CN2407534Y - Braodcasting digital TV data transmitter with 2MB/S rate - Google Patents
Braodcasting digital TV data transmitter with 2MB/S rate Download PDFInfo
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- CN2407534Y CN2407534Y CN 00204943 CN00204943U CN2407534Y CN 2407534 Y CN2407534 Y CN 2407534Y CN 00204943 CN00204943 CN 00204943 CN 00204943 U CN00204943 U CN 00204943U CN 2407534 Y CN2407534 Y CN 2407534Y
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Abstract
The utility model relates to a broadcasting digital television transmission device with 2 Mb/s rate, which uses MPEG2 as the standard of video compression; a code rate is 2Mb/s; image quality is maintained in the level of broadcasting transmission. A video front processor additionally arranged in a video encoder at an originating end is connected with a central processing unit and a frame encoder; a video rear processor additionally arranged in the video encoder at a receiving end is connected with an MPEG2 decode chip and a PAL signal encoder, wherein, the video front processor uses a two-dimensional corrected median filter which is realized by a stack filter; the video rear processor is an adaptive two-dimensional spatial filter to carry out low-pass filtering along a block edge.
Description
The utility model relates to a kind of transmitting device of Digital Television, relates to a kind of 2 MBPSs (2Mb/s) broadcast level digital tv transmission device or rather.
TV is the important tool of reception information and amusement in people's daily life, and in current information-intensive society, radio and television are familiar with by the public as the infrastructure of society just increasingly extensively.And along with the develop rapidly and the combination thereof of microelectronics, photoelectron, computer and the communication technology, people are growing on and on the contrary to the demand of television broadcasting service, thereby have promoted the development of tv broadcasting technology more.
But because TV signal is an analog signal, and present existing communication network, as public telephone network, become digital network more and more based on the packet switching network of agreement X.25 and all kinds of local area network (LAN)s etc., therefore television image can not directly enter in the digital communication network and transmit, and must just can enter through after the digitized processing.
Press ITU-RBT 601 standards, the data rate after one tunnel TV signal digitlization is 216Mb/s, near the bandwidth of 3400 speech channels, therefore, for more economical TV signal after transmitting digitized effectively, needs to adopt compression coding technology reduce transmission rate.
The 2Mb/s digital television transmission system is exactly that TV signal with 216Mb/s is compressed into 2.048Mb/s, compression ratio is 100: 1, and the transmission rate of 2Mb/s is (other interface code check is 34Mb/s, 140Mb/s, 155Mb/s etc.) that meets the interface code check of Communication in China dictyosome system.But because compression ratio is big, coarse can the generation as image deflects such as " blocking effect ", " definition decline ", " ringing effect " because of quantizing under low code check.
The digital television transmission system of 2Mb/s belongs to the live image transmission system, but has tangible difference with other system in the live image transmission system.H.61 and MPEG1 one class live image transmission system is to adopt ITU, mpeg 4 standard (MPEG1, MPEG2, MPEG4 etc. are a series of Standard of image compression, MPEG is the english abbreviation of Motion Picture Experts Group), video conferencing for example, video telephone and VCD etc., about bit rate output 1.5Mb/s, suitable with the bit rate output of 2Mb/s digital television transmission system, but it is low that it recovers the picture quality percent articulation, be up to 353 * 288 pixels (CIF or SIF form), only can reach family expenses video recorder VHS level, and have tangible blocking effect and motion hangover for some image, can not satisfy the requirement of people to high quality graphic.Another kind of live image transmission system is to adopt the MPEG2 standard, the MPEG2 standard adopts interframe DPCM/DCT hybrid coding, can obtain the television-quality of studio centre level, but when code check is reduced to 2Mb/s when following, meeting generation " blocking effect and motion hangover " etc., because this moment, various side informations were compared with useful information, the ratio that accounts for is increasing, makes image restored good when adopting the MPEG1 standard on the contrary.Extensively adopt at present the MPEG2 standard as the compression standard that transmits the broadcast level Digital Television in the world, employing be the variable bit rate form of 3Mb/s up to 15Mb/s.
The purpose of this utility model is the broadcast level digital tv transmission device of a kind of 2 MBPSs of design, adopts the MPEG2 standard, as the compression standard of broadcasting transmitted image, finally reach the code check of 2Mb/s, and picture quality can also keep the broadcast level transmit level.
