Survey of Error Correction Mechanisms for Video Streaming over the Internet <s> IV. ERROR RESILIENT <s> We review feedback-based low bit-rate video coding techniques for robust transmission in mobile multimedia networks. For error control on the source coding level, each decoder has to make provisions for error detection, resynchronization, and error concealment, and we review techniques suitable for that purpose. Further, techniques are discussed for intelligent processing of acknowledgment information by the coding control to adapt the source coder to the channel. We review and compare error tracking, error confinement, and reference picture selection techniques for channel-adaptive source coding. For comparison of these techniques, a system for transmitting low bit-rate video over a wireless channel is presented and the performance is evaluated for a range of transmission conditions. We also show how feedback-based source coding can be employed in conjunction with precompressed video stored on a media server. The techniques discussed are applicable to a wide variety of interframe video schemes, including various video coding standards. Several of the techniques have been incorporated into the H.263 video compression standard recently, and this standard is used as an example throughout. <s> BIB001 </s> Survey of Error Correction Mechanisms for Video Streaming over the Internet <s> IV. ERROR RESILIENT <s> We describe an effective method for increasing error resilience of video transmission over bit error prone networks. Rate-distortion optimized mode selection and synchronization marker insertion algorithms are introduced. The resulting video communication system takes into account the channel condition and the error concealment method used by the decoder, to optimize video coding mode selection and placement of synchronization markers in the compressed bit stream. The effects of mismatch between the parameters used by the encoder and the parameters associated with the actual channel condition and the decoder error concealment method are evaluated. Results for the binary symmetric channel and wideband code division multiple access mobile network models are presented in order to illustrate the advantages of the proposed method. <s> BIB002 </s> Survey of Error Correction Mechanisms for Video Streaming over the Internet <s> IV. ERROR RESILIENT <s> Resilience to packet loss is a critical requirement in predictive video coding for transmission over packet-switched networks, since the prediction loop propagates errors and causes substantial degradation in video quality. This work proposes an algorithm to optimally estimate the overall distortion of decoder frame reconstruction due to quantization, error propagation, and error concealment. The method recursively computes the total decoder distortion at pixel level precision to accurately account for spatial and temporal error propagation. The accuracy of the estimate is demonstrated via simulation results. The estimate is integrated into a rate-distortion (RD)-based framework for optimal switching between intra-coding and inter-coding modes per macroblock. The cost in computational complexity is modest. The framework is further extended to optimally exploit feedback/acknowledgment information from the receiver/network. Simulation results both with and without a feedback channel demonstrate that precise distortion estimation enables the coder to achieve substantial and consistent gains in PSNR over known state-of-the-art RD- and non-RD-based mode switching methods. <s> BIB003 </s> Survey of Error Correction Mechanisms for Video Streaming over the Internet <s> IV. ERROR RESILIENT <s> We present a system for video streaming well adapted to the unpredictable and varying nature of Internet. The proposed system uses a superposition of several multiple description coding (MDC) schemes, each with N = 2 descriptions, to reach rate scalability and adaptability to varying channel conditions. Each MDC (N = 2 descriptions), that we will call base MDC has a bit rate and a redundancy associated. The superposition of several base MDC results on a MDC scheme for N > 2 descriptions with different bit rates, allowing rate scalability, for different redundancies. The proposed scheme is well adapted to varying channel conditions. In the proposed method multiple descriptions are generated by the coder and downloaded in the server, leaving to the server the only task to choose sending out the right description at the right time depending of channel conditions (bandwidth and loss rate). <s> BIB004 </s> Survey of Error Correction Mechanisms for Video Streaming over the Internet <s> IV. ERROR RESILIENT <s> A new multiple description coding (MDC) scheme is proposed in this paper. It utilizes the advanced video coding tools and features provided in H.264/AVC to introduce redundancy into descriptions. The proposed MDC scheme produces two descriptions, each consisting of two slice groups. One of them, called main slice group (MSG), is encoded in the normal way as main information. The other one, called side slice group (SSG), is encoded with fewer bits as redundancy by using larger quantization step sizes. Spatial and temporal correlations between neighboring macroblocks in video frames are exploited to achieve efficient redundancy coding. Experimental results show that the proposed MDC scheme achieves better rate-distortion (R-D) performance than previous slice-group based MDC schemes. <s> BIB005
Error-resilient mechanism is developed to mitigate the effect of packet losses or to prevent and limit the distortion error propagation from compression perspective by adding redundancy at the source coding level. The error-resilient composed of resynchronization marking, data partitioning, data recovery like reversible variable-length coding (RVLC) BIB002 BIB001 for wireless video. These tools are targeted at errorprone environment like wireless channel and may not be suitable to Internet environment. For video transmission over the Internet, the limit of a packet already provides a synchronization point in the variable-length coded bit-stream at the receiver side. Packet loss may cause the loss of all the motion data and its associated shape/texture data, mechanisms such as resynchronization marking, data partitioning, and data recovery may not be useful for Internet video communications. Therefore, in the packet-switched networks, error resilient source coding may use the optimal mode selection BIB003 [22] for each packet or multiple description coding (MDC) BIB004 BIB005 . These are the techniques used for robust Internet video transmission.