modelled after aarch64 code
on Cortex-A8, s16 and s32 code is about 2x faster,
float code about 7x faster
Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net>
Signed-off-by: Martin Storsjö <martin@martin.st>
This allows AudioMix to be treated the same way as other conversion contexts
and removes the requirement to allocate it at the same time as the
AVAudioResampleContext.
The current matrix get/set functions are split between the public interface
and AudioMix private functions.