The purpose of this utility model is achieved in that a kind of broadcast level digital tv transmission device of 2 MBPSs, comprise the video encoder of making a start and the Video Decoder of receiving end, the video encoder of making a start comprises CPU and frame encoder, the Video Decoder of receiving end comprises that MPEG2 separates chip and PAL signal coder, it is characterized in that: also include video pre-processor in the described video encoder, be connected with the vision signal and the described frame encoder of input, and be connected with described CPU; Also include video post-processor in the described Video Decoder, separate chip with described MPEG2 and the PAL signal coder is connected.
Described video pre-processor is the median filter that two dimension is revised, and is realized by the stack filter; The intermediate value comparator that comprises first line buffer that is used for a line delay, second line buffer that is used for a line delay, two input maximum comparators, two input minimum value comparators and three input variables; The vision signal of input connects the input of first line buffer and an input of two input maximum comparators and two input minimum value comparators respectively, the output of first line buffer connects a variable input of the intermediate value comparator of the input of second line buffer and three input variables, the output of second line buffer connects another input of two input maximum comparators and two input minimum value comparators respectively, and two input maximum comparators are connected two variable inputs of the intermediate value comparator of three input variables with the output of two input minimum value comparators.
The median filter that described two dimension is revised is to realize on the FLEX10K of altera corp series monolithic EPLD device.
Described video post-processor is the self-adaption two-dimensional space filtering that carries out low-pass filtering along block edge, comprise through after blocking effect valuation, adaptive block edge filter and the block sort, for 3 * 3 average filters of smooth region, to 5 * 5 medium filterings that contain strong fringe region with for 3 * 3 medium filterings that contain texture region.
Described video post-processor is to adopt the XC4000E series monolithic FPGA device of Xilinx company to realize.
The broadcast level digital tv transmission device of per second 2 megabits of the present utility model, with the MPEG2 that revised as Standard of image compression, before increasing, rear video pre-, technology such as reprocessing improve compression ratio, finally reach the code check of 2Mb/s, solve MPEG2 and be coded in the problem that how to improve picture quality under the low bit rate, make picture quality with the 3Mb/s code check that is not less than the MPEG2 regulation, the picture quality that promptly is higher than video conferencing, little distortion or transmit the high-speed motion image without distortion, and can reduce the common blocking effect distortion that under big compression ratio, produces etc.
The broadcast level digital tv transmission device of per second 2 megabits of the present utility model, be the Digital Television of the image that on the transmission code rate of 2Mb/s, transmits the broadcast level quality simultaneously, high-quality sound and high-speed data, help multimedia communication and high speed information highway and application.
Further specify technology of the present utility model below in conjunction with embodiment and accompanying drawing
Fig. 1 is the digital television transmission system structured flowchart of 2Mb/s
Fig. 2 is a video encoder principle structure block diagram
Fig. 3 is a Video Decoder principle structure block diagram
Fig. 4 is a video pre-processor principle structure block diagram
Fig. 5 is the median filter principle structure block diagram that the video pre-processor two dimension is revised
Fig. 6 is the enforcement circuit diagram of video pre-processor and peripheral cell
Fig. 7 is the blocking effect process flow block diagram of video reprocessing
Fig. 8 is the enforcement circuit diagram of video post-processor and peripheral cell
Referring to Fig. 1, the digital television transmission system structure of 2Mb/s shown in the figure comprises broadcast level digital tv transmission device and the digital communication network of 2Mb/s, and the broadcast level digital tv transmission device of 2Mb/s is connected with digital communication network 10 by E1 or E2 interface.Making a start of the broadcast level digital tv transmission device of 2Mb/s 11 comprises video encoder 111, audio coder 112, data encoder 113 and packing and channel encoder 114.The receiving end 12 of the broadcast level digital tv transmission device of 2Mb/s comprises channel-decoding and bale breaker 124, Video Decoder 121, audio decoder 122 and data decoder 123.
In order to realize that transmission code rate is the purpose of 2Mb/s, must picture signal be compressed to about 1.6Mb/s with big compression ratio, can adopt many new compress techniques, (these coding techniquess also are in theoretical research stage at present as Coding with Wavelets, fractal image with based on object-oriented coding of model etc., do not reach actual application level), the international standard MPEG2 that the utility model adopted, then being to adopt inter motion compensation prediction/detection mixed coding technology, is the mature technology (the minimum 3Mb/s of code check form) of energy practical application.By in video encoder 111, increasing video pre-processor and in Video Decoder 121, increasing video post-processor and other technology improves compression ratio, make image code rate reduce to 1.6Mb/s.112,122 pairs of sound of audio frequency coding and decoding device adopt MPEG layer I, the international compression standard of layer II, passing one road stereosonic code check is 194Kb/s, add digital coding and error correction coding, total transmission code rate of making a start meets the G.703 2.048Mb/s standard of interface requirement of ITU.
