Hi :) first of all, it seems to be solved, but borderline. I'll go on with test-producing on Linux.
If you reply, keep in mind that I don't receive mails send by the 64 Studio dev list, because I disabled this. *Is it Qtractor*? If so, I guess it's not because of Qtractor alone, anyway there are other issues that belong to Qtractor. Is it the kernel? Is it Jack audio? It doesn't seem to be ALSA MIDI alone, because I sang to an audio track and get troubles, when there was no MIDI used. Here's a Link to the report about the experiment I did yesterday: http://lists.64studio.com/pipermail/64studio-users/2009-May/003022.html This is what I did today: 64 Studio 3.0-beta3 2.6.29-1-multimedia-amd64 jackdmp version 1.9.2 spinymouse-s...@64studio:~$ jackd -Rdalsa -dhw:0 -r48000 -p64 -n2 Qtractor Version 0.4.1 without VST support spinymouse-s...@64studio:~$ qtractor Audio: PCI sound card TerraTec EWX 24/96 (Envy24) MIDI : USB MIDI device swissonic Track 1: MIDI ch 2 connected to external 19" drum sample module Alesis D4 Dry Acoustic Track 2: MIDI ch 10 FluidSynth DSSI plugin Acoustic drum set.SF2 Track 3: Audio Left D4/ Right SF2 When playing from bar 2 to bar 4 by transport loop enabled, no recorded audio track, but the external and FluidSynth kick in unison, it starts phasing and after a few cycles it becomes not only an early reflection like, but real delay effekt. The two kicks get completely out of sync, but this only seems to happen, while transport loop is enabled. I made a test song, I gave 4 to the floor (constantly Note On (36) C1/ Velocity 64/ Duration 00:00:00.060 = 1/16), a clip (also known as segment or part for other sequencers) has a length of 2 bars, the clips starts at bar 2. I repeated the first clips 104 times, to get a song that starts with 2.01.000 (2 Seconds @ 120 BPM) and ends with 212.01.000 (7 Minutes and 2 Seconds @ 120 BPM). Punch in at 1.04.000 (1.5 Seconds) and punch out at 212.01.000 (7 Minutes and 2 Seconds). I tried to recorded a WAV Microsoft Signed 24-Bit, for playback Sinc (Best Quality) was chosen, but Qtractor didn't record. After that I launched Jack by spinymouse-s...@64studio:~$ jackd -Rdalsa -dhw:0 -r48000 -p128 -n2 The same, even if I tried only to record the D4, like I did yesterday, nothing is recorded, the track is armed, record for the transport is enabled too, all buses etc. are fine, the mixer shows a signal, but nothing is recorded to the track. The test song today based on the test song from yesterday, so I loaded the version from yesterday and tried to record and it worked. Okay, I played a little bit with buses and dedicated outputs, but reset everything, maybe a bug by Qtractor, once you changed something and you reset it again, you can't go on with this project. Completely new, resp ... spinymouse-s...@64studio:~$ jackd -Rdalsa -dhw:0 -r48000 -p64 -n2 spinymouse-s...@64studio:~$ qtractor I loaded the song from yesterday and saved it by another name. I made a test, recording is fine. It's Track 1: MIDI ch 2 connected to external 19" drum sample module Alesis D4 Dry Acoustic Track 2: Audio empty track I added Track 3: MIDI ch 10 FluidSynth DSSI plugin Acoustic drum set.SF2, in the meanwhile I needed to re-edit Program change for the Alesis, because it was set to (none) by random. I don't report all the seg faults, because once everything is set Qtractor is fine, but doing the setup is a PITA. It's still possible to record. I copied the clip for the Alesis to the Track for the FluidSynth DSSI. The clip (4 to the floor) is from 2.01.000 to 4.01.000. Again I copied the clips 104 times. Now recording the Alesis still is fine, I set connections to record the Alesis and FluidSynth DSSI. Punch in and out are set the same as for my first test today, mixing levels are fine tuned and here we go, starting a punch in and out recording at punch in position. Phew, now everything seems to be fine, excepted that the GUI added some off-beats (I didn't listen while recording). By the way GNOME Terminal with 2 tabs and Qtractor were the only running desktop applications (excepted of the panel), while recording. The recording connections for Jack audio and ALSA MIDI were: Qtractor Master/out_1 --> system playback_1 Qtractor Master/out_2 --> system playback_2 system capture_1 --> Qtractor Master/in_1 Qtractor Master/out_2 --> Qtractor Master/in_2 129:Qtractor 1:Master --> 20:USB Device 0:MIDI 1 For playback I set them to: Qtractor Master/out_1 --> system playback_1 Qtractor Master/out_2 --> system playback_2 129:Qtractor 1:Master --> 20:USB Device 0:MIDI 1 1. I muted both MIDI tracks and listened to the Audio track, left Alesis D4 and right FluidSynth DSSI, but set to mono by an external console. I stopped at bar 146, there were no unwanted off-beats, there was no early reflection or delay like effect. The phasing changed a little bit. 2. I un-muted the MIDI tracks, kept everything at mono. I stopped at bar 66, while playing I sometimes listened to the left or right channel only and muted and un-muted the Alesis D4. The phasing wasn't stable, but it didn't become an early reflection or delay like effect. 3. Audacity Should be / left D4 is / right DSSI is = 10500.000 ms / ~ 10501.670 ms / ~ 10500.510 ms = 11000.000 ms / ~ 11001.750 ms / ~ 11000.510 ms = 11500.000 ms / ~ 11501.775 ms / ~ 11500.510 ms = 12000.000 ms / ~ 12001.760 ms / ~ 12000.510 ms The external D4 max. delay + 1.775 ms min. delay + 1.670 ms In other words constant delay + 1.670 ms jitter + 0.105 ms DSSI constant delay + 0.510 ms no jitter Resumee: If I can keep a latency of 2.67 ms, external sources are borderline fine, jitter seems not to be an issue, but the constant delay. Listening to the 4 to the floor about a wide range of bars, it might be, that there will be more jitter, maybe there might be negative delay too, but assumed that there will be a range of - 0.5 ms to + 2.0 ms for recorded external sources, beeing able to give the tracks a (negative) delay of - 0.5 ms, there would be a range of - 1.0 ms to +1.5 ms, so the difference to DSSIs will have a range about - 1.5 ms to + 1.0 ms. Assumed that there will be a relative constant delay around + 1.7 ms for external sources, the same negative delay given to recorded tracks of external sources will make external sources,resp. the track and DSSIs nearly perfectly fit together. The better choise would be to give DSSIs a correction, so DSSIs and external equipment can be recorded on the same track. Maybe guitar, vocals etc. will have less delay, if so, it will be fine. It's not clear what's the lion's share here. Is it the USB MIDI output delay or is it the audio input delay? It can be said, that a latency of 10.7 ms makes it impossible to make music, while a latency of 2.67 ms seems to make it possible to make music, even without any correcton. I didn't test 5.33 ms, but it can be expected that this latency will be extrem borderline and needs the option to give tracks positiy or negative delay, an option that should be available anyway, e.g. to give even 100% to the beat synced drum tracks a negative delay, to get a positive stress for the groove. I also didn't test decreased latencies, maybe they are fine too. It also can be said, that for people that only will use internal, virtual synth and FX, there seems to be absolutley no problem with sync. The DSSI had a constant delay of 0.51 ms, so if all DSSIs have the same delay, it's not delay anymore. Cheers, Ralf _______________________________________________ 64studio-devel mailing list [email protected] http://lists.64studio.com/mailman/listinfo/64studio-devel
