Audio offset after rendering part

[Rhinetone]

Hi folks,

I have recently started to use MuLab and I'm liking it a lot. I have run into an issue which I can't understand yesterday.
I have a small 4 bar loop playing a MuDrum instrument.
When I rendered the part, MIDI and the resulting audio part are playing in sync, I can just hear the expected phasing between the MIDI generated notes and the audio if I play both tracks.

If I render the same part, but with plenty of plugins within MuDrum, on the various pads, the resulting audio bounce is offset, actually placed before the MIDI notes. I should say I'm using a few high-latency plugins, so I assume the offset is the summed latency of the plugins.

But why is the audio then placed before the MIDI events? Does PDC not take the latency into effect when bouncing?
Should I switch PDC off when I'm rendering a part? If so - how do I do this?

How can I find out how much the offset is? It would be simple enough to nudge the track backwards by however many samples the offset is, but in audio editor I can't figure out how to set the grid in beats and bars. Is there a way? It only shows me the time and changing the grid only allows selections of samples.

Any suggestions how to optimise my workflow here?

Thanks!
Andy

[MuTools]

I cannot repeat the issue.
Please share a simple project that demonstrates the issue, preferably without using VSTs, rather use the built-in Latency Generator to generate the latency.

[Rhinetone]

Ok, I have done a very simple loop, starting from a new project.
Insert just one instrument, MuDrum.
Program a quick loop - kick on 1 and 3, snare on 2 and 4 with hihat playing 8ths.
Render the part - see first picture. MIDI and audio line up correctly.

No latency added:

Render.jpg

Then I added a latency generator with 512 samples to the kick's 'sample effect' and also to the kick's 'pad effect'.
You can clearly see that in this rendered track, the kick no longer aligns - in fact it is before the beat.
Important: I have not ticked 'apply delay' when adding the latency generator. I couldn't find anything about the latency generator in the online documentation. It's not mentioned under the 'Audio Processors' as far as I can see. Does this option stand for 'Apply PDC'?

Render with latency.jpg

In any case, I have made another render where I have ticked the option to 'apply delay'.
Now everything is fine again, all signals line up perfectly.

If I'm not mistaken this looks like I have one (or more) plugins which do not report their latency correctly? Am I on the right track?
Can I add this value manually?

Audio before.jpg

This was an interesting little exercise, I really hope there's a solution to this.
I am looking forward to your analysis.

Andy

[MuTools]

You're right the docs did not yet include the Latency Generator, thx for the notification.
That doc page have been updated now: http://www.mutools.com/info/M8/docs/mux ... dules.html

Yes to simulate a vst plugin with latency using the Latency Generator both Report Latency and Apply Delay should be ON. (In the next version Apply Delay will also be ON by default)

Hope this answered your questions.

[Rhinetone]

Thanks for your response!
Well, to be honest, my main question isn't so much about the Latency Generator. I was only using it because you suggested it for testing (which I can understand since you can't possibly have all the plugins we're using).
Is there anything I can do so the parts render correctly when I'm using my plugins?

As far as I can see it, either the plugins are not reporting the latency correctly, or MuLab's PDC can not adjust sufficiently.
Is there a max number of samples MuLab can deal with? Like I said in my original post, these are high latency plugins. Reaper reports this particular plugin as having 2459 samples latency. Should MuLab be able to compensate?

Any ideas how I can render the track so it aligns correctly? Any adjustments I can make?

Many thanks!

Andy

[MuTools]

As far as I can see it, either the plugins are not reporting the latency correctly

Can't you identify the VST that reports a wrong latency?
Easiest way is using the green On/Off switch, because when switching off a VST its latency is ignored.

or MuLab's PDC can not adjust sufficiently.

If things work correct with the Latency Generator then it proves MuLab is working correct.

Is there a max number of samples MuLab can deal with? Like I said in my original post, these are high latency plugins.

No there is no maximum latency wrt compensating the audio/evet/modulation signals. There currently is a max of 1 sec wrt the visual latency compensation but that's pure GUI and doesn't affect rendering so it's not relevant in this topic.

Reaper reports this particular plugin as having 2459 samples latency. Should MuLab be able to compensate?

Yes, that's absolutely no problem. Most of the time, during M8.4 R&D, i used much much higher latencies.

Any ideas how I can render the track so it aligns correctly? Any adjustments I can make?

Try to find the VST that reports a wrong latency and let me know.

[Rhinetone]

Thanks for your response.
These are Acustica Audio plugins, several of them showing the same behaviour.
However, rendering with the same plugins works correctly in Reaper.

The first picture below shows the track rendered in Mulab. 1st audio is without plugins.
Second audio is with the plugin as a pad effect within MuDrum.
The third render is with the plugin in an insert slot after MuDrum.

The second picture shows the rendering in Reaper, first audio without plugin, second audio is with the plugin.

MuLab Render.jpg

Reaper Render.jpg

[MuTools]

Ok i can repeat the issue, researching it...

[MuTools]

Mmm, i thought i could repeat it, but in fact i cannot. I was tricked (again) by ReaFir not reporting changed latency after choosing another FFT size. @ReaperDevs: Please properly notify the host DAW when initialDelay has changed ie. send a audioMasterIOChanged.

Rhinetone, i have this question: When you encounter the out of sync issue upon rendering, is it just after having inserted a latency plug into MuDrum? I mean: When you save that project and reload it and then do the rendering, then does it sound right or is the out of sync still there?

And is the out of sync issue also there when playing back the song or are you saying it all plays fine but the out of sync is only there when rendering?

Please also let me know specificly which latency VSTs you are using in MuDrum when the out of sync rendering happens.

[Rhinetone]

Thanks for getting back to me. I've done more tests based on your questions and it's really interesting.
As you already suspected, it does make a big difference if I render after inserting the plugin or if I have saved and re-loaded the project.

New render 2.jpg

The first audio track is rendered after just inserting the plugin into MuDrum.
I then saved and opened the project again and did another render. It's still not bang on, but the offset is much smaller than before, as you can see.

Now for the really weird stuff. In this instance the track which has more delay plays in sync with the MIDI track. The rendered part which is much closer to the beat actually plays back completely out of sync.

I am sure, based on your questions, you already had some suspicions in this direction.
I have emailed you a short video which demonstrates that the track which is visually more aligned with the beat plays back out of sync, but the track which is more 'off' plays in sync.

I'm looking forward to hearing your analysis of this. Thanks again for your attention to this.

Andy

[MuTools]

Andy, please update to MuLab 8.4.19 and retry the same tests and let me know how it works.
See viewtopic.php?f=79&t=540372

[Rhinetone]

Thanks very much! I only had time for a very quick test tonight, but it's very promising.

If I insert the plugin and render the part, MIDI and the audio waveform line up. If I play both the rendered audio and the MIDI track, they play back is misaligned, there's a clear delay between tracks - I assume the delay being the plugin's latency.
But if I save the track after rendering and then re-open the project, everything is in sync, both visually as well as far as audio playback is concerned.
I hope I can do further tests tomorrow, but it's a definite improvement.

Thanks very much for your quick response. It's much appreciated!

Andy