Research On Error Resilience Techniques For H.264 Video Transmission Over Wireless Networks

With the rapid development of multimedia,network and communication technology, video communication is becoming the main service in wireless communication networks and the Internet. As the new efficient video compression and codec standard, H.264/AVC not only has excellent compression performance, but also has good network compatibility. As kinds of efficient coding algorithms are widely used in H.264, the compressed data is sensitive to the channel impairment.So it is a great challenge for the encoded video to transmit over wireless networks or Internet. Therefore, to guarantee the quality of video transmission, the research on the effective error resilience techniques is of great importance in both theory and practice. This paper focuses on the error resilience techniques for video transmission. Two types of error resilience methods are studied as follows:(1) On the basis of the information hiding technique and error recovery techniques for video transmission, a new I frame error recovery method for H.264 video transmission based on data hiding is proposed. At the encoder, for I frame, various kinds of important data based on scene change are extracted and embedded adaptively into the video packets. At the decoder, if available, the extracted important data will facilitate the adaptive spatial-temporal error recovery methods to recover the corrupted MB; otherwise, the WPA (Weighted Pixel Averaging) algorithm is used for error concealment. This method improves H.264 video transmission quality at various packet loss environments, especially for large motion frame and scene change frame. Moreover, the RTP extension headers are used for data hiding in this paper. Thus, it solves the lack-of-space hiding problem, and does not degrade the original encoded video data, which further improves the video quality.(2) On the basis of the LDGM Triangle Unequal Error Protection (LDGM Triangle-UEP) algorithm and real-time forward error correction (FEC) for video transmission, the error resilience method for real-time H.264 video transmission based on LDGM Triangle-UEP is proposed. At the sender end, the frames in a Sub-GOP are encoded based on LDGM Triangle-UEP. At the receiver end, to decode and display one frame in the Sub-GOP, the video decoder only needs packets belonging to this frame. If some packets of this frame get lost during transmission, error concealment is applied to conceal the lost packets. In this manner, the decoder does not need to wait for all the packets belonging to this Sub-GOP. Therefore, there is no delay on the decoder side. Later, when the transmission of all packets of this Sub-GOP is finished, the LDGM Triangle decoder would try to recover the lost packets. If the LDGM Triangle decoder is able to recover all the lost packets of this Sub-GOP, the video decoder will re-decode this Sub-GOP with all the received and recovered packets, updating the reference frame, so the concealment distortion would not propagate to later frames. Experimental results show that this method improves the reliability of the real-time video transmission system.