Improved rate control and motion estimation for H.264 encoder

In this paper, we describe rate control and motion estimation in x264, an open source H.264/AVC encoder. We compare the rate control methods of x264 with the JM reference encoder and show that our approach performs well in both PSNR and bitrate. In motion estimation, we describe our implementation of initialization and show that it improves PSNR. We also propose an early termination for simplified uneven cross multi hexagon grid search (UMH) in x264 and show that it improves the speed by a factor of 1.5. Finally, we show that x264 performs 50 times faster and provides bitrates within 5% of the JM reference encoder for the same PSNR.