VLSI Implementation of H.264 Transform and Quantization Algorithms

G. Dileepvamshi, P. Ramakrishna

Abstract: The video compression efficiency achieved in H.264 standard is not a result of any single feature but rather a combination of a number of encoding tools. As it is shown in the top-level block diagram of an H.264 Encoder in Figure 1, two of these tools are the transform and quantization algorithms. Even though most of the previous video coding standards, e. g. MPEG-1, H.261, MPEG-2, H.263 and MPEG-4, use the 8x8 Discrete Cosine Transform (DCT) to transform the residual data, H.264 uses a 4x4 integer transform for transforming residual data. The integer transform achieves very similar results to 8x8 DCT without any floating point operations. In addition, all the multiplication operations in the forward and inverse transform algorithms can be implemented in hardware with low cost binary shifters. Since the inverse transform in H.264 is defined by exact integer operations, inverse transform mismatches are avoided. Since a scaling factor is used in the quantization algorithm, a multiplier is needed for its implementation

Keywords: H.264, forward transform, quantization