"They are submitted to the endpoint's queue. The actual transmission is managed by the controller's hardware and happens later, once per microframe."
Okay, but why are the 12 urbs (4 for sync) despatched one every microframe ONLY on the initial start of a stream? After they have been sent it backs off and sends urbs at the correct interval (as specified in the usb device descriptor). It just seems a bit odd. "This sounds like a bug in your firmware." Hmm.. Possibly. I'll need to do some more testing on other machines etc.. In the meantime I'll just have to get my DIY device to drop or increase the buffer to handle 12+ urbs. Thanks, Phil. On 13 September 2015 at 17:11, Clemens Ladisch <cladi...@googlemail.com> wrote: > Phil Quinton wrote: > > When an audio stream starts (play), 12 urbs get sent (very close > > together) to the main isosynchronous end point > > They are submitted to the endpoint's queue. The actual transmission > is managed by the controller's hardware and happens later, once per > microframe. > > > This is causing a buffer overrun on my DIY usb audio device. > > This sounds like a bug in your firmware. > > > Regards, > Clemens >
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