Lets Do The Time Warp Again

[kents27989677]

I've been tracking a professional EP for the  past 3 weeks and every day I encounter a condition where Audition is recording a single track and upon playback the track is misaligned with drift occurring over the course of the recorded track - meaning I cannot make a single re-alignment and have a good track because the drift occurs irregularly during the take leaving multiple points where time warping has occurred.

No errors are indicated such as lost sample detected. It is only upon playback that the defect is detectable.

I have thrown massive amounts of hardware at the issue and even now with an extraordinarily capable machine I still get the issue after a couple hours of contiguous use of Audition which has led me to suspect the root cause is Audition itself not freeing resources and / or effectively managing memory (cache and /or RAM) during certain events where flushing and resetting should occur.

Here's the typical day. Start recording around 10am. Mostly single and occasionally two tracks recorded simultaneously. By noon I have to reboot because a take will be ruined on playback. By ruined I mean the timing of the performance is clearly defective and no single edit to realign the file to the program material works because the drift is not a single fixable event. The deviation from actual performance may shift multiple times during the recorded track. Minute shifts but clearly defective.

I have been debugging and characterizing the issue for 3 weeks and there's a LONG list of things I've done to try and resolve the issue including:

- Windows 10 optimizations (described @ Focusrite.com -> support -> optimizations -> Windows 10

- Upgrading CPU, RAM and storage (see current system info below)

- Disabling all plug-ins / effects

The current hardware in play here is as follows;

Dell 8900 quad core i7-6700 (6th gen)

32G RAM (ddr4-2133, dual mode)

525G SSD OS, C: Drive (Crucial MX300 motherboard M.2 mount)

525G SSD Audition recording, cache, I: Drive (Crucial MX300 SATA)

Current release of Audition CC.

Windows 10 Home-64.

Waves Platinum 64-bit VST3 effects

Focusrite 6i6 and Focusrite 2i4 USB interfaces tested

The issue began while I was running another machine, a 6th gen Core i5 quad with 16G of RAM and running Audition to the external SSD with identical symptoms.

What I suspect to be the case (reiterating that I am purely speculating) is the following in regard to Audition:

- If a session is launched with FX enabled, powering them off with the "power button" track control does disable playback of the effects but retains some performance impact. In order to fully bypass efx, after depowering them you must exit Audition and relaunch the session with the effects disabled to avoid "loading" them.

- When performing a "Close All" to end a session without actually quitting Audition there remain significant resources from that session cached somewhere in Audition's internals. One of the key steps in reproducing this issue is to Close All and then open another complex session (without exiting the program). When the next session is opened after a couple hours of running and recording the former session, the timing issue begins to occur. This has been the case each time I have experienced the problem.

I should be able to mix a session with full effects running, close that session and open another session to begin recording without having to reboot my computer.

I'm not halfway through this project and I'm having to stop, save, exit and reboot several times a day to compensate for Audition's inability to record tracks with absolute precision and again - no errors are reported during tracking.

In addition to fully freeing internal resources when files are closed there is clearly a gap in error checking that should report to the user that an issue has or may have occurred.

CPU typically stays well below 20% occupancy at full load. RAM is vastly underutilized if the files in play were actually being held in memory versus cached on "disk". Audition is NOT leveraging the hardware available to it's fullest extent and performance is subpar. Everything in my system is prepared for high performance and I'm not getting it. LatencyMon (http://www.resplendence.com/latencymon_whatsnew) indicates no issues with system performance. I'm convinced the problem is Audition.

Thank you for your attention to my observations.

[SteveG_AudioMasters_]

What are your master clock sync settings set to?

[Bob_Howes]

Other question:  are you using the latest ASIO drivers from Focusrite?  I ask because ASIO drivers provide Audition with the necessary information to compensate for timing differences between playback and live recordings.

[kents27989677]

Yes of course, latest drivers available and have been re-installed. Thx. -K

[kents27989677]

FYI the buffer size is fixed at 1024 and Audition traps (crashes) if I attempt to lower it using the Focusrite MixControl app and then launch AA afterwards. Recording is 24/96.

[kents27989677]

I have tested with 2 Focusrite units, the 6i6 and 2i4 and both use internal clocking. There is no external clock option that I'm aware of. These are USB interface devices. Thx. -K

[SteveG_AudioMasters_]

Okay, I've checked on the situation with Focusrite and sync options, and basically they don't give you any - you are stuck with internal sync only. Which means that Audition will record with sync provided by your sound device, but what that means in terms of playback isn't so clear - I suspect that what should happen is that whilst recording, Audition is going to use that source for everything - but on playback after the event, it may well not take its sync from the Focusrite at all. There have been all sorts of funny sync issues over the years (mainly to do with Creative Labs cards) and, it has to be said, the sync stability of many cheaper devices leaves quite a lot to be desired - it can drift out more than you might think.

Bottom line is that I don't know exactly what's causing this - but hopefully one of the devs will be along to explain exactly what the sync situation is, because I'm pretty sure that this is at the root of your problems. One of the things you could try, to see if it makes any difference, is an alternative driver option in Audition - like WASAPI. If that behaves itself, then at least you'd have some sort of idea of where the problem might lie...

[kents27989677]

Thank you Sir.

The only factor I would point out is that I have run the latency monitor while the problem was actively occurring, which looks at the i/o queue timing in microseconds, and nothing shows up in terms of driver latency concerns. I can see the timing for graphics, system kernel, network i/o, etc as well. Nothing indicates the problem is with the Focusrite.

-K

[kents27989677]

I'm also aware that the system monitoring tools add their own latency - I was using the monitor tools after the issue began, not before.

