Severe audio (and some visual) distortion

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jtenney

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Severe audio (and some visual) distortion

PostMon Dec 02, 2019 11:59 pm

I'm trying to track down a problem that seems to involve processor overloading. I have a project in 16.1.1 (Mac 10.14.6, 32 gb ram), 29.97 framerate, with 7 wav file audio tracks running and few visual effects yet. I am getting serious distortion and stuttering in audio, especially in edit view. When I switch to Fairlight, the audio is generally good, but sometimes the video window there is showing stuttering. When I started this project, I set the framerate in the project window to 29.97 because that was the framerate of the majority of the clips I was using; in other projects I have let the software set it in response to a query about incompatible framerates. I compared this project to a finished project with the same framerate and less audio tracks, but which was running even more CPU percentage, and with no distortion at all. I am stumped. Any ideas?? Thanks in advance to all!
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John Paines

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Re: Severe audio (and some visual) distortion

PostTue Dec 03, 2019 12:24 am

This more complete explanation than the one you offered earlier suggests that it's not so much audio distortion as faltering playback. Your system may be overwhelmed by the 7 audio tracks+video with effects, along with clips which don't conform to the project frame rate. On some pages (also depending on settings) the video is the priority, on others the audio, which may explain the performance differences you're seeing.

The first thing you could try is caching the video, particularly if you're using an H.264 codec.
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jtenney

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Re: Severe audio (and some visual) distortion

PostTue Dec 03, 2019 12:50 am

Thanks, John. I understand now about the video vs. audio priorities on different pages, and I agree about faltering playback maybe being a better way of describing the problem. But I still don't understand why this one project is overloading at all, when other less processor-intensive projects are running just fine. I do have caching set up on my main hard drive, and a lot of my source video is H264...
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jtenney

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Re: Severe audio (and some visual) distortion

PostTue Dec 03, 2019 9:20 pm

Since my last message, I have combed through my project settings, tried lowering resolution in proxy mode, tried optimizing in a couple different ways, still no progress. Yuck...
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Marc Wielage

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Re: Severe audio (and some visual) distortion

PostWed Dec 04, 2019 2:12 am

Which hardware (CPU, GPU, RAM, disk I/O speed)? What source material? What timeline resolution? What framerate? How does your system rate under the BMD Disk Speed test?

If most of the material is at 29.97, it should play back fine. Do you see an error message when you play back in the color page, looking at the source window? Do you get a green dot?
marc wielage, csi • VP/color & workflow • chroma | hollywood
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jtenney

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Re: Severe audio (and some visual) distortion

PostWed Dec 04, 2019 4:13 am

Marc, I do see a green dot, and a framerate of 24 eventually. Stopping and restarting, the framerate can go as low as 4, and bounces up to 24 within a couple of seconds. Overload, definitely. Still sounds perfect in Fairlight view. I am using iMac 2017 (so Retina 5K), 32gb RAM (4 2400 Mhz 8gb), Radeon Pro 580 Metal 8gb video card. The OS is regularly optimized using Disk Warrior, and is functioning well. I just downloaded the BMD Disk Speed app, am trying to interpret it with the manual, and am attaching a screenshot. Thanks so much for your help.
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DiskSpeedTest 12-19.png
DiskSpeedTest 12-19.png (226.38 KiB) Viewed 282 times
Last edited by jtenney on Wed Dec 04, 2019 4:27 am, edited 1 time in total.
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jtenney

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Re: Severe audio (and some visual) distortion

PostWed Dec 04, 2019 4:18 am

One additional thing: is it possible the Cache Clip file is overloaded and needs to be cleaned? There are 6600 items, almost 6gb. Can one delete them, with the system regenerating them as needed if older projects are revisited? That's the way it works in Logic Pro, for example...
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jtenney

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Re: Severe audio (and some visual) distortion

PostWed Dec 04, 2019 4:43 pm

I fixed the problem! It was easy, and I am feeling a little sheepish, but after all I am a newbie (maybe for all time...) I changed playback frame rate to be the same as timeline frame rate; they were different, and of COURSE that's gonna make playback poor, duhhhh. <face palm> OK I'm done beating myself up, onward and if not upward at least sideways... Thanks to Marc and John who tried to help me!

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