FabFilter

Hi Maximilian,

Spectral processing is a linear phase process. Linear phase processing always have latency. This should be compensated by your host. Please note that some hosts only update the delay compensation when not in playback.

It doesn't seem that Q4 is reporting latency problerly in Ableton 12 when in linear, either by spectral node or the entire plug. I can reproduce it in multiple projects, enabling linear processing pushes the relevant track out of sync with the rest of the project despite having delay compensation activated in Ableton.

I just checked here in Ableton and it does seem to properly compensate for Pro-Q 4's latency. Could you send us a small video of your issue so we can check your situation?

Sure. Let me know if you need the project as well.
youtu.be/K0P99WoM57g

Hi Magnus,

I'm not sure how Ableton handles delay compensation in combination with the click track. If I simply duplicate a track and set one track in linear phase mode, they both play back simultaneously. This would show that the reported latency is correct.

If you can send me a copy of a project in which you can reproduce the issue I can have a look.

im also having delay compensation / latency issues with proq4 in pro tools. i dont get any delay compensation warning from PT as would normal happen in this circumstance, but the audio is clearly out of step. even when committing the audio its still doing strange things with the delay compensation, athe audio itself is actually printing early? interestingly when i disable the plug in the issue still remains until i actually remove it, which seems bizarre? would be great to have some clarity on this as atm i cant really use the plug in.

Hi
I have also the "delay compensation problem"
ProQ4 (not only), Bouncing mix, Freeze Track, Render audio (no ARA) or other don"t solve my internal (bus) rec correctly. Input listening is OK problem appear during recording (printing my mix)

If you want I have the an example in my protools (M4mini Pro, Sequoia, Protools 2024-10-2, Pro Q4 402), bugging most of the time at the same place.

Thanx ..

Was just experiencing the same issue, in 2 out of 3 DAWs I tested, with various levels of problems (latest versions of everything on M1 Mac). Tested with just two tracks on 48khz/512: drums on one, guitar on another with a Pro-Q4 instance on it. Pro-Q4 on zero latency mode, with no latency reported.

• Logic Pro, AU: Add a new (single) spectral node during playback, Logic goes out of sync, Pro-Q4 now on "5120=0.1sec" samples of latency, Logic did not compensate. Stop playback, start again, everything is back in sync. (I can live with that small level of interruption).
• Studio One 7, CLAP: same issue with 'live' node insertion. But S1 struggles to recover. Several stop/play/back-to-beginning/save project/play attempts later and it catches on eventually (and breaks the flow completely. I've stopped using S1 due to this issue, I'd rather change the DAW than EQ).
• Reaper 7, CLAP: Same test, two tracks, insert a spectral node, Reaper makes a small pop but keeps it all in sync without stopping. Same sample delay reported as Logic, 5120. No issues here.

So, looks to me that Cockos are the only ones in this test that know how to implement proper PDC? (I'm not surprised tbh)

(On a side, I think Pro-Q4 needs a bit more cooking, there are other UI bugs I encountered here and there, but will report separately once I have 100% repro case)

@Bojan: Hosts can compensate for different latency in different ways. Some hosts, like Pro Tools, Reaper and Ableton, will adjust the delay compensation on the fly. This means that if you change a plug-in during playback, the host will adjust the compensation right away. This will give you a little glitch in the audio but the signal will be in time with the rest of the tracks right after that.

Other hosts like Logic only adjust the delay compensation when the track is not playing. So when you e.g. enable spectral processing during playback, your track will be out of sync until you stop playback. When stopped the host will adjust the compensation and it should be in sync from the next time you play it.

@KIDK & Christian, can you elaborate on the issue a bit?

Dear Ralph

please find there a protools session with audio-media.

www.swisstransfer.com/d/39e4a471-7cd3-44c0-b7f9-b9640a1dcacd

I let only few examples. You can view and listen quickly where problems are happening with markers and rec files.

