Auto input latancy compensation?

[James Drake]

Hi, I was playing today.

I generated some tone on a track and sent it out one output of my Mbox. Took a cable and linked this output back to an input. Recorded this input on another track.

There is no delay!

The two tracks line up perfectly.

What's going on here? Have I missed something? I didn't know ProTools did this for you. Any documentation anywhere?

[kRokksOn]

Input latency has never been an issue for pro tools in recording, only in what you hear back. You can be sure that what you play goes to the timeline at the exact same time as you play it.

[James Drake]

Yeah, but what's happening here?

Is ProTools shifting back the audio after you hit stop? Does it adjust the timestamp accordingly? How does it know how much to shift back the audio?

I can't find this in the manual.

[DigiTechSupt]

The output of the Mbox is being recorded directly to it's input - since electricity conduction is at nearly the speed of light, you shouldn't see any delay between the output and the recorded input.

[kRokksOn]

Yeah, but what's happening here?

Is ProTools shifting back the audio after you hit stop? Does it adjust the timestamp accordingly? How does it know how much to shift back the audio?

I can't find this in the manual.

I don´t know this for sure but knowing the latency is very easy for the system since the user decides the latency in the playback engine dialog.

[James Drake]

The output of the Mbox is being recorded directly to it's input - since electricity conduction is at nearly the speed of light, you shouldn't see any delay between the output and the recorded input.

This coming from a representative of Digi? Seriously...

I like to know what's going on with the gear while I'm using it. What's wrong with that?

I have showed that Pro Tools is doing something to the audio during record. When I can't find documentation to back-up what I have witnessed, I start to doubt myself. The fact that Digi themselves cannot even add a constructive comment is worrying.

Why am I alone on this?

[Roghog]

This coming from a representative of Digi? Seriously...

I like to know what's going on with the gear while I'm using it. What's wrong with that?

I have showed that Pro Tools is doing something to the audio during record. When I can't find documentation to back-up what I have witnessed, I start to doubt myself. The fact that Digi themselves cannot even add a constructive comment is worrying.

Why am I alone on this?

as far as I can see the digiman just told you what is happening inside the box.
the track with your test tone and the track you recorded with your test will have no latency as it happens at the same time. for digidesign to document this they would have to send along "basic electronics" along with the manuals

[James Drake]

OK, try this test.

Set Pro Tools to input monitoring only.

Take some signal from an external source (not ProTools).

Route this signal to your Pro Tools interface and setup a new mono track to record it. Route this track to a spare output.

Take a cable and route this output back to a spare input. Set up a new mono track in Pro Tools to record this input.

Hit record for a few seconds.

Have a look at the waveforms. According to Digidesign they should be completely phase coherent. Are they?