Help! Audio drops in exports

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nucelar

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Help! Audio drops in exports

PostTue Oct 26, 2021 9:22 am

Hi, I'm having serious problems with random audio drops appearing on all exports I do.

- I believe this started to happen when upgrading to v17 and setting up a shared project server.

- Never happened in v16 afaik. been working on these machines over 1 year without issues.

- happens when exporting from two different machines (same specs), drops appear in different places

- This happens when exporting to quicktime mov, mxf, wav, etc. (format doesn't matter)

- Happens with stereo or multichannel audio. Random drops (complete silence) appear in any channel at different points in time. drops are generally shorter than one frame (about 100 to 800 samples long)

- Two consecutive exports of the same timeline will generate these drops at different points in time. The source audio is 100% ok. I confirmed this many times.

-Tried to delete project cache from resolve, drops still happen

- I moved / created projects in the local database, drops still happen. I cannot find a way to export without random audio drops.

Thanks for any help. I'm now stuck with 3 unusable workstations,

MAC OS 10.15.6 - catalina
Davinci Resolve 17.4.build 12
Processor: Intel core i9 2,8GHz
RAM: 32Gb 3200Mhz DDR4
Graphics: AMD Readon Pro 580X 8Gb
SSD 2TB

Screenshot1: zoomed drops (2)
Screenshot2: 7 min of multichanel audio, red lines are drops

Image

Image
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Reynaud Venter

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Re: Help! Audio drops in exports

PostTue Oct 26, 2021 9:29 am

Are audio only exports artefact free?

Can you bounce successfully on the Fairlight Timeline without dropouts?

What is the Timeline resolution and which settings are configured on the Deliver page?
⟦ Mac Pro 7,1 Rack ⊕ 16-core 3.2GHz ⊕ 32GB RAM ⊕ Radeon 580X • Resolve Studio 18.6.6 • macOS 14.3.1 ⟧
⟦ Fairlight Studio Console ⊕ Fairlight Audio Accelerator ⊕ Merging Hapi • Anubis • Ravenna CoreAudio VAD ⟧
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nucelar

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Re: Help! Audio drops in exports

PostTue Oct 26, 2021 10:02 am

Reynaud Venter wrote:Are audio only exports artefact free?

No, export as wav also creates drops.

Can you bounce successfully on the Fairlight Timeline without dropouts?

I don't need to bounce
I work with continuous audio files (wav) in stereo or mono. (Not complex audio edits, no FX)
Think of it as a file format conversion application, or adding/replacing an extra audio to an existing movie

What is the Timeline resolution and which settings are configured on the Deliver page?
1920 x 1080

All different Deliver settings create drops (mov, mxf, wav, video with embedded audio)

Now I'm trying audio export with an M1 Mac mini, to see what happens


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Reynaud Venter

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Re: Help! Audio drops in exports

PostTue Oct 26, 2021 10:15 am

Are the source and destination file paths both local?
⟦ Mac Pro 7,1 Rack ⊕ 16-core 3.2GHz ⊕ 32GB RAM ⊕ Radeon 580X • Resolve Studio 18.6.6 • macOS 14.3.1 ⟧
⟦ Fairlight Studio Console ⊕ Fairlight Audio Accelerator ⊕ Merging Hapi • Anubis • Ravenna CoreAudio VAD ⟧
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nucelar

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Re: Help! Audio drops in exports

PostTue Oct 26, 2021 10:31 am

Reynaud Venter wrote:Are the source and destination file paths both local?


Not always, source can be from a shared resource on another Mac. (Shared as afp://...)

destination is always local, to internal SSD
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nucelar

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Re: Help! Audio drops in exports

PostTue Oct 26, 2021 10:47 am

Just to update..
Also happens when source (USB) and destination is local (internal ssd)
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nucelar

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Re: Help! Audio drops in exports

PostWed Oct 27, 2021 8:39 am

Well,
I managed to find a workaround but this is still totally unacceptable.

I lowered the setting "Render Speed" to 10 % and although painfully slow , the output was drop free.

So the manual says Render Speed can be adjusted when sharing content on a SAN, so that one's Render does not monopolize bandwith against other users. That's understandable but should absolutely be unrelated to output quality.

