Digi 003 Rack Latency chart needed

[Kempo]

Hi guys and girls,
I'm looking for a Latency chart with the delays (in samples) of both ADC and DAC.

I know it changes with both sample rate and audio engine buffer, so I need a chart like this:

With Low Latency Monitoring Activated
Sample rate 44.100
BUffer 128 adc delay 1234 samples DAC delay 4321 samples
buffer 256 adc delay 2345 samples DAC delay 5432 samples
....
buffer 4096 adc delay 4567 samples DAC delay 7654 samples

Sample rate 48.000

Sample rate 88.200

Sample rate 96.000

With Low Latency Monitoring Deactivated
Sample rate 44.100
BUffer 128 adc delay 1234 samples DAC delay 4321 samples
buffer 256 adc delay 2345 samples DAC delay 5432 samples
....
buffer 4096 adc delay 4567 samples DAC delay 7654 samples

Sample rate 48.000

Sample rate 88.200

Sample rate 96.000

Help is much apreciated

[Kempo]

Anyone?

Digi Tech Support?

[albee1952]

You may need to figure this out as its not anything I have ever seen(or seen it asked before either). Maybe the real question(for me) is why its so important for you

[Shan]

Originally Posted by Kempo

Hi guys and girls,
I'm looking for a Latency chart with the delays (in samples) of both ADC and DAC.

I know it changes with both sample rate and audio engine buffer, so I need a chart like this:

Pro Tools LE compensates for the input delay induced by the audio interface A/D conversion after a record pass no matter what the buffer or session sample rate is set at.

Print a click track, route it out of the hardware and back in. Set the buffer to 1024. Record the input signal on a new audio track. Since the buffer is at 1024 you will definitely hear the lag and delay during recording. Hit stop. Hit play and zoom in to see and hear the compensated audio. Repeat this procedure with all buffer settings and you will get the same result. Here are the results:

A/D/A compensated at H/W Buffer Size: 64

A/D/A compensated at H/W Buffer Size: 128

A/D/A compensated at H/W Buffer Size: 256

A/D/A compensated at H/W Buffer Size: 512

A/D/A compensated at H/W Buffer Size: 1024

Unlike PT HD, it doesn't have a preference toggle to bypass it so it's always on. Nonetheless, there is a way to bypass it in LE with some simple routing. This is the routing you need to do to bypass the A/D/A compensation and get the round trip latency value. Here are the results:

A/D/A compensation bypassed at H/W Buffer Size: 64

A/D/A compensation bypassed at H/W Buffer Size: 128

A/D/A compensation bypassed at H/W Buffer Size: 256

A/D/A compensation bypassed at H/W Buffer Size: 512

A/D/A compensation bypassed at H/W Buffer Size: 1024

There have been many of these sorts of charts your asking for created by the users over the years on many of the different Digi I/O boxes. Since whatever value it is does get compensated for anyway, having the exact value would be of no applicable use as it is indeed accurate. Having said that, once you have the exact value, it's a guessing game as to what the AD and DA latency values really are individually. You could get the whole round trip value via the above routing, but would dividing this value by 2 really give the exact separate value for the AD and DA? If the total round trip latency was 200 samples, how would you determine the AD and DA separately? The AD might really be 50 samples and the DA might be 150 samples.

Having said that, this is a chart you could quickly do and tabulate on your own. It will be slightly different with the various Digi hardware I/O boxes, or at least it use to be many years ago.

There seems to be an ongoing myth floating around internet audio forums for quite some time now, including the DUC, that LE doesn't compensate for the input delay induced by the audio interface conversion after a record pass. It indeed does as demonstrated above, and it always has, even on the old AMIII Card and 001. Imagine what a session would sound like using Low Latency Monitoring and recording at a buffer of 1024 if this wasn't compensated for. Now imagine what overdubbing in this same uncompensated session would be like. One would have latency piling on top of latency and the session would be quite the mess. Your top local studio drummers would be scratching their heads as to why they've been fired.

Hope that helps.

Shane

[TOM@METRO]

Originally Posted by Shan

There seems to be a myth floating around internet audio forums for quite some time now, including the DUC, that LE doesn't compensate for the input delays induced by the audio interface conversion after a record pass. It indeed does as demonstrated above, and it always has, even on the old AMIII Card and 001. Imagine what a session would sound like using Low Latency Monitoring and recording at a buffer of 1024 if this wasn't compensated for?

Hope that helps.

Shane

I've seen posts as recently as the past few days where someone with little knowledge of PT Native systems was trying to dispute this long-standing fact.

Thanks to Shane for the clear wording on this.

[Kempo]

Originally Posted by albee1952

You may need to figure this out as its not anything I have ever seen(or seen it asked before either). Maybe the real question(for me) is why its so important for you

I want to understand how my gear work, to be able to do the best I can using it

[Kempo]

First of all THANK YOU for the infos.

I didn't know PTLE compensate for ADC and DAC latency.
I was trying to optimize the recording session.

Imagine you have a midi track controlling an external Synthesizer, and you want to record the audio from it.

When you record you find an initial gap between the midi data and the audio data.

Now, wich SHAN told me ADC and DAC are compensated, I know this is caused by midi interface latency + synthesizer MIDI in latency + (if digital synth) Synth D/A conversion latency. NOT 003 ADC Latency.
This is a little step forward for me.

Now I would to understand how much latency is introduced by my Cranesong HEDD 192 during the ADC conversion. I use it as AD converter, connected on SPDIF.

Assuming 003 ADC is compensated (this means PTLE is aware of the latency of 003 ADC and subtract it in the recorded file timeline), I can do I thing like this:
Send the same signal (for example through a Y cable) from a Synthesizer to both 003 line in 8 and HEDD, record it, and the difference (in time ) between the two signal is the HEDD latency.

can this work?


Thank you

P.S.
I'm trying to understand as much as I can about my gear, and I believe that most ITB VS OTB wars, and marketing [bleep][bleep][bleep][bleep][bleep][bleep][bleep][bleep], are caused and allowed by lack of knowledge.

[Shan]

Originally Posted by Kempo

Imagine you have a midi track controlling an external Synthesizer, and you want to record the audio from it.

When you record you find an initial gap between the midi data and the audio data.

This should have been in your first post. What you want to study up on is MIDI offset and how to offset your MIDI tracks so that everything will be in sync.

Hope that helps.

Shane

[kbruff]

Originally Posted by Shan

This should have been in your first post. What you want to study up on is MIDI offset and how to offset your MIDI tracks so that everything will be in sync.

Hope that helps.

Shane

DIGI needs to hire you!
No really, you apply with systematic method to your assistance, I think we every DAW forum needs analytical thinkers like you.

[Kempo]

Originally Posted by kbruff

DIGI needs to hire you!
No really, you apply with systematic method to your assistance, I think we every DAW forum needs analytical thinkers like you.

Yes Digi should hire Shan,
his help is awesome, and the fact he his reading our posts and explaining things to us for free is amazing!