Buffering / Latency / Not-really-sure issue in Reaper

[Drew Stephenson]

I generally have to run my computer with a buffer size of 1024 samples to get things to play properly as I get towards a full project (50-60 tracks typically, including buses). Which is occasionally vexing but generally fine.
Recently though, and I can't put my finger on when, I must have accidentally changed something so that the plug-in displays, metering in particular, are not in sync with the audio.
So, for example, I'll see a gain reduction meter kick-in well ahead of the audio that's actually triggering it.
This is occasionally problematic and generally frustrating.

I suspect my fat clumsy fingers have accidentally changed something in this sub-menu:

Any guesses?

[RichardT]

It looks like you have everything set to default values, so it’s probably something else. Though I suppose it could be the anticipative FX processing setting.

Have you knowingly or otherwise installed any updates recently?

Is the audio you hear in sync with the playback head in Reaper?

[Drew Stephenson]

Have you knowingly or otherwise installed any updates recently?

Nope, not that I'm aware of. I'll check the log tomorrow. (See below)

Is the audio you hear in sync with the playback head in Reaper?

Yes, audio and playhead are in sync, it's just the plugins that are playing ahead.
I did try loading another older project to test that but at that point my computer threw a complete fit and became unusable.
I don't think these things are related since the buffering problem was happening yesterday as well but maybe?

I have now given up for the night.

I don't have many purchase regrets in my studio but that machine is one of them.

[Wonks]

That page is talking about a very different sort of buffer to your AI one. Your 1024 sample buffer setting is much shorter than the 1.2 second (1200ms) media buffer in that list.

Without any explanation I can’t say that I understand what it’s talking about, but have you tried ticking the ‘disable media buffer for selected tracks’ option?

Possibly it’s giving a large buffer for processing what should be playback-only tracks to reduce the overall processing load, but you don’t want that delay when recording or using plug-ins on a track.

[Drew Stephenson]

That page is talking about a very different sort of buffer to your AI one. Your 1024 sample buffer setting is much shorter than the 1.2 second (1200ms) media buffer in that list.

Without any explanation I can’t say that I understand what it’s talking about, but have you tried ticking the ‘disable media buffer for selected tracks’ option?

Possibly it’s giving a large buffer for processing what should be playback-only tracks to reduce the overall processing load, but you don’t want that delay when recording or using plug-ins on a track.

I shall give that a try.

[Drew Stephenson]

Without any explanation I can’t say that I understand what it’s talking about, but have you tried ticking the ‘disable media buffer for selected tracks’ option?

I shall give that a try.

That made no difference.

[Wonks]

Have you tried turning it off, throwing it on the ground, hitting it with a sledgehammer, swearing at it in a very loud voice and turning it back on again?

[tea for two]

Or giving it mince pies, pigs in blankets.

This is a shot in the dark, could possibly mebe be a graphics driver issue, preehaps reinstalling latest or recent graphics card driver.
Also reinstalling audio card drivers.

[James Perrett]

Somewhere in one of your plug-in chains you are using a plug-in that has a large latency. Reaper is sending audio to that plug-in (and others in the chain) well before it is needed at the output to compensate for its latency. I've had this happen when using something like ReaVerb and forgetting to turn on the low latency option in it.

Another possibility is that you are using high quality sample rate conversion somewhere - Reaper's implementation of R8Brain has a latency of over 3000 samples.

[Aled Hughes]

Does the problem persist if you bypass all plugins? (Ctrl+click ond the master channel FX button)

[Drew Stephenson]

Have you tried turning it off, throwing it on the ground, hitting it with a sledgehammer, swearing at it in a very loud voice and turning it back on again?

Not yet but it has been threatened with that...

Or giving it mince pies, pigs in blankets.

This is a shot in the dark, could possibly mebe be a graphics driver issue, preehaps reinstalling latest or recent graphics card driver.
Also reinstalling audio card drivers.

Drivers is a good shout, should have thought of it already, will reinstall.

Somewhere in one of your plug-in chains you are using a plug-in that has a large latency. Reaper is sending audio to that plug-in (and others in the chain) well before it is needed at the output to compensate for its latency. I've had this happen when using something like ReaVerb and forgetting to turn on the low latency option in it.

Could it be a plugin in a chain on a different channel? I do have some new plugins being used on a couple of these projects I think. I'll do a test case on a new project.

Another possibility is that you are using high quality sample rate conversion somewhere - Reaper's implementation of R8Brain has a latency of over 3000 samples.

I'm just on the standard Sinc Interpolation: 192pt - if I'm looking in the right place? (render menu)

Does the problem persist if you bypass all plugins? (Ctrl+click ond the master channel FX button)

The problem only exists in the plugins, unless you mean bypassing all the plugins on other channels? Which is an easy test that I shall now do.

