KR101107320B1 - Distrubuted video coding apparatus - Google Patents

Abstract

The present invention provides a splitter for splitting an input video signal into an intra frame and a Weiner-Ziv frame, an intra encoder for encoding an intra frame separated from the splitter, and a splitter. A wine-jib encoder which encodes a separate wine-jib frame and outputs a parity bit for detecting an error generated during decoding of the wine-jib frame, and is connected to the splitter and input to the wine-jib encoder A bit error rate estimator for estimating a bit error rate of a Weiner-Jib frame, wherein the Weiner-Jib encoder adjusts a parity bit output according to an estimated bit error rate from the bit error rate estimator A device can be provided.

Distributed video coding, bit error ratio

Description

Distributed video coding device {DISTRUBUTED VIDEO CODING APPARATUS}

The present invention relates to a distributed image coding apparatus. More particularly, the present invention relates to a distributed image coding apparatus capable of reducing delay caused by calculation by removing feedback between an encoder and a decoder.

The present invention is derived from a study conducted as a part of the IT growth engine technology development project of the Ministry of Knowledge Economy and the Ministry of Information and Communication Research and Development. [Task Management No .: 2008-S-012-01, Title: Convergence SoC-based Smart Eye]

Current video compression techniques such as ITU-T H.263, H.263 +, H263 ++, ISO MPEG-4 and JVT H.264 are very efficient in the compressed video domain. The ability to achieve good visual quality at relatively low bit rates has led to increased popularity for video applications in emerging multimedia applications for bandwidth limited channels such as wireless channels. However, the prediction characteristics of the compression techniques commonly used in the current video codec make the compressed video bit streams very vulnerable and easily degraded due to packet loss in the channel.

Channel errors or packet loss can result in a loss of synchronization between the video encoder and the decoder. More specifically, the video frame before encoding at the encoder and the video frame after decoding the encoded signal at the decoder may not match. This loss of synchronization between the video encoder and decoder can sometimes result in a large loss in decoded video quality. Various studies are underway to compensate for these losses.

The present invention relates to a distributed image coding apparatus capable of reducing the loss caused between the encoder and the decoder and reducing the delay time caused by the feedback calculation.

The present invention provides a splitter for splitting an input video signal into an intra frame and a Weiner-Ziv frame, an intra encoder for encoding an intra frame separated from the splitter, and a splitter. A wine-jib encoder which encodes a separate wine-jib frame and outputs a parity bit for detecting an error generated during decoding of the wine-jib frame, and is connected to the splitter and input to the wine-jib encoder A bit error rate estimator for estimating a bit error rate of a Weiner-Jib frame, wherein the Weiner-Jib encoder adjusts a parity bit output according to an estimated bit error rate from the bit error rate estimator A device can be provided.

The Weiner-Jib encoder is a quantizer which lowers the data value of the input Wiener-Jib frame to a predetermined representative value and extracts only upper bits to form a bit plane, and a bit stream of each bit plane output from the quantizer. A turbo encoder for outputting parity bits by encoding in a plane unit, and a buffer for adjusting and outputting the parity bits input from the turbo encoder according to the bit error rate estimated by the bit error rate estimator.

The wine-jib encoder may include a lookup table in which information about a transmission amount of parity bits to be output from the buffer is stored according to the estimated bit error rate.

The bit error rate estimator may estimate a bit error rate by comparing a current frame input to the wine-jib encoder with a previous frame and a subsequent frame of the current frame.

The bit error rate estimator may estimate a bit error rate for each bit plane by extracting a change pattern of the pixel value of the current frame as a statistical standard deviation using the previous frame and the subsequent frame.

According to the present invention, it is possible to obtain a distributed image coding apparatus capable of reducing the loss generated between the encoder and the decoder and reducing the delay time caused by the feedback calculation.

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

1 is a block diagram of a general distributed video coding (DVC) apparatus. Conventional video compression standards MPEG2, MPEG4 and H.264 have a problem that it is difficult to operate for a long time in a mobile device and a medium that requires low power due to the complexity and computational complexity of the encoder. An alternative to this problem is distributed video coding (DVC). Unlike the existing video compression technology, DVC method is one of video compression model algorithms that theoretically propose encoder model that can be mounted on portable devices or low-power media by lowering the complexity of encoder and increasing the complexity of decoder.

