[alsa-devel] How does ALSA detect underrun in OSS emulation?

Timur Tabi timur at freescale.com
Mon Feb 25 16:22:41 CET 2008

Can someone explain to me the exact method that ALSA uses to detect underrun 
with OSS emulation?  I have a driver that reports underrun on almost every 
period when I use OSS emulation and I'm playing with a non-supported sample 
rate.  So I'm assuming that maybe my hardware is playing the audio too fast or 
too slow, and the driver is returning periods before ALSA expects them.  What I 
don't understand is: how does ALSA know that a period was finished too early. 
Does it use a timer, or is it purely application driven?

Timur Tabi
Linux kernel developer at Freescale

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