[linux-audio-dev] OpenGL + Audio = Bad Idea?

Ge Wang gewang at CS.Princeton.EDU
Sat May 21 16:16:41 UTC 2005

OpenGL + Audio can be a good thing.  We at the SoundLab have been using 
this combination in many of our apps.  It is important to structure the 
audio callbacks in such a way that it can operate independent of the main 
render function.  I have to jump on a plane to Vancouver (NIME2005), but 
here are some apps that involves audio and opengl:


     (look at the audio callback vs. the render function in sndpeek.cpp)


     (see rt_lpc.cpp)

soon the audicle:


Hope this helps.


On Sat, 21 May 2005, Richard Spindler wrote:

> Hi,
> I have a little Problem:
> I'm using OpenGL in my Program, in combination with OSS via portaudio.
> The Updates of the OpenGL display are triggered by the audio callback,
> protected using the available Methods of the GUI-Toolkit that I use
> (fltk).
> And I'm experiencing very strange effects, like: without Audio the
> OpenGL works fine. without the OpenGL, the audio works fine, however
> when used in combination, the Audio Thread (callback) stops very soon,
> and I have no Idea why?
> I used efence to discover wheater I'm screwing up memory somewhere,
> but I couldn't find anything. I ran valgrind, but it couldn't find
> something helpful either.
> I ran it from within gdb, but the program behaves correctly if run
> from gdb (heisenbug?). It even works better whenever I insert some
> cout's for debugging purposes.
> in gdb it also reports a signal like this when initializing the
> openGL, but I believe that might be propably unreleated.
> http://music.columbia.edu/pipermail/linux-audio-user/2004-October/016821.html
> BTW. I'm running an unmodified ubuntu warty.
> Any tips or pointers??
> Thanks
> Richard
> PS.: (writing this message led me to some more experiments ;) )
> I'm fairly sure that something is screwed up within thread
> syncronisation, because I can "fix" it by inserting a usleep() call at
> a certain position, but I do have a fairly hard time imagining what
> could be wrong. I'm considering to switch to blocking IO for Audio
> because, latency and stuff is not really an issue.

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