-sampling), then extract the sub-image, repeat this operation, and finally divide the original image into several Subimages with the same sampling rate but different phases.

Embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

Fig. 1 is the block diagram of existing digital video broadcasting system;

Fig. 2 is the block diagram that the present invention utilizes existing digital video broadcasting (DVB) equipment to transmit the block diagram of the system of high-definition television; Fig. 3 utilizes existing digital video broadcasting (DVB) equipment to transmit high-definition television according to the present invention A block diagram of the receiving part of the system;

Fig. 4 is a schematic diagram of frame image segmentation method;

Fig. 5 is a schematic diagram of field image segmentation method;

Fig. 6 is a schematic diagram of the sub-sampling segmentation method.

Referring to Fig. 2, based on the existing DVB equipment in the originating system, a high-definition television A/D converter 1, an image divider 2 and a controller 9 are added.

The high-definition television video signal becomes a digital signal after being processed by the A/D converter 1 first, and its output interface format can adopt the standard format of ITU-R BT. Structure (for example, the line and field synchronous signals are transmitted to the subsequent image divider through another signal line, so that the extraction of line and field signals can be omitted).

Then the digital signal is sent to the image segmentation processor for segmentation processing. The specific segmentation processing method will be described in detail later. The high-definition television digital video signal forms several sub-video data streams after the image segmentation process, and the present embodiment divides the high-definition television signal into four sub-video data streams, and these sub-video data streams pass through the D1 or CCIR656 digital video interface And other interfaces acceptable to common digital television coding equipment are sent to several common digital television encoders 3 for compression and coding processing. These compression encoders are DVB original equipment. Each compression coder performs compression coding processing on the input sub-video code stream as an independent program, and they are not correlated with each other, and operate independently and in parallel. The operating parameters (such as quantization matrix, data rate, etc.) of each encoder can be different, which is determined by the segmentation method (described in detail in the following image segmentation), and is configured and processed by the system controller 9. control.

In order to splice the divided images together at the decoding end, the same program clock reference (PCR) should be provided to each encoder here, and at the same time, it should be ensured that each sub-image originally belonging to the same frame has the same PTS ( Display Time Scale) and DTS (Decoding Time Scale).

Each compression encoder outputs MPaML video compression code stream conforming to MPEG-2.

The compressed sub-video code streams are sent to the original multiplexer 4 of DVB as independent program video compressed code streams for multiplexing. The input code stream is PES stream (Packeted Elementary Code Stream), which contains time information such as PTS (Display Time Scale), DTS (Decode Time Scale) and PCR (Program Clock Reference). The controller controls the multiplexer to add the identification information of image segmentation in the transport stream. The identification information is used for identification of the system, identification of the segmentation method, and identification of each sub-video stream of the same program. Among them, the system identification information is used to identify the identification of the system, that is, indicating that the code stream is generated by the system, and the system identification information can be stored in the network information table (NIT, networks information table) of the transport stream (transport stream) , the table is user-defined in MPEG-2.

The multiplexer multiplexes the input video code streams as video streams of several programs. This is because the multiplexer used in this system is the original DVB equipment. In order to splice the divided sub-images together at the receiving end, on the basis of not changing the original equipment, some special soft settings are carried out by the system controller 9 to meet the special requirements of the system.

These special treatments are as follows: each video sub-stream of the same high-definition television program is identified by a PAT table (program association table) and a PMT table (program mapping table), that is, each video sub-stream of the same high-definition television program The PTD number is mapped to the same program number (program-nrmber), so that each video sub-stream belonging to the same program can be picked up from the multiplexed code stream at the receiving end. The relative relationship of each video sub-code stream (that is, which part of a video sub-code stream is the original image) can be identified by agreement on PID or stream-ID (for example, the frame image is divided into four pieces, and these four pieces The PID numbers of the sub-images can be assigned as base-value-ue, base-value+1, base-value+2, base-value+3 respectively, where basevalue is a multiple of 4, so that it can be identified that it belongs to each position code stream of the sub-image).

The output of the multiplexer is a transport stream (tranport stream) conforming to the MPEG-2 standard. Among them, the video code stream conforming to MPEG-2 MPML level is multiplexed. These video code streams are sub-programs of one high-definition TV program, but in the view of the original DVB equipment, it thinks it is several programs.

The number of ordinary digital TV encoders used by one channel of high-definition television varies according to the image segmentation method, and a specific example is given in the description of the image segmentation method below.

The transport stream (Transport stream) output by the multiplexer is sent to the original DVB channel encoder and channel modulator 5 for channel encoding and modulation processing. The channel equipment can be terrestrial, cable or satellite channel equipment, depending on the original equipment. The modulated signal is finally broadcast and transmitted through the original transmitting device 6 .

