I was looking at the AHI source briefly.
I'm not sure if I understood how/if AHI supports more HW channels.
Can you or anyone help me to understand this?
AHI supports Mono, Stereo and 7.1 (aka
output channels, no other number of channels (so if you really want to have 5.1 channel output, you would need to use the 7.1 mode).
Changing the number of supported output channels is a PITA, because there are dozens of optimized mixing routines for each sample type combination (see SelectAddRoutine in mixer.c) and addroutines#?.[c|s].
However, AFAIK it supports any number (<256?) of "voices" (again with the given width Mono, Stereo and 7.1) that may be mixed together to that output HW channels mentioned above.
The question is:
If the HW for example supports 8 independent Channels, each with 8 or 16 bit samples, independent frequency and independent volume.
Will AHI make 100% use of this. I.E. will a 8 voice audio piece run fully on HW or will AHI still do some software mixing or upsampling of the channels?
There is a mode where the driver may take over the mixing completely (makes it possible to do this in hardware or via DSP). I just looked it up, you can actually mix different sample types of a "voice" to the output channels.
AFAIR the Paula DMA drivers use this mode (no mixing is done, but limited to <4 "voices").
Martin Blom is still around these days and is very helpful
