[alsa-devel] Missing exactly 3 of 8 audio packets?

Daniel Mack zonque at gmail.com
Thu Nov 22 22:32:23 CET 2012

On 21.11.2012 21:13, Daniel Griscom wrote:
> On to the next problem we're having with our USB audio card. Recap: 
> simple USB Audio Class embedded stereo audio card, running at 44.1kHz 
> or 48kHz, using the 3.6.6 kernel and its associated ALSA modules to 
> drive it, running on Jetway ND9D-2700, with an Atom D2700 and NM10 
> chipset. Output of "sudo lsusb -v" for card is appended below.
> Problem: we're experiencing strange hiccups in the delivery of audio 
> from the motherboard to the card. At 48kHz, the motherboard should 
> send a 6-frame packet to the card once per high-speed microframe 
> (every 125us). This usually works, but sometimes there are two 
> closely related failures:
> 1) Once in a while (every few seconds or minutes) a single packet 
> will be missed
> 2) Once in a longer while (every few minutes or hours), the system 
> will go into a continuing error condition where three of every eight 
> packets are missed.
> In both cases, "missed" means that ALSA consumes the output audio 
> from my motherboard application, but never sends a packet to the 
> audio card. No USB errors, no logged messages; it just disappears.

I missed that detail before. What makes you so sure ALSA actually
consumes audio it never sends out? Are you sending a test pattern which
is interrupted in your USB analyzer traces?


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