I will try higher settings, but it's still unacceptable that higher settings or "Maximum" setting generates errors without warning.

Please fix this, we have received several QC rejections because of this errors. We need to be confident that Resolve's output is 100% artifact free under any conditions, or at least give us a error message.
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Marc Wielage

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Re: Help! Audio drops in exports

PostFri Nov 19, 2021 2:28 am

nucelar wrote:Not always, source can be from a shared resource on another Mac. (Shared as afp://...)
destination is always local, to internal SSD

How does the shared drive rate if you run the Blackmagic Disk Speed test app?

What we've been doing for our projects at work is, we copy all source material (temporarily) from shared storage to a local SSD RAID, do the project, then render the finished project to a shared "Render" drive. So far, no issues, very fast render speeds, no glitches, no dropouts. When we finish, we archive the project to other attached storage and then load up the new project.
marc wielage, csi • VP/color & workflow • chroma | hollywood
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nucelar

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Re: Help! Audio drops in exports

PostMon Dec 27, 2021 7:18 pm

Hi, I've been able to do some more tests and think i'm narrowing it down...
So I started simple: local project database, local media and local render output.
May I mention my projects mainly consists of taking an existing movie (1 large ProRes) and replacing / adding new audio tracks. So I generated some 90min test tone wavs to act as audio tracks, then it's easier to visually inspect them after render for any problem.
So the first render I did (all local) had indeed some audio dropouts. What caught my attention is that the dropouts seemed to occur in the first moments of the render. Like a stuttering engine starting and stabilizing after a while. The last 80% of the render was drop-out free.
Also a curious fact, the first dropout was at 0,5s exactly (24000 samples) which is half of the sampling rate (48.000 Hz). other dopouts were at more random locations.
So I checked Prefernces - audio I/O and saw the playback buffer was at 2048 samples. It probably was left there during my dozens of previous tests. So I increased the buffer to maximum (4096) and rendered again. Surprise: there were many more drop-outs than in the previous render, but also only at the beginning. So I did another render setting the playback buffer to the other extreme (32). Surprise! The render had NO DROPS.
So I finally found something that affects my renders directly! or at least I thought so.... Because I set the buffer back to 4096 to see if drops appeared once again, but no!! The output was perfect again...

So it definitely has to do something with the local audio engine and how it handles buffer sizes. Maybe the buffer gets corrupted and does not reset properly when it changes size.. I don't know... Will do some more tests tomorrow...
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nucelar

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Re: Help! Audio drops in exports

PostThu Dec 30, 2021 5:15 pm

Hi I'm still not sure what's happening.

Can someone quickly check one of their recent exports and see if there's a short drop in the audio waveform at 12 frames? you will need an audio editor that allows to zoom in to the sample level, for example twistedwave,

What i'm doing:
Place a Prores video (1080p, 25fps) in the timeline.
Remove all its embedded audio tracks
Create 8 mono audio tracks and place test tone in each of them. I have prepared these test tone wavs externally.
Export to ProRes, set it o export all timeline tracks, one channel for each track.


I always get audio drops at the beginning of the export. Always at 12 frames and depending on the buffer size at other places as well.
At buffer size 4069 the output is just disastrous.
See screenshots.

https://photos.app.goo.gl/876NiNrNiq7PbLW48

Please help me to troubleshoot, I cannot believe I'm the only one experiencing this.
Attachments
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Reynaud Venter

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Re: Help! Audio drops in exports

PostFri Dec 31, 2021 10:58 am

nucelar wrote:you will need an audio editor that allows to zoom in to the sample level, for example twistedwave
Fairlight zooms down to the sample level, simply perform a load back.

I always get audio drops at the beginning of the export. Always at 12 frames and depending on the buffer size at other places as well.
No audio dropouts with 1080p/25 or 2160p/25 deliverables via the ProRes Master preset or with custom presets.

