Dynamisches Bitratensteuerungssystem für Video und entsprechende Audiokodierung sehr niedriger Datenrate.

摘要

For the very low bit rate video and associated audio coding, the audio bitstream spends about similar scale of bandwidth as the video bitstream. The conventional audio and video coding system is usually composed of a constant bit rate audio encoder and a constant bit rate video encoder. However, there are redundancies in the audio signal which can be detected to save the audio encoding bit rate in a variable bit rate coding mode. This audio bit saving has not been well utilized to increase the very tight video coding bit rate so as to improve the coded picture quality. This specification presents an invention of dynamic bit rate control coding system for the video and associated audio signals. The new coding system comprises a variable bit rate audio encoder which is able to generate skipped audio frames to save the bits. The audio encoder reports the bit saving to a bit rate allocator, which calculates the available bits for the current picture coding based on the value of audio bit saving, the previous picture coding spending and the fullness of a FIFO buffer. Depending on the bits available for the current picture coding, a coding mode selector selects a picture coding mode from an I picture coding, a P picture coding or an extra P picture insertion. Once the picture coding mode is selected, a variable bit rate video encoder is used. The coded variable audio and video bitstreams are sent to a FIFO buffer for the generation of a constant system bitstream output by a system multiplexer.