Please note,
the recorded (master) audio file : I let the problem so you can listen it (two kind of problems : delay or big plop)

Listening input : few times the problem happen
recording : often it's happen.

If I play from the first marker to the bug marker , it's happening
stop, rec just before the new audio file : most of the time it's not happening, but another audio file later will have the problem.

If you need more informations let me know.
I remember to have some time automated the "spectral mode or not" for deessing, maybe that is my mistake.

Thank you. Good luck !
Christian

@Ralph - the click track was incidental, the rest of the project is out of time as well, both when using MIDI triggering samples and with samples straight on audio track.

I recreated the issue in Bitwig and Nuendo 13 as well, I'll ship you the files asap.

I'm in the middle of a client mixdown now, and it just happened again in a production. Took a round towards the end to do some spectral ducking to create space, and suddenly multiple tracks starts slipping. It's also printed to the audio both when I record and freeze the output of the tracks with Q4 on them.

I've used the same routing/bussing system for years without issues (lotsa Q3 dynamic ducking using sidechain), and now it's starting to fall apart at different stages when using spectral in Q4. There is definitely something going on.

@Magnus I found out what the issue is. Any plug-in that introduces latency needs to be placed after any plug-in that changes the rhythm of the track, like these rhythmic gates you are using. Latency compensation simply calculates the total latency of each track, and delays tracks with less or no latency so they stay in sync with tracks with more latency. The delay compensation happens at the output of the track, and it does not know where in the chain the latency occurs (or maybe it knows but does not take that in account). So when you put a plug-in with before one of these rhythmic gates, these gates will get out of sync with the tempo, as their input signal is delayed. If you put the plug-in with latency after the rhytmic gate your session should stay in sync.

@Christian can you explain the session a bit more? I am hearing some doubles or unaligned signals at the markers. But when I renounce the TV track at the second marker I don't get the double in the render.

There's definitely an issue with spectral processing, at least in Pro Tools. If you enable spectral processing and have automation involved, a glitch in the plugin can inadvertently enable/disable it's linear phase mode while the playhead is moving.
I was getting random audio skips across all my tracks around a specific place in the timeline. Eventually I narrowed it down to a single instance of Q4 with spectral processing enabled. I had automated the plugin it in that area, and the skipping was happening right at the spot where my automation write ended and the plugin was returning back to it's default setting. This was also causing the plugin to turn off spectral mode under the hood, and thus was changing the delay comp reporting from the plugin. This happening while playhead moving was what was causing the skipping, so I opted to stop using spectral processing to avoid this happening again.

@Michael Yes that's an issue that we unfortunately can do little about. The enable/disable spectral mode button is disabled from automation as it would change the latency. However, automating the range of a spectral band to 0dB, or disabling a whole band that is spectral will also adjust the delay compensation, but we can't exclude these parameters from automation. If you need to automate these parameters you can put the whole plug-in in linear phase mode. This way the latency stays the same whether a band is in spectral mode or not.

I am unfortunately having the same problem.
Not always, but sometimes when I use spectral dynamics in Q4, my track goes out of sync.

At the moment, I don´t know what could be triggering this behaviour.

Cubase Pro 14 on win 10.

Hey everyone, I'm experiencing the same thing in Pro Tools. If I send a track directly out the output, no delay compensation issues; but if I send a track with Pro-Q4 through an aux (Folder Track) then to the output, there is often a sync issue.

Must be that the plugin is not correctly reporting delay compensation / offsets to Pro Tools.

If anyone at Fabfilter would like a session so that they might be able to see this reproducible issue, I am happy to provide.

Warm regards,
Joe Trapanese

Ah to clarify - I'm in Zero Latency mode, no spectral processing.

I'm having PDC issues as well, this time in Logic Pro on the iPad.

If I use Pro-Q4 in spectral mode on a track that is bussed within a group, the timing is out.

