On Sat, Jul 6, 2013 at 9:39 PM, James Stone <jamesmst...@gmail.com> wrote: > On Sat, Jul 6, 2013 at 9:36 PM, James Stone <jamesmst...@gmail.com> wrote: >> On Sat, Jul 6, 2013 at 3:41 PM, Alan Stern <st...@rowland.harvard.edu> wrote: >>> On Sat, 6 Jul 2013, James Stone wrote: >>> >>>> The output when I try to start jack with 128 frames/period is: >>>> >>>> /usr/bin/jackd -dalsa -r44100 -p128 -n2 -D -Chw:USB,0 -Phw:USB,0 -I512 >>>> -O512 -S >>>> jackdmp 1.9.9.5 >>>> Copyright 2001-2005 Paul Davis and others. >>>> Copyright 2004-2012 Grame. >>>> jackdmp comes with ABSOLUTELY NO WARRANTY >>>> This is free software, and you are welcome to redistribute it >>>> under certain conditions; see the file COPYING for details >>>> no message buffer overruns >>>> no message buffer overruns >>>> no message buffer overruns >>>> JACK server starting in realtime mode with priority 10 >>>> audio_reservation_init >>>> Acquire audio card Audio0 >>>> creating alsa driver ... >>>> hw:USB,0|hw:USB,0|128|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 = 128 frames (2.9 ms), buffer = 2 periods >>>> ALSA: final selected sample format for capture: 32bit integer little-endian >>>> ALSA: use 2 periods for capture >>>> ALSA: final selected sample format for playback: 32bit integer >>>> little-endian >>>> ALSA: use 2 periods for playback >>>> ^CJack main caught signal 2 >>>> >>>> ..the device is unusable with the lights flashing on and off. Jack >>>> then shuts down as seen above. >>>> >>>> At 256 frames/period it starts OK. >>> >>> What happens if you run JACK with input only, no audio out? >>> >>> Alan Stern >>> >> >> It works fine with both input only or output only - down to 16 >> frames/period. At 8 frames/period it shows the same behaviour as at >> 256 frames/period in duplex - but that is a ridiculously low latency >> of 0.2ms, so hardly surprising it won't work. >> >> I have now got an error message when jack fails to start in duplex mode: >> >> ALSA: prepare error for playback on "hw:USB,0" (Protocol error) >> JackAudioDriver::ProcessAsync: read error, stopping... >> >> James > > Sorry - slight misinformation there. I can go down to 16 frames/period > for capture only, but for playback only, it will only go down to 128 > frames/period. Anything lower: > > /usr/bin/jackd -dalsa -r44100 -p64 -n2 -Phw:USB,0 -I512 -O512 -S > jackdmp 1.9.9.5 > Copyright 2001-2005 Paul Davis and others. > Copyright 2004-2012 Grame. > jackdmp comes with ABSOLUTELY NO WARRANTY > This is free software, and you are welcome to redistribute it > under certain conditions; see the file COPYING for details > no message buffer overruns > no message buffer overruns > no message buffer overruns > JACK server starting in realtime mode with priority 10 > audio_reservation_init > 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. James -- 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
