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What to do if Recording Delay value is inconsistent?


bencuri
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There is an advice on Youtube that you should ping the looped output and input of your system with the I/O plugin, and add the value you get there to the Recording Delay field in Audio Preferences. However I noticed that this value is not constant. If you open a new project, and ping the system, the plugin reports +30 as Latency Offset. But, in case I open an ongoing project with about 20 tracks (with software instruments and audio tracks in it) and ping the system, I get +2235 samples as Latency Offset. I run a test myself with a  click sample recording it looped, and indeed there was the same amount of delay visible in the recorded track compared to the original. Moreover it did not disappear when I clicked the Low Latency Mode button and re-run the test.  So how can you regulate this fluctuation? This way as the project is going on, Logic will start misplacing recordings more and more. What can you do to avoid it and make the Latency Offset Constant? 

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  1. Your audio card has latency which depends the size of the buffer.  The driver for your audio device will "report" its known latency which depends on the size of the buffer and the way the driver was written and the device itself.   Sometimes the "reported" latency is accurate, sometimes not.
     
  2. Some plugins may add additional latency and they usually report that latency when they do.  This is more predictable then device drivers.  They are able to report exactly the amount of lookahead latency they require.  You should keep plugins out of initial tests and configuration.
     
  3. The reason for doing the loopback test you mentioned is to find out if your audio card's reported latency is correct or not.  So first determine that.  If its reported latency is correct, then there is nothing else you need to do, LogicPro is already compensating correctly based on the reported latency.  If it does NOT match, then you might use record offset setting to make up the difference.  Note that this might be different per buffer size, so test out the loopback with all possible buffer sizes.
     
  4. record offset is something that DAW's do to decide where to play recorded audio and midi into the track, based on the "known" latency.  As long as the reported latency is accurate, it should be placing recording audio and midi in the correct place with the record offset slider set to zero.  You should only adjust that slider for situations where something is not reporting latency correctly, in particular if your audio device is for some reason not reporting correctly, or perhaps if you are using any other external digital gear which adds some latency, then that would be one reason the reported latency would not be accurate, for example.  So you might tweak the record offset in that case, for example.  Also...there are some rare bugs in LogicPro under certain circumstances where record offset does not appear to be accurate, so record offset might be a work around.
     
  5. As you add plugins to your project, especially to AUX and master channels, you will find all kinds of new latency, which may be disconcerting, but its normal and as long as you have verified your system's latency per above, then you should not adjust record offset either, LogicPro will automatically take all of that into account.
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Okay but how is it the latency is still there if I switch Low Latency Mode on? In the ongoing project with many plugins and software tracks, as I said i can measure +2235 samples lag, that is visible on the recorded test track, it is that much behind. If I calculate correctly, that is 50ms lag. However I have set 5ms max as allowed latency for Low Latency Mode settings, and the Low Latency Mode is switched on. I do not understand how the +2235 samples lag can still be present? 5ms is 220 samples if I calculate correctly (at 44.1Khz sample rate). Why does not Logic limit that latency if i set it to 5ms? According to the manual it should limit to that amount, but it does not do that. 

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The only thing low latency mode does is temporarily disable latent plugins that are directly in the signal path of the currently selected record enabled track .  When they are disabled they also aren’t affecting the sound.  

but it does not change latency if your audio card and does not disable plugins on other aux channels which can cause the mix to be latent.

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Yeah, but take this into consideration: I open a new project, measure the needed offset, it is +30 samples. That means Logic makes this much error when trying to compensate the latency of the system. This is the amount how much Logic incorrectly determines. I add this to the Offset settings, rerun the latency test, everything is aligned. So theoretically from that point Logic should align everything correctly now. Start doing the project, the latency is growing, but Logic is dealing with the latency compensations, and you cannot notice it. At least until you direct monitor. But then you need to software monitor for something, you know that latency became +2235 due to the plugins, so you will hear that with software monitoring. So you switch on Low Latency Mode, limit set to 0, and what you get is that the latency is still there. According to the manual that mode is for switching of plugins over the limit. It does not happen. the +2235 samples latency is there and audible, you cannot software monitor. Why is the Low Latency Button then?

