On Thu, 11 Jul 2013, James Stone wrote: > Hi Clemens, > > On Mon, Jul 8, 2013 at 2:12 PM, James Stone <jamesmst...@gmail.com> wrote: > <Snip!> > >> Acquire audio card Audio0 > >> creating alsa driver ... hw:USB,0|-|64|2|44100|0|0|nomon|swmeter|-|16bit > >> Using ALSA driver USB-Audio running on card 0 - Focusrite Scarlett 2i4 > >> USB at usb-0000:00:12.2-3, high speed > >> configuring for 44100Hz, period = 64 frames (1.5 ms), buffer = 2 periods > >> ALSA: final selected sample format for playback: 32bit integer > >> little-endian > >> ALSA: use 2 periods for playback > >> ALSA: poll time out, polled for 2176094 usecs > >> JackAudioDriver::ProcessAsync: read error, stopping... > >> > >> This is a definite reduction in performance compared to earlier kernels. > >> > > > > Some further info - on 3.5.0-28, I can start jackd in playback only > > with 8 frames/period, and capture only at 16 frames/period. > > > > Any thoughts on further investigating this bug with the 3.8.0 kernel > with the Focusrite Scarlett 2i4? I'm happy to continue with any > further testing if it would be helpful..
Clemens, if it's not already clear, I have reached the limit of my knowledge at this point. We are both hoping that you can help solve this new bug. James, I can offer one suggestion: Try running JACK under strace, with playback-only at 64 frames/period. The strace output may indicate why JACK thinks an error occurred when in fact the USB transfers worked perfectly. > One thing is that another person affected by the same bug reports that > it may be hardware-specific: See: > > https://bugs.launchpad.net/ubuntu/+source/linux-lowlatency/+bug/1185563 > > Jori Neimi reports: "My laptop can handle jackd with a latency of 32 > samples on my Focusrite Scarlett 2i2 and 3.8.0-25 lowlatency kernel. > On my desktop jackd won't even start with a latency of less than 512 > samples using the same kernel and same USB audio device. No help from > the proposed 3.8.0-26, so I'll continue using 3.5.x kernels on my > desktop." > > Could this mean it is specific to some type of USB hardware on the > motherboard?? Yes, with the existing drivers hardware differences can affect the result. But with Clemens's new patch applied, the hardware shouldn't matter. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
