[alsa-devel] question on hardware mixing

Clemens Ladisch clemens at ladisch.de
Tue Dec 9 09:52:51 CET 2008

Harsha, Priya wrote:
> In the trigger function - I see that from substream->runtime->private_data,
> voice specific parameters are extracted. How and can somehow user space
> fill in some private data to the driver so that driver can process voice
> in a different way and music in a different way?

On the Emu10k1 chip, the hardware voices are used for both PCM playback
and wavetable (MIDI) playback.  Voice-specific parameters are set for
MIDI data; the parameters come from the soundfont that was loaded to
specify how the instruments sound.  (Here, the term "voice" has no
relation to the sound of a human voice.)

As far as PCM playback is concerned, ALSA does not have any predefined
mechanism to differentiate between voice and music audio streams.  It
would be possible to define mixer controls to switch between these
settings for each substream.


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