MPEG-4 CODEC with Spatio-Temporal Rate Control

In the case of the video delivery system which is constructed by constant bit-rate channel, encoder must send a constant number of bits per unit time period. Therefore, the number of bits used in encoding must be regulated by the rate control algorithm. Basically, the rate control of video signal such as MPEG-4, is realized by adaptive quantization. However, since adaptive quantization has the limitation of bit regulation, the temporal resolution conversion is also introduced. The temporal resolution conversion is effective for decreasing the number of bit for encoding, however, the conversion causes the decrease in temporal resolution. Decreasing of the temporal resolution becomes jerky degradation. In this paper, in order to keep the temporal resolution, we introduce the spatial resolution conversion for rate control algorithm. Moreover, we show how to choose the temporal resolution conversion or the spatial resolution. Thus, the proposed method realizes the low bit-rate video coding while preserving the original frame-rate.