Referring to FIG. 1, the distributed image coding apparatus 100 may include an encoder 101 and a decoder 102. The encoder 101 may encode a video signal, and the decoder 102 may receive a signal encoded by the encoder and decode it into an output video signal.

The encoder 101 of the distributed image coding apparatus 100 first encodes an intra frame to be used as a key frame in the decoder 102, transmits the intra frame to the decoder 102, and then waits for the intra frame to be transmitted. A Wyner-Ziv frame may be encoded and transmitted.

The decoder 102 receives the encoded intra frame and the Weiner-Jib frame to receive side information necessary for channel decoding of a plurality of key frames and a Weiner-Jib frame constituting between the plurality of key frames in time. information) and the parity bits transmitted from the encoder can be received and restored. In this process, the difference between the side information generated for the wine-jib frame and the original image of the wine-jib frame is generally referred to as an error rate for the virtual channel. According to the error rate, the decoder may perform effective channel decoding only by varying the amount of parity bits to be transmitted from the encoder.

In the distributed image coding apparatus 100, in order to perform encoding and decoding on a Weiner-Jib frame, an optimal parity bit amount may be matched using Rate Compatible Punctured Turbo Coding (RCPT) coding. The RCPT method requires parity bits many times when it is impossible to accurately determine the initial parity bit amount transmitted from the encoder to the decoder, and thus the latency of the entire distributed image coding apparatus due to the repeated calculation of channel decoding. There was a disadvantage to increase.

The encoder 101 may include a splitter 110, an intra encoder 130, and a wine-jib encoder 120.

The splitter 110 may divide the input video signal into an intra frame and a wine-ziv frame. When the input image signal is viewed in time, a plurality of intra frames and a plurality of wine-jib frames positioned between the plurality of intra frames may be included. In the splitter 110, the video signals input continuously may be divided into an intra frame and a wine-jib frame.

The intra encoder 130 may reduce redundancy in the intra frame. In this embodiment, the intra encoder 130 may use an intra encoding algorithm of the H.264 standard.

In general, H.264 is designed to increase the compression efficiency of intra frames by performing the prediction process before the transform. This is based on the fact that adjacent MacroBlocks have similar characteristics. H.264 can provide nine prediction models that can be applied to a 4 × 4 luma block. Nine prediction models including DC (Mode 2) can select an optimal prediction mode at the time of coding. In addition, four prediction modes (DC, Vertical, Horizontal, and Planner) are provided for 16 × 16 luma blocks, and four prediction modes (DC, Vertical) for 8 × 8 chrominance blocks. , Horizontal, and Planner).

The intra encoder 130 transmits only a flag when the prediction mode is predictable through adjacent blocks in order to reduce the amount of information on the prediction mode that occurs frequently in each block, thereby maximizing efficiency.

The wine-jib encoder 120 may include a quantizer 121, a turbo encoder 122, and a buffer 123 that quantize the separated wine-jib frame.

In the quantizer 121, four bit planes may be formed using only the upper four bits while discarding the lower four bits of the pixel data in the frame. It may be transmitted to the turbo encoder 122 in the order of the bit plane.

The turbo encoder 122 may encode each bitplane binary sequence input from the quantizer 121 for each bitplane and output the parity bit binary sequence. In particular, in the RCPT (Rate Compatible Punctured Turbo) scheme, the amount of data to be transmitted by turbo decoding may be determined by updating through an iterative request.

The buffer 123 may store parity output from the encoder 101 to the decoder 102. In the RCPT structure, a parity amount to be transmitted from the encoder to the decoder may be updated and transmitted through a repetitive request by a feedback line by decoding.

The decoder 102 may include a turbo decoder 171, an inverse quantizer 172, a decompressor 173, an intra decoder 175, a side information generator 174, and an image integrator 176. Can be.

The intra decoder 175 may receive and decode an intra frame encoded by the intra encoder 130. The intra frame decoded by the intra decoder 175 may be delivered to the side information generator 174 and the image integrator 176.

The turbo decoder 171 may perform error correction using the parity binary sequence transmitted from the encoder 101 region and the binary sequence transmitted from the side information generator. This process can serve as a recovery function for the top four bits of the pixel value in the frame.

