Clips with audio jitter

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rawdesigns
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Clips with audio jitter

Post by rawdesigns » Fri Mar 15, 2019 22:31

When I play clips with audio or timecode, especially large ones, playback is jittery. Looks like it skips a few frames and almost like stop motion. Once I remove audio it’s fine.
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Joris
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Re: Clips with audio jitter

Post by Joris » Tue Mar 19, 2019 12:49

When playing back an AV file, the audio engine decides when it's time to display the next frame. So the perceived fluidity of the playback depends entirely on what you have set up in your audio preferences. In particular, very high or very low buffer sizes on a default PC audio driver can be problematic, so it's best to avoid those.

PERCYJOSEPH
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Re: Clips with audio jitter

Post by PERCYJOSEPH » Thu Mar 21, 2019 15:43

But Joris, we need to playback a lot of files with audio and specially for an award shows most of the files have audio in it and even i find it keeps jumping frames and looks awkward during the show. please suggest a way out or as you have suggested on the audio setting, please suggest what setting we need to use there.

Joris
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Re: Clips with audio jitter

Post by Joris » Thu Mar 21, 2019 17:08

I'm not sure what you'd like me to say.

I was trying to explain to rawdesigns why AV playback is different from regular video playback, and give an indication on where he can start troubleshooting. His post didn't have any more info, so it's difficult to say anything else.

We regularly test sync and playback with AV files on a variety of machines. When using the default audio settings (which is 44.1 kHz sample rate and a 1024 bit buffer on most drivers), playback is no different from video playback.

If you are experiencing differently, there is something different about your setup and we have no way of knowing what that something could be. So I cannot say anything meaningful about it.

I'm not saying I don't believe you, I'm not saying that the problem is your fault and I'm not saying that we don't want to fix it. But it is impossible for us to fix a problem that we don't see.

PERCYJOSEPH
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Re: Clips with audio jitter

Post by PERCYJOSEPH » Fri Mar 22, 2019 08:34

I got the point but the fact remains the same. I am not sure whether the issue is with my machine or it is getting worse when connected to the LED controller but for the last 6 years i have been using Resolume. I started using it on windows platform and using the Nvidia graphics card and the output were smooth but after switching over to the mac platform the smoothness has gone and the only advance is having a steady machine to work on. I am using 2 mac pro, 1 macbookpro and the latest Imac but the issue of smooth playback is my biggest worry. Is there any setting need to do on these mac platform like we do on the nvidia card settings. please advice. I will upload the clips once i get it from the channel to show what i mean by saying.

For Joris
I am sharing a link showing the work i have done 2 days back using resolume which is a full LED set using 11 outputs from 4 machines.

https://wetransfer.com/downloads/2698c0 ... 423/853128

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rawdesigns
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Re: Clips with audio jitter

Post by rawdesigns » Fri Mar 22, 2019 16:02

Thanks Joris!
Also tracks played by timecode do the same thing is it the tempo on the DJ’s end that messes with playback on my end?
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Joris
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Re: Clips with audio jitter

Post by Joris » Fri Mar 22, 2019 17:09

When playback is locked to SMPTE, playback is completely out of our hands. Because it's locked to SMPTE.

SMPTE is literally a signal telling Resolume "SHOW THIS FRAME...NOW SHOW THIS FRAME...NOW SHOW THIS FRAME....NOW SHOW THIS FRAME" @30 times per second (or whatever your SMPTE framerate is set to). We have no control over whether those commands match the clip's framerate, the display refresh rate, or Resolume own rendering fps.

In order for completely fluid playback, your output should draw a new frame at exactly the same time as 1) when Resolume has finished rendering what the current composition output looks like and 2) when the clip is ready to display a new frame. When any of those things are off by a few milliseconds, you'll get perceived microstuttering.
fps.png
So you'll get the best results when your SMPTE framerate, your clip framerate, Resolume's comp framerate and your display's refresh rate all match (or are multiples of each other).

But even then, we can't guarantee that your SMPTE source won't tell Resolume to advance the clip to the next frame just as your output is drawing. That's the nature of the protocol.

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