8x8 Transformation Based All Zero Block Detection for H.264/AVC Encoder

Currently, 8x8 integer transformation was added to H.264/AVC for enhancing the performance of high profile, while much more complexity increased. All Zero Block (AZB) detection algorithms can help to early terminate DCT and quantization parts to reduce complexity with almost no PSNR loss. Due to the great complexity of 8x8 integer transform and quantization, however, the previous works are only concentrated on the 4×4 SAD all zero block detection. This paper proposes SAD and SATD based 8×8 AZB detection algorithms: By using the statistical analysis instead of complicated matrix derivation, through 17 QCIF sequences, 12 CIF sequences and 7 sequences of 720p test, which covers most video application, the 8×8 SAD value based all zero block threshold has been calculated. While using the SATD as the block matching criterion, the relationship between the 8x8 SAD and SATD has been derived theoretically from the energy point of view. Finally, according to this relationship and proposed SAD thresholds, the 8×8 SATD AZB thresholds have been derived. The proposed SAD value based AZB detection algorithm has saved nearly from 5% to 40% DCT and quantization calculation for QCIF, CIF and 720p sequences, while the SATD value based AZB detection algorithm achieved about from 10% to 43% calculation reduction.