Even with new audio systems such as stereo or surround blocks, the HDTV audio signal is relatively small in data size, so there is no problem with segmentation. One channel of high-definition television audio signal can be inserted into any segmented sub-program and processed by the audio encoder 31, other channels of sub-program may not carry audio signal, but only contain video information. The processing of audio signal compression, multiplexing, demultiplexing, decompression, etc. is exactly the same as that in DVB, and the original equipment is completely used.

The structure of the receiving system is shown in Figure 3. Compared with the IRD of common digital TV, this integrated receiving decoder (IRD) has increased image mosaic 75, D/A conversion and post-processing circuit 76 related to high-definition TV, other circuits, such as demodulation circuit, demultiplexer , video decoder, etc. all use the original circuit board of DVB, but the corresponding number should be increased according to the method of image segmentation.

The radio frequency signal is demodulated by the demodulation circuit 71 and sent to the demultiplexer 72 . The demultiplexer 72 should first identify the system identifier of the system from the network information table, so as to confirm that the received code stream is a code stream that the system can process and display. Then the demultiplexer taps out a number of video code streams according to the PAT and PMT tables. This is different from the common integrated receiving decoder. Here, several road video code streams should be tapped (these code streams are composed of one high-definition Each sub-video code stream of the degree TV program), instead of just branching one way as in the ordinary digital TV receiving equipment. The demultiplexer outputs PES stream (packetized elementary stream), which carries PTS and DTS information.

At the same time, the demultiplexer outputs each sub-video code stream to a designated output port according to the relative relationship of each sub-video code stream provided in the transport stream.

These tapped PES code streams are sent to each video decoder 73 for decompression processing. These video decoders 73 work independently and in parallel, but the system provides them with the same reference time. At the same time, the decoder extracts the timing information in the PES code stream, compares it with the reference time, and outputs the video decompressed code stream aligned with the reference time through the delay processing of the buffer.

The decoded video code stream is input into the image splicing circuit 75, and its signal format is D1 or CCIR656 or other signal formats designed by the decoder manufacturer. There are horizontal and vertical synchronization signals on it, or horizontal and vertical synchronization signals are provided through other signal lines. These video signals are time aligned with a reference. The image splicing circuit 75 and the image segmentation circuit 2 are the opposite processing procedures.

Finally, the spliced video code stream is processed by the A/D conversion and post-processing circuit 76 for A/D conversion and filtering, and then sent to the high-definition television display device 81 for display.

The HDTV audio signal inserted into one of the divided subprograms is also sent to the HDTV display device 81 after being decoded by the audio decoder 74 .

The image segmentation method will be introduced below by taking the 1440*1152 interlaced scanning image format as an example.

1) Frame Image Segmentation Method (Figure 4)

The frame image segmentation method is to divide the high-definition television image into several sub-images suitable for ordinary digital television encoders in units of frame images.

Taking the 1440*1152 interlaced scanning image as an example, the frame image is divided into four interlaced sub-frame images of 720*576 format by the method of cross division, as shown in Figure 4, these four sub-images can be Sent to four encoding devices for compression encoding. The frame field adaptation method is used in the compression.

In practical application, although the input image of ordinary digital encoding equipment is in 720*576 format, it actually processes an effective image frame of 704*576 in the compression process (the vertical bars of 8 pixels are cut off on the left and right, so that the horizontal The number of effective pixels is a multiple of 32), therefore, when dividing the high-definition television image, the left and right sides of the 1440*1152 image are respectively cut off vertical bars with a width of 8 pixels, and then divided according to the 720*576 format. When the right side of the left sub-image and the left side of the right sub-image overlap the vertical bars of 16 pixels, after entering the encoding device, there is no overlapping part after image cutting.

In order to solve the problem of moving out of bounds, according to the fact that the viewpoints of people viewing images are mainly concentrated in the center, control the parameters of the encoder so that the number of bits allocated at the dividing line is more, and the number of bits allocated at the four corners of the original image is less, so that In the case of ensuring that the data rate does not exceed the limit, it can eliminate the blurring phenomenon caused by the movement beyond the boundary at the center of the high-definition TV restoration image.

2) Field image segmentation method (Fig. 5)

The field image segmentation method is to divide the high-definition television image into several sub-images suitable for ordinary digital television encoders in units of field images.

For the interlaced scan image in 1440*1152 format, the odd field image is divided into two left and right sub-images which are progressively scanned in 720*576 format, and the even field image is divided into two left and right sub-images which are progressively scanned in 720*576 format Like, as shown in Figure 5, the divided sub-pictures are sent to common digital television encoders for compression coding. When compressing, the frame method is used for compression processing.

