(A) High-performance Low-cost CAVLC Architecture with Fast Scanning

Abstract

Context-adaptive variable length coding (CAVLC) is one of two entropy codings for quantized transform residues in h.264. CAVLC, which is a lower-complexity alternative to Context-adaptive binary arithmetic coding(CABAC) for the coding of quantized transform coefficient values. Because CAVLC is a lower efficiency entropy coding, CABAC is prefer to CAVLC in main or high profile. But, in 2007, 7. Version(April 2007) amendment containing the addition of High 4:4:4 Predictive and four Intra-only profiles (High 10 Intra, High 4:2:2 Intra, High 4:4:4 Intra, and CAVLC 4:4:4 Intra) are released. These profiles are four additional all-Intra profiles, which are defined as simple subsets of other corresponding profiles. These are mostly for professional (e.g., camera and editing system) applications. So, a high performance CAVLC also is required. Pipeline architecture of previous works has good performance. Because of double buffering, hardware cost is high. Therefore the statistic buffer should be one for low cost. We have proposed the high-performance and low-cost CAVLC architecture with one statistic buffer. The proposed architecture is similar to the pipeline architecture, but just one statistic buffer with fast scanning. So, cycle per MB is similar to the pipeline architecture, but the number of gate count is lower than the pipeline architecture.