A low-complexity, high-quality, 64-Kbps audio codec with efficient bit allocation

This paper presents a very low-complexity audio codec that provides audio playback quality similar to the MPEG-I/audio level 3 codec at 64 Kbps for a monophonic-channel signal. This well-designed low-sophistication scheme uses a simple noise-masking model, a specialized nonuniform quantizer, an effectively recursive refinement module, and an adaptive arithmetic coder with multiplication-free adaptation. For bit allocation, we propose an appropriate nonuniform quantizer incorporating noise-masking effects and designed for fast implementation as well as efficient acceleration of the proposed refinement process. This recursive refinement algorithm effectively improves recovered perceptual audio quality after quantization. The adaptive arithmetic coder uses two fast adaptation algorithms that do not require multiplication to quickly obtain efficient bit allocation. A Taylor series expansion is used to simplify the frequently executed functions in the masking threshold formulas. Thus, the proposed high-quality audio codec appears to be a very valuable consumer electronic approach or a software solution at low cost.