H.264/AVC over IP

Abstract

H.264 is the ITU-T's new, nonbackward compatible video compression Recommendation that significantly outperforms all previous video compression standards. It consists of a video coding layer (VCL) which performs all the classic signal processing tasks and generates bit strings containing coded macroblocks, and a network adaptation layer (NAL) which adapts those bit strings in a network friendly way. The paper describes the use of H.264 coded video over best-effort IP networks, using RTP as the real-time transport protocol. After the description of the environment, the error-resilience tools of H.264 and the draft specification of the RTP payload format are introduced. Next the performance of several possible VCL-and NAL-based error-resilience tools of H.264 are verified in simulations.

Engineering wireless broadband access to IPTV

“…The current authors have introduced various error resilience measures [19]: different rates and types of Intrarefresh Macroblocks (MBs) [20], Constrained Intra Prediction (CIP) [21] and where necessary, redundant datapartitioned Network Abstraction Layer (NAL) units (codec level packets) [22]. The impact of each of these measures is analyzed in isolation from each other, for Constant BitRate (CBR) as well as Variable BitRate (VBR) streaming.…”

Rate Adaptive Selective Segment Assignment for Reliable Wireless Video Transmission

“…In particular, in this paper, we study data partitioning and slicing. Data partitioning (DP) [4] is a low-cost error resilience feature, supported by the extended AVC profile, which can be exploited to introduce a layered structure in H.264/AVC. The DP feature of H.264/AVC effectively prioritizes a video stream by partitioning it into classes of different importance to video reconstruction with a very small rate penalty compared to the AVC standard without error resilience.…”

“…A low-cost option is the DP [4,11] which supports the partitioning of a frame/slice in up to three partitions (NAL units), based on the importance of the encoded video syntax elements for video reconstruction (see Figure 1(a)). DP A contains the most important data comprising slice headers, quantization parameters, and motion vectors.…”

“…Another scheme available in the baseline profile is slicing [4], which enables the partitioning of a frame into two or more independently coded sections, called slices. Each slice in a frame can have either a fixed number of assigned MBs or fixed data rate.…”

“…H.264 Advanced Video Coding (AVC) [4] is the state-ofthe-art video coding standard achieving significant compression efficiency and gaining widespread use in the emerging communications standards and applications. When transmitting H.264/AVC video over a wireless channel, due to significant fluctuations of channel characteristics, the video is encoded at a fixed source rate and the redundancy (i.e., LT coded symbols) is added to avoid error effects.…”