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IDProjectCategoryView StatusLast Update
0001490ardourbugspublic2007-02-11 20:40
Reportermtaht Assigned To 
Status newResolutionopen 
Summary0001490: Jack Sync issue - ardour not calculating delay correctly with rosegarden or vice versa
DescriptionI did some extensive testing with surfaces head and rosegarden 1.5 the other night.

It used to be that a typical rosegarden generated drum track would lag the actual beat by X. Which was OK, and expected of midi devices, and still editable in ardour.

Now, somehow - it seems to be leading the beat by a few ms, which makes editing the results kind of painful. The only thing I can remember doing different on this recording was that I do have an amp plugin enabled, but that shouldn't make a difference, should it? I will try raw.

For now the workaround appears to be to tell rosegarden to arbitrarily delay midi for it's recorded output by 10ms, but that kind of impacts live performance.

Uploading a screenshot and rg file the demonstrates the problem

TagsNo tags attached.


2007-02-11 18:01


Screenshot.png (129,064 bytes)   
Screenshot.png (129,064 bytes)   


2007-02-11 18:04

developer   ~0003204

The uploaded rg file has delay set to 10ms. Change it back to no delay to see the problem


2007-02-11 18:17

developer   ~0003205

Tried it on a fresh ardour surfaces instance, no template, same problem.

The midi file is quantised to start right on the beat.

(as an aside, the button prelight for record seems to be working worse than before)


2007-02-11 18:45

developer   ~0003207

Last edited: 2007-02-11 19:33

Well... once... I swear... I saw the audio move back to where it belonged via twiddling with JACK->latency->XXX - but I have twiddled with it and still can't move rosegarden's output back behind the beat marker where it belongs.

Also, it JACK->latency seems to be reset to 32 on every load of a file with the template I'm using. Ignore this. With a new template it seems to work.

(11:04:46 AM) mtaht5: OK, so I finally got it closer to doing the right thing...
(11:06:14 AM) mtaht5: jack is set to: 96khz, 2 periods, 256 frames/period
(11:06:53 AM) mtaht5: Ardour is now set to 96khz, JACK->Latency = 512, which appears to move the rosegarden generated audio to about 128 samples behind the beat.
(11:07:09 AM) mtaht5: so I'm going to try everything setup at 512...
(11:07:10 AM) mtaht5: brb
(11:08:45 AM) SpeS left the room (quit: Remote closed the connection).
(11:11:53 AM) mtaht5: nope. Made being ahead of the beat worse.

(11:13:12 AM) mtaht5: changed to 512 frames/period in jack, JACK->latency of 512 = rosegarden's audio is now ~ 690 samples ahead of the beat.

(11:15:58 AM) mtaht5: possible that last datum was closer to 965

So I moved to 1024 samples/period in jack and Ardour's JACK->latency is also 1024.

rosegarden is now roughly 1710 samples ahead of the beat.


2007-02-11 18:48

developer   ~0003208

Last edited: 2007-02-11 19:00

And adding 10 ms latency to rosegarden really is a bit painful...
See screenshot-2

2007-02-11 18:49


Screenshot-2.png (155,816 bytes)   
Screenshot-2.png (155,816 bytes)   

2007-02-11 20:31


Screenshot-4.png (209,697 bytes)   
Screenshot-4.png (209,697 bytes)   

2007-02-11 20:36


Screenshot-5.png (150,332 bytes)   
Screenshot-5.png (150,332 bytes)   


2007-02-11 20:39

developer   ~0003210

Screenshots 4 and 5 demonstrate the problem. The closest I've been able to get to something reasonably closely synced so far has been:

Jack set to 1024 samples/period. 2 periods
Ardour set to same.
Rosegarden delaying the midi drum track 20ms and keeping the linuxsampler piano at 0 ms (both tracks are quantised to start on the beat, however!)

2007-02-11 20:40


yesidobigandclose.rg (312,074 bytes)

Issue History

Date Modified Username Field Change
2007-02-11 18:00 mtaht New Issue
2007-02-11 18:01 mtaht File Added: Screenshot.png
2007-02-11 18:04 mtaht File Added: yesidobigandclose.rg
2007-02-11 18:04 mtaht Note Added: 0003204
2007-02-11 18:17 mtaht Note Added: 0003205
2007-02-11 18:45 mtaht Note Added: 0003207
2007-02-11 18:48 mtaht Note Added: 0003208
2007-02-11 18:49 mtaht File Added: Screenshot-2.png
2007-02-11 19:00 mtaht Note Edited: 0003208
2007-02-11 19:30 mtaht Note Edited: 0003207
2007-02-11 19:33 mtaht Note Edited: 0003207
2007-02-11 20:31 mtaht File Added: Screenshot-4.png
2007-02-11 20:36 mtaht File Added: Screenshot-5.png
2007-02-11 20:38 mtaht File Deleted: yesidobigandclose.rg
2007-02-11 20:39 mtaht Note Added: 0003210
2007-02-11 20:40 mtaht File Added: yesidobigandclose.rg