Edited by bencuri
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Alesis iO4 and Audient iD4. Low Latency Mode does not work with any of them. The only difference is the offset between the two: for iO4 it is +30, for iD4 it is -10 or so, I don't remember clearly now. But what happens with both is that you load this project I am talking about, and as soon as you switch software monitoring on, you can hear the big delay. And you cannot record another software instrument track, because no matter you swtich Low Latency Mode on, the big lag is audible. How is that possible? With latency tolerance limit set to 0???

I made a mistake in the initial post though, because I wrote offset is fluctuating, but I guess it is not the offset, it is just that once you set the offset and make Logic align things properly, the extra latency is adding up, over the offset you measured, but Logic seems to deal with it when direct monitoring. So it is not an offset fluctuation I guess, it is just that there is extra latency, and you cannot eliminate it with the Low Latency button. But that is weird. 

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Go back and read what I wrote earlier to reach better understanding.  Set record offset to zero for now and leave it there.

low latency mode only affects plugins, not your audio device latency

There is no magic pill to eliminate latency.  Fact of life in daw work

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1 hour ago, Dewdman42 said:

Go back and read what I wrote earlier to reach better understanding.  Set record offset to zero for now and leave it there.

low latency mode only affects plugins, not your audio device latency

There is no magic pill to eliminate latency.  Fact of life in daw work

I seems we are talking about two different things. But it is my fault. I researched this, and found the  source of the oddity, but I don't understand what causes it. I wonder if you have an idea:

So, the case is: it is the I/O plugin that messes up things. This is what is going on:

1. I open a new project, measure the latency offset with looping, software monitoring off. I get the result +30 samples, add it to preferences, everything is aligned perfectly from that time on.

2. I open an ongoing project, I do a latency test again with looping, software monitoring off. This time, I do the test in a way that I load a click sample, and record it through the loop. Lots of plugins in the project, YET!!!! THE TEST IS OK! Everything aligned correctly. Latency Offset still the same. And all this with Low Latency Mode off.

I cannot believe this, what was the problem before then? I managed to figure out:

3. Still in the ongoing project, I do a latency test, but this time with the i/O plugin. Software monitoring off, Low Latency mode off. This time, the result is: +2235 samples off!!! I deactivate (not remove) the I/O plugin, and I do a loop test recording onto the track where I added the I/O plugin. The recorded sample is +2235 samples OFF!!! Then, I remove the deactivated I/O plugin from the track, redo the test, EVERYTHING ALIGNED!

This is what confused me. When I did my measurements initially, I used the I/O plugin, I noticed it showed a big lag, so I switched the plugin off and run a loop test with a click sample myself, onto the same track. And I confirmed the I/O plugin was right, but had no idea what causes the lag. I did not know it is the I/O plugin itself. And this is why I thought the Offset is fluctuating.

Now the question is: why is this??? And can it happen with other plugins? I absolutely had no clue the I/O plugin has such an effect that you deactivate it, yet it is still adding the lag it measured. Even when Low Latency Mode was switched on. It is totally crazy. 

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On 6/9/2023 at 3:03 AM, bencuri said:

 

1. I open a new project, measure the latency offset with looping, software monitoring off. I get the result +30 samples, add it to preferences, everything is aligned perfectly from that time on.

You're making it too complicated.  set the preferences to zero and turn software monitoring back on.

On 6/9/2023 at 3:03 AM, bencuri said:

2. I open an ongoing project, I do a latency test again with looping, software monitoring off. This time, I do the test in a way that I load a click sample, and record it through the loop. Lots of plugins in the project, YET!!!! THE TEST IS OK! Everything aligned correctly. Latency Offset still the same. And all this with Low Latency Mode off.

