Context-based complexity reduction of H.264 in video over wireless applications

The Achilles' heel of video over wireless services continues to be the limited bandwidth of wireless connections and short battery life of end-user handheld devices such as cell-phones and PDAs. Efficient coding and compression techniques are required to meet the QoS (Quality of Service) requirements of such services while effectively managing the aforementioned resources. H.264, the latest coding and compression standard from ITU-T, is currently dominating the field by offering a flexible architecture and compression gain of up to 50%. The compression efficiency in H.264, however, is achieved at the expense of processing time. With demands for video-streaming and video-conferencing over wireless growing rapidly, the performance of H.264 for wireless and mobile platforms, in terms of picture quality, bit-rate and battery power consumption needs to be benchmarked, and the H.264 operating modes most suitable for these services need to be determined. This paper proposes strategies to reduce the complexity of various H.264 operations. Using the knowledge of the context of the scenes in the video sequences, unimportant regions in the frames are isolated and unnecessary processing is avoided. Experimental results, obtained using a test-bed, are presented to demonstrate the viability of the proposed strategies in minimizing the battery power consumption by H.264 while maintaining desired frame quality and low bit-rate.