Junichi Ohki

A single-board video codec using video image signal processors

Abstract This paper discusses a newly developed single-board video codec using Video Image Signal Processors (VISPs). The codec has both a CCITT H.261 mode and a proprietary mode. Two VISPs, one for encoding and one for decoding, are used. The board size is 210 by 295 mm, the maximum frame rate is about 7.5 f/s, and the picture size is 180 by 144 pels.

Feedforward Control Of Hybrid Transform / Predictive Coder

A new feedforward control method to control encod-ing parameters is proposed for low bit rate video encoding. At low transmission bit rates, all input video frames cannot be transmitted and an encoding frame interval varies with the information amount in each encoded frame. Subjective video quality is evaluated from both picture degradation and encoding frame intervals. Because picture degradation and encoding frame intervals are traded off, encoding parameter control is very important. The proposed method is based on a hybrid transform predictive coding scheme with adaptive coefficient selection. The method estimates the amount of information for some encoding parameters and selects parameters so that given control characteristics can be achieved. Computer simulations for both the proposed method and a conventional feedback method show the effectiveness of the new method. This method will be applied to an NETEC series low bit rate video codec.