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In this video I want to talk about using Automatic Delay Compensation, a feature now standard in all versions of Pro Tools. Host-based RTAS plug-ins and HD only TDM plug-ins are both real-time effects; it takes a little time for your computer to process the audio signals that pass through them. This processing delay can be measured in number of samples or milliseconds, and it can be significant. Some plug-ins, like the stock EQ plug- ins in Pro Tools, require very little processing power and have zero delay.
However, processor-intensive plug-ins, like pitch correction plug-ins, long delay effects, look ahead mastering limiters like the maxim plug-in, and noise reduction plug-ins can have much larger delay times. For example, one instance of the maxim plug-in has 1,024 samples of delay, and the delay literally adds up. The total delay of a track is equal to the sum of all the delays from all of the plug-ins on that track. So you have three maxim plug-ins on one track that will cause over 3,000 samples of delay.
Let's listen to an example here. I have got two guitar tracks that are in sync with each other, and I'll play him in your hear how they sound. (Music playing.) Now if I go up here and I activate three maxim plug-ins, now I have got over 3,000 samples of delay time, and let's hear how that affects the sound.
(Music playing.) And you can hear that it obviously affects the timing. The second guitar track is far behind the first guitar track. To combat this delay, Pro Tools can add the same amount of delay to each track, and this is called Automatic Delay Compensation. Let's go up to the Options menu and choose Delay Compensation.
Pro Tools will ask you if you want to open the playback engine in order to enable it. We'll say okay. And right here in the middle of the window, you can choose between None, Short, and Long. None, allocates any resources for Automatic Delay Compensation. Short allocates a small amount of resources for ADC, and it's more efficient than the Long setting. So you should use Short when you have a smaller session with not very many plug-ins. The Long setting allocates the maximum amount of resources for ADC; use this with larger sessions with a lot of plug-ins.
Now we can see that 4,095 samples per channel is the long value, and this value will differ depending on the sample rate of the session. But for this session, we have 44.1 kHz as the sampling rate, and that's the number of samples that we have here, 4,095, for that particular sampling rate in this session. So I am going ahead and choose Long, and Pro Tools will ask if I want to save the session and then reopen it with that Automatic Delay Compensation setting, and I'll say yes, and I need to click the OK button here, and Pro Tools will reopen the session with the Automatic Delay Compensation on.
And you'll notice one thing down here: the delay compensation is shown at the bottom of these tracks. If you don't see this, you can go to View > Mix Window Views, and choose Delay Compensation. Now let's talk about what's showing down here. dly stands for delay, and that shows the total plug-in and hardware insert delay per track. Green values mean that the delay is enabled, but the track does not exceed the Automatic Delay Compensation limit. Orange, as we see on this acoustic guitar track number two, means that the delay is enabled and that particular track has the longest delay of all the tracks, but it still does not exceed the maximum ADC limit.
If this were red, then it would show that it's exceeding the ADC limit, and we can do that by activating this other maxim plug-in. Now it's red, and you'll remember that the maximum delay for this session was 4,095 for the Long setting. We have 4,096 here, so it exceeds it by one sample. If these values were gray, then that means that the track delay is bypassed. Down below we have the plus and minus, and this field enables you to manually adjust the ADC by adding a user offset.
Now why would you do this? If you had a plug-in that is incorrectly recording its delay amount, you can add or subtract values in here. Or if you want to manually adjust the timing or the feel of the track, you can click in here. So I am going to click in there once, and I can type in a number, or I can click and move the mouse, or I can use the up and down arrows to type in a value. Hit Enter or Return to enter that value. Below that we have the Track Compensation Indicator, and this shows how much ADC is applied to each track.
When it's green, that means that the track does not exceed the ADC value. It will turn blue if the ADC is force- enabled, like if the track is record enabled and ADC is not suspended. And it will be red, as we can see here, when the delay exceeds the ADC limit. Again, it will turn gray if the track delay is bypassed, and I will show you how we can bypass the track delay in just a few minutes. So we are looking at these delay compensation values in terms of samples.
Now if we wanted to look at it in terms of milliseconds, we can do that. If we go up to Set Up > Preferences, and in the Operation page, you can go down to this area, Delay Compensation Time mode, and switch it to milliseconds. Hit OK, and you'll see the delay shown in milliseconds instead of samples. And I am going to go up here and take this last maxim, so that we actually have delay compensation that is working and is not exceeding the value. And let me play this back for you with the compensation in there, and you'll hear that these two tracks are totally in time.
(Music playing.) We can make the delay compensation inactive for the moment, by just choosing option Delay Compensation and unchecking this, and you'll see these be grayed out, and let's listen. (Music playing.) So obviously, we can hear the benefit of activating the delay compensation.
In addition to accounting for delays caused by plug-ins, Automatic Delay Compensation also accounts for delays in internal mixer routings due to bussing and sends, as well as from hardware inserts, and this is called the system delay. We can view that by going to Setup > Session, and we will see the system delay is shown here. Now you'll notice that it's slightly larger than the delay that's on these tracks. These delay indicators on the tracks don't show the entire system delay. So if you really want to see the whole delay, you've got to go to the Session Setup window.
So what happens if the total delay on a track exceeds the ADC limit? Now let's make that happen. Go over here and activate this maxim plug-ins, so now we have more delay than can be accounted for by the ADC. Well, if had out ADC setting at Short, we could make it Long, and that would fix it. Or now because we have it set at Long, there is a different technique that we have to use. So basically what we need to do is go and bypass this delay, and I'll use Ctrl+ Command on my Mac and click that, and it will gray it out.
On a PC, you would press Start+Ctrl, and click that value. And then I am going over to the Edit window, and I am going to look at the beginning of this track. I am actually going to have nudge this audio data earlier in time, by the amount of delay reported in the Track Delays Indicator; that was 92 milliseconds. So on a separate playlist, I made this happen. I nudged the track ahead in time, and now we can listen to these two tracks playing in time, even though this has been nudged, and it has all this delay on it, because of all these maxims, but they'll play in time together.
So I am going to press Play. (Music playing.) And it works. So Automatic Delay Compensation is a great feature, and it can really help you make your mix sound more accurate and time-aligned. I recommend activating ADC every time you play back a session in Pro Tools, and most importantly, when you're working on mix.
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