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  #11  
Old 11-24-2010, 10:54 AM
WinTaper WinTaper is offline
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Default Re: Manual Delay Comp Problem

Okay one more try - here is an analogy...

Let's say I have really bad headphones that introduce a 1 second delay (48000 samples @ 48K). For sake of example, assume zero input latency. I'm overdubbing a track, so I'm playing along with something coming from Pro-Tools. Obviously, with my bad headphones, by the time I hear something, the transport is already 1 second ahead (48000 samples). I play along with the music as I hear it.

If I look at the tracks in edit view and zoom in, I can see/hear that the overdubbed part is 48000 samples late - the amount of delay introduced by the bad headphones.

What should happen if everythign were correctly aligned, is the recorded track would get 48000 samples discarded at the head and the start point moved up by the same amount, thus compensating for the headphone delay. The track would then be aligned with the existing track and the physical wave files on the disk would also align.

Alt+H doesn't change the physical files - I'd never be able to export the session and there's no way to tell from the files themselves which ones need what offset. Back to the example...

Since I use the same headphones for everything I do, I'd like to be able to enter this offset as a fixed value somewhere. Its not an insert. Its not about low/no latency monitoring. Its about sample-accurate alignment of overdub tracks.

Now, in my case, the additional delay isn't from bad headphones, but rather from my mic pre-amp A/D converter connected via ADAT to the RME 9652. Its basically a fixed offset on all hardware inputs but its not being reported by the RME card back to Pro Tools.

This offset is in samples - not milliseconds. So anything recorded through this interface would need this offset applied. Exception: as someone else pointed out ... theoretically, if I'm recording all new and not overdubbing I wouldn't need this compensation. It wouldn't hurt anything tho.

Somehow I'm getting the feeling PT doesn't do this.
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  #12  
Old 11-24-2010, 11:40 AM
DontLetMeDrown DontLetMeDrown is offline
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Question Re: Manual Delay Comp Problem

Quote:
Originally Posted by WinTaper View Post
Somehow I'm getting the feeling PT doesn't do this.
Yep, same here. I'm coming from Sonar so I'm used to this being done automatically. I posted in a thread about it on Gearslutz. Everyone essentially told me that "recording delay compensation" was not necessary which I find kind of odd.
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  #13  
Old 11-24-2010, 11:52 AM
WinTaper WinTaper is offline
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Default Re: Manual Delay Comp Problem

I'm rather surprised there's no advanced setting to accomodate additional system-wide latency, but it seems there really isn't.
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  #14  
Old 11-24-2010, 12:55 PM
DontLetMeDrown DontLetMeDrown is offline
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Default Re: Manual Delay Comp Problem

I found the thread:

http://www.gearslutz.com/board/high-...ml#post6027398

Check out the responses to post #7
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  #15  
Old 11-24-2010, 01:09 PM
miketeachesclass miketeachesclass is offline
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Default Re: Manual Delay Comp Problem

Quote:
Originally Posted by WinTaper View Post
Okay one more try - here is an analogy...

Let's say I have really bad headphones that introduce a 1 second delay (48000 samples @ 48K). For sake of example, assume zero input latency. I'm overdubbing a track, so I'm playing along with something coming from Pro-Tools. Obviously, with my bad headphones, by the time I hear something, the transport is already 1 second ahead (48000 samples). I play along with the music as I hear it.

If I look at the tracks in edit view and zoom in, I can see/hear that the overdubbed part is 48000 samples late - the amount of delay introduced by the bad headphones.

What should happen if everythign were correctly aligned, is the recorded track would get 48000 samples discarded at the head and the start point moved up by the same amount, thus compensating for the headphone delay. The track would then be aligned with the existing track and the physical wave files on the disk would also align.

Alt+H doesn't change the physical files - I'd never be able to export the session and there's no way to tell from the files themselves which ones need what offset. Back to the example...

Since I use the same headphones for everything I do, I'd like to be able to enter this offset as a fixed value somewhere. Its not an insert. Its not about low/no latency monitoring. Its about sample-accurate alignment of overdub tracks.

Now, in my case, the additional delay isn't from bad headphones, but rather from my mic pre-amp A/D converter connected via ADAT to the RME 9652. Its basically a fixed offset on all hardware inputs but its not being reported by the RME card back to Pro Tools.

This offset is in samples - not milliseconds. So anything recorded through this interface would need this offset applied. Exception: as someone else pointed out ... theoretically, if I'm recording all new and not overdubbing I wouldn't need this compensation. It wouldn't hurt anything tho.

Somehow I'm getting the feeling PT doesn't do this.
Unless I'm missing something, the point that was being made before is that you can adjust for this in milliseconds.

Just convert samples to milliseconds.
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  #16  
Old 11-24-2010, 01:20 PM
WinTaper WinTaper is offline
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Default Re: Manual Delay Comp Problem

Quote:
Unless I'm missing something, the point that was being made before is that you can adjust for this in milliseconds.
First of all, converting samples to milliseconds is sample-rate dependent - so that's a pretty lousy way to handle it. Secondly, there's a rounding error. Thirdly, it only applies to hardware inserts - not inputs. Fourthly, it applies to playback, not record.
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  #17  
Old 11-24-2010, 02:00 PM
miketeachesclass miketeachesclass is offline
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Default Re: Manual Delay Comp Problem

Quote:
Originally Posted by WinTaper View Post
First of all, converting samples to milliseconds is sample-rate dependent - so that's a pretty lousy way to handle it. Secondly, there's a rounding error. Thirdly, it only applies to hardware inserts - not inputs. Fourthly, it applies to playback, not record.
Yep. You're right. I stand corrected.
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  #18  
Old 11-24-2010, 02:15 PM
WinTaper WinTaper is offline
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Default Re: Manual Delay Comp Problem

I guess what I expected to see/find was something similar to the I/O Setup's HW Insert settings, but on the Input tab and expressed in Samples.
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  #19  
Old 11-24-2010, 02:32 PM
WinTaper WinTaper is offline
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Default Re: Manual Delay Comp Problem (solved?!)

Well I think I found it - this is from the help file ...

Compensate for Delays After Record Pass (Pro Tools HD Only)

Pro Tools provide two options for compensating for input and output latency (due to ADC and DAC) after recording.

Compensation for Input Delays After Record Pass

When enabled, this option provides automatic compensation for any analog or digital input delay with Pro Tools|HD interfaces. Enable this option for all recording situations. When recording from a digital source, both the Compensation for Input Delays After Record Pass and the Compensation for Output Delays After Record Pass options must be enabled.

The Compensation for Input Delays After Record Pass option is only available in the Input page of the I/O Setup.

Compensation for Output Delays After Record Pass

When enabled, this option provides automatic compensation for any analog or digital output delay with Pro Tools|HD audio interfaces. Enable this option when you are synchronized to an external clock source. When recording from a digital source, both the Compensation for Input Delays After Record Pass and the Compensation for Output Delays After Record Pass options must be enabled.

The Compensation for Output Delays After Record Pass option is only available in the Output page of the I/O Setup.

...

Seems to be an HD only option - I guess the M and LE systems have it built in and no one else has needed it until now. Looks like nudging is the hack-around for now. Kinda lame.
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  #20  
Old 11-24-2010, 03:11 PM
DontLetMeDrown DontLetMeDrown is offline
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Default Re: Manual Delay Comp Problem

Agreed. I guess most people aren't concerned?
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