Research On Bit-rate Control For H.264 Video Coding

Bit-rate control algorithm is an important part of the H.264, which is used to moderate the bit rate of video transmission on the limited bandwidth channel, and to control bit allocations in order to improve visual quality.Firstly, this paper analyses the H.264 video coding standard. Then we discuss MPEG-4 and H.264 bit-rate control algorithms and basic principles.Secondly, the research effort is focused on the bit allocation bit-rate control considering complexity. We propose an optimized MAD-based bit allocation method with both frame and macro block layers. When the motion in a frame becomes fast and complex or has a scene change, we propose an improve frame skipping scheme and an effective scene change detection method, considering PSNR-based method as a complexity measurement. Then we propose a Lagrange multipler in RDO and an adaptive QP adjustment scheme. Based on those methods, we obtain the overall improved H.264 bit-rate control strategy. All the results of the simulation and experiment can prove that the proposed optimized bit-rate control strategy achieves significant performance improvement.Finally, this dissertation describes a bit-rate control algorithm under the low delay constraint with smaller buffer area. In response to this feature, we improve bit allocation considering frame complexity measure, and propose accurate QP detection and adjustment by taking into consideration the actual encoding results of previously coded macroblocks. The experiments show that our bit-rate control strategy has better visual quality and prevents the small buffer from overflow or underflow at low delay video transmission than H.264 bit-rate control strategy.