A constant-time quantization strategy for a real-time MP-3 encoder

This paper reports an efficient quantization strategy for the implementation of a real-time MP-3 encoder based on a digital signal processor. Since the well-known two-loop quantization method requires a large and unpredictable amount of computation, it is not suitable for real-time encoders. Therefore, we develop an algorithm to reduce the computational burden of this part using a single three-iteration loop. Experiments show that the quality of our quantization method is close to the best possible quantization with fixed scalefactors in the distortion loop. Based on a 16-bit fixed-point digital signal processor, the proposed encoding scheme requires 35 MIPS of computation for encoding 128 kbps stereo music.