I cannot believe this, what was the problem before then? I managed to figure out:

3. Still in the ongoing project, I do a latency test, but this time with the i/O plugin. Software monitoring off, Low Latency mode off. This time, the result is: +2235 samples off!!! I deactivate (not remove) the I/O plugin, and I do a loop test recording onto the track where I added the I/O plugin. The recorded sample is +2235 samples OFF!!! Then, I remove the deactivated I/O plugin from the track, redo the test, EVERYTHING ALIGNED!

Its correct that deactivating a plugin will not actually remove its reported latency. You have to remove it how are you doing the test though with the io plugin removed?

What does your entire project look like, please share the project file here for others to inspect.

IO plugin does not add a big lag....  something else is happening in your setup..  Do you have other digital DSP gear anywhere in the external audio signal?

The way latency works in all DAW's is that the audio card latency is a fixed value based on the buffer size and whatever the audio card driver reports.  Ok..so you know that audio card latency can't be reduced any other way then lowering the size of the buffer.

Plugins also have a fixed latency, many are zero latency.  Some plugins require a certain fixed amount of latency.  Because its a fixed amount, it can be reported any the plugin to the DAW.

So the DAW knows exactly how much latency is at play, including audio interface, and plugins. It can then do automatic delay compensation.  It can not eliminate the latency.

Latency compensation can get complicated in big projects with complex routing.

with logicPro the way latency compensation works is that your audio tracks and software instrument tracks will play back the region data early, by the known latency, in order that what you hear will be on time.  Unless of course you are playing a live track, then it can't be fed early.  However AUX channels, output channels, including the master channel...they are considered like always live.  They can't get their audio early.  So when you put latent plugins on those channels, the entire rest of the project will be delayed to match it.

Low latency mode simply disables plugins THAT ARE IN YOUR CURRENT LIVE SIGNAL PATH, so that they are neither processing audio nor reporting latency.  Its a temporary work around so that you can record a track without latency.  HOWEVER, see the previous paragraph about AUX channels, low latency mode will not turn those off if they are outside your current live signal path...so depending on how you have routing setup in your project you can easily have a situation where low latency mode will not stop the delay from happening because its happening in an AUX or master channel.

The best advice is to avoid latent plugins while you are actually recording tracks and care about low latency.  Temporarily use low or zero latency plugins in your master channel and any and all aux channels.  The track you are recording to, also try to use low latency plugins order to have a little verb or whatever...or just turn them off temporarily with low latency mode.

After you are done tracking everything, than you can increase the size of the buffer and put all your high latency plugins back in and you won't notice any delay, it will all be compensated.

I've written enough on this topic...there are many posts on this forum on this topic, do some searching to find out more...  I think you're making things too complicated, but generally you are just confused about how latency and auto compensation works in daw's and logicPro.  This comes up a lot, you are not alone.  I wish someone would write up an excellent summery of latency handling and pin it somewhere on the forum to avoid having to re-explain all these things to new people that come along.  Its also kind of complicated and can depend on use case.

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Indeed, I cannot wish more that the care you dedicated to this topic. But these things that you mention I already know. They are in the manual. But this is not the problem here. Everything was fine until I added the I/O plugin. I thought leaving it deactivated is enough, but when I saw the offset is not what I measured in a new project I got confused. I thought it is some system problem, I have just noticed it was the I/O plugin itself on the test track. I am not an expert, so I don't have a clue why it behaves like that, but since I removed the I/O plugin everything is fine, the offset I measured earlier is correct, and when I do a looped test recording everything is precisely placed.

I am just curious about why the I/O plugin behaved that way, that being deactivated it still introduced the lag that it measured to the whole project when recording. I did a test with placing AD Limiter on the test track, even with the limiter active, the loop test was OK. Everything precisely placed. I just wonder if the I/O plugin behaved that way, are there any other plugins where I need to be careful, to remove them from the track when recording?

