Available distributed video coding codecs are mostly based on decoder ratecontrol scheme where the parity bits for decoding can be achieved over a feedback channel. Meanwhile, the frequent requests over feedback chan...
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Available distributed video coding codecs are mostly based on decoder ratecontrol scheme where the parity bits for decoding can be achieved over a feedback channel. Meanwhile, the frequent requests over feedback channel increase the transmission delay. The feedback-free distributed video coding, relying on encoder rate control in literatures, has overcome the aforementioned shortcoming. However, when performing parity bitrate estimation and other operations, the feedback-free distributed video coding systems based on bit-plane usually require high precision of bitrate estimation and high quality of side information at the encoder. In this paper, we propose a frame-level distributed video coding system based on encoder rate control. The innovations include three parts: 1) an adaptive coding mode selection algorithm is proposed, which utilizes both temporal and spatial correlation and reduces the complexity of encoder;2) a bit-plane rearrangement method is adopted, which makes the coding rate on each bit-plane homogeneous and effectively reduces the accuracy requirement of the parity bitrate prediction and improves the efficiency of rate estimation;3) a frame-level parity bitrate estimation scheme is presented to enhance the efficiency of rate estimation on the basis of a look-up table. Numerical results verify that the proposed scheme remarkably improves the rate distortion performance of distributed video coding at low bitrate.
In Distributed Video Coding (DVC) the encoder compresses frames at source rates that rely on the statistical dependency involving the Wyner-Ziv (WZ) and side information frames. A significant issue that individuals ad...
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ISBN:
(纸本)9781479933433
In Distributed Video Coding (DVC) the encoder compresses frames at source rates that rely on the statistical dependency involving the Wyner-Ziv (WZ) and side information frames. A significant issue that individuals address in this paper provides the encoder with a mechanism to spot the origin rate to be found in encoding a WZ frame. One possible solution is to check out a feedback approach;the encoder starts by sending a tiny amount of data (low source rate). Just in case the decoder fails to recuperate the compressed frame, it offers the encoder with a feedback requesting more bits. This solution results in using source rates which can be ideal in the sense that they're the minimal rates that cause successful decoding. Nevertheless, this solution mightn't be practical for visual sensor networks as it can exhaust limited bandwidth and energy resources. To fix these problems, we propose a book encoder rate control (ERC) algorithm for Transform-domain distributed video (TDDV) coder without feedback channel at the price of slightly increased encoder complexity. The experiment results reveal that the performance obtained using our ERC algorithm can be compared to that obtained utilizing the decoder ratecontrol (DRC) algorithm.
Typical distributed video coding architecture always controls rate at the decoder via a feedback channel, which is not realistic in application. In order to remove the feedback channel, an efficient encoderrate contr...
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ISBN:
(纸本)9780819497215
Typical distributed video coding architecture always controls rate at the decoder via a feedback channel, which is not realistic in application. In order to remove the feedback channel, an efficient encoder rate control method is proposed for unidirectional distributed video coding in this paper. First a low-complexity motion estimation method is proposed to create estimated side information at the encoder, in which the motion consistency between frames is utilized to reduce the search range and obtain accurate motion vectors. Then the conditional entropy of each bitplane is computed based on the inter-bitplane correlation, which is further curve-fitted as the estimated rate. Experimental results show that our proposed encoder rate control method could estimate the required rate accurately with much lower complexity.
This paper proposes a unidirectional encoder rate control (ERC) scheme in the interpolation based distributed video coding. As the encoder is complexity constrained, accurate estimation of number of bits to decode eac...
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ISBN:
(纸本)9780769547299
This paper proposes a unidirectional encoder rate control (ERC) scheme in the interpolation based distributed video coding. As the encoder is complexity constrained, accurate estimation of number of bits to decode each bit plane is indeed difficult at the encoder. In case of under-estimation of the bits, correction of the errors in the decoded bit planes, by utilizing the available information, is one of the important tasks at the decoder. This was addressed by recent schemes. In this paper, we present an improved ERC, considering higher group of pictures(GOP). The contributions of the proposed scheme are (1) adaptive rate estimation, considering the dependency across Wyner-Ziv frames (2) motion adaptive reconstruction and (3) Side information refinement after decoding all the frames in the GOP. The proposed scheme is tested with several sequences, showing improvements in the case of GOP-4.
