Help Slaving Logic Studio to Pro Tools

[bashville]

Originally Posted by digilogin

hello,

consistently.


digilom

If you leave the "H/W Buffer" in Protools the same, but increase the "I/O Buffer" size in Logic, do the attacks get even further apart?

[DigiTechSupt]

logic is set to "external", if i understand you correctly. just to be sure we are talking about the same thing, tell me exactly what field you are referring to.

This would be the setting when you go to File>Project Settings>Synchronization and click on the drop-down next to Core Audio - 'External or Free' should be the option chosen.

Just to be absolutely clear on this - can you tell me how you know, or how you're measuring, that Logic is 45 subframes 'off'?

I'm going to try to find some time today to test this, but I doubt I'll be able to before Monday. I don't use the IAC bus myself, so I can't say for sure if there's anything missing. The fact that your devices are not clocked to each other certainly could play a part, though I'm not convinced by any stretch that it's the culprit here.

[digilogin]

Originally Posted by DigiTechSupt

This would be the setting when you go to File>Project Settings>Synchronization and click on the drop-down next to Core Audio - 'External or Free' should be the option chosen.

Just to be absolutely clear on this - can you tell me how you know, or how you're measuring, that Logic is 45 subframes 'off'?

I'm going to try to find some time today to test this, but I doubt I'll be able to before Monday. I don't use the IAC bus myself, so I can't say for sure if there's anything missing. The fact that your devices are not clocked to each other certainly could play a part, though I'm not convinced by any stretch that it's the culprit here.

hello,

yes, i have it set on "external or free". i am measuring the 45 subframes by just listening to the flamming and nudging the pro tools file forward until it locks. i have not done it down to the sample level because it do not know if that is relevant, or if it will lock that tight. we are just trying to get smpte to line up at this point, right?

i do not think its a clocking issue in this scenario, although ultimately the clocking would need to be addressed. possibly just the lag for the usb connection to the x-station? let me know if you come up with anything, and i will look at bashville's suggestions also.

digilom

[digilogin]

Originally Posted by bashville

If you leave the "H/W Buffer" in Protools the same, but increase the "I/O Buffer" size in Logic, do the attacks get even further apart?

hello,

yeah, the buffer settings changes it. there are probably are whole bunch of things to nail down to get this all cozy and tight. tally ho.

digilom

[DigiTechSupt]

What are your Pro Tools and Logic buffer sizes set to?

I think it's just a matter of playback buffer size - 45 sub-frames = ~15ms, which would be approximately equal to a 512 sample buffer size (this is at 44.1k).

In that case, does the delay get less as you reduce the buffer size in Pro Tools and Logic?

[digilogin]

Originally Posted by DigiTechSupt

What are your Pro Tools and Logic buffer sizes set to?

I think it's just a matter of playback buffer size - 45 sub-frames = ~15ms, which would be approximately equal to a 512 sample buffer size (this is at 44.1k).

In that case, does the delay get less as you reduce the buffer size in Pro Tools and Logic?

hello,

i had them both set at 512 when i did the nudging and came up with the 45 subframe offset. but remember its at 192khz. maybe you have some interfaces around there that you can set up of "best conditions" test and see if there is any lag. i can't help but think that the usb connection to the x-station must be causing some sort of delay. no?


digilogin

[digilogin]

Originally Posted by digilogin

hello,

i had them both set at 512 when i did the nudging and came up with the 45 subframe offset. but remember its at 192khz. maybe you have some interfaces around there that you can set up of "best conditions" test and see if there is any lag. i can't help but think that the usb connection to the x-station must be causing some sort of delay. no?


digilogin

hello,

anyhow, whenever we figure out the lag time formula, i still want to know where the iac smpte timecode offset field is [hopefully].

if we are dealing with logic just not reacting at all until after the buffer delay, then i guess you also have to figure out the different a to d converters' latencies, subtract one from the other, and factor that in along with the buffer delay, and anything else i am not thinking of, in order to come up with the offset. make sense?

digilom

[DigiTechSupt]

anyhow, whenever we figure out the lag time formula, i still want to know where the iac smpte timecode offset field is [hopefully].

This *should* be controlled by the Global MIDI Offset option in Pro Tools Preferences.

if we are dealing with logic just not reacting at all until after the buffer delay, then i guess you also have to figure out the different a to d converters' latencies, subtract one from the other, and factor that in along with the buffer delay, and anything else i am not thinking of, in order to come up with the offset. make sense?

It's not a 'reaction' time, per se. All DAW's must buffer audio before you'll hear anything - the amount being controlled by the HW buffer size.

Since your session in Logic is 192k, but your interface is 48k, I'm not sure exactly which determines the actual buffer. I'm not even absolutely sure what the ultimate cause of the delay is yet. Since this configuration is not even on my 'grid' of things to qualify or test when I create the Logic/Pro Tools integration documentation, I doubt I'll be able to spend too much time on sussing out all the possible problems with this configuration until I've done everything else.

So, for now, hopefully the Global MIDI Offset will get you in the right direction. I'll return to this after I finish the other Logic guides, but I just don't have the time or resources to dedicate too much more to this at the moment.

[digilogin]

Originally Posted by DigiTechSupt

This *should* be controlled by the Global MIDI Offset option in Pro Tools Preferences.



It's not a 'reaction' time, per se. All DAW's must buffer audio before you'll hear anything - the amount being controlled by the HW buffer size.

Since your session in Logic is 192k, but your interface is 48k, I'm not sure exactly which determines the actual buffer. I'm not even absolutely sure what the ultimate cause of the delay is yet. Since this configuration is not even on my 'grid' of things to qualify or test when I create the Logic/Pro Tools integration documentation, I doubt I'll be able to spend too much time on sussing out all the possible problems with this configuration until I've done everything else.

So, for now, hopefully the Global MIDI Offset will get you in the right direction. I'll return to this after I finish the other Logic guides, but I just don't have the time or resources to dedicate too much more to this at the moment.

hello,

i think you may not be quite on point about the buffering. the x-station is probably not creating a problem by being a base sample rate device. it does not have to be switched on way or the other, it just translates digital to analog at the base sample rate, and it seems to me that is the computer and logic that buffering and so forth.

i guess i could just use the computer's audio in and out and take the x-station out of the equation to see what that does.

are you thinking that, if i was just running a midi synth click in pro tools and a midi synth click in logic they would be locked? maybe i can see about that.

i guess the question is whether or not smpte over the iac bus is subject to any kind of inherent delay, apart from any issues of buffers or other variables. do you have any thoughts in that regard.

if you are doing a guide that's great! when do we see it?

digilom

[digilogin]

hello,

does anyone know if logic has something similar to the "global midi offset" thing that is in pro tools.

digitechsupt: are you saying that the global midi offset thing will advance or delay the midi time code that is generated?

thanks.



digilom