| Summary: | 碩士 === 國立清華大學 === 電機工程學系 === 88 === Video conference is an Internet application which provides an environment for people to see and talk to other persons who are far away.
A video transcoder is required in a multipoint video conference to convert input streams into different format, especially different bit-rate. Ordinary transcoder degrades temporal quality by setting a fixed frame-rate, but the requirement of motion smoothness changes with video properties. It’s necessary to adjust the frame-rate to a proper value to achieve better spatial and temporal quality.
We propose a dynamic frame rate control scheme to adjust frame-rate to fit the property of video. By using frame-rate and motion level of object as measurement of temporal quality, spatial and temporal quality can be considered at the same time. When bit-rate decreases, frame-rate will be decreased to improve frame quality. When motion level increases, frame-rate will be increased to provide better continuity.
Since the adaptive control method is used and all parameters are extracted from original transcoder processing, our proposed scheme is suitable for real-time applications.
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