When I  do a test I simply loop the input output, and play a click sample from a track and record to the test track. When I do this in a new project, I measure +30 sample offset, I add that to preferences. And it seems to be correct in ongoing projects as well, even with heavy plugins, except for these cases when you put the I/O plugin on a track. I have not experienced anything like this before. From that moment you place that plugin on the track, it totally messes up the alignment of recordings. Until you remove it, the offset you measured before will be false. But as soon as you remove it, Logic starts placing recordings precisely again.

I cannot share the project because this is an album project of an artist, I am adding some tracks to it, but it is a copyright protected stuff. I have no mandate to share it.

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  • 2 weeks later...

Wondering if you gotten any further with this.

I understand the problem but I don’t know the solution. i’ve experienced inconsistent results using the i/o plugin. The theory in my mind goes : if you send out of the interface and back in via channel outputs and inputs, the result should be exactly the same as using the i/o plugin with zero offset. I’ve found the actual results vary. My wild guess is the i/o plugin does something different with reported driver latency (but my knowledge of these things is zero).

If you’re hybrid mixing, this stuff can drive you nuts.

Something similar to you is I’m currently using an Audient EVO 16 paired with an SP8. The latency between the two units (connected via adat) is about 2 to 8 samples depending on the day. The problem might be built into the Audient driver - maybe not … who knows. I’m seriously considering finding another interface. Either that or a passive summing mixer so once it’s out of the box, I mix there until i return with a final mix bus.

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  • Solution

The title became misleading because meanwhile it turned out in this particular case described, it is more likely a bug of the plugin than the fluctuation problem you also mention. When I was measuring latency, I did it with the I/O plugin first while looping the I/O with cable on the interface. Then I switched it off and did "manual" tests: myself recording samples through the loop. One day I noticed (still in the same project on the same track) that when the project is loaded with lots of tracks and plugins, the latency offset measured by myself is in the thousands. I did not understand why, when I already measured and set the offset to +32. In the end it revealed, no matter that the I/O plugin was switched off days before on the test track, it caused the test recording to be late with the overall latency present in the project. As soon as I removed the I/O plugin, the test recording was aligned properly again by Logic, with the original offset that I set before. So it was a false conclusion from me half way this is a fluctuation.

The type of fluctuation you mention, I also noticed that, but mostly with my old iMic, that does not behave too fine with Logic anyway. But I did not do detailed tests to see what's happening. So for that thing I do not have a solution, because at the moment with my Alesis IO4, my recents projects work fine. I don't have too much heavy stuff in them, though, just percussion as software instrument and some basic plugins besides the audio tracks. 

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  • 6 months later...

I did a bit of a dive into this. It’s essentially there for you to correct the difference between the reported latency and the actual measured latency if there’s a difference.

There’s a software out there called something like RTL (real time latency) where you can measure the latency of your interface. It shows you the reported latency and the measured latency. If it’s different and it’s important to you, you can then use that slider to adjust for that difference.

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17 hours ago, CwC Studio said:

 There’s a software out there called something like RTL (real time latency) where you can measure the latency of your interface. It shows you the reported latency and the measured latency. If it’s different and it’s important to you, you can then use that slider to adjust for that difference.

 

Use RTL with a caution. I read in certain comments that the results from it are not exact. Do not know the background of those posts but better going on with the loop record method to make sure everything works fine. 

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17 hours ago, clandise said:

i would like to know how to use the recording delay slider. Many of the discussions recommend setting it to zero. If that is the correct setting, why is it there?

Screenshot 2024-01-09 at 10.41.02 PM.png

I have a friend who is a professional musician, has been using logic for 20 years and has never set that offset. Moreover, at the moment he is attending a music production course in London in a college, they use Logic during the course, but when I asked whether the teacher instructed them to set the recording delay, he said no. Everyone is recording with 0 being written there. 