Any instance of the plugin in spectral mode on a bus has this probem, it doesn't matter if I set it to Linear Phase or not.

@Joseph: Can you indeed send a session to info@fabfilter.com? When Pro-Q 4 is running in zero latency the track should only be compensated for the latency of other tracks. If routing it through a bus will make the track go out of sync there's something going on with the delay compensation of the aux.

@Richard: Please note that Logic only updates the delay compensation when you're not in playback. If you enable or disable a spectral band during playback the track will be out of sync until you stop and restart playback.

Wouldn't the correct thing to do be that IF a band has SPECTRAL switched in (which is not automated) then REGARDLESS of the dynamic threshold, that band is ALWAYS treated as in Spectral? That way the delay comp wouldn't be changing with the automation

That way you wouldn't have this issue.

The current situation renders spectral unusable.

Hi Jonathan,

Spectral mode and automation are a difficult issue. Especially with spot automation, people sometimes use a band in spectral mode and sometimes not. It would be impossible to "lock" a certain band to spectral mode.

For now the only workaround we see is to put the whole instance in linear phase mode if you want to use spectral processing. This way spectral mode can be enabled and disabled without adjusting the latency.

@Ralph thanks for the reply, but I need to clarify that the latency is permanent once Pro-Q4 is in spectral mode.

I can stop the transport, but the project will be out of sync as long as Pro Q4 is in spectral mode on a bus. It's very obvious, because the timing is out.

I'm happy to send videos or a sample project, but this bug should be easy to identify IMO. Just use Pro Q4 on a bus in Logic, and listen for the audible latency.

Hi Richard,

In that case it sounds like you've reached the maximum latency compensation that Pro Tools can handle. If it's unable to compensate for the delay the track will get out of sync. Can you send us a copy of your project to info@fabfilter.com so we can have a look?

Understood Ralph on what you're saying.

Setting Linear Phase would be safe, yes. It does lose you the "dual" phase types - of Spectral bands being linear but being able to use a different mode for the other bands.

Maybe we could allow a permanent setup where you could force the DUAL condition into an "on" state.

So you could set Zero or Natural Phase WITH linear-med for Spectral bands?

Hi Jonathan,

Spectral bands are always linear phase. The thing is that all bands can be made spectral, so there's not really a way to have a permanent setups where some specific bands are set to spectral and some not.

@Ralph - I will try and get a file to you in the next few days.

@Ralph bug repost emailed just now, with sample project

I have the exact same problem in Logic Pro for iPad. When I enable spectral mode, the track is delayed / out of sync.

I accidentally discovered a workaround.. if I turn Pro Q off and on, it’s back in sync. I have spectral set at medium.

If I change this to high, it’s out of sync again until I power cycle the plugin.

It all goes out of sync again if I restart logic / load a new project, forcing me to power cycle whatever Pro-Q 4 instances I have in spectral mode. This is a bit of a pain but just about liveable for now.

Hi Tim,

That's an interesting workaround. I tested here and I though that Logic on iPad simply had a lower maximum delay compensation limit than on Mac, and that that limit is also lower than the latency of spectral processing. But if disabling and reabling Pro-Q 4 seems to resolve the issue this does not seem the case.

In any case I'm afraid it seems something in Logic's delay compensation. I tried in AUM as well and when you create a spectral band the signal immediately syncs up and is corrected properly.

Hi! Workaround with turn off/on works in Cubase also. It looks like the plugin reports its latency to the host when it opens. And since the latency changes when you select spectral processing, the host doesn't update. Turning off and on (not bypass) apparently transmits the current latency data and everything works correctly. I know nothing bout that, but logically, it feels like this.

So there is a solution that I have found so far:
1. open Pro-Q 4, enable spectral processing
2. turn it off/on
3. make it do nothing (gain wise)
4. save as "default preset".

After that, when adding a plugin to a track, everything works as it should and the track remains in sync with the project.