Subband based MPEG audio mixing for Internet streaming applications

We investigate a special-purpose application of MPEG-1 layer II audio streaming. First, we discuss how two or more already coded MPEG-audio bitstreams can be manipulated and mixed within the coded subband domain by using an appropriate algorithm for combining and recalculating the bit allocation. Next, we show that very significant speedups can be obtained compared with mixing in the temporal domain. We also illustrate that, at the same time, the system can act as a bit rate scaling device, using one of the bit allocation-combination algorithms which we implemented. The results obtained with these different algorithms are discussed and compared. Finally, we report on how the developed software was integrated into an Internet audio streaming system, which is now able to allow simple, yet efficient, real-time mixing of several MPEG-audio coded signals.