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Old 04-12-2008, 07:39 PM
lachlan lachlan is offline
Join Date: Apr 2008
Posts: 70
Default Protools LE Plug in Delay Compensation

Hello to all,

I have just bought the magnificent Protools LE with the 003 Rack and I am running it on a Mac Pro computer. I have been really strugglng to find definitive information about the delay compensation feature implemented? to compensate for delay resulting from using plug ins (which have inherent latency) as inserts on tracks.

The electronic pdf Digirack Plug Ins Guide states on page 13 that Delay Compensation is enabled on Pro Tools LE and can not be turned off. The white paper by Dusty DiMercurio on the Digidesign website states in its second paragraph that Pro Tools LE does NOT have Automatic Delay Compensation. Despite this discrepancy, from a conversation I had last week with my retailer, I now understand that LE does have delay compensation but only up to a maximum of 1024 samples or the selected H/W buffer size. Based on this concept I tested the RTAS plug in delays on the plug ins that came with my LE purchase.

I recorded a mono audio guitar track and then duplicated it. I inserted a short time adjuster plug in to both tracks. ( I had to use the time adjuster on both tracks because the time adjuster has an inherent delay of 4 samples which is not delay compensated to allow the tool to be used as an adjuster) I then inverted the phase on one time adjuster and heard silence as a result of full phase cancellation between the two tracks. I then started inserting RTAS plug ins to just one track as a way of seeing if any were creating a delay. I tested every RTAS plug in that I have presently got.

Only two RTAS plug ins had delay.

1) The Amplitude 1.X LE had 68 samples of delay. ( This delay appeared in the vol/pk/dl window ) Inserting it did not let me hear the guitar and so I assume this plug in is delay compensated.

2) The Digirack Expander/Gate dyn 3 mono showed 96 samples of delay and DID allow me to hear the guitar. By adding 96 samples to the time adjuster on the other track I was able to hear silence again. This plug in produces a delay and is not Delay Compensated.

So I conclude that some RTAS are Delay Compensated and others not.

Can anyone tell me why this is please?

Does Pro Tools not recognise the Digi Rack Expander/Gate?

Is it because the Epander /Gate has a look ahead function?

Will I have to check every plug in that I use to double check on the implementation of the Delay Compensation feature?

I have registered with the DUC service only today and I am really hoping that someone can help me. The retailer is getting angry with my calls becasue his knowledge base is challenged and I am not making a purchase.

Thank you all in advance,
Kind Regards
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Old 04-12-2008, 08:23 PM
albee1952 albee1952 is offline
Join Date: May 2004
Location: Norwich, CT
Posts: 35,841
Default Re: Protools LE Plug in Delay Compensation

LE does not have compensation for plugin latency. You are doing the right thing by testing and checking as many plugins have no latency, while others have a ton. Choose wisely. Anything that looks ahead will have latency and the Waves mastering stuff (C4, L2, etc) have tons of latency. Many others like BF76 and several EQ plugins seem to have none at all.
Gigabyte X79/intel i7 3930K, 32GB RAM, DIGI003 Rack

The better I drink...the more I mix.....

BTW, my name is Dave, but most people call me.........................Dave
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Old 04-13-2008, 03:32 AM
Phil Ogden Phil Ogden is offline
Join Date: Jul 2007
Posts: 2,109
Default Re: Protools LE Plug in Delay Compensation

As Dave (albee1952) says, and AFAIK there's no auto Plug-in Delay compensation in LE. I've read that there's no inherent delay caused by bussing (excluding the latency of any plugs) so that's maybe where the confusion arises.

As I understand it, plug-in latency is simply due to the math in some algorithms taking longer to compute. The differences are down to how individual plugs are programmed and what features they have.

lachlan - no need to perform phase cancellation exercises, just command click the track meter twice and the delay (in samples) will be displayed.

There are 2 options for dealing with PDC,

1. Using a combination of busses and the Time Delay plug-in, set-up compensatory delay for all tracks so as they all have the same delay.
2. Nudge individual tracks back to compensate for any realtime processing.

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Old 04-13-2008, 09:58 AM
Roey Roey is offline
Join Date: Mar 2005
Location: London
Posts: 85
Default Re: Protools LE Plug in Delay Compensation

As the others stated, LE does not offer automatic plugin delay compensation.

Just to clarify the plugin delay issue, there could be two possible reasons for the output delay some plugins have:
  • As part of the calculation the plugin perform, it need more samples than those provided by the application (Hardware Buffer Size, e.g. 1024). Examples would be all Linear-phase equalizers or most plugins that offer look-ahead.
  • Plugins that run on a dedicated DSP card (like the UAD) need some extra time to communicate with the card.

Roey Izhaki
Author, Mixing Audio
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Old 04-15-2008, 10:10 AM
royallion royallion is offline
Join Date: Apr 2006
Posts: 12
Default Re: Protools LE Plug in Delay Compensation

Just so I'm sure I understand...

If I find that a track is delayed by a certain number of samples, then I DO need to compensate for that delay by
A) nudging it to the left by that number of samples, or
B) delay all the other tracks by that many samples.

What if I have 13 different tracks, all delayed by a different number of samples, and another 11 tracks which are not delayed at all? Move them all to the right in varying amounts so they are all delayed by the same amount of time?

I thought we have computers so they can take care of all the tedious manual processes so we can get on with being creative.
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Old 04-15-2008, 11:56 AM
req06 req06 is offline
Join Date: Jan 2006
Location: United Kingdom
Posts: 412
Default Re: Protools LE Plug in Delay Compensation

welcome to Pro Tools LE.

If as you say you have 13 tracks with varying delays I would suggest aligning all to the track with the longest dealy.

For instance Sonnox Trans Mod has 20 samples delay

massey ct-4 has 1 sample

soundtoys has over 60 samples (ish)

So I would insert as the last plug in on the sonnox/massey channels a plugin called timeadjuster, this is found in the delay section of rtas plugins. Add as many samples as needed (sonnox 40, massey 59) to match the delay caused by soundtoys.

On the tracks which are "dry" add a timeadjuster plug in with 60 samples delay to each channel (or bus them all to a timeadjusted aux)

It is a pain. It is partly the reason I use mostly URS and MCDSP plugins, since they generally do not create any latency.

Hope this helps

G5 dp 2.0Ghz, 2.5 gb RAM/ G4 Powerbook 15" 1.33mhz, 2gb RAM/ 002r/Lacie D2 FW800/PTLE 7.4
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Old 04-15-2008, 12:13 PM
Phil Ogden Phil Ogden is offline
Join Date: Jul 2007
Posts: 2,109
Default Re: Protools LE Plug in Delay Compensation

Just to add to req06's post. In reality (well mine, at least), you'll often find that a number of tracks with the same plug-in delay and it can save some CPU overhead to bus these to an aux and use just one instance of the Time Adjuster plug-in.

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