SP and SI frames in the H.264 video coding standard can be used for error resilience, bitstream switching or random access. Despite a widespread interest in these new types of frames, no work so far has investigated, in a systematic way, their rate-distortion efficiency. In this paper, we propose a model for the rate-distortion performance of SI and SP frames. A comparison to experimental results, obtained with our implementation of an SP encoder, recently adopted by JVT, confirms its validity. The model predicts how the relative sizes of SP
and SI frames can be traded off. We analyze, both theoretically and experimentally, how this can be used to minimize the transmitted bit-rate when SP frames are used for video streaming with packet losses.
SP and SI frames are new picture types introduced in the latest video coding standard H.264. They allow drift-free
bitstream switching and can also be used for error-resilience and random access. We investigate the benefits
of SI and SP frames for error resilience as compared to periodic I frame insertion. We discuss the rate-distortion
performance of SI and SP frames based on empirical rate-distortion curved obtained with our implementation
of an SP/SI frame encoder. Experiments carried out over a simulated bandwidth-limited network analyze the
influence of loss rate and delay on the congestion-rate-distortion performance of streaming with SI and SP frames.
Our results help identify scenarios for which SI and SP frames provide an attractive alternative to streaming
with I frames.
In current interframe video compression systems, the encoder performs predictive coding to exploit the similarities of successive frames. The Wyner-Ziv Theorem on source coding with side information available only at the decoder suggests that an asymmetric video codec, where individual frames are encoded separately, but decoded
conditionally (given temporally adjacent frames) could achieve similar efficiency. We propose a transformdomain Wyner-Ziv coding scheme for motion video that uses intraframe encoding, but interframe decoding. In this system, the transform coefficients of a Wyner-Ziv frame are encoded independently using a scalar quantizer and turbo coder. The decoder uses previously reconstructed frames to generate side information to conditionally decode the Wyner-Ziv frames. Simulation results show significant gains above DCT-based intraframe coding and improvements over the pixel-domain Wyner-Ziv video coder.