A unified transform unit for H.264

This paper presents a unified transform unit that can efficiently perform forward integer transform, quantization, dequantization, inverse integer transform, and Hadamard transform in H.264/AVC. To reduce hardware cost, the proposed architecture uses shifters, adder/subtractors instead of multipliers for quantization and de-quantization, and reuses 1-D transform unit for all supporting transforms. Hardware utilization is maximized to achieve required performance with low cost. It takes about 250 cycles to perform forward integer transform, quantization, de-quantization, and inverse integer transform for a macroblock, and additional 35 cycles for forward and inverse Hadamard transforms. The architecture can process about 6,000 frames of QCIF at 150 MHz. The unified transform unit can be widely used in mobile devices.