Logic I/O plugin pings

[Text_Edifice]

Hi guys,

anyone have insight into Logic's I/O plug and the behavior of the ping function?

I understand this is to combat latency induced by routing to external hardware (and it's great to have this implemented within the I/O plug with v9) but i've noticed it will behave quite differently depending on what day of the week I'm mixing.

For example this week the latency offset generated by sending a ping has varied between +28 samples (seemingly ridiculously low) and +1068 samples on the same mix with the same outboard in the same configuration.

Worse the latency detection within the i/o plug doesn't appear to compensate accurately enough to enable the use of outboard comps in parallel.

As this is a new feature in 9 I'm wondering if it's buggy / I'm missing something in the settings / this is just down to something in my setup?

Cheers

[Text_Edifice]

Or maybe it's down to processor load?

[jkhuri44]

probably something similar to the reason midi note recording f@#$s up by small random amounts in PCs. XP resolved those issues, however win 7 pcs still have things that mouse position, screen updates, and such which influence latency, and in this case, probably ping. i assume in your mac, the issue is down to processor scheduling/conflict.

[Text_Edifice]

Thanks Jamil,

think it has to be something OS / Mac side as I would have assumed latency incurred through the converters / outboard would be reasonably constant.

[jkhuri44]

^ thats what i meant by processor scheduling, you're CPU, etc.

[Alistair]

I don't know why it doesn't work, but I intended to use the I/O plug.... and now have another patchbay and a summing mixer. I found it impossible to use without massive phasing issues.
For printing tracks with outboard, I did a few tests and found that latency is a consistent 93 samples through my converters. If I'm printing, I just set the recording delay to -93 samples and everything is perfectly in phase.
Don't waste too much energy on it, I feel it's a dead end.
This is L8 by the way, not sure if 9 is better.

[Text_Edifice]

Thanks Alistair, am on L9. Have traditionally mixed on a PT system but decided to try and transition to Logic as my main DAW (at least for mixing) with this project. Thought the I/O plugin would work the same as a hardware insert in PT and be compensated for automatically but this doesn't appear to be the case.

In general using I/O for verbs and inline processors is tolerable but things fall apart when doing parallel processing.

Little frustrating but I could still print / time align and, as you suggest, might not be worth spending time fussing over if it just doesn't work.

[Text_Edifice]

For future reference - turned up a thread over on another forum ( http://www.logicprohelp.com/viewtopic.p ... sc&start=0 ) that suggested the i/o plug works best on busses rather than aux channels.

This is a bit of a cludge for workflow within Logic but I guess makes a sort of sense and pretty easy to template.

Will give it a whirl tomorrow...

[Alistair]

Yeah I'm not sure why no-one can get the ADC happening except for PT, but I wasted about 2 days trying to get it happening on Logic before quitting. I tried out Reaper for fun the other week- their ADC/IO makes Logic look pretty good!
I have been keeping an eye on this stuff though- when Logic 9 came out there was a flurry saying that they had the ADC sorted and it all worked perfectly now... seems that's still not the case, so I'm sticking with L8 for now!

[Text_Edifice]

Here's a new one for you – got the i/o plug set up on the bus, seems to work a little better in terms of consistent latency compensation values but haven't tried it on parallel duties yet as have already abandoned this till I have time to tinker.

Anyway – I'm a couple of hours into a mixing session and suddenly logic starts looping two bars of audio. I stop playback and the loop keeps playing. After turning off the monitors (coz something supremely weird is happening) I start to go through and check what's going on.

The bus I am using the i/o plug on is still metering... odd.

So then I un-route everything to the bus - still metering... very odd.

Then I bypass the i/o plug - silence...

Save the session, and reopen. Same problem.

Double check nothing metering on the inputs of the converters... nope.

Close logic entirely and reboot and now the i/o plugin doesn't work at all - won't pass signal.

I'm going to power-cycle everything but thought I'd share my ghost-in-the-machine story first, in case everything goes skewiff....

[Text_Edifice]

So 1 powercycle later and the i/o plug has just stopped working. Interface is working fine and I can route to / from it manually.

Moved the i/o to a new aux channel and we're back in action.

Extraordinarily odd.

[Alistair]

Welcome to logic!

[Text_Edifice]

Mixes deliverable tomorrow...

Realise there are lots of variables here and some of the oddities could be down to my setup but I don't recall L8 being so buggy (though I only mixed ITB with it).

In general I've enjoyed Logic as a mix environment and it's been good to convince myself I'm not tied to PT workflow but it's also been a very weird experience.

[Alistair]

As someone who has used Logic pretty exclusively for the past 4-5 years, I can say that I really like it, it makes a lot of sense to me, everything is easy to do (bar complicated editing), but it just craps out a lot. Every project I do I get some weird errors, completely unrelated to anything, that will happen once or twice, scare the shit out of me, waste 30 mins and then never happen again. It's bizarre.

[original_min]

Well!
I have just been through all of this, for weeks it seems.
Finally it works for me, here's what I know in as little time as possible.

Make sure your interface clock is right.
Decide on a buffer size, sample rate.
Draw a 1 sample 'pip', play it out of the interfaces analog i/o and record back in.
Measure the sample delay between 'Output' to 'Input' with the sample editor using search peak & view in samples.

Enter that in your Recording Offset preferences as a negative.
Test it, recorded pip should be at sample 1, and the i/o is good to go.

Setup your Aux tracks with i/o insert.
Patch from selected hardware out to hardware in, or put the outboard machine in bypass.
Ping the analog i/o, then the digital i/o, (they are different values).
If the ping value is always changing your external hardware is not in bypass or your audio clock is shifting.

Save your template. I also locked preferences but it's not essential.

Now here's the rub.
On my machine this setup can be left alone when using 'Hardware Monitoring'.
If I switch to Logic's 'Software Monitoring' I find the i/o 'Record Offset' value to change on ANY plugin insertion/removal.

No idea if that's a bug, or even on other machines. I don't care now I have it working reliably,
But it's only hassle free with hardware monitoring.

Sorry for the length of response and for the radical punctuation.
Couldn't resist!

[Text_Edifice]

Thanks for the tips - much appreciated.

So manual offset is still the best way to go...

Will have to investigate the software / hardware routing thing – clocking doesn't appear to be an issue and only using analog sends / returns in this instance.

Have some other mixes to do in early Jan so will have a tinker.

[Text_Edifice]

Quick update for anyone that cares.

I spent today mixing with a similar setup to the mixes I was working on in December. From the get-go i/o plugs seemed to 'just work' (no weird shifting latency values) but I also unchecked software monitoring and set a recording offset of -25 samples (the time it takes for a signal to make a round trip from the converters).

Got a good afternoons work done with no hiccups whatsoever.

Still can't process in parallel though.