Fast Block Mode Decision for H.264/AVC on a Programmable Digital Signal Processor

Variable block size motion estimation (ME) is one of the new coding tools for H.264/AVC encoder to enhance the video performance. However, the complexity of the variable block size ME is very high because the motion estimation and rate-distortion optimization need to be performed repeatedly for all the possible block mode combinations. In order to reduce this, we propose a new block mode decision algorithm, which can decide the block mode efficiently without trying all the block modes by using the spatial property of image sequences. The experimental results on a VLIW (Very Long Instruction Word) - SIMD (Single Instruction Multiple Data) programmable digital signal processor (DSP) show that the proposed algorithm can save the CPU clock cycles by 47% for the integer-pel ME and 83% for the sub-pel ME. The video performance degradation in terms of PSNR and bitrates is 0.12 dB and 1.04%, respectively.