QLab 4 - Video Cue - Images, not video - Fade - Choppy - Stutter - Jitter

[Marc Beth]

I'm using photos for video cues (not videos), and using Video Fade Cues for image movement, with rotations, translation, and scaling.

At almost every fade cue, there is a jitter/stutter/flicker. Brand new MacBook Pro. QLab 4.

Anyone encounter this? I'm about ready to abort this path, as the quality is not acceptable. Help, anyone?

[luckydave]

Are you experiencing this with the first fade you try, or is it only after a few cues have run? Are you stopping cues that are no longer needed once you're done with them? QLab doesn't know when you're done with a still image cue, so if you fade it out, for instance, you need to enable the "stop target when done" function on the fade cue, so the cue you're no longer using doesn't continue to use system resources that future cues require.

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luckydave

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[Marc Beth]

It does seem to get worse as the sequence goes on. Basically, I've got a large image that I'm panning across, controlling the "camera" with geometry settings. So, the same image is in use for 5 minutes, through 40 or so cues. Is that just a limitation of QLab?

[luckydave]

Is it just one image? What are its pixel dimensions? If they're larger than its displayed dimensions, then try pre-scaling the image to match its displayed dimensions, so you're using as few resources at the moment of playback as possible. The more pixels you send QLab to work with, the more work it has to do with them, so large scaling operations can lead to unnecessary performance issues.

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luckydave

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[Marc Beth]

One image. Very large, with tight zoom, camera panning. It seems that the size of the image might be the issue. That's a shame, because I wanted to have a smooth transition, without crossfades.

[luckydave]

Is the image larger than necessary though? If you're scaling it down to 50%, try pre-scaling the image, and leaving the scale in QLab at 100%. That way, QLab doesn't have to throw away half of the pixels each time it renders one frame of the animation.

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luckydave

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[Marc Beth]

I tried a few things. I scaled it down, but kept some scaling in the cueing. No help. Then, I scaled the image LARGER, but took out the QLab scaling, and it fixed it. I was able to use rotation and translation even, and no issues. I still wish I could do some scaling to simulate camera zoom, but I'll take this.

[luckydave]

What kind of Mac are you using? It's possible you're just asking more of your graphics card than it's capable of.

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luckydave

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[Marc Beth]

Specs:

MacBook Pro 2016

2.7 GHz i7

16 GB RAM LPDDR3

GFX: Radeon Pro 455 2048MB, Intel HD Graophics 530 1536 MB

[luckydave]

That should be sufficient for quite a lot of video work. What are the pixel dimensions of your image?

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luckydave

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[Marc Beth]

Current image that works is 7000 x 5497. This one works, with no scaling. As small as 2000 x 1400 did NOT work with scaling.

[luckydave]

What version of QLab are you using? You can find the version number in the About QLab window, from the QLab menu. The current version is 4.1.1, so if it's anything less than that, check for updates, also from the QLab menu.

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luckydave

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