[alsa-devel] User-space control elements in ext PCM plugin

Colin Guthrie gmane at colin.guthr.ie
Wed Apr 7 13:32:59 CEST 2010

'Twas brillig, and Marcus Weigelt at 07/04/10 11:01 did gyre and gimble:
> Hi,
> I´m having an external PCM plugin that should do some processing on
> the audio. That part works fine. Now I´d like to have some way to
> modify the way to give some parameters to the plugin to tell it how
> the processing is done (eg. set delay time, pan, attack time, ...). 
> I´ve searched the web for days and hours, but could not really find
> something. On the alsa mailing list there was a similiar question
> three years ago, and the answer was, that one could create user-space
> control elements in the plugin. How is that done? I could not find
> examples or good documentation about it. Did I miss something out?
> Can anyone give me a hint, maybe a link to some docs about it or
> source of a PCM plugin creating/using user space control elements?
> Thanks a lot.

Try looking at the PulseAudio plugin. It presents userspace sliders to
control the volume. If I've not misunderstood your request this should
do what you need.



Colin Guthrie

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