[LAD] supporting a dedicated DSP chip with ALSA

Jussi Laako jussi at sonarnerd.net
Sat May 30 20:37:07 UTC 2009

Ziv Haziz wrote:
> The problem with OpenMAX is that most of the common players (at least
> the ones I looked into mplayer and mpg123) doesn't support them
> natively.

I don't see much point in that anyway since, AFAIK, those players don't
support offloading decoding to DSP anyway. If the support is added, then
it should be fairly trivial to use some other than ALSA interface for
the purpose. For good video synchronization there should be timing
feedback from the decoder output (D/A feed stage).

However, these are fairly simple cases compared to environmental 3D
audio... (environment parameters, passive scene objects, active scene
objects with streams, etc) Some of these could be implemented through
ALSA control interface and virtual channels, but there are still various
interaction issues left and those passive objects are a bit problematic
to represent this way.

> If I will use sample format "special" will the alsa know not to try and
> do manipulation over it? (resampling, volume, etc...)

One of the common cases would probably be to feed AC-3 or dts audio to
S/PDIF. These should work?

More information about the Linux-audio-dev mailing list