A new dynamic bit allocation scheme for sub-band coding

This paper presents a new dynamic bit allocation scheme applied to sub-band coding. The technique is based on the use of quadrature mirror filters for separating each sub-band signal. The main feature of the scheme consists of suppressing every side information (SI) associated with each sub-band. This leads to only one kind of transmitted bits, the quantization bits, and consequently the frame synchronization is greatly simplified. An added advantage is that an adaptive quantization algorithm could and has been developed due to this new dynamic bit allocation. Autocorrelation of sub-band signals and linear prediction were also studied. Although the scheme can be applied to a wide range of bit rates, the study was focused on 16 Kbps because of some concerns with satellite and mobile-radio communications. Results of our 16 Kbps coder are presented via an objective measure of speech quality based on a frequency representation of signal and noise instead of the conventional temporal representation.