latency i/o

[hungrydave]

Background info: I'm using the built in monitoring on my saffire and muting the logic track i'm recording onto.

 

Is the latency coming out of the interface (that the performer is playing along to) accounted for somewhere in logic? Because surely if not, then the recorded track is going to be a teeny bit out of sync from the latency of monitoring D/A and then also the latency of recording the part A/D.

 

I ask because i had a weird experience recording a drum today just on beats 2&4 (so timing is really obvious) and the timing was late whereas it had sounded fine while i was direct monitoring it through the saffire. I did the take again with 'low latency mode' switched on (i just switched it on, didn't mess with any settings) and the take sounded ok. But now i'm concerned that although it sounded ok, low latency is not zero latency and if i'm building up takes, monitoring latent parts then monitoring those doubly latent parts etc etc, i'm concerned that this small issue can get bigger, and even if you can't hear that the part is out of time, you might feel it in terms of the tightness of the piece as a whole.

 

In core audio preferences, logic tells me that my roundtrip latency is 17.7ms. Underneath that is a slider called 'recording delay'. Do i have to offset that to a positive value to counteract the 17.7ms? If so, do i half that value as there is only A/D latency when recording, not D/A latency.

 

Really, i'm a bit confused

[triplets]

Whoa! 17.7ms is a huge amount of latency!

 

Put the I/O buffer as low as you can, 128, 64 or ideally 32.

 

Nobody can work with more than 10ms latency. Above 5 ms is already obvious for some drummers.

 

If you cannot achieve that with the Saffire then get an interface that can do it.

 

Remember that what Logic indicates as roundtrip latency might not be all. It all depends on the manufacturer's driver.

[hungrydave]

"Whoa! 17.7ms is a huge amount of latency!"

 

Yeah, i know. I can feel it when playing plugs. I tend to start a project at 64 which says 9ms. At some point it will start clicking and popping so i add latency as the track builds. Recording live instruments is ok because i can monitor direct on the saffire.

 

Do you use the low latency mode, and if so how do you have it set up?

[triplets]

If you start your session at 64 and already you have 9ms latency, there's something creating latency or the saffire drivers are crap.

 

I use a Motu Ultralite at 32, which gives me less than 3ms. After including the firewire safety buffer it's officially 4.4ms roundtrip latency.

 

Make sure you don't have any latency-inducing plugins like Multipressor, Adaptive Limiter, Linear Phase EQ anywhere.

 

Also make sure Plugin Latency Compensation is set to Off.

[Eric Cardenas]

Do you use the low latency mode, and if so how do you have it set up?

 

Low Latency mode will remove plug-in latency under the specified value (default is 5 ms) in your recording path. It does not have anything to do with your converter latency or I/O buffer.

Low Latency mode will only work "properly" when setting Plug-In Latency Compensation to All.

 

Also make sure Plugin Latency Compensation is set to Off.

I don't find this being a good solution.

Your mix will fall apart due to differences in plug-in latency on different channels, auxes and outputs when you set PDC to off.

[hungrydave]

Triplets, thanks for your responses on this

 

"Make sure you don't have any latency-inducing plugins like Multipressor, Adaptive Limiter, Linear Phase EQ anywhere."

 

If i understand it correctly, low latency mode should switch those off when engaged

 

"Also make sure Plugin Latency Compensation is set to Off."

 

Isn't that kind of necessary to make sure tracks play back together in sync?

 

Regarding my rubbish latency, if it starts ok at 64, then needs to be raised as more tracks and plugs are added. Does that mean that the 64 is the limit of the interface and all extra latency is due to not having enough chip/RAM?

[hungrydave]

Hi eric

"Low Latency mode will remove plug-in latency under the specified value (default is 5 ms) in your recording path. It does not have anything to do with your converter latency or I/O buffer."

 

I see, it just deals with the additional latency from the plugs.

 

So ideally i want to see how low i can get my latency (buffer) before recording any takes - and possibly this will change depending on how much processor different bits of the music use.

 

As i'm direct monitoring through the saffire, what i'd really like would be an offset that takes place after the recording, nudging the track forward by an amount that matches the latency. That way i could record with the buffer set safely high

[Eric Cardenas]

As i'm direct monitoring through the saffire, what i'd really like would be an offset that takes place after the recording, nudging the track forward by an amount that matches the latency. That way i could record with the buffer set safely high

 

You don't need to do this as long as your interface is reporting the "right" value to Logic.

Logic will automatically compensate for the latency reported via Core Audio.

So don't touch the offset.

 

UNLESS...

 

Your interface is reporting the roundtrip latency incorrectly. Thats what the offset is for.

[hungrydave]

Thanks eric. I feel like i'm actually starting to understand latency a bit now, this has been very helpful.

 

"You don't need to do this as long as your interface is reporting the "right" value to Logic.

Logic will automatically compensate for the latency reported via Core Audio.

So don't touch the offset.

 

UNLESS...

 

Your interface is reporting the roundtrip latency incorrectly. Thats what the offset is for."

 

OK, so i think it probably is reporting the correct roundtrip latency most of the time. The saffire is a little bit wonky, for example today i was recording some sax and after a certain amount of takes the sax player told me that my voice went all grainy and weird over talkback. I assumed it was clipping, so i tried a few things that didn't alter it. As we were nearly done we decided to ignore it as he could make out what i was saying just about. We did the last few takes, packed up the mics then listened back. At the same point where he'd reported the talkback going weird the takes were going weird too (we'd both been direct monitoring so obviously didn't notice at the time). They were very delayed and distorted.

