An Enhanced MP3 Encoder Quantization Algorithm
Sheng Xu · Audio Engineering · 2004
MP3 is the most popular audio format nowadays, although MP3 decoder has been widely used, there are few successful real-time encoder available. This results from that MP3 encoder is much more complicated than the decoder, and the quantization module consumes a large amount of computation. In order to realize a real-time MP3 encoder that can be used in portable devices,the complexity of quantization module should be greatly reduced. After analyzing some available improvements, an enhanced algorithm is proposed, which can limite scalefactor band to filter high frequency signals, compute the initial scalefactors to decrease outer iterations and adaptively change global gain after computing its initial value that is close to the ideal output so that inner iterations are greatly reduced. Tests show that this algorithm can not only produce high quality audio outputs, but also minimize the computation load to 6% of the standard realization. Therefore, the whole encoder consumes only 64% resources of the standard encoder. Combining with simplified psychoacoustic model and fast analysis filter bank, a real-time MP3 encoder can be implemented on a single DSP or ARM.