Old 09-13-2016, 02:16 PM   #1
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Default FX Blend Latency Issue

Did something change recently with the FX blend performance?

I need to do some further testing this evening but one plugin I use regularly and often mix to less than 100% was giving me an issue.

I had the Plugin Alliance Vertigo VSM-3 inserted on an item, with a few other plugins inserted before and after it.

There were times when I would skip to the item and press play and there was some serious bad phasing. I traced it to the mix of that plugin. Usually stopping playback and waiting a moment before playing again would solve the issue.

I need to test if this is specific to that plugin or if I can reproduce the issue with any plugin.

I just wanted to get the ball rolling and see if something may have changed with this recently as it seems to be a newer issue to me.
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Old 09-13-2016, 02:43 PM   #2
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PS. This didn't seem to start happening until I started using additional pins on the first plugin inserted on an item.

I wonder if there is somehow some relation?

It seems to also happen with UAD FX so I'm guessing this isn't specific to any one plugin.
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Old 09-13-2016, 03:06 PM   #3
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Yes. It seems that something about making a mult of the stereo signal from the first FX inserted on an item by using the plugin pin connectors can cause latency issues with some FX following that have the blend set to less than 100%, most noticeable at 50% of course.

As soon as I removed the extra pins routed to 3/4 these problems went away.

I'm not really sure how to make a reproducible case so it probably can't be solved.

I will say that I was experiencing random results. If I jump to an item and quickly play it, then it was more likely to happen. If I waited a second or two to start playback, then the issue happened.
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Old 09-14-2016, 07:09 PM   #4
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I can definitely confirm that weird and random latency/phasing issues happen when changing from 2 to 4 pins.

I can hear it if I change the pin settings during playback which is not totally surprising but the issue also happens just on random playbacks. If I suddenly move to an item and press play quickly, I can trigger the problem but also, as I played a session some of the items had this item FX issue so it really can't be trusted.

I'm not ruling out user error here, but the fact that the issue only happens on some playback attempts makes me wonder if it's a bug or weakness.
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Old 02-23-2017, 05:21 PM   #5
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I stopped using plugin pins but I still have this issue now and then. The new dynamic PDC didn't really seem to solve it.

It would be appreciated if some stress testing could be done when say 5 to 10 plugins are inserted on an item, and some of those FX are blended to less than 100%. I am not using any stock REAPER plugins, but rather a mix of Plugin Alliance, UAD, FabFilter, iZotope etc.

I'm also sending the source track to two different hardware stereo outputs, and recording back in to a new stereo track. That may be adding to the issue.
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Old 02-23-2017, 07:21 PM   #6
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I've also noticed the phasing issue with the mix knob and plugins with latency. Looks like the track channel processing is at the root of the issue as you reported:

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Old 02-24-2017, 06:37 AM   #7
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Quote:
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I've also noticed the phasing issue with the mix knob and plugins with latency. Looks like the track channel processing is at the root of the issue as you reported:

Interesting. I just haven't had time to troubleshoot this too deep, and the fact that it's more of a random/intermittent issue also makes it hard.
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Old 02-24-2017, 08:00 AM   #8
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It is not random. It's clearly reproducible with the simple steps shown above. Hopefully this can be adressed some time in the future.
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Old 02-24-2017, 10:12 AM   #9
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It is not random. It's clearly reproducible with the simple steps shown above. Hopefully this can be adressed some time in the future.
I should have been more clear that it's random in my case. I haven't had time to put together a clear reproducible case.

I have times when everything is OK, and then sometimes I'll recording a pass of 12 items with item FX (some blended to less than 100%) and on that particular playback, there is an obviously latency issue and I have to reprint it.

I hope Justin and/or Schwa can take a closer look at this and resolve it.
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Old 02-24-2017, 10:46 AM   #10
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Oh I see you're using item fx. Well, hopefully it's the same issue in that case too.

In the mean time, plugins that add latency and using the blend knob, probably not a good idea. :P

PS. do you also get phasing with blended zero-latency plugins as item FX?
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Old 02-24-2017, 10:50 AM   #11
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Oh I see you're using item fx. Well, hopefully it's the same issue in that case too.

In the mean time, plugins that add latency and using the blend knob, probably not a good idea. :P

PS. do you also get phasing with blended zero-latency plugins as item FX?
Yes, item FX only basically. I'll have to test some zero-latency plugins but I don't think the issue happens there.

