Approved By:

This thesis describes the design, implementation and performance analysis of a transcoder for MPEG – 2 streams. When streaming MPEG video over a heterogeneous network such as Internet, the available bandwidth is not the same at different points of the broadcast chain. Video transcoding is one of the key technologies required to dynamically adapt the bit-rate of the video stream to the available bandwidth along a heterogeneous network. However, in the process of conversion from higher bit rate to a lower bit rate, some delay is introduced in the bit stream. In interactive applications such as video conferencing this delay has to be minimized. In this thesis, two methods for the transcoding of MPEG streams have been implemented. The first is by increasing the quantization scale and the other by dropping of B-frames. Both the methods perform the task with minimum storage and computational requirements and hence introduce very less delay. The quantization scale is changed in the DCT domain itself. This means that the MPEG stream need not be decoded and then re-encoded completely. Also, the motion vectors are re-used and re-computation of motion vectors is avoided in the process.