Survey of Error Correction Mechanisms for Video Streaming over the Internet <s> B. Multiple Description Coding <s> The problem of error control and concealment in video communication is becoming increasingly important because of the growing interest in video delivery over unreliable channels such as wireless networks and the Internet. This paper reviews the techniques that have been developed for error control and concealment. These techniques are described in three categories according to the roles that the encoder and decoder play in the underlying approaches. Forward error concealment includes methods that add redundancy at the source end to enhance error resilience of the coded bit streams. Error concealment by postprocessing refers to operations at the decoder to recover the damaged areas based on characteristics of image and video signals. Last, interactive error concealment covers techniques that are dependent on a dialogue between the source and destination. Both current research activities and practice in international standards are covered. <s> BIB001 </s> Survey of Error Correction Mechanisms for Video Streaming over the Internet <s> B. Multiple Description Coding <s> Real-time audio and video data streamed over unreliable IP networks, such as the Internet, may encounter losses due to dropped packets or late arrivals. This paper reviews error-concealment schemes developed for streaming real-time audio and video data over the Internet. Based on their interactions with (video or audio) source coders, we classify existing techniques into source coder-independent schemes that treat underlying source coders as black boxes, and source coder-dependent schemes that exploit coder-specific characteristics to perform reconstruction. Last, we identify possible future research directions. <s> BIB002 </s> Survey of Error Correction Mechanisms for Video Streaming over the Internet <s> B. Multiple Description Coding <s> Delivering real-time video over the Internet is an important component of many Internet multimedia applications. Transmission of real-time video has bandwidth, delay, and loss requirements. However the current Internet does not offer any quality of service (QoS) guarantees to video transmission over the Internet. In addition, the heterogeneity of the networks and end systems makes it difficult to multicast Internet video in an efficient and flexible way. Thus, designing protocols and mechanisms for Internet video transmission poses many challenges. In this paper, we take a holistic approach to these challenges and present solutions from both transport and compression perspectives. With the holistic approach, we design a framework for transporting real-time Internet video, which includes two components, namely, congestion control and error control. Specifically congestion control consists of rate control, rate-adaptive encoding, and rate shaping; error control consists of forward error correction (FEC), retransmission error resilience, and error concealment. For the design of each component in the framework, we classify approaches and summarize representative research work. We point out there exists a design space which can be explored by video application designers and suggest that the synergy of both transport and compression could provide good solutions. <s> BIB003 </s> Survey of Error Correction Mechanisms for Video Streaming over the Internet <s> B. Multiple Description Coding <s> Two novel error concealment techniques are proposed for video transmission over noisy channels in this work. First, we present a spatial error concealment method to compensate a lost macroblock in intra-coded frames, in which no useful temporal information is available. Based on selective directional interpolation, our method can recover both smooth and edge areas efficiently. Second, we examine a dynamic mode-weighted error concealment method for replenishing missing pixels in a lost macroblock of inter-coded frames. Our method adopts a decoder-based error tracking model and combines several concealment modes adaptively to minimize the mean square error of each pixel. The method is capable of concealing lost packets as well as reducing the error propagation effect. Extensive simulations have been performed to demonstrate the performance of the proposed methods in error-prone environments <s> BIB004
Multiple Description Coding (MDC)[2, 27] is another way to achieve trade-off between compression efficiency and error robustness. Fig. 6 .shows, the structure of multiple description coding. A raw video sequence is compressed into multiple streams (descriptions). Each description can provide good visual quality even if only one description is received while if more one description is received that will improved the visual quality (Highest). When lose happened multiple description decoder will borrow the corresponding frame from another description. MDC has two important features. First, robustness: even if one description received and other lost, it can give good visual quality. Each description can be decoded independently. Second, if receiver received more than one description, it can combine all description received together and provide better visual quality. V. ERROR CONCEALMENT Error concealment is a post-processing technique executed only by decoders/receivers. Unlike the error resilient, that is applied to avoid the packet loss before it happened (this call preventive approach). Error concealment is applied by the receiver to handle the packet loss that already occurred BIB001 (this is called reactive approach).Error concealment is used to conceal the lost data and make the presentation less displeasing to human eyes. The error concealment has been useful to use for video and audio streaming over Internet BIB002 . There are two basic approaches for error concealment to handling the packet loss. Spatial and temporal domain interpolation BIB003  BIB002 BIB004 . In the spatial interpolation, missing data values are reconstructed using neighboring spatial information, whereas in temporal interpolation, the lost data is reconstructed from previous frame. Spatial interpolation is used to reconstruct the missing data in intracoded frames (I-frame), while temporal interpolation is used to reconstruct the missing data in inter-coded frames (B-frame). Several error concealment schemes have been proposed to be applicable to Internet video application BIB003 . In first scheme, the receiver replaces the whole frame with the previous reconstructed frame. Second scheme, the receiver replaces a corrupted block with the block at the same location from the previous frame. Third scheme, the receiver replaces the corrupted block with the block from the previous frame pointed by a motion vector. Motion vectors are used to compress video by storing the changes to an image from one frame to the next.