The 2Mb/s broadcast level digital tv transmission device of embodiment, input video is the analog composite pal signal, component vide meets the CCIR.601 standard; Audio interface meets the IEC268-15 standard; Channel interface is followed G.703 suggestion; Each layer of MPEG-2 respective standard followed in compressed encoding and packing.
Referring to Fig. 2, Fig. 4, Fig. 5, Fig. 6, the principle structure of video encoder shown in Fig. 2 111 comprises video preprocessor (preceding) processor 201, CPU (CPU) 202, I frame encoder (Encoder) 203, buffer (FIFO) 204, code stream control circuit (FPGA) 205, quickflashing random access memory (FlashRAM) 206, rebuild encoder (R Encoder) 207, motion search encoder (S Encoder) 208, dynamic random access memory (DRAM) 209, static RAM (SRAM) 210 and dynamic random access memory (DRAM) 211.The difference of video encoder of the present utility model and general video encoder is to have increased video preprocessor (preceding) processor 201 making a start.
The effect of video encoder is to receive the pal video of simulation input (Video input) signal, be converted to 4: 2: 2 that CCIR.601 advises through the Phase Alternation Line system decoding, the YCrCb signal of 720 * 576 forms, carry out preliminary treatment then, send into the MPEG-2 video encoder at last and carry out the ES stream encryption, video compression coding meets MPEG 2 standard main profile at main level.Video encoder is operated under the control of master cpu 202.
Because the quality of information source has significant effects to the performance of compressed encoding thereafter, especially when the export target code check of coding is low, more seem important.Because noise has increased the amount of information of input, and the correlation of image weakens, and can make the follow-up compressed encoding difficulty that becomes.The preliminary treatment of making a start is exactly pre-filtering, and filtering is mingled in the noise in the useful signal, removes insensitive boundary's details of human eye or employing noise reduction technology in the original image, the amount of information of input is reduced, to improve the performance of compressed encoding.Experiment shows: the signal to noise ratio (snr) of original image is improved 8db, can make the compression multiple of MPEG improve 20% to 25%.
It is pre-filtering that video preprocessor of the present utility model is handled, widely used two dimension median filter device is eliminated impulse disturbances (belonging to nonlinear filtering) in the employing image filtering, but two dimension median filter has its some intrinsic shortcomings, the utility model adopts through improved stack filter, by revising the details (definition) that keeps image, the ability of its anti-impulse disturbances is better than the two dimension median filter device.
The utility model, combines this algorithm in the algorithm based on the feature selecting of medium filtering that nineteen ninety proposes according to Jimmy Li with the stack filter, and adopted a kind of can elimination owing to data line is lost the filter that causes noise.
Fig. 4 illustrates the principle structure of the hard-wired stack filter of a kind of usefulness, comprise first line buffer 41 that the video data input signal is carried out 1 line delay, second line buffer 42 to first line buffer 41 outputs carrying out, 1 line delay, the output signal of the video data input signal and second line buffer 42 is carried out maximum two input maximum (Max) comparators 43 relatively, the output signal of the video data input signal and second line buffer 42 is carried out the output signal that minimum value two intermediate value comparator 45, three input variables of importing minimum value (Max) comparators 44 and three input variables relatively comprise minimum value comparator 44, the output signal of the output signal of maximum comparator 43 and first line buffer 41.(m, n) binary signal send compressed encoding to the intermediate value comparator 45 output y of three input variables.(m n) is corresponding filter binary signal output to y.
Median filter based on the two dimension correction of Fig. 4 structure can be realized on the FLEX10K of ALTRA company series monolithic EPLD device, need not external memory cell, the catenation principle block diagram of itself and peripheral circuit as shown in Figure 5, with the enforcement circuit of peripheral circuit as shown in Figure 6.
Among Fig. 5, PAL decoder 51 receives the pal video input signal of simulation, be converted to 4: 2: 2 that meet the CCIR.601 suggestion through the Phase Alternation Line system decoding, the YCrCb signal of 720 * 576 forms, then through buffering, frame deposit 52 and the median filter 53 revised of two dimension carry out preliminary treatment, send into the MPEG-2 video encoder at last and carry out ES stream compressed encoding, whole process is by master cpu 54 controls.
