[alsa-devel] Rates/formats available upstream from the plug plugin

Raymond Yau superquad.vortex2 at gmail.com
Tue Aug 3 17:35:55 CEST 2010

2010/8/3 Pavel Hofman <pavel.hofman at ivitera.com>

> Hi,
> mplayer checks hw_params for availability of the current format
> http://mplayer-ww.git.sourceforge.net/git/gitweb.cgi?p=mplayer-ww/mplayer-ww;a=blob;f=libao2/ao_alsa.c;h=57f0bd07cb5ec300d327682a0b5209ba9dc10e30;hb=09ab9f6346aaf15d20792ca3df761a45fe46d83d#l514
> . If the check fails, it uses 16bits as fixed default.
> Now if we define the card to be plughw:0, the check still fails for
> formats unsupported directly by the card. Which in fact is incorrect
> since the plug plugin takes care of most formats known. The same holds
> for sample rates.
> IMO either the plug plugin should reconfigure hw_params for upstream
> use, or mplayer should use a different API call for checking parameters
> of the actual alsa device (not just the hardware itself, as defined by
> its alsa driver) - which one?
> Thanks a lot,
> Pavel.

AFAIK , "plug" plugin does not support AC3 encode/decode , and alsa spdif
device support AC3 passthrough

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