A fast block size decision algorithm for intra prediction in H.264 for video coding in space missions
Sabin S Sabu, L Sandhya, G. Subha Varier · 2016
To efficiently transmit the huge volume of data captured during stage separation of launch vehicle in space missions, it is necessary to develop a robust video compression system which meets all the real time requirements. The major constraints in transmitting this massive amount of mission critical data are bandwidth and computational time. In this paper, we aim to develop an entropy based video compression system based on H.264 standard which suits the demands of on-board space application. One of the most time consuming part of H.264 encoder is the intra prediction stage involving exhaustive mode decision criteria. Here, we focuses on developing a fast intra prediction algorithm which provides acceptable performance measures with less computational time to incorporate in the robust H.264 system under development. This paper proposes an efficient block size decision algorithm for intra prediction based on the texture feature of macro blocks. Emphasis was given for luma component of I frames, which are generally coded either using 4×4 or 16×16 blocks. The proposed algorithm can decide the best block size for each MB based on texture feature at an initial stage of prediction instead of examining all block sizes exhaustively as followed in standard JM software. After deciding the best block size using proposed algorithm, three step search algorithm is implemented to find the intra 4×4 prediction mode to achieve further reduction in computational time. Experimental results showed that the proposed algorithm achieves about 96% decision accuracy with PSNR loss less than 0.0002 dB. Time reduction of around 30 % was obtained with negligible increase in bit rate.