[SteveG_AudioMasters_]

There's a significant difference between latency and sync! If your track merely ends up offset, then that's almost certainly a latency issue somewhere, and although generally they are compensated for, this doesn't always quite go to plan, and the devs might have something to say about that. But if the track gets increasingly out of time, rather than offset, then this is a lack of synchronisation, and not a latency issue at all.

And it's your mention of time-warping that says clearly to me that it's a sync issue rather than a latency one - it's the gradually getting out of step that gives it away!

[kents27989677]

Clearly I have misused a perfectly good Rocky Horror Picture Show reference when I should have busted out a little Dobie Gray instead. I bow to your syntactic superiority and appreciate your attention to detail.

[kents27989677]

I may have made a significant discovery in regard to this problem.

I reiterate "may", but I'm hopeful this information may be of use to the design team.

During today's tracking sessions I (of course) encountered the issue again and one instance of the drift problem occurred after booting the computer (versus after a long tracking session). So I have clarity about exactly what was going on when it happened and I'm hoping this information is germane.

Stacking Tracks

One of the ways I work with Audition is to "stack" tracks while tracking - meaning that upon completion of recording I typically make a decision to either "Undo" (Control Z) and disregard the take, or alternatively if I decide the track is worth keeping I will "stack" it. What  stacking entails is the following workflow;

- Since the just-finished track is typically the "highlighted" track, I issue a "alt-A" to create a new track below the currently highlighted track.

- Next I drag the Clip from it's current track into the newly created track, and then Mute that track preparing for another take at the performance.

- Hit record and re-use the track used for the prior take.

I think this is significant.

The reason I do this is to simplify comping a series of takes into a single composite later, and by re-using the same Track then I preserve a filename sequence. When I first create the track used to record, I name it something meaningful, for instance "Bass" and the automatically generated filename is sequential. Bass-001, Bass-002, etc. It makes it simple to refer to a particular take as "file 001" or "file 002" etc. Having each take stacked makes it simple to audition (no pun intended) each take, muting one and moving to the next adjacent Track to hear another take while comping.

Today, shortly after booting the machine, I stacked a track and proceeded to the next take which was immediately defective. There was no "hours of tracking" in the cache, buffers, etc and absolutely no plugins in memory as I have stripped them all way from the effects box and rebooted prior to tracking this instance. When start first open Audition, when I load the first session and that session contains plugins in the effects box on any track, the Waves (the brand of plug-ins I'm using) logo flashes momentarily as part of the loading process for the session in Audition. In today's example I had cleared all plugins, rebooted and reset the Focusrite interface prior to launching Audition. There were 6 other tracks playing while I recorded 1 track, which is a light load for this machine.

So this action of "stacking" tracks, or moving a clip from where it was originally recorded into a newly created and empty Track seems to be a common denominator for my issue as I look back over every session where I encounter the problem with sync.

Could there be some error in creating the new clip after the previous clip is moved to another track? I don't know - that's the thing I think needs to be explored.

The good news for me today is that I've discovered by zooming in the waveform where the previous take and the currently being recorded take can be viewed as the recording in progress begins, I can see immediately if the recording is defective and I have a screenshot to attach demonstrating the obvious defect in the currently being recorded track.

Another significant discovery today is that once the issue occurs it may NOT necessarily recur on the next attempted recording. Having the ability to immediately discern when a track has gotten off on the wrong foot (so to speak) makes it a quick matter to stop and restart the recording and what I discovered is that the sync issue is not persistent. Once the defect has reared it's ugly head, now being discovered by the first or second note of the track under way, I can reasonably ask my client to wait while I reset and have another go. Several takes later, no drift. Seemed to just be the first take after stacking a track!

Below is my view at the beginning of a recording where the delayed capture of the very first note is evident. This is two takes of the same part (a bass guitar). When I see this misalignment I know that the take is useless and stop immediately which is of course a pain for a paying client but better than getting to the end and discovering 4 minutes of wasted effort. This screenshot was not taken in realtime (you  don't see a red recording armed indicator) but is an accurate recreation. I placed the short clip back into the multi-track editor to show two tracks as they appeared earlier.

-Kent

[SuiteSpot]

What you do regarding 'stacking' I do pretty much every day and at the very least in every recording session for as many years as I can remember and with each session having anywhere from 20 to 50 tracks playing at the same time. Also I have done that with every version of Audition ever released and have never encountered such a problem as yourself.

Logic tells me that if the software is flawed then both of us (and every other user) should also see this issue manifest itself every time we record and 'stack' tracks. But this is clearly not the case.

So the only logical explanation points to something in your particular setup - perhaps the Focusrite - are you able to get hold of another interface to prove or disprove that theory?

Maybe something in the Waves fx you are using - have you tried sessions without any of these fx at all (rather than just disabled)?

Anyway, its just a thought...

[kents27989677]

Thanks SuiteSpot.

I have tried two different interfaces, albeit both of them are Focusrite products. I have removed all the Waves plugins and still have the issue.

[Bob_Howes]

Clutching at straws, you mention the Focusrite Mix Control won't let you go below 1024 latency.  This sounds awfully high to me--I use around 256 on a much less powerful machine than yours.  What happens if you set latency in Audition first then match the Focusrite control?

Beyond that, you're working at 24/96.  Have you tried 16/44.1 just to see if that makes a difference.  Also maybe experiment with different USB ports.

[kents27989677]

Thanks Bob.

If I try to change the latency number in Audition, it takes me to the Focusrite control panel.

I have not tried 16/44 since I'm actually in the middle of a 5 song project well underway, but I have tried different USB ports and ensuring I'm not competing with keyboard/mouse USB hubs.

Thanks again.

-Kent