The basic idea is to write out the signal that came in with the same number of
channels as it had when it came in. Things get a bit more complicated when
one output block may be derived from more than one input block, each having
different numbers of channels. When this happens, the input blocks with fewer
channels are upmixed, so as not to lose (or distort) any signal in the block
with more channels.
HRTFPanner no longer uses exponential decay (with time constant 20ms) for
delay changes, but a smoother linear transition during cross-fade time (~45ms).
--HG--
rename : content/media/webaudio/DelayProcessor.cpp => content/media/webaudio/DelayBuffer.cpp
rename : content/media/webaudio/DelayProcessor.h => content/media/webaudio/DelayBuffer.h
extra : rebase_source : 18453d631779cd7d0672b5325e110b107ab4237d
so that old cross-fade info does not distort new sound when a PannerNode
finishes and restarts.
--HG--
extra : transplant_source : I%A9%DAx%9F%AE%B8%88%90FN%3B%3E%FC%FE%827%CB%10%8C
