MIDI latency problem, ... but in just one project?!

[A Tolerable Quietude]

This is a weird problem, and it's not the end of the world if I can't resolve it, but I'm curious to understand what's going on.

I've got a single project that's somehow developed a midi latency problem.  For context, I've got two MIDI keyboards on my system, and normally they are very snappy--hit a key and the VST instrument in Cakewalk sounds instantly.  In this one project though, there's a lag of about 1/8th of a second between playing the note, and the vst sounding.  This happens with either MIDI keyboard, so it's not a hardware or interface issue (each keyboard uses a different interface into the computer).  And besides, if I create a new project (or open any other existing project) the MIDI latency isn't there.  It's only a problem for this single project.

To make it even weirder:  Midi notes on the piano roll play perfectly in time with the music when Cakewalk is playing.  But if I use the mouse to manually select a note on the piano roll keyboard (on the left-hand side of the screen), it's got that same 1/8th-ish second delay in this single project.

Where should I look to try to troubleshoot this?  Have I accidentally changed a setting in this project that would create this behavior?  Any insight would be welcome!

[scook]

The delay is likely due to audio buffering.

The buffers you have control over are

• the Mixing Latency settings in Preference > Audio > Device Settings (or software supplied by the hardware manufacture) and
• Plug-in Delay Compensation - some plug-ins require time for processing. The DAW uses PDC to keep everything in sync. Toggle the FX button in the Mix Module. as a quick test for PDC induced latency. If bypassing FX noticeably reduces latency, then one or more plug-ins somewhere in the project are the cause. Usual suspects are dynamics processors and IR-based reverbs. Consider temporarily bypassing the plug-ins or replacing them with less resource intensive plug-ins during recording. Also review the PDC button page.

[A Tolerable Quietude]

Thanks, Scook!  Very helpful!

The FX bypass button got rid of the problem (and the problem plugin turned out to be a *very* resource-hungry iZotope mastering plugin).  Funny that I've never noticed this situation before, but I guess my usual workflow is to record all my MIDI and audio before slapping any FX on things.  Good to keep in mind going forward!  I think I'm going to turn off FX by default in my templates, and be much more mindful of what I've got running when I'm recording, freezing tracks with FX as necessary to keep PDC to a minimum.

Really appreciate the insight!

[Lord Tim]

Mastering plugins are notorious for adding latency.

They usually include linear phase EQ, and limiters with look-ahead, which both add a HEAP of time to audio sync, so even if you have a super beefy machine that didn't care about the CPU requirements, these things would still introduce latency because of how they work.

[Byron Dickens]

I really don't get why people insist on loading in the mastering plugins while they are still tracking and editing.

[A Tolerable Quietude]

19 minutes ago, Byron Dickens said:

I really don't get why people insist on loading in the mastering plugins while they are still tracking and editing.

I don't do that normally!  I usually master from a single mixdown in an entirely separate cakewalk project.

But I'm trying to get better at mastering, specifically learning how to master a track while leaving the relative balance of the mix intact. 

So for this one project I've included my mastering chain in the main project file, to allow me to go back and forth between tracking mode, mixing and editing mode, and mastering mode.  Trying to get a better sense of how choices I make in one stage of the process effect the possibilities in another.

[Lord Tim]

I tend to do something along those lines, but it's rare that I keep tracking once the mastering effects are on - it's purely mixing into the mastering chain so latency doesn't really come into play.

On the rare occasions that I think "Ah crap, forgot a synth part" I'll go through and disable any effects that introduce latency until it's fine and back at the mix stage again.

[scook]

2 hours ago, Lord Tim said:

On the rare occasions that I think "Ah crap, forgot a synth part" I'll go through and disable any effects that introduce latency until it's fine and back at the mix stage again.

Another approach if one has to record late in the process is

• bounce the project down to a scratch track
• archive everything except the scratch track (bypass FX on the master bus if any)
• record new stuff

once the recording is done

• unarchive all the working tracks/buses (enable FX on the master bus if any)
• archive or delete the scratch track 

[Lord Tim]

^^ Great tips, and I do this as well.

[John Vere]

I’ve never had a problem once I simply bypass the effects. The latency goes away.  The only issue that my come up is this shuts off a bunch of compressors and limiters so some tracks will go in the red. 
@scook  plan would solve that.