A dynamic slice control scheme for slice-parallel video encoding

Slice-parallel video coding with a fixed number of slices and uniformly allocated coding regions would cause extra waiting time among slice threads, especially when the encoding machine is also busy running other applications. In this paper, we propose to adaptively decide the number of slices before encoding each frame by computing the expected value of the coding time of the encoder under two kinds of machine states: busy and free based on a Markov system. We also manage to balance computational complexity among slices by utilizing the estimated encoding time of each allocation unit in the frame to be encoded. Experimental results show that the proposed scheme can further improve the coding speed of an H.264 based fixed-slice parallel encoder by 30% on average, while the rate-distortion performance change is marginal.