DCT Based Fast 4X4 Intra-Prediction Mode Selection

In the H.264/AVC, intra prediction plays an important role with respect to compression and complexity. It has a significant meaning to reduce the encoder complexity without rate-distortion performance degradation from the real- time implementation perspective. Here, we present an improved tool enabling H.264 encoding in low complexity. The proposed encoding approach makes use of DCT coefficients to estimate intra prediction directions. The accuracy of mode estimation can be improved since the DCT coefficients of the 4x4 blocks are calculable with relatively small computations. The proposed method can be implemented in low computational complexity without a noticeable RD performance degradation. According to the simulation results, it saves around 33% of the computation time, with a negligible PSNR degradation less than 0.2dB in average, while the bit rate increases in a negligible amount of less than 6% in average with all test sequences. It is evidently shown that the proposed method achieves a significant computational reduction without sacrifice in terms of PSNR video quality and bit rates.