The inverse quantizer 172 configures four bits generated by the turbo decoder 171 as the upper four bits of the pixel value, and generates the lower four bits, in order to generate eight pixel values of the pixel. Can be delivered to.

The reconstruction unit 173 may implement an algorithm for filling the lower four bits of the pixel value. The lower 4 bits are determined by comparing the upper 4 bits received from the inverse quantizer 172 with the pixel value of the side information generator 174, or using the lower 4 bits of the side information pixel as it is or using a maximum of 4 bits. You can take the value, or the minimum value.

The side information generator 174 may receive a key frame decoded by the intra decoder 9175 as an input, and generate side information that is in charge of the cysteric binary sequence of the turbo decoder 171. . The side information generator may generate a frame that is most similar to a frame currently encoded as a wine-jib frame by a motion compensation temporal interpolation (MCTI) algorithm. In general, the MCTI algorithm may generate a frame similar to the wine-jib frame by using an intra frame that comes before and after the wine-jib frame in time.

The image integrator 176 may export a decoded frame as an output according to the image play order of the frame.

2 is a configuration diagram of a distributed video coding apparatus according to an embodiment of the present invention.

Referring to FIG. 2, the distributed image coding apparatus 200 according to the present embodiment may include a splitter 210, a wine-jib encoder 220, an intra encoder 230, and an error rate estimator 240.

The splitter 110 may divide the input video signal into an intra frame and a wine-ziv frame. When the input image signal is viewed in time, a plurality of intra frames and a plurality of wine-jib frames positioned between the plurality of intra frames may be included. In the splitter 210, the video signals input continuously may be divided into an intra frame and a wine-jib frame.

The intra encoder 230 may encode an intra frame separated by the splitter 210. The intra encoder 230 may reduce redundancy within an intra frame. In this embodiment, the intra encoder 230 may use an intra encoding algorithm of the H.264 standard.

In general, H.264 is designed to increase the compression efficiency of intra frames by performing the prediction process before the transform. This is based on the fact that adjacent MacroBlocks have similar characteristics. H.264 can provide nine prediction models that can be applied to a 4 × 4 luma block. Nine prediction models including DC (Mode 2) can select an optimal prediction mode at the time of coding. In addition, four prediction modes (DC, Vertical, Horizontal, and Planner) are provided for 16 × 16 luma blocks, and four prediction modes (DC, Vertical) for 8 × 8 chrominance blocks. , Horizontal, and Planner).

In this embodiment, the intra encoder 230 may maximize the efficiency by transmitting only a flag when the prediction mode is predictable through adjacent blocks in order to reduce the amount of information on the prediction mode that frequently occurs in each block. To make it work.

The wine-jib encoder 220 may encode a wine-jib frame separated by a splitter, and output a parity bit for detecting an error generated when decoding the wine-jib frame.

In this embodiment, the Weiner-Jib encoder 220 may include a quantizer 221, a turbo encoder 222, a buffer 223, and a lookup table 224.

The quantizer 221 may lower the data value of the input wine-jib frame to a predetermined representative value and extract only the upper bits to form a bit plane. That is, in the quantizer 221, the eight bits forming the data value of each pixel in the frame input to the quantizer are lowered to a prescribed representative value, so that the lower four bits are discarded and only the upper four bits are extracted to extract four bit planes. Can be formed. It may be transmitted to the turbo encoder 222 in the order of the bit plane.

The turbo encoder 222 may encode each bit plane binary sequence input from the quantizer 121 for each bit plane and output the encoded bit sequence as a parity bit binary sequence.

The buffer 223 may adjust the parity bit input by the turbo encoder according to the bit error rate estimated by the bit error rate estimator 240 and output the parity bit to the decoder 202. The buffer 223 may store the parity bits output from the turbo encoder 222.

In the present embodiment, the wine-jib encoder 220 stores a lookup table 224 in which information on the amount of transmission of parity bits to be output from the buffer 223 is stored according to the bit error rate estimated by the bit error rate estimator 240. It may include. The buffer 223 may adjust the parity bit output based on the bit error rate of the frame input to the wine-jib encoder 220 using the data stored in the lookup table. The data of the parity bit transmission amount according to the bit error rate stored in the lookup table 224 is a value extracted through simulation and test on the performance of the decoder and may be stored in advance.

