On 07/14/2010 04:22 PM, Ralf Mardorf wrote: > Hi Robin :) > > On Wed, 2010-07-14 at 15:44 +0200, Robin Gareus wrote: >> On 07/14/2010 03:23 PM, Ralf Mardorf wrote: >>> [..] >>> AND IT'S AUDIBLE THAT THERE IS MUCH MORE JITTER BUT 1.1 ms. >>> >>> Any hints how to solve this are welcome. >> >> Did you try to start jackd with -p64 instead of -p1024 > > A good argument, because when I made tests in the past for the USB MIDI, > things become better at >= -p256 (when I had this Windows test install > latency for the EWX 24/96 audio was less high than for Linux). The > problem here is, that I need at least -p512 and even than I'm not safe > regarding to issues for JACK audio, that's why I used -p1024 instead of > -p512. For a test -p64 should work, but when recording music I would > need to increase it step by step until a minimum of -p512.
I'm sorry; don't understand that. Are you getting [audio] x-runs or what is the problem using -p64 (or even -p32)? I was hinting that the audible midi-jitter could be a result of midi-messages getting 'quantizied' to jack-periods. A JACK-MIDI app which does not honor 'jack_midi_event_t->time' but simply processes all queued midi-events on each jack_process_callback() will result in the symptoms you describe (snare & kick on the same beat). One example of such an app is "a2j". > IIRC when I did tests for the USB MIDI with -p64 or even -p125 (I'm not > sure) it theoretically did work, but this isn't a solution, because at > some point JACK audio will fail. How does it fail? x-runs? JACKd works quite robust here with the UA25 and FA101 at 64fpp. >> using JACK-midi, I've encountered a similar issue with fluidsynth always >> synchronizing note-start/ends to jack cycles. >> >> Simply lowering the frames-per-period got me playing again so I did not >> check if it's related to JACK-midi or FluidSynth 1.1.1 in general. > > At least FluidSynth DSSI (host is Qtractor) is able to play in unison > with any DSSI or virtual ALSA MIDI and JACK MIDI (-Xseq) synth on my > machine. Just 'in unison' for virtual synth to hw synth there sometimes > is more delay, but just an early reflection like effect. > > Note! It was hard to groove when I connected the master keyboard to ALSA > hw MIDI in --> DIRECTLY TO --> ALSA hw MIDI out and this to a 100% ok > drum module. Directly connecting the master keyboard to the drum module > there were no issues. Aha, by this we can infer that your problem is ALSA or kernel/timing related. To verify this, take everything up from there (eg. qtractor, fluidsynth) out of the picture for now. 1) Use 'amidiplay' to send a some midi-song directly to your drum-module. -> Is there still audible jitter? 2) Do you have a Hardware MIDI Sequencer? Have it play a simple metronome beat and dump incoming MIDI-messages. See if the timestamps of each midi-note-on message are identically spaced. 'aseqdump' (at least version 1.0.22 which I currently use) does not print timing-info, 'kmidimon' does. > I need to do something else now, but I take time off. From Friday > (perhaps earlier) until next Sunday noon I could spend the whole days > for this MIDI issue only. > > Resume: > > I assume that -p64 would solve this 'looooooong early reflection like > effect/async', but then hard disk recording will become impossible. > > The target is, that Linux at least replace the Atari ST as sequencer + > an analog 4-Track machine synced by SMPTE. With -p64 4-track recoding > would become impossible. I'm pretty sure that you can get a stable 64fpp setup, but one thing at a time. let's keep this thread to MIDI just now. > 'Read you later' today or at the latest on Friday. enjoy a good long week-end. > Cheers! > > Ralf ciao, robin -- Robin Gareus mail: [email protected] site: http://gareus.org/ chat: xmpp:[email protected] blog: http://rg42.org/ lab : http://citu.fr/ Public Key at http://pgp.mit.edu/ Fingerprint : 7107 840B 4DC9 C948 076D 6359 7955 24F1 4F95 2B42 _______________________________________________ Linux-audio-dev mailing list [email protected] http://lists.linuxaudio.org/listinfo/linux-audio-dev
