In real-time, two way video communications, how to minimize the end-to-end delay for transmitting video data is very important. Since the delay produced by bits accumulated in the encoder buffer must be very small, we need an improved rate control to encode the video with high quality and maintain low buffer fullness. One approach to reduce the buffer fullness is to skip the encoding frames, but the frame-skipping will produce undesirable motion discontinuity in the encoded video sequence. 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 control the quantization parameter of each I-frame to avoid the buffer overflow and frame-skipping. Since encoding the I-frame by different quantization parameter will generate different rate and distortion for a group of pictures (GOP), we use Lagrangian optimization to find the tradeoff between rate and distortion for a GOP. By the estimation models of rate and distortion for a GOP, calculate the Lagrangian cost for each possible quantization parameter of I-frame, the quantization parameter with minimum Lagrangian cost will be our choice for I-frame. 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.

Video streaming is an important field of global communications and data processing. It is divided into server and client sides connected via network. Video streaming is concerned with delivering video data from server to client over the network as fast and with as little loss as possible. In this study the possibilities to minimize the amount of data transferred over the network in video streaming are investigated and a video streaming technique comprised of server and client sides is proposed. To expand the flexibility and adaptability of the proposed video streaming technique an operational parameter system was constructed and the parameter value ranges were defined. The proposed video streaming technique was then applied to three sample videos. Before streaming the server side of the proposed technique reduced the frame count of input videos based on operational parameter values while the client side reconstructed the skipped frames. Then the quality of the resulting videos was measured and evaluated. To evaluate the reconstructed frames and videos the PSNR measurement method was used. The study concludes that by using the proposed video streaming technique it is possible to reduce the amount of transfer data by dropping frames on the server side and reconstructing them on the client side.