On Sat, Jul 6, 2013 at 3:41 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> 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 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
