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Video Sequence Editor playback is choppy
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My System is

Manjaro KDE Edition (17.1.12)

Ryzen 1600 @stock
GTX 1060 6GB @stock
16GB Corsair Vangeance Ram @stock 3000MHz

Blender Version
Broken??: 2.8 Hash (6b551c0b8cb)
Worked: 2.79b Hash (32432d91bbe)

Short description of error

I can't get the Video Sequence Editor (2.8) to run smoothly its always full of hickups.

Exact steps for others to reproduce the error

I Just open a new instance of Blender 2.79b go to "video editing" import the (my first animation) file i attached and it plays without hickups from the beginning.

Now i do the same exact steps in Blender 2.8 and i can't get it to without hickups. In addition to this, it seems like the Memory usage increases with every play and pause i do by around 20-30 MB so like you can see on my screenshots, i reached 5GB in no time and its still choppy.

Event Timeline

Kolton Yager (kjy) added a comment.EditedSep 12 2018, 2:42 AM

Can you confirm whether or not 'AV-sync' is on or off in both versions? The default is different in 2.8. Turned out not to be relevant

I believe I've tracked down the root cause of the performance loss. Instead of just building the movie cache when loading frames it also caches frames into the color manager cache, adding greater delay and significantly increasing memory footprint. The memory limit is reached quickly causing the sequencer to thrash. Overall movie cache misses are more common and more problematic.

The key condition at fault here is the ColorManagedLook for the image buffer, which is currently "Filmic - Base Contrast" and has process_space = "Filmic Log" on the 2.8 branch. In 2.79 the value is "None" with process_space = "" which allows skipping color management caching.

I'm new to Blender Dev so I don't have a strong understanding of the color management code, or what changes are being made to it for 2.8. As such I'm not certain if this is a bug or just a side-effect of a WIP, and I can't make a informed patch. I'll continue looking into it and submit a patch if nobody more experienced picks this up first.

Sven Sahlmen (Cyii) added a comment.EditedSep 12 2018, 12:17 PM

I hope this is easy fixable.

And i did check the Sync mode in Both releases, in 2.79b it was active and in 2.8 i did play with all the options in the playback menu on the lower left. nothing helped.


Sergey Sharybin (sergey) triaged this task as 30 priority.Oct 29 2018, 4:23 PM

@Sven Sahlmen (Cyii), is is still an issue with latest builds from buildbot? If so, please share simple .blend file, so we see your settings.

So far, doing factory startup, then creating new VSE project and adding single video strip there stays at 24 fps for me.

hey there, yeah it seems like im doing something wrong.

im back from Manjaro to Win10.

same video file and nothing else.

i open the latest blender build (downloaded 5 minuts ago), and i have the same problem. different OS different driver.

Bastien Montagne (mont29) raised the priority of this task from 30 to Normal.Nov 22 2018, 11:41 AM
Sergey Sharybin (sergey) changed the task status from Unknown Status to Unknown Status.Jan 23 2019