Tested on both 2018 MacBook Pro with Mojave and on Mac Pro with Catalina and Monterey.
⟦ Mac Pro 7,1 Rack ⊕ 16-core 3.2GHz ⊕ 32GB RAM ⊕ Radeon 580X • Resolve Studio 18.6.6 • macOS 14.3.1 ⟧
⟦ Fairlight Studio Console ⊕ Fairlight Audio Accelerator ⊕ Merging Hapi • Anubis • Ravenna CoreAudio VAD ⟧
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Georg Riha

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Re: Help! Audio drops in exports

PostFri Apr 08, 2022 2:04 pm

I just found out that all of our Video Masters we made with Resolve 17 have exactly the problem you described. The audio tracks have random, one sample long dropouts. (randomly distributed throughout all audio tracks).
Mostly unnoticable but sometimes producing a click noise.
I checked all our masters from the last years and unfortunately all that were made with Resolve 17 have this problem. No matter on which of our two workstations they were made.
We're on Win10Pro btw.
However, videos made with v16 are perfectly fine, so it seems to be a problem that was introduced with v17.

I couldn't find any solution so far. I tried different audio and export settings.
It happens on all exports that contain video and audio no matter which wrapper and codec you use.
Only way to get clean audio exported is to do an audio-only export as WAV.

Do you have any news about this issue? Did you contact support?
I can't believe that there aren't more people having this issue.
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nucelar

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Re: Help! Audio drops in exports

PostFri Apr 08, 2022 3:13 pm

Hi,
I'm sorry to hear that, it is indeed a fault that can get unnoticed easily, but automated QCs will catch it without mercy.

Yes, I did a formal support request, but the proposed solutions were of no help (deep unistall and install from scratch) Due to the random nature of the error it is difficult to reproduce.
I have no idea under which specific conditions this happens, and it also baffles me there is not a "global complain" about this issue.

I have been throttling render speed to "10" and let it render overnight and that produces good output most of the times.

In the last days I have used the option "use fixed busing" in the Project Settings (under Fairlight) . This option seems to fix the issue, even at full render speed, but I have not been able to do systematic tests yet.

Also, this option can only be set just after the Project is newly created, not on existing v17 projects.

Could you do a test with this "fixed busing" checked?

Best regards
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Georg Riha

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Re: Help! Audio drops in exports

PostFri Apr 08, 2022 3:27 pm

Thanks for your reply.
I'll do some tests with the "use fixed busing" option and let you know if it makes any difference on our systems.

Btw. all of our faulty masters slipped through the broadcaster's QCs! Even one that was broadcasted worldwide recently. :shock:
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nucelar

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Re: Help! Audio drops in exports

PostFri Apr 08, 2022 3:42 pm

Hi Georg, lucky you :) I guess it depends o the QC system in particular and how it is set up..
Anyway.. how long are your drops? you said just 1 sample.. are you sure? or did you mean one frame?
Cheers
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Georg Riha

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Re: Help! Audio drops in exports

PostSat Apr 09, 2022 12:36 pm

I don't feel very lucky tbh. I would have preferred they catched it. Don't like the fact that we've been delivering faulty masters for over a year now...
Yeah, you're right the dropouts aren't one sample long, but they're not one frame long either.
Ther're around 10ms. That should be half a frame on our 50fps sequences if my math isn't completely off.
I did some tests with the "use fixed busing" option. Without luck unfortunately. Still getting dropouts... :(
Seems like you cannot rely on Resolve to produce flawless masters. Quite dissappointing and frustrating...
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Georg Riha

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Re: Help! Audio drops in exports

PostMon Apr 11, 2022 6:23 pm

I'm out of ideas.
Disabled LAN controllers and Advanced Power Management in BIOS, disabled Anti-Virus, disabled various background processes, used different harddrive sources and destinations... everything without luck. The exports have audio dropouts.

I did some test export from Resolve, Premiere and Media Composer using the same video and audio sources. Only the exports from Resolve have dropouts! :roll:
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Matt.perrott

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Re: Help! Audio drops in exports

PostSun May 01, 2022 11:16 am

Just came across this thread via the DUC. Ran your sample test with 18 beta, Pro Res was a proxy file I had on hand, 8 mono 1khz tones, and no dropouts.

Running new Mac Studio, media on NAS and outputting to external SSD. Still looks troublesome
Matt Perrott - Mighty Sound

DR Studio 18.x
Mac Studio M1 Max 32GB Ram - Ultra Studio 4k Mini, MTRX Studio / Digiface DANTE
MBP 16 Inch M1 Max 32GB Ram

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