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Globally optimized dynamic bit-allocation strategy for subband ADPCM-based low delay audio coding

This paper presents an extension and global optimization of a bit-allocation strategy for use in a low delay subband ADPCM-based audio coding scheme. The framework employed for the assignment of bits to subband quantizers is based on a subband level estimation of the signals used for the prediction error normalization. It is modified to reduce switching artifacts and extended to contain a mapping to predefined allocation presets. Since our bit-allocation scheme as well as the subband coding involve several partially interacting parameters that are hard to adjust manually, a framework for their global optimization is presented. Experiments and their results show that in our coding scheme a significant improvement of audio quality without large signaling overhead can be achieved by the use of the modified bit-allocation. Furthermore, the global optimization allows for an additional gain in audio quality compared to manually adjusted parameters.