Segment reencoding of buffer constrained variable bit rate video streams

A scheme is presented to reencode segments of buffer constrained video stream. This scheme provides a flexible and effective means to reencode only the part of the stream necessary for quality improvement or bit rate change instead of reencoding the entire stream so that great savings in production cost, storage space, and transmission bandwidth can be achieved. The scheme includes the algorithms for target rate allocation and buffer level adjustment. The rate allocation algorithm incorporates the picture quality measurement to achieve better and smoother video quality. The buffer adjustment algorithm ensures that after the reencoded segment is merged with the other portions of the original stream, the resulting new stream will still conform to all buffer constraints. The scheme has been implemented for a DVD (digital versatile disc) authoring system and the test results have shown that it is very effective and flexible.