[LAD] mixing while using libao and libsndfile

Andrea Del Signore sejerpz at gmail.com
Mon May 16 21:44:37 UTC 2016


> I've been knocking my head against a wall for more than a year trying to
> figure out how to correctly mix two streams of audio while using
> libsndfile for input and libao for output.  My main requirement is that
> I cannot assume anything about the output drivers -- that is, I cannot
> depend on the output driver (ALSA, OSS, Sun, etc) being able to do the
> mixing for me.  Many of my target platforms lack any sort of mixing
> services.  I need to do this myself.  I tried starting a mixer/player
> thread that would work in a producer/consumer relationship with one or
> two audio file decoder threads.  I can play one sound at a time just
> fine. When I try to do both, I get distortion followed by a segfault.

Hi,

not sure if I understood correctly: do you just want to mix N files?

Like you I'm learning libsndfile and libao so this is my attempt to mix
some audio files:

http://pastebin.com/dm7z8b3Z

HTH,
Andrea

P.S.
Can someone explain line 88 (I already read the sndfile FAQ)?

On Mon, May 16, 2016 at 11:30 PM, <
linux-audio-dev-owner at lists.linuxaudio.org> wrote:

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> ---------- Forwarded message ----------
> From: Andrea Del Signore <sejerpz at gmail.com>
> To: linux-audio-dev at lists.linuxaudio.org
> Cc:
> Date: Mon, 16 May 2016 21:26:40 +0000 (UTC)
> Subject: Re: [LAD] mixing while using libao and libsndfile
> On Sun, 15 May 2016 16:34:34 +0000, David Griffith wrote:
>
> > I've been knocking my head against a wall for more than a year trying to
> > figure out how to correctly mix two streams of audio while using
> > libsndfile for input and libao for output.  My main requirement is that
> > I cannot assume anything about the output drivers -- that is, I cannot
> > depend on the output driver (ALSA, OSS, Sun, etc) being able to do the
> > mixing for me.  Many of my target platforms lack any sort of mixing
> > services.  I need to do this myself.  I tried starting a mixer/player
> > thread that would work in a producer/consumer relationship with one or
> > two audio file decoder threads.  I can play one sound at a time just
> > fine. When I try to do both, I get distortion followed by a segfault.
> >
> > So, I'm back to a demo program.  What must I do to this program to cause
> > it to start playing one audio file, then play another N seconds later?
> >
> > David Griffith dave at 661.org
> >
>
> Hi,
>
> not sure if I understood correctly: do you just want to mix N files?
>
> I'm a noob with both libsndfile and libao :)
>
> Here my code: http://pastebin.com/dm7z8b3Z
>
> HTH,
> Andrea
>
> P.S.
> Can someone explain line 88 (I already read the sndfile FAQ)?
>
>
>
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