Among Fig. 6, the enforcement circuit of video encoder shown in the figure.The median filter that two dimension is revised is to realize connected frame memory (FIELD Store), master cpu (central microcontroller ADSP2181), digital visual interface (INTERFACE) and the PAL decoder (PAL television decoder HMP81 12A) of including on the FLEX10K series monolithic EPLD device as visual pretreatment unit.
Video pre-processor of the present utility model is also optimized the algorithm of MPEG, and the variety of option in the MPEG algorithm of using under low bit rate has been carried out optimum organization.
Referring to Fig. 3, Video Decoder comprises CPU (CPU) 301, the interface unit 302 with channel, FPGA control module 303, MPEG2 decoding chip 304, video post-processor 305, clock generator 306, dynamic random access memory group (DRAM) 307, voicefrequency circuit (DA) 308, sound out-put circuit 309, PAL signal coder 310, video output 311, panel interface 312 and RS232 port 313.The utility model Video Decoder is to have increased preprocessor in receiving end with the difference of general Video Decoder.
Video ES code stream carries out reprocessing, after the PAL code conversion becomes analog video signal output after buffer memory and MPEG 2 decodings.
Digital television transmission system can produce degradation image deflects under blocking effect, ringing effect and the definition under low code check, blocking effect wherein is because the correlation that coarse quantification has destroyed between piece and the piece is caused, and ringing effect and definition decline also are because it is caused to quantize back high frequency coefficient loss.
Digital tv transmission device of the present utility model is taked post-processing technology to alleviate in the Video Decoder of receiving end or is eliminated these defectives, carrying out low-pass filtering along block edge is to eliminate a kind of method the most intuitively of blocking effect, but the motion compensation meeting makes the blocking effect diffusion, this method can not provide good subjective quality, and simple filtering also can make the image detail loss.The utility model adopts the self-adaption two-dimensional space filtering technology based on rim detection to remove blocking effect and ringing effect.
Referring to Fig. 7, the operating process of the space filtering of self-adaption two-dimensional shown in the figure, comprise: step 601, the blocking effect valuation is done in input to image block, can adopt more traditional simple method for measuring, and the compression anteposition has very big correlation in the adjacent image point of different masses, and the compression back weakens the correlation between them because of the reason that quantizes greatly, represent the order of severity of blocking effect with regard to the quadratic sum of the difference of available these pixels, when the valuation result represents serious blocking effect is arranged, just do the average of block boundary; Step 602, the adaptive block edge filter calculates valuation and average with number of picture elements to each image block; Step 603, block sort are rim detection, thereby tell level and smooth (smooth) zone, strong fringe region and texture region, take different filter smoothing images at different zones again; Step 604, smooth region is because radio-frequency component seldom, can take simple 3 * 3 average filters to come the blocking effect of filtering diffusion; Step 605, for the zone of containing strong edge, the medium filtering of employing 5 * 5 comes the filtering ringing effect, and median filter has good maintenance effect for block edge, and is little to the damage of image detail; Step 606, for the zone that contains texture, because the masking effect of human eye, various defectives are also not obvious here, so 3 * 3 medium filterings are adopted in this zone; Step 607 makes up back output to each road picture signal after different filtering.
The basic thought that improves image definition is exactly the color-resolution that the high frequency composition that reasonably improves image increases image, comprise and strengthen spatial domain edge of image contrast, when making enhancement process, distinguish big edge, little edge and noise earlier, carry out different processing again, as large and small edge being carried out enhancing in various degree, then suppress for noise etc.
Referring to Fig. 8, the video post-processor of embodiment, adopted XC4000E series monolithic FPGA (the VIDEO POST PROCESSING) device of Xilinx company to realize that its peripheral circuit comprises interface circuit (INTERFACE) and digital PAL encoder (PAL ENCODER BT866).
In sum, 2Mb/s digital tv transmission device of the present utility model utilizes special-purpose MPEG 2 codec chips, carries out the image compression encoding algorithm optimization and adopts preliminary treatment and post-processing technology, improves picture quality.The result shows through transmission experiment: the main performance index of 2Mb/s digital tv transmission device is better than meeting 2Mb/s video conferencing and 2Mb/s MPEG 1 Digital Television H.261, with 3Mb/s MPEG 2 Digital Television quite or better.
