Ultra low delay wavelet audio coding with low complexity for real time wireless transmission

Wireless systems are often subject to the constraints of the available channel bandwidth. The key enabling technology for digital wireless products is audio compression. For real time wireless transmission, very low encoding and decoding delay has become an essential prerequisite. In live productions, the tolerable total delay time is less than a few milliseconds. Current audio coding schemes like MPEG standards or wavelet technique can hardly reach such a threshold by using overlapping frames of input signal with psychoacoustic model. This paper presents a new wavelet audio coder with ultra low delay for real time wireless transmission using non-overlapping short block processing and embedded coding. Two dimensional (2D) fast lifting wavelet transform with boundary effects minimized is developed for further exploring the correlation of the audio signal. A modified 2D SPIHT (set partitioning in hierarchical trees) algorithm with more bits used to encode the wavelet coefficients, is implemented to reduce the correlation between the coefficients at different decomposition levels and inside each band at scalable bit rates. Experimental tests demonstrate that the proposed coder is efficient and has low complexity with less memory requirements in implementation.