Of course, in practical applications, there is also the problem of image clipping, and its processing method is the same as that of frame image segmentation. For the central dividing line, the encoder parameters can be controlled so that the number of bits allocated there is more, so as to solve the blurring phenomenon at the center caused by the movement out of bounds.

3) Sub-sampling segmentation method (Figure 6)

This method uses a certain proportion of sub-sampling method to extract a number of pixels from the origin of the original high-definition TV image to form a sub-image that can be processed by an ordinary digital TV encoder, and then change the sampling start phase (that is, the level of sub-sampling) Or vertical starting point shift), then extract the sub-image, repeat this operation, and finally divide the original image into several sub-images with the same sampling rate but different phases.

For the high-definition television frame phenomenon of 1440*1152 interlaced scanning image format, it can be divided into four sub-images of 720*576 format. Each sub-image is a 1:2 sub-sampled image of the original high-definition image, and its respectively sampled pixels are shown in FIG. 6 . The divided sub-image adopts frame mode when doing compression processing.

Regarding the edge cropping problem in practical applications, it can be ignored, because the edge of the sub-sampled sub-image is the edge of the original image, and there will be no problem that the center of the original image is clipped.

The image splicing method will be described below by taking the frame cross division method of a 1440*1152 interlaced scanning format image as an example. First, the divided sub-image data stream is input into the buffer, written at low speed and read at high speed, so that the data stream read out reaches the data code rate of high-definition television images, and at the same time, the left half of the image is read One line, and then the right half image reads one line, so that the sub-images can be spliced to restore the high-definition television image data stream. In addition, the system controller also controls the insertion of horizontal and vertical synchronous signals, or provides horizontal and vertical signals through other signal lines.

All other image segmentation methods are similar to this, that is, the inverse processing of image segmentation processing. At the same time, the row and field signals are corrected accordingly.

Claims (4)

1. one kind is utilized the system that has digital video broadcasting (DVB) device transmission high definition TV now, its transmitting terminal comprises a plurality of ordinary numbers television encoders (3), multiplexer (4), chnnel coding and modulation circuit (5), emission system (6) etc., its receiving terminal comprises Integrated Receive Decoder (7), it comprises demodulator circuit (71), demodulation multiplexer (72), ordinary numbers television video decoder (73) and audio decoder (74) etc., it is characterized in that:

Its transmitting terminal also comprises: A/D converter (1), and image Segmentation device (2) and controller (9) etc.,

High definition television video signal becomes digital signal after handling through A/D converter (1) earlier, its output interface is connected with image Segmentation device (2), image Segmentation processor (2) carries out dividing processing to the high definition TV digital video signal, form the experimental process video data stream, these sub video data streams are fed to a plurality of ordinary numbers television encoders (3) and carry out the compressed encoding processing.The operating parameter of each encoder (quantization matrix for example, data transfer rate etc.) dispose and control by system controller (9), make each encoder have same timer reference of programs (PCR), and make each image subsection that belongs to same frame originally have same show time scale (PTS) and decoding markers (DTS)

Each sub-video code stream of coding is sent to multiplexer (4) as program video compressed bit stream independently and carries out multiplexingly, and the parameter setting of system controller (9) control multiplexer (4) is to satisfy the requirement of image Segmentation and splicing;

The Integrated Receive Decoder of its receiving terminal also comprises image connection circuit (75), D/A conversion and post processing circuitry (76), image connection circuit (75) receives through demodulator circuit (71), demultiplexing circuit (72) and a plurality of ordinary numbers television video decoders (73) and handles video decompression code stream that the back obtains and carry out the splicing of image according to carve information wherein, splicing video code flow well undertaken by A/D conversion and post processing circuitry (76) that A/D changes and processing such as filtering after be sent to high definition TV display device (81) and show.

2. have the system of digital video broadcast device transmission of high distinctness TV according to the utilization of claim 1 now, it is characterized in that said image Segmentation device (2) is that unit is divided into the image subsection that four suitable ordinary numbers television encoders of every frame are handled with the frame image with high definition television images.

3. have the system of digital video broadcast device transmission of high distinctness TV according to the utilization of claim 1 now, it is characterized in that said image Segmentation device (2) resembles high definition television images with field pattern be that unit is divided into the image subsection that two every suitable ordinary numbers television encoders are handled.

4. have the system of digital video broadcast device transmission of high distinctness TV now according to the utilization of claim 1, it is characterized in that said image Segmentation device (2) initial point from former high definition television images begins to extract out some pixels and forms the treatable image subsection of ordinary numbers television encoder, change the sampling start-phase then, be about to the level or the vertical starting point displacement of subsampling, carry out the extraction of image subsection again, repeat this operation, become several sampling rates identical former image Segmentation at last, but the different image subsection of phase place.

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