Nec Corporation

Kiyoshi Ishiyama

Hidenobu Harasaki

A picture encoding system conversion device and a code rate conversion device for realizing the conversion taking into account both time delay and picture quality using the information on the code volume of the encoding parameters, input and output buffers and an input bitstream. There are provided a decoderincluding an input buffer, a VLD unit, an inverse quantizer, an IDCT unit, an adder, a frame memoryand a motion compensation prediction unit; an encoderincluding an adder, a DCT unit, a quantizer, an inverse quantizer, an IDCT unit, an adder, a frame memory unit, a motion compensation prediction unit, a VLD unitand an output buffer; and a transcoder controllerincluding a decoder monitor unit, an input buffer monitor unit, a reception transmission channel monitor, a sending transmission channel monitor, an output buffer monitor unitand a quantization step controller. The quantization step controllermodifies the quantization step of the encoder based on the information from the input buffer monitor, output buffer monitor, decoder monitor, reception transmission channel monitor and sending transmission channel monitor.

Picture encoding system conversion device and encoding rate conversion device

To improve qualities of audio and picture signals by distributing adaptively the code quantities of audio codes and picture codes and by adopting variable rate audio coding. The audio/picture processing apparatus handles audio presence information, audio characteristics information, audio quality information, picture quality information, code quantity distribution information, and line capacity information. A code quantity control means decides the distribution of the audio and picture codes, an audio coding format, and a coding rate, whereby the audio signal and picture signal are coded by a picture encoder and an audio encoder. The outputs from the picture encoder and the audio encoder are multiplexed by a multiplexer in order to transmit a multiplexed bit stream onto the network.

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Tokyo, Japan

Kiyoshi Ishiyama