[adrian_k]

Hmmmm. I don’t use Reaper so I’m probably just adding to the confusion, but having something called “Anticipative FX processing” switched on might result in the behaviour you describe. In a multiprocessor environment the FX meters might move when the processing takes place, ahead of playback which happens only when all of the plugins on all tracks have filled their buffers.

Have you tried switching this off?

Edit - this might have just become noticeable if you have recently added high latency plugins to the project.

[James Perrett]

I'm just on the standard Sinc Interpolation: 192pt - if I'm looking in the right place? (render menu)

The project settings dialogue is the place to look. If you actually are using the Sinc 192pt setting then I would avoid doing any sample rate conversion because it will audibly degrade your sound. The R8Brain setting is the one to use (and I believe it is the default for new installations).

[Drew Stephenson]

Hmmmm. I don’t use Reaper so I’m probably just adding to the confusion, but having something called “Anticipative FX processing” switched on might result in the behaviour you describe.

Tried switching that off, project becomes unplayable as it's then trying to process all the FX in real time.

Weirdly, this effect of plug-in being ahead of audio, only applies to the plugins on the individual channels, not the ones on the master bus.

I did try turning off all the plugins apart from the monitored channel, it then worked on that channel. No particular plugin appeared to trigger the problem but gradually adding channels back in increased the delay. With 50ish channels and about 120 plugins total the meter was over a beat ahead.

Starting with a blank project I went up to 256 channels with a channel strip plugin on (which I use on everything) to get to the same level of CPU use and I couldn't replicate the problem.

Run out of time for further experimentation now but if anyone has any further ideas I'm all ears.

[Aled Hughes]

The problem only exists in the plugins, unless you mean bypassing all the plugins on other channels? Which is an easy test that I shall now do.

Ah yes of course - sorry, my bad.

[adrian_k]

Ah well. Blimey that is a lot of channels! (in my world).

Weirdly, this effect of plug-in being ahead of audio, only applies to the plugins on the individual channels, not the ones on the master bus.

I can imagine that might be the case - the individual tracks can be processed asynchronously (apart from any side chaining), but it all has to be in sync on the master bus.

It does sound like a particular plugin or combination of plugins on a track in this project have a very high processing overhead and associated latency. You can play back the project by letting the software schedule the processing of tracks when there is available processing power (anticipatory FX) but when you ask it to do everything all at once it chokes.

It’s a theory anyway. But I’m afraid it doesn’t help does it ?

Edit - if this is the case then the plugin that seems to get ahead of the track is not the high latency one.

[RichardT]

All the tracks have to be delayed to sync with the track with the highest latency, I guess, so the behaviour you’re seeing makes sense.

The plugins on the master bus are running off the already-synced sum of all the tracks and so they are not going to show a problem.

There are some other tracks that have a high latency and are causing the tracks with meters, which have a lower latency, to be ahead. This assumes that any delay on the tracks with lower latencies is implemented after the track has already been computed, which makes sense.

That explains why the delay on your monitored track goes up bit by bit as you add the other tracks back in. You’re adding in a whole series of tracks with differing latencies, and when you add one in with a higher latency than your monitored track, a delay is added to your monitored track to compensate.

This is an issue that must affect all of us sometimes, but I’ve never thought about it before. James had it exactly right, I think.

If this is the cause, then there is nothing fundamentally wrong!

[Drew Stephenson]

If this is the cause, then there is nothing fundamentally wrong!

This may be the case, I've just never noticed it before despite using very much the same set of plugins and similar track counts. It's a bit disconcerting watching a compressor react to the note before the one you're hearing (yes I know I should be listening not looking etc. etc. etc. ).

[Wonks]

Are you recording a version of Jethro Tull's 'Living In The Past'?

[Drew Stephenson]

Nah, it's a cover of Cyndi Lauper's Time After Time.

[RichardT]

Youssou N’Dour and Neneh Cherry’s 7 Seconds?

[Wonks]

Let’s do the time warp again?

[Martin Walker]

Somewhere in one of your plug-in chains you are using a plug-in that has a large latency.

I've suffered from this in the past, by having two or three plug-ins on my stereo buss set to their 'incredibly wonderful' audio settings intended for final rendering, and then wondering why I'm hearing things that happened in the distant past.

You could try your Reaper project in ‘Open with FX offline (recovery mode)’ as I described in this SOS feature ages ago:

https://www.soundonsound.com/techniques ... t-recovery

This will get your project initially running with no plug-ins at all, and then you can start re-enabling the more likely culprits one by one, to see when the problem reoccurs.

Good luck!

Martin

[Drew Stephenson]

Yep, that's what I tried (thanks to your tip on a previous occasion!) but it's not down to a single plugin unfortunately.