Most Wyner-Ziv (WZ) video coding solutions in the literature use a feedback channel (FC) based decoder ratecontrol (DRC) strategy to adjust the bitrate to correct the side information (SI) errors. More recently, some...
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Most Wyner-Ziv (WZ) video coding solutions in the literature use a feedback channel (FC) based decoder ratecontrol (DRC) strategy to adjust the bitrate to correct the side information (SI) errors. More recently, some encoder rate control (ERC) strategies have been proposed to address application scenarios where a FC is not available. The ERC based WZ video coding RD performance depends not only on the (encoder) parity rate estimator (PRE) accuracy but also on the decoder "intelligence" in dealing with the residual errors due to parity rate underestimation. In this context, the main objective of this paper is to propose a more efficient and powerful ERC solution for transform domain WZ (TDWZ) video coding by simultaneously tackling the two issues aforementioned with the following technical novelty: 1) integration in an ERC context of Gray mapping for the quantized DCT coefficients to enhance the correlation between WZ and SI data;2) more accurate PRE to better estimate the needed parity rate to avoid undesired parity rate underestimations and overestimations;3) novel soft reconstruction function to reduce the impact of the residual bitplane errors in the decoded WZ frame quality;and 4) weighted overlapped block motion compensation technique to refine the SI used in an iterative WZ decoding framework with the correlation noise model parameters dynamically updated. Experimental results show a considerable RD performance improvement with a reduction of up to about 2 dB of the gap between the ERC and DRC based approaches in TDWZ video coding solutions, thus making this ERC based WZ codec the most efficient available and competitive regarding DRC based WZ video coding solutions.
In Wyner-Ziv video coding (WZVC), powerful error correcting codes must be used to achieve high compression efficiency;turbo codes are the most commonly used error correcting codes in WZVC. To improve the turbo coding ...
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ISBN:
(纸本)9781424479948
In Wyner-Ziv video coding (WZVC), powerful error correcting codes must be used to achieve high compression efficiency;turbo codes are the most commonly used error correcting codes in WZVC. To improve the turbo coding performance in the context of WZVC, this paper proposes a probability updating technique (PUT) acting as an outer loop of the common turbo decoding operation. Whenever a turbo decoded bitplane is not error-free, the proposed technique attempts to correct bitplane errors by updating the correlation noise probabilities for the most likely in error bits, followed by turbo re-decoding. The new tool is evaluated both in the context of encoder rate control (ERC) and decoder ratecontrol (DRC) turbo based WZVC scenarios with average overall PSNR gains up to about 0.5 dB in ERC and average WZ rate savings up to about 6% in DRC.
A recent trend in video coding is toward the low-complexity distributed techniques which provide an adaptive way to distribute the computational complexity among the encoder(s) and the decoder. One of the well-known a...
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A recent trend in video coding is toward the low-complexity distributed techniques which provide an adaptive way to distribute the computational complexity among the encoder(s) and the decoder. One of the well-known architectures for Distributed Video Coding (DVC) is the Stanford architecture. This structure imposes the presence of a feedback channel from the decoder to the encoder, causing the codec to be impractical in some applications. However, the feedback channel can be eliminated if the encoder estimates the desirable bitrate during the encoding process. In this paper, we introduce a new method for bitrate estimation using v-SVM regression with the aid of a novel set of features. We also present a Hybrid coding mode which reduces the computational complexity in a conventional Stanford codec. The presented methods are evaluated using three different video sequences. The simulation results for the feedback-free method show that the average decrease in PSNR of the decoded frames is 0.7 dB for low-motion and up to 3 dB for high motion videos. While preserving the same PSNR quality as the conventional Stanford codec, the Hybrid method reduces the computational complexity by a factor 3, thereby speeding up the decoding process by imposing an overhead bitrate of 3 kb/s.
