[alsa-devel] User-space control elements in ext PCM plugin
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.
Marcus
'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.
Col
Hi Colin,
thanks for your answer. In general the pulse plugin does more or less what I want - present controls in userspace, right. But the PulsePlugin actually consists of two plugins, a PCM plugin (pcm_pulse.c) and control plugin (ctl_pulse.c). As far as I understand, the control events/messages from the user space sliders are directed to the pulse audio server via the ctl_plugin. My question is actually, how to make use of them directly in the pcm plugin?
As I told, a similiar request was done three years ago:
http://article.gmane.org/gmane.linux.alsa.devel/50181
That´s where I got the idea of creating the user-space control elements directly inside of the PCM plugin, or did I get it wrong?
Marcus
-------- Original-Nachricht --------
Datum: Wed, 07 Apr 2010 12:32:59 +0100 Von: Colin Guthrie gmane@colin.guthr.ie An: alsa-devel@alsa-project.org Betreff: Re: [alsa-devel] User-space control elements in ext PCM plugin
'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.
Col
--
Colin Guthrie gmane(at)colin.guthr.ie http://colin.guthr.ie/
Day Job: Tribalogic Limited [http://www.tribalogic.net/] Open Source: Mandriva Linux Contributor [http://www.mandriva.com/] PulseAudio Hacker [http://www.pulseaudio.org/] Trac Hacker [http://trac.edgewall.org/]
Alsa-devel mailing list Alsa-devel@alsa-project.org http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
On Wed, 7 Apr 2010, Marcus Weigelt wrote:
That´s where I got the idea of creating the user-space control elements directly inside of the PCM plugin, or did I get it wrong?
The build-in softvol plugin uses this mechanism. But I'm not sure, if this way is supported in the external PCM plugins interface.
Jaroslav
----- Jaroslav Kysela perex@perex.cz Linux Kernel Sound Maintainer ALSA Project, Red Hat, Inc.
Yes, I think the softvol plugin is the closest thing to what I want to do. So I think I will just try it :) Thanks for your support!
Marcus
-------- Original-Nachricht --------
Datum: Wed, 7 Apr 2010 13:58:40 +0200 (CEST) Von: Jaroslav Kysela perex@perex.cz An: Marcus Weigelt noize007@gmx.de CC: alsa-devel@alsa-project.org Betreff: Re: [alsa-devel] User-space control elements in ext PCM plugin
On Wed, 7 Apr 2010, Marcus Weigelt wrote:
That´s where I got the idea of creating the user-space control elements directly inside of the PCM plugin, or did I get it wrong?
The build-in softvol plugin uses this mechanism. But I'm not sure, if this way is supported in the external PCM plugins interface.
Jaroslav
Jaroslav Kysela perex@perex.cz Linux Kernel Sound Maintainer ALSA Project, Red Hat, Inc.
participants (3)
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Colin Guthrie -
Jaroslav Kysela -
Marcus Weigelt