Rate Control Algorithm In H.264 Video Coding Standard Under Low-Delay Constraint

H.264 is jointly made by ITU Video Codec Expert Group(VCEG) and ISO/IEC MPEG Video Team named as joint video team(JVT), and plays important role in video codec research in few years. The video coding standards describe the bistream syntax and semantics, the decoder process in detail, but give no requirement of the encoder process, in which rate control plays an important role.Rate-control algorithm affects the output rate and the quality of encoded video directly. Rate control guarantees the optimal bit allocation among the different parts of video information and maintain high quality, by choosing different quantization level, frame rate, coding pattern.Firstly, we introduce the video coding standard where the rate control algorithm is used.Secondly, we introduce the rate control algorithm in the video coding standard, then discuss MPEG-4 rate control algorithms and H.264 rate control algorithms and basic principles, and analyses the corresponding result.At last, in this thesis, we study the impact of low delay constraint in H.264 rate control and its improvements. The drawback of the H.264 rate control is it cannot handle the frame-skipping mechanism well. To modify this, we regulate adaptively the quantization parameter of each I-frame according to GOP complexion to avoid the buffer overflow and frame-skipping. Simulation results show that our proposed rate control encode the video sequence with less skipped frames and with higher PSNR compared to H.264 rate control under low delay constraint.