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IDProjectCategoryView StatusLast Update
0006385ardourbugspublic2015-12-28 16:58
Reporterhimhui Assigned To 
PrioritynormalSeveritymajorReproducibilityalways
Status newResolutionopen 
Product Version4.0 
Summary0006385: latency compensation failure
DescriptionArdour doesn't compensate latency correctly among tracks and buses when high latency plugins are inserted such as nebula and acqua.
TagsNo tags attached.

Activities

x42

2015-07-15 09:09

administrator   ~0016881

There is no latency compensation for busses. It should work for tracks though. How large is the latency?

There's a test-plugin that we use https://github.com/x42/nodelay.lv2 up to 4 sec latency (with 48KSPS).

on most Linux distros it comes with "x42-plugins" package.

OSX & windows installers are available from
http://x42-plugins.com/x42/osx/x42-nodelay-v0.2.1.dmg
http://x42-plugins.com/x42/win/x42-nodelay-v0.2.1-w64-Setup.exe
http://x42-plugins.com/x42/win/x42-nodelay-v0.2.1-w32-Setup.exe

I don't have access to the plugins you mention, is it just because the latency is large or maybe it's simply that communicating the latency plugin -> ardour fails for some reason.

himhui

2015-07-15 10:51

reporter   ~0016883

Last edited: 2015-07-16 00:51

Acquas are sample base plugins so that they've large latency which're average around 2200ms@plugin or more. I tried the nodelay plugin several times, it was supposed to detect automatically but it reported once only (the value seems correct for 2 acqua plugins with 4.0XXXs) and on the other hand nodelay crashed ardour 4 when project was quit. Is it possible for Ardour to raise the bar of maximum latency supported more than that of the present value in the new future?

Thanks for your kind support.

Ken

himhui

2015-07-18 10:06

reporter   ~0016900

4.1.4 looks better now but it sounds intermittent with dsp 57%

x42

2015-07-18 17:53

administrator   ~0016903

There is no limit in Ardour's latency compensation. (when used on OSX with air-play for example, there's a > 5 sec latency compensation).

The test plugin (nodelay) is limited (max delayline buffer), but that's just for testing.

Ardour only updates its internal latency compensation on "stop", So after adding a plugin you may have to play/stop.

himhui

2015-07-19 03:15

reporter   ~0016905

Last edited: 2015-07-19 03:31

Thanks X42!

I tried again today, nodelay still didn't update the latency on either Ardour 4 or MB3. On the other hand, MB3 doesn't compensate latency like what manual mentioned. I doubt that it is the commumication problem,as you said, between the host and plugins on windows side.....

SadKo

2015-12-28 16:26

reporter   ~0017747

Today while testing latency compensation port of my LV2 plugin:

WARNING: latency compensation is not possible.

Still not working?

Sometimes I get:
LatComp: buffer resize in progress. latency-compensation-pending: 30 want: 40
LatComp: buffer resize in progress. latency-compensation-pending: 30 want: 50
LatComp: buffer resize in progress. latency-compensation-pending: 30 want: 60

But still it's not working.

x42

2015-12-28 16:31

administrator   ~0017749

Last edited: 2015-12-28 16:33

"WARNING: latency compensation is not possible."

indicates an ambiguity that cannot currently be resolved. Ardour has no latency compensation for busses, but already compensation for sends.

The message comes from the "send to bus"
eg. track -> send to bus-A -> master AND bus-A -> master.

If there's a latent affect after the send or on the bus, ardour cannot currently compensate for its latency. There are other - more complex - situations as well (e.g multiple sends) which can currently lead to this.

SadKo

2015-12-28 16:39

reporter   ~0017750

My scheme is simple:
mono bus (put pink noise source) is connected to the master bus directly to the left channel and via delay bus to the right channel. Then I put delay plugin that reports latency to the bus that stays between noise and master.
In normal condition the noise keeps sounding mono.
While rolling knob, I get Haas effect (the noise begins sounding stereo). Pressing play and stop doesn't help. Instead I get curious messages in console.

x42

2015-12-28 16:56

administrator   ~0017751

There is no latency compensation on Busses.

Currently latency-compensation is only effective on Playback from Tracks: audio/midi region read-ahead write-behind.

SadKo

2015-12-28 16:58

reporter   ~0017752

Hope in the future that will be possible.

Issue History

Date Modified Username Field Change
2015-06-18 13:59 himhui New Issue
2015-07-15 09:09 x42 Note Added: 0016881
2015-07-15 10:51 himhui Note Added: 0016883
2015-07-16 00:51 himhui Note Edited: 0016883
2015-07-18 10:06 himhui Note Added: 0016900
2015-07-18 17:53 x42 Note Added: 0016903
2015-07-19 03:15 himhui Note Added: 0016905
2015-07-19 03:31 himhui Note Edited: 0016905
2015-12-28 16:26 SadKo Note Added: 0017747
2015-12-28 16:31 x42 Note Added: 0017749
2015-12-28 16:33 x42 Note Edited: 0017749
2015-12-28 16:39 SadKo Note Added: 0017750
2015-12-28 16:56 x42 Note Added: 0017751
2015-12-28 16:58 SadKo Note Added: 0017752