 

So yeah, i guess a similar thing could have happened when my drum recording went strange (see my original post), and i think the rest of the time, the saffire is reporting correctly. I live and learn. I guess it's best for the performer to direct monitor and the control room to monitor through logic (either that or methodically check back every take)

 

thanks again

[Eric Cardenas]

You're welcome Dave!

 

You can test if your interface is reporting the correct latency by connecting a patch cable from output A to input A.

Insert a I/O plugin on a Channel Strip and set it to Output and input A. - Now Ping... The interface is reporting the wrong value If your get a Latency Offset other than 0.

[triplets]

Triplets, thanks for your responses on this

 

"Make sure you don't have any latency-inducing plugins like Multipressor, Adaptive Limiter, Linear Phase EQ anywhere."

 

If i understand it correctly, low latency mode should switch those off when engaged

 

"Also make sure Plugin Latency Compensation is set to Off."

 

Isn't that kind of necessary to make sure tracks play back together in sync?

 

Regarding my rubbish latency, if it starts ok at 64, then needs to be raised as more tracks and plugs are added. Does that mean that the 64 is the limit of the interface and all extra latency is due to not having enough chip/RAM?

 

Plugin Delay Compensation set to Off when recording I should have said. Of course you have to set it back to All once you start mixing.

 

If the adaptive Limiter is on the stereo output and you engage low latency mode, it doesn't make a difference, I don't know if that's a bug or not but I remove those plugs on the stereo output.

 

The fact that you already have 9ms latency at 64 doesn't speak well of the interface, not the ram you have.

[hungrydave]

Eric,

I set up the patch cord and hit the ping. Nothing changed. There is a slider under the ping where you can offset the latency. That stayed on 0. Does that mean it's all good or should the info come up as text?

dave

[Eric Cardenas]

If the adaptive Limiter is on the stereo output and you engage low latency mode, it doesn't make a difference, I don't know if that's a bug or not but I remove those plugs on the stereo output.

 

Low Latency mode will remove the latency in the recording path. It will not bypass the plug-ins on your output, but by routing your recording signal after the last latency inducing plug-in on your output it will actually remove the latency for the recorded part. Very smart actually.

Remember thou that this will only work "properly" in All mode.

[Eric Cardenas]

Eric,

I set up the patch cord and hit the ping. Nothing changed. There is a slider under the ping where you can offset the latency. That stayed on 0. Does that mean it's all good or should the info come up as text?

dave

 

That means that you are good to go and that the Focusrite driver is reporting the correct roundtrip latency.

[hungrydave]

"That means that you are good to go and that the Focusrite driver is reporting the correct roundtrip latency."

 

Magical

 

"Low Latency mode will remove the latency in the recording path. It will not bypass the plug-ins on your output, but by routing your recording signal after the last latency inducing plug-in on your output it will actually remove the latency for the recorded part. Very smart actually. "

 

So low latency mode only affects the input monitoring, and as i'm using direct monitoring anyway, it holds no benefit for me? Correct?

[Eric Cardenas]

So low latency mode only affects the input monitoring, and as i'm using direct monitoring anyway, it holds no benefit for me? Correct?

 

You got it!

 

Dave?

Why don't you use the quote function of the forum instead of quoting with "" ?

It makes it lot easier to read.

[hungrydave]

So low latency mode only affects the input monitoring, and as i'm using direct monitoring anyway, it holds no benefit for me? Correct?

 

You got it!

 

Dave?

Why don't you use the quote function of the forum instead of quoting with "" ?

It makes it lot easier to read.

 

like this?

 

"The fact that you already have 9ms latency at 64 doesn't speak well of the interface, not the ram you have."

Aye, my base rate is bad, but seeing as how even with a better interface i'd still have to be bumping up latency (from a superior base rate), i reckon i can get more bang for my buck by improving my mac perhaps?

[Eric Cardenas]

So low latency mode only affects the input monitoring, and as i'm using direct monitoring anyway, it holds no benefit for me? Correct?

 

You got it!

 

Dave?

Why don't you use the quote function of the forum instead of quoting with "" ?

It makes it lot easier to read.

 

like this?

 

I love it!

 

One of the benefits of using "direct monitoring" is that you can set the buffer size to 1024 samples if you want. It will not make any difference whatsoever in your monitoring path.

The huge downside is that you can not hear inserted plug-ins.

[triplets]

"The fact that you already have 9ms latency at 64 doesn't speak well of the interface, not the ram you have."

Aye, my base rate is bad, but seeing as how even with a better interface i'd still have to be bumping up latency (from a superior base rate), i reckon i can get more bang for my buck by improving my mac perhaps?

 

Latency has a lot to do with the drivers of the interface. Improving your mac is not gonna change that.

[hungrydave]

"The fact that you already have 9ms latency at 64 doesn't speak well of the interface, not the ram you have."

Aye, my base rate is bad, but seeing as how even with a better interface i'd still have to be bumping up latency (from a superior base rate), i reckon i can get more bang for my buck by improving my mac perhaps?

 

Latency has a lot to do with the drivers of the interface. Improving your mac is not gonna change that.

 

RAM and chip have no effect on latency?

[Eric Cardenas]

RAM and chip have no effect on latency?

 

RAM has absolutely no direct effect on latency of your system.

 

CPU is directly connected to the buffer-size. A faster CPU will allow you to process more stuff within the buffer time thus enabling you to work at lower values. This is crucial when using CPU intensive Software Instruments.

 

I think what triplets is saying is that a "good enough" computer will let you use a decent buffer size IF the drivers are well written.

A top of the notch computer will not help you if you have bad drivers.

[triplets]

Thanks Eric, you got my point perfectly!

[Eric Cardenas]

Thanks Eric, you got my point perfectly!

 

You're welcome triplets.