[LAU] ALSA: Using a plugin only for capture

[Paul Davis]

On Tue, Dec 6, 2011 at 5:43 PM, Fons Adriaensen <fons at linuxaudio.org> wrote:

> So, are you telling us that ALSA inserts the plugin in both
> the capture and playback paths ? That would be absolutely
> braindead.

doesn't work that way at all.

the app opens "plughw:ladspa" (for example) for playback. presto: the
ladspa plugin is applied to the playback stream.
the app opens "hw:0" (for example) for capture. no plugin processing
on the capture stream.
the app opens "plughw:ladspa" (for example) for capture. presto: the
ladspa plugin is applied to the capture stream.

remember that there is no such thing as a duplex ALSA stream (similar
to several other audio device APIs).

> If the ALSA device doesn't provide enough level on the mic
> input then there is something wrong with either the driver
> or its configuration.

agreed.