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2.80 Backround Clip Problem
Open, Needs Triage by DeveloperPublic


System Information
Operating system: Windows 10 64 bit
Graphics card: Nvidia GTX 1060 256 bit 6 GB

Blender Version
Broken: (example: 2.80, edbf15d3c044, master, 2018-11-28, as found on the splash screen)
Worked: (optional) Blender 2.79b

Short description of error
While you're camera tracking or matching your clip with your cg element you need a decent frame rate to work with to be able to get the best feedback from your footage however in Blender 2.80 (the final built) when you add a clip the fps is not going above 15 fps( or simply is not making up for it's fps limit which was 29.97 for me with a basic scene had no more than 1k polygons) for me and it's just becoming so much harder to match the cg element with the playing clip whose base fps is 29.97. I wanted to try this with the older 2.79 built and though it worked butter smooth I've noticed something: Blender 2.79 seems to be baking its animation keyframes to some kind of a cache. While the fps wasn't that great at the first place just like it was in Blender 2.80, after finishing playing the clip till the end, it kept playing it at it's maximum fps limit which was 29.97 and i was able to get a perfect feedback out of it. I think it's some kind of a bug in 2.80. I looked for the settings to see if there were any animation caching settings but i couldn't find such a thing. Hope it'll be fixed soon.
Exact steps for others to reproduce the error
Just add a clip to your camera and see the playback fps in 2.80.



Event Timeline

Appears to be working for me. Are you stuck on 15 fps even on the default scene, when you add the background clip?

Appears to be working for me. Are you stuck on 15 fps even on the default scene, when you add the background clip?

Exactly, even with a fresh startup when I add a clip it doesn't live up to the fps that I've set in the output settings. I tried using the playback options
such as av sync and frame dropping but it was the same. In addition to that I thought the problem could be related to my preferences and restored them to their factory settings but still no luck :(

PS: I tried to add a different video clip other than my own camera's and it worked! i tried adding a video that i had downloaded from youtube a while ago and it was able to play it to its max set fps. I'm encoding my camera footage now and will try with the encoded video clip and see if it works as well. If that works the problem might just have been related to my footage actually. I'll let you now.

I think i finally debug this. The issue was due to the clip resolutions. If the clip is 1080p you'll get stuttering and most likely will stuck with low fps count but when you use 720p (basically any resolution lower than 1920x1080) you get more than 29 fps but again you can't go beyond 46 fps this time. (I believe this may change depending on your CPU threads) So i'm guessing the more resolution you have the more processing power it takes and as a result you get a low frame rate. I still think this shouldn't be the case and blender should be able to run smoothly at 1080p as well. My problem is kind of solved here because I'll be comfortable to work with 720p+29fps. That's enough for my scenery but I think someone should look over to this subject since blender is planning to go more pro with the upcoming updates, optimizing this would be a major ease when it comes to match moving btw. thank you for your interest @matc (matc) :)

Maybe Proxy Render Size does work out for you. You can build proxies from the Movie Clip Editor.