The bit error rate estimator 240 may be connected to the splitter 210 to estimate a bit error rate of a wine-jib frame input to the wine-jib encoder. In the present embodiment, the bit error rate can be expressed as the ratio of the number of error bits generated to the total number of bits of the digital signal transmitted at the predetermined measurement time, and the bit error rate is the level of the received signal, that is, the reception sensitivity and modulation. Method, transmission bandwidth, bit rate, and the like. The bit error rate of the wine-jib frame input to the current wine-jib encoder estimated by the bit error rate estimator 240 may be provided to the buffer of the wine-jib encoder.

As described above, the distributed image coding apparatus according to the present embodiment may output parity bits to be output in the current frame using information of pre-stored data instead of feedback of decoder information to adjust the parity bits output from the encoder. Therefore, the performance of the entire image coding apparatus may be improved by significantly reducing the delay time generated during decoding.

3 is a view for explaining the operation of the bit error rate estimator used in the image coding apparatus according to the present invention. The operation of the bit error rate estimator 340 according to the present embodiment will be described with reference to FIG. 3.

The splitter 310 may separate an intra frame and a wine-jib frame from an input video signal.

The intra frame and the wine-jib frame separated by the splitter 310 may be transmitted and encoded to the intra encoder and the wine-jib encoder, respectively. The bit error rate estimator 340 according to the present embodiment connects a wine-jib frame, which is connected to the splitter 310 and inputs to the wine-jib encoder, to a current frame F1, and a frame before and after the wine-jib frame, respectively. The previous frame F2 and the subsequent frame F3 may be input.

The bit error rate estimator 340 may estimate the bit error rate by comparing the current frame F1 with a previous frame F2 and a subsequent frame F3. In the present embodiment, the bit error rate estimator 340 may estimate bit error rate for each bit plane by extracting a change pattern of the pixel value of the current frame as a statistical standard deviation using the previous frame and the subsequent frame. have.

The bit error rate estimated by the bit error rate estimator 340 is transferred to a buffer of a wine-jib encoder, and the buffer is applied to the estimated bit error rate by referring to the information of the parity bit value according to the bit error rate stored in the lookup table 324. Therefore, the parity bit can be output.

It is intended that the invention not be limited by the foregoing embodiments and the accompanying drawings, but rather by the claims appended hereto. Accordingly, various forms of substitution, modification, and alteration may be made by those skilled in the art without departing from the technical spirit of the present invention described in the claims, which are also within the scope of the present invention. something to do.

1 is a block diagram of a distributed image coding apparatus according to the prior art.

2 is a configuration diagram of a distributed video coding apparatus according to an embodiment of the present invention.

3 is a view for explaining the operation of the bit error rate estimator in a distributed image coding apparatus according to the present invention.

<Code Description of Main Parts of Drawing>

210: splitter 220: wine-jib encoder

230: intra encoder 240: bit error rate estimator

Claims (5)

A splitter for splitting an input video signal into an intra frame and a Wiener-Ziv frame; An intra encoder for encoding the separated intra frames in the splitter; A wine-jib encoder that encodes the wine-jib frame separated by the splitter and outputs a parity bit for detecting an error generated when decoding the wine-jib frame; And A bit error rate estimator coupled to the splitter for estimating a bit error rate of a wine-jib frame input to the wine-jib encoder; Including; And the wine-jib encoder adjusts the parity bit output according to the bit error rate estimated from the bit error rate estimator. The method of claim 1, The winery-jib encoder is, A quantizer for lowering a data value of an input wine-jib frame to a predetermined representative value and extracting only upper bits to form a bit plane; A turbo encoder for outputting a parity bit by encoding a bit stream of each bit plane output from the quantizer in the bit plane unit; And A buffer for adjusting and outputting a parity bit input from the turbo encoder according to a bit error rate estimated by the bit error rate estimator Distributed image coding apparatus comprising a. 3. The method of claim 2, The winery-jib encoder is, And a lookup table in which information on a transmission amount of parity bits to be output from the buffer is stored according to the estimated bit error rate. The method of claim 1, The bit error rate estimator, And comparing a current frame input to the wine-jib encoder with a previous frame and a subsequent frame of the current frame to estimate a bit error rate. 5. The method of claim 4, The bit error rate estimator, And a bit error rate for each bit plane by extracting a change pattern of the pixel value of the current frame using the previous frame and the subsequent frame as a statistical standard deviation.

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