Context: Conventional video encoding is a computationally intensive process that requires a lot of computing resources, power and memory. Such codecs cannot be deployed in remote sensors that are constrained in terms ...
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Context: Conventional video encoding is a computationally intensive process that requires a lot of computing resources, power and memory. Such codecs cannot be deployed in remote sensors that are constrained in terms of power, memory and computational capabilities. For such applications, distributed video coding might hold the answer. Objective: In this paper, we propose a distributed video coding (DVC) architecture that adheres to the principles of DVC by shifting the computational complexity from the encoder to the decoder and caters to low-motion scenarios like video conferencing and surveillance of hallways and buildings. Method: The architecture presented is block-based and introduces a simple yet effective classification scheme that aims at maximizing the use of skip blocks to exploit temporal correlation between consecutive frames. In addition to the skip blocks, a dynamic GOP size control algorithm is proposed that instantaneously alters the GOP size in response to the video statistics without causing any latency and without the need to buffer additional frames at the encoder. To facilitate real-time video delivery and consumption, iterative channel codes like low density parity check codes and turbo codes are not used and in their place a Bose-Chaudhuri-Hocquenghem (BCH) code with encoder rate control is used. Results: In spite of reducing the complexity and eliminating the feedback channel, the proposed architecture can match and even surpass the performance of current DVC systems making it a viable solution as a codec for low-motion scenarios. Conclusion: We conclude that the proposed architecture is a suitable solution for applications that require real-time, low bit rate video transmission but have constrained resources and cannot support the complex conventional video encoding solutions. Practical implications: The practical implications of the proposed DVC architecture include deployment in remote video sensors like hallway and building surveillance,
Distributed video coding (DVC) is new video coding paradigm for emerging applications such as wireless video cameras, wireless low-power surveillance networks, disposable video cameras, sensor networks, networked camc...
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Distributed video coding (DVC) is new video coding paradigm for emerging applications such as wireless video cameras, wireless low-power surveillance networks, disposable video cameras, sensor networks, networked camcorders, etc. In traditional video coding standards (MPEG/H. 264/DivX/VC1), typically the encoder is five to 10 times more complex than the decoder, which is well suited for broadcast and streaming video-ondemand systems, where video is compressed once and decoded many times. However, the emerging applications require dual system, i.e. low complex encoders, possibly at the expense of high complex decoders. Here, low complexity encoders are must because memory, computational power and energy are scarce at the encoder. Distributed coding exploits source statistics in decoder and hence encoder can be very simple, at the expense of the more complex decoder. In literature, various DVC Architectures proposed depend on availability of feedback channel from decoder to encoder, to achieve minimum rate for target quality. In practical systems usually bidirectional communication channels are not available. Other implications are in terms of decoding delay and decoder complexity, due to usage of feedback channel. Hence it is highly desirable to design DVC without need for feedback channel. In this paper, feedback-free DVC Architecture is proposed and C model implementation results are presented.
Wyner-Ziv (WZ) video coding - a particular case of distributed video coding (DVC) - is a new video coding paradigm based on two major Information Theory results: the Slepian-Wolf and Wyner-Ziv theorems. Many of the pr...
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ISBN:
(纸本)9781424414369
Wyner-Ziv (WZ) video coding - a particular case of distributed video coding (DVC) - is a new video coding paradigm based on two major Information Theory results: the Slepian-Wolf and Wyner-Ziv theorems. Many of the practical WZ video coding solutions available in the literature make use of a feedback channel (FC) to perform ratecontrol at the decoder which implies there must be a FC available in the application scenario addressed. The FC-based DVC solutions also have implications in terms of delay and decoder complexity since several iterative decoding operations may be needed to decode the data to the target quality level. In this context, this paper proposes an encoder rate control (ERC) solution for the transform domain WZ coding architecture previously using a FC driven ratecontrol. Although this is the first solution in the literature, promising results are achieved with the proposed ERC solution without significantly increase the encoder complexity.
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