[pulseaudio-discuss] Crash/Underruns observed randomly when system alert is mixed with audio stream in Pulse Audio

[Lennart Poettering]

On Wed, 10.02.10 20:28, Lakshmi N V (lakshminv at gmail.com) wrote:

> Hi,
> I'm using the Pulse Audio v0.9.21 with Moblin 2.1 OS on an embedded system.
> I've observed that when a audio stream is in progress through Pulse Audio
> and a system alert is generated through libcanberra-gtk-play, the system
> alert is mixed successfully for the first time, but in the second iteration,
> Pulse Audio either crashes or goes into continuous underruns.
> Similar issue is observed, when system alerts are generated continuously
> using libcanberra.
> As I understand, the underruns could be occuring because of latency added by
> software mixing in Pulse Audio. Is this a possibility?
> Has this behaviour been observed on any other platform? Are there any known
> issues with playback of short streams like alerts through Pulse Audio?

I actually did very exhaustive testing of canberra event sound playing
recently, so I am actually pretty sure this should be rock solid on
normal hw, even if you loop event sounds excessively or generate a lot
of them at the same time.

My educated guess what is going on here is that your driver might have
problems with ALSA's snd_pcm_rewind()? For this call PA is basically
the only client ever calling this, so problems with this will show up
only in PA. Also, everytime we start an event sound we use this call,
which kinda matches your problem case.

We had quite a bit problems with snd_pcm_rewind() on a lot of
drivers. I'd suggest trying to figure out if it really works properly
on your device/alsa kernel driver.

Lennart

-- 
Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net
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