[pulseaudio-discuss] Getting the pollfds from the PA mainloop

Stephan Soller stephan.soller at helionweb.de
Sun Mar 30 10:48:40 PDT 2014

On 03/30/2014 07:08 PM, Thomas Martitz wrote:
> Am 30.03.2014 17:04, schrieb Stephan Soller:
>> Hi,
>> is there a way to get the pollfds out of the poll() based Pulse Audio
>> mainloop? Basically I want to do the poll() myself so I can poll for
>> other stuff as well (some v4l2 devices and UNIX domain sockets).
>> In ALSA there is the snd_pcm_poll_descriptors*() family of functions
>> to get the required pollfds. But I haven't found an equivalent Pulse
>> Audio function for that kind of stuff.
>> I looked at the PA mainloop source code and found no matching
>> functions
>> (http://cgit.freedesktop.org/pulseaudio/pulseaudio/tree/src/pulse/mainloop.c).
>> I found the pollfds and n_pollfds members in the pa_mainloop struct
>> but no way to access them from the outside. Does that mean I'm stuck
>> with ALSA?
>> A little background: I'm currently building an audio/video live mixing
>> program. It combines several video and audio streams (webcams, frame
>> grabber, mics, ...) into one live stream and sends it to an encoder
>> process (ffmpeg).
>> One big poll() loop fechtes video and audio data and manages some UNIX
>> domain sockets to send the result onwards. OpenGL is used to combine
>> the different video streams. The program only shuffles data around and
>> if possible I want to keep everything in one single threaded poll() loop.
>> Any ideas are welcome.
> Alternatively you can add your FDs to the pa mainloop using
> mainloop_io_new(). The end result (all FDs are covered with a single
> poll() call) is the same.
> Best regards

Thanks for the quick reply Thomas. :)

This looks like a possibility. I'll give it a try tomorrow. But I have 
to admit that it feels like the wrong way around (PA handling video and 
socket server events...). But what works works I guess.

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