Internetworking and Media Communications Research Laboratories
Department of Computer Science,
SCALABLE TRANSCODING FOR DYNAMIC
VIDEO RATE ADAPTATION
Dr. Javed I. Khan
This research investigates
techniques for extreme scalable video communication. With the advent of more
dynamic and heterogeneous network it seems rate transcoding
is also becoming increasingly important.
In network delivery of digital video, if the bandwidth required for a
video is not available, the video has to be served at a reduced bit rate.
Adaptation is also required if digital video have to be served to terminals
with varying memory, processing power and display sizes. It is also highly
desirable that the transcoding be carried out in real
time while maintaining reasonable image quality. Besides speed and quality,
another important challenge is the transcoding ratio.
Current transcoding techniques use variants of
quantization-based method and achieve transcoding
ratio less than
In this thesis we investigate a
fast transcoding technique for expanding the transcoding ratio beyond the current state of the art. We propose a technique, which combines
traditional quantization based technique with tiling. We also show how to
determine the optimum operation point between the quantization step size and
tile size. We also show technique for corresponding motion vector inference
that can avoid costly motion vector estimation and achieve faster transcoding. We have implemented an MPEG-2 ISO/IEC 13818-2
complaint transcoding scheme using this technique.
The system achieves a transcoding ratio of
approximately 1:60 on average. The thesis will present the technique and
performance characteristics of this new transcoding
Last Modified: November 2002.