Systematic lossy error protection based on H.264/AVC redundant slices and flexible macroblock ordering

The authors propose a scheme for Systematic Lossy Error Protection (SLEP) of an H.264/AVC compressed video bit stream, using standard compatible features such as redundant slices, and flexible macroblock ordering. The systematic portion consists of a conventional H.264/AVC bit stream. For error resilience, an additional Wyner-Ziv bit stream is also transmitted. The Wyner-Ziv bit stream allows the decoding of a coarsely quantized description of the original video signal, and is efficiently gen- erated by using H.264/AVC redundant slices in conjunction with Reed-Solomon coding. The Wyner-Ziv bit stream is decoded in order to recover the redundant video descriptions, which are used in lieu of portions lost from the original video signal due to channel errors. SLEP allows the video quality to degrade gracefully with worsening channel conditions, and provides a flexible trade-off between the achieved error resilience and the coarseness of the redundant description. The performance can be improved especially for low motion video sequences, by applying SLEP to a region-of-interest in the video frame, using flexible macroblock ordering (FMO). Experimental results provided for two video transmission scenarios, demonstrate the advantages of SLEP over forward error correction (FEC) as an error resilience scheme.