Technology of the present utility model, by digitized video signal is compressed, cooperate digital transmission technology again, can effectively transmit more data in the Channel Bandwidth, as being the transponder of 36MHz for the satellite frequency range, can only transmit 2 to 3 frequency modulation satellite television programmings in the past, and can transmit 6 to 9 TV programme now, can improve efficiency of transmission greatly.In addition, digitlization along with radio and television, will open various new business, comprise video conference, video on demand VOD (Video On Demand), near video on demand, monitoring TV, remote teaching, tele-medicine, far do shopping, real-time military affairs or public security on-the-spot transmission, delayed broadcast, recreation, far work, program request Karaoke and news on demand etc.
Claims (5)
1. the broadcast level digital tv transmission device of a MBPS, comprise the video encoder of making a start and the Video Decoder of receiving end, the video encoder of making a start comprises CPU and frame encoder, the Video Decoder of receiving end comprises that MPEG2 separates chip and PAL signal coder, it is characterized in that: also include video pre-processor in the described video encoder, be connected with the vision signal and the described frame encoder of input, and be connected with described CPU; Also include video post-processor in the described Video Decoder, separate chip with described MPEG2 and the PAL signal coder is connected.
2. the broadcast level digital tv transmission device of 2 MBPSs according to claim 1 is characterized in that: described video pre-processor is the median filter that two dimension is revised, and is realized by the stack filter; The intermediate value comparator that comprises first line buffer that is used for a line delay, second line buffer that is used for a line delay, two input maximum comparators, two input minimum value comparators and three input variables; The vision signal of input connects the input of first line buffer and an input of two input maximum comparators and two input minimum value comparators respectively, the output of first line buffer connects a variable input of the intermediate value comparator of the input of second line buffer and three input variables, the output of second line buffer connects another input of two input maximum comparators and two input minimum value comparators respectively, and two input maximum comparators are connected two variable inputs of the intermediate value comparator of three input variables with the output of two input minimum value comparators.
3. the broadcast level digital tv transmission device of 2 MBPSs according to claim 1 and 2 is characterized in that: the median filter that described two dimension is revised is to realize on the FLEX10K of altera corp series monolithic EPLD device.
4. the broadcast level digital tv transmission device of 2 MBPSs according to claim 1, it is characterized in that: described video post-processor is the self-adaption two-dimensional space filtering that carries out low-pass filtering along block edge, comprise through after blocking effect valuation, adaptive block edge filter and the block sort, for 3 * 3 average filters of smooth region, to 5 * 5 medium filterings that contain strong fringe region with for 3 * 3 medium filterings that contain texture region.
5. according to the broadcast level digital tv transmission device of claim 1 or 4 described 2 MBPSs, it is characterized in that: described video post-processor is to adopt the XC4000E series monolithic FPGA device of Xilinx company to realize.
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| CN 00204943 CN2407534Y (en) | 2000-03-03 | 2000-03-03 | Braodcasting digital TV data transmitter with 2MB/S rate |
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| CN 00204943 CN2407534Y (en) | 2000-03-03 | 2000-03-03 | Braodcasting digital TV data transmitter with 2MB/S rate |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105791861A (en) * | 2009-04-20 | 2016-07-20 | 杜比实验室特许公司 | Directed interpolation and data post-processing |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105791861A (en) * | 2009-04-20 | 2016-07-20 | 杜比实验室特许公司 | Directed interpolation and data post-processing |
| CN105791861B (en) * | 2009-04-20 | 2018-12-04 | 杜比实验室特许公司 | Orient interpolation and Data Post |
| US10194172B2 (en) | 2009-04-20 | 2019-01-29 | Dolby Laboratories Licensing Corporation | Directed interpolation and data post-processing |
| US10609413B2 (en) | 2009-04-20 | 2020-03-31 | Dolby Laboratories Licensing Corporation | Directed interpolation and data post-processing |
| US11477480B2 (en) | 2009-04-20 | 2022-10-18 | Dolby Laboratories Licensing Corporation | Directed interpolation and data post-processing |
| US11792429B2 (en) | 2009-04-20 | 2023-10-17 | Dolby Laboratories Licensing Corporation | Directed interpolation and data post-processing |
| US11792428B2 (en) | 2009-04-20 | 2023-10-17 | Dolby Laboratories Licensing Corporation | Directed interpolation and data post-processing |
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