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:
- Once in a while (every few seconds or minutes) a single packet
will be missed
- 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?
Daniel