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Most people should not need to touch it.  These days most audio drivers are accurate in what they report.  The main reason why you might need to change it would be if you are using some outboard digital gear that is adding a little more latency that the daw doesn’t know about, which is unusual also these days.

but if you want peace of mind then measure it with Rtl utility, which by the way is an audio loop back measurement tool.  That's exactly what it does, it just makes it easier to execute an audio loop back measurement.  You still have to setup audio loop back and measure it using RTL utility.

But like I said, most times these days you are going to measure exactly what your soundcard driver is already reporting, unless you have some external digital gear

Edited by Dewdman42
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Oh one more reason might be if you use some kind of old laggy midi interface, midi devices don’t report their latency especially external gear again.  But unfortunately if you were going to use that slider for that then you would literally have to set it to zero for recording audio and set it potentially to some different value for when you will be recording midi parts.  It’s also very difficult to measure the midi latency and determine what you would set it too; but perhaps you could guess at a reasonable offset you like for recording midi and use zero for audio recording unless rtl utikity says otherwise 

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As far as I know, the recording offset is audio - it does not affect midi.

Fair play to what others say and do with the offset slider; for me, personally that doesn’t mean anything. Each system is different so I agree - you should test it yourself. I always test it myself to know what the interface does. My experience testing a number of interfaces (a few quite recent and expensive releases) has been a number of them do not report exactly what the measured latency is (and many using core audio). It was very surprising.

During that testing, I measured my own loop back testing in logic vs RTL and it was pretty accurate.

Even if the measured and reported latency isn’t perfectly matched, it still may not be cause to adjust the slider.

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13 minutes ago, CwC Studio said:

As far as I know, the recording offset is audio - it does not affect midi.

Yes it only affects audio, but the record offset of midi events is directly affected by when LogicPro thinks you heard the instrument output.  if you are recording midi through software instruments, then you very well may get some value out of adjusting the slider to account for when you will actually hear the audio, or when LogicPro thinks you are hearing the audio so that the midi record offset will be changed.

I personally thing LogicPro needs two sliders, one for midi and one for audio, but they don't.  So...  if you are having some issues with midi and instruments and feel the timing is off...this slider may in fact offer a solution even if your audio device driver is reporting exactly the same as loop back test.  But the downside of this hack is that you would have to change it to that value for when recording midi tracks and change it back to zero for when you are recording audio tracks...which most of us probably don't want to do we just get used to quantizing what we record via midi.

13 minutes ago, CwC Studio said:

Fair play to what others say and do with the offset slider; for me, personally that doesn’t mean anything. Each system is different so I agree - you should test it yourself. I always test it myself to know what the interface does. My experience testing a number of interfaces (a few quite recent and expensive releases) has been a number of them do not report exactly what the measured latency is (and many using core audio). It was very surprising.

which devices?  Please report.  IMHO that is unusual, would like to hear more.

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Yeah it’s something I did a couple of months back and it was eye opening. I don’t have all the figures with me but tested UAD, Focusrite, Audient, Apogee, Antelope, RME.

I tested using RTL software as well as a loop back of a sine wave sample and measuring the difference.

Apogee was the only one that was dead on. Most were close.

Also did blind listening tests between the converters. Really not much difference in them for that. Gosh converters are good now days.

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My methods were solid enough for one of those companies to trigger a firmware update on one of their devices and review the firmware across the rest of the line. dm me and I’ll share more info.

The method is pretty simple. Send an audio signal out of logic to an output and loop it directly back to an input to a new audio track. No plugins, no system wide stuff. As you know it’s a very basic test.

Im also not saying this is a reason to not use or buy any of these. I just like know from testing myself what everything in my system does.

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I have an Alesis IO4 that is an older, maybe 10-12 years old device, and an Audient iD4 MK1 that is newer. Both does inaccurate loop recordings when I test them in Logic. The Alesis is late with 32 samples, the iD4 is early with 17 samples or so.

 

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