Jump to content

What to do if Recording Delay value is inconsistent?


bencuri
Go to solution Solved by bencuri,

Recommended Posts

well 32 samples is less then 1 ms.  That is starting to get into the realm of imperfect loopback measurement, not necessarily that the driver is reporting wrong though it certainly could be and if its coming up with that difference every time consistently then yes

but its also probably close enough to just leave the record offset slider at zero and don't lose sleep over it.

But anyway I'm not trying to talk anyone out of doing the loopback test, by all means do it, but make sure you are doing it correctly too...  Peter Schwartz's explanation from ages ago is very good.

Link to comment
Share on other sites

7 minutes ago, CwC Studio said:

When I spoke to Audient, they said they were aware of the difference in the reported latency and it was due to changes in core audio. Not sure if future firmware releases will address that though.

If that is true that CoreAudio threw everything off...than that kind of change would affect EVERYONE for all devices...  I would like to hear more about that if it's actually true or not, that seems like it would have been a very dumb move by Apple to do that.

Link to comment
Share on other sites

6 hours ago, Dewdman42 said:

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.

Sorry if this is off topic - trying to understand this clearly. Logic automatically offsets midi recording by the amount of audio output latency?

Link to comment
Share on other sites

This is a complicated topic, some of it we can only guess based on complicated factors and its in a black box.

There are several things going in.  One is that when we play midi through software instruments there is a delay between when we press the key and when we hear the sound.  The natural human tendency is to adjust for that.  So they say, anyway, that is the presumed operating mode, that we will likely play ahead of the beat, in order to hear it on the beat, when there is a delay between when we play it and when we hear it.

DP for example, has a checkbox to set record offset to be either according to software-monitoring of the instrument or not.  There is still a lot we don't know what that means, due to more complication I will shortly explain, but that rests on the idea that do we want the midi event registered when we played the key (or as close as possible to that moment, even though we heard a delayed sound), or do we want it registered according to when we heard it?  The default is the latter, and I believe that is the only thing in LogicPro unless you move the record offset slider.

So on top of all of that there is still more because the DAW is doing things to attempt to synchronize the GUI with the known latency.  When it knows the latency it can make the appearance so that they play cursor is exactly passing each beat grid line exactly as we hear metronome clicks.  It knows the audio to our ears is delayed, so it delays the GUI to match it by that exact amount.  It give us illusion that this system during playback doesn't even have any latency at all.  Behind the scenes, internally, logicPro's guts are going all kinds of calculations in a very non-realtime manner.  It has to use math to line up various timestamps according to what it thinks we were hearing as we performed whatever we were performing, and it takes into consideration known latency while doing that.

Well anyway during recording, it's keeping track of all of that and allegedly attempting to register the midi event as a relationship between when you hit the key and when it thinks you hear it which is all according to the known latency.  And of course there is all the midi delay, which actually it doesn't even know because that isn't reported in the audio driver.  Most people have a hard time figuring out what it's doing because it's very hard to measure.  You can try to put a mic near your keyboard to record the sound of your finger hitting the key down along with the sound in a software instrument and see how it ends up.

In any case, adjusting the record offset slider can impact the recording of midi events, as I understand it, it has been a while since I messed with it, because basically you fool LogicPro into thinking you're hearing it sooner or later then you really are.  Some people have complained that in some mode all their midi recording is chronically early or late compared to how they played it.  It's hard to prove that as a user, but that is how they feel.  You can adjust the record offset slider as a temporary hack to get around that discrepancy.  But..  Then it will probably be off for audio recording, so you'd need to move the slider back.

 

 

  • Like 1
Link to comment
Share on other sites

8 minutes ago, Dewdman42 said:

This is a complicated topic, some of it we can only guess based on complicated factors and its in a black box.

It is not a complicated debate. It is just that manufacturers don't describe in the manual what to do, and we don't know what's going on. 

  • Like 1
Link to comment
Share on other sites

19 minutes ago, bencuri said:

If you could link that we could easily put an end to the imprfect or not loopback test debate. 

David actually already did earlier in the thread.

I'm not interested in debate either way.. I've already stated my opinion you can take it or leave it.. You are pretty new here but this topic has come up on this forum a lot of times in the past.. bottom line is that as you said.. we don't know for sure what is going on, but...yes if you are consisently recording midi parts early or late, you can use the slider to adjust for it.. But probably that will be a different setting then when recording audio.

 

15 minutes ago, bencuri said:

It is not a complicated debate. It is just that manufacturers don't describe in the manual what to do, and we don't know what's going on. 

and I will add that it doesn't seem to always be working properly.

Link to comment
Share on other sites

On 1/13/2024 at 4:58 PM, CwC Studio said:

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.

thank you for the RTL link.

forgive me if this is a a  dumb question, (maybe philosophical?) but the slider had a positive and negative delay correction. How can you have a negative delay? I understand zero ( no delay) I understand xxx ms delay (some amount of delay in ms or samples) but I don't understand a negative delay. How can you have delay that happens before the sound occurs ? Are we hearing it before it exists?

I know this sounds stupid but there must be some buffer thing or somesuch that I don't understand 

thanks for your patience

Link to comment
Share on other sites

3 hours ago, clandise said:

thank you for the RTL link.

forgive me if this is a a  dumb question, (maybe philosophical?) but the slider had a positive and negative delay correction. How can you have a negative delay? I understand zero ( no delay) I understand xxx ms delay (some amount of delay in ms or samples) but I don't understand a negative delay. How can you have delay that happens before the sound occurs ? Are we hearing it before it exists?

I know this sounds stupid but there must be some buffer thing or somesuch that I don't understand 

thanks for your patience

I still say be careful with RTL. In a post somewhere online it was commented that it mislead the user with false results. Not sure how it happened, but do not rely on it exclusively, I recommend. 

3 hours ago, Dewdman42 said:

David actually already did earlier in the thread.

I'm not interested in debate either way.. I've already stated my opinion you can take it or leave it.. You are pretty new here but this topic has come up on this forum a lot of times in the past.. bottom line is that as you said.. we don't know for sure what is going on, but...yes if you are consisently recording midi parts early or late, you can use the slider to adjust for it.. But probably that will be a different setting then when recording audio.

 

and I will add that it doesn't seem to always be working properly.

Later today I do a test, record it on camera. If it is wrong, you can direct me what to do differently. I want to see now for sure if we made a mistake. I want to learn in case we did it wrong. 

Link to comment
Share on other sites

23 hours ago, Dewdman42 said:

David actually already did earlier in the thread.

 

Here is how I measure it. Please check it and let me know if I am doing something wrong. If you want to suggest an adjustment let me know. What is missing from the video:
-when creating the track, Input 1 was selected as track input, and Output 1+2 as track output. 

I have been measuring 30-33 samples for 8 years. It reduced to 30 when I moved the system to SSD I guess. 

Link to comment
Share on other sites

This is the test that I do. I use a chopped sine wave as I find it easier to see a start point for the wave form and also, it lets me align phase perfectly if I'm using direct outputs (instead of the insert plugin).

You can measure the offset in the audio edit window, but I've found the results to be the same as the ping measurement in the i/o plugin (and the plugin is faster to do).

I don't really use the recording delay offset though. The only time I would use it is if I'm sending to outboard gear via the direct outputs and not using the i/o plugin which is rare.

Logic RTL test.pdf

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...