There are a few Brainworx plugins that seem to have this issue more than others. I'll have to check the reported latency.
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Old 02-24-2017, 11:14 AM   #12
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Quote:
Originally Posted by MRMJP View Post
Did something change recently with the FX blend performance?

I need to do some further testing this evening but one plugin I use regularly and often mix to less than 100% was giving me an issue.

I had the Plugin Alliance Vertigo VSM-3 inserted on an item, with a few other plugins inserted before and after it.

There were times when I would skip to the item and press play and there was some serious bad phasing. I traced it to the mix of that plugin. Usually stopping playback and waiting a moment before playing again would solve the issue.

I need to test if this is specific to that plugin or if I can reproduce the issue with any plugin.

I just wanted to get the ball rolling and see if something may have changed with this recently as it seems to be a newer issue to me.
Interesting.

I think there have been some limitations in PDC for a while now.

This sounds related:
I'll duplicate a track with ReaVerb on it (as you do to make the other channel for true stereo convolution reverb - dup and then edit the impulse to the other channel and repatch the inputs).

When I first click play, there is a large lag on the new (duplicated) track (at least a second or so). Simply hitting stop and then play again fixes it. Apparently PDC isn't getting updated when it should and doesn't catch it until the stop/start. This is a native Reaper plugin so no pinning the blame on a 3rd party here!

Not a show stopper or anything. But repeatable.

You get little bits of buffer spit back out at after hitting stop sometimes in a larger project and if you stubbornly use known buggy 3rd party plugins. Yes, the root cause is a plugin in this case. Just a comment on the fact that the service it leads to crashing appears to be PDC.
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Old 02-25-2017, 06:26 AM   #13
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Quote:
Originally Posted by serr View Post

When I first click play, there is a large lag on the new (duplicated) track (at least a second or so). Simply hitting stop and then play again fixes it. Apparently PDC isn't getting updated when it should and doesn't catch it until the stop/start. This is a native Reaper plugin so no pinning the blame on a 3rd party here!

Not a show stopper or anything. But repeatable.

You get little bits of buffer spit back out at after hitting stop sometimes in a larger project and if you stubbornly use known buggy 3rd party plugins. Yes, the root cause is a plugin in this case. Just a comment on the fact that the service it leads to crashing appears to be PDC.
Yes, when using item FX, I've been experiencing a lag sometimes when I try to play an item. It was especially bad on a projects I was mastering from two stems (music and vocals). I had item FX on each stem which where on folder tracks and part of the same parent track. Instead of instant playback, there was often a few second lag.

I really think PDC, FX blend, and other related things could use another look so we don't have these problems. The big showstopper for me is when REAPER decides to incorrectly handle PDC when FX blend is used because then there is bad phasing issues and that song needs to be reprinted.
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Old 02-25-2017, 07:49 AM   #14
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Quote:
Originally Posted by serr View Post
This sounds related:
I'll duplicate a track with ReaVerb on it (as you do to make the other channel for true stereo convolution reverb - dup and then edit the impulse to the other channel and repatch the inputs).

When I first click play, there is a large lag on the new (duplicated) track (at least a second or so). Simply hitting stop and then play again fixes it. Apparently PDC isn't getting updated when it should and doesn't catch it until the stop/start. This is a native Reaper plugin so no pinning the blame on a 3rd party here!

Not a show stopper or anything. But repeatable.
Hmm I can't duplicate this -- perhaps there's something specific you're doing that causes it? If you could make a .gif of the steps involved to get incorrect output -- For example:




The OP is probably speaking of issues with Audio Units and not adjusting PDC correctly on the fly, which may be due to the fact that the plug-ins in question don't notify REAPER of their PDC changes via the proper notification channels...
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Old 02-25-2017, 07:54 AM   #15
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The OP is probably speaking of issues with Audio Units and not adjusting PDC correctly on the fly, which may be due to the fact that the plug-ins in question don't notify REAPER of their PDC changes via the proper notification channels...
Maybe it's time to officially move to VST except in cases of Goodhertz where they currently only offer AU? I know FabFilter had the issue of some settings not being remembered but I believe I have a beta version of FF where this is now resolved.

The weird thing for me is that it doesn't always happen, only sometimes. My sessions have one item after another on a track. When REAPER plays through the entire session in one pass, sometimes certain items with certain plugin changes have a PDC calculation issue and it's an obvious problem in cases where the FX blend is used.

I don't really know what to do about it other than maybe try to use VST now?
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