On Fri, Feb 28, 2014 at 12:57 PM, Gianfranco Ceccolini < [email protected]> wrote:
> > creating alsa driver ... hw:0|hw:0|128|2|48000|0|0|nomon|swmeter|-|32bit > > configuring for 48000Hz, period = 128 frames (2.7 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 > > > When starting it on the Beaglebone Black I get: > > > /usr/bin/jackd --realtime -P80 -dalsa -r48000 -p128 -n2 -Xraw > > > creating alsa driver ... hw:0|hw:0|128|2|48000|0|0|nomon|swmeter|-|32bit > > configuring for 48000Hz, period = 128 frames (2.7 ms), buffer = 2 periods > > ALSA: final selected sample format for capture: 32bit integer little-endian > > ALSA: use 16 periods for capture > > ALSA: final selected sample format for playback: 32bit integer > little-endian > > ALSA: use 16 periods for playback > > > - what are those "periods" in the ALSA lines? (2 for the PC and 16 for the > BBB) ? > these are the number of "segments" or "periods" that the h/w buffer is divided into. Input latency is determined by period size, playback latency is determined by buffer size. the device will wake the CPU every time it has 1 period of date/space available. > > - on the ArchWiki page on Jack there is a D-bus call > > jack_control eps realtime true > > stating that it "Sets JACK to realtime mode in its own internal setup." > What is this internal setup? How do I address this when not using D-Bus? > JACK starts in realtime mode by default. It can be "forced" to do that with -R or you can turn it off with -r.
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