Bit rate control using short-term and long-term performance

Abstract

The performance of video encoding is characterized both over the short term (e.g., based on the previous encoded frame) and over the long term (e.g., based on the previous n encoded frames). An encoding parameter (e.g., the global quantization level) is selected for the current frame based on the short-term and long-term performance characterizations and the current frame is encoded using that selected encoding parameter. In a preferred embodiment, the global quantization (Q) level is permitted to change for only certain (i.e., adjustable) frames. In addition, the global Q level for key frames is generated using special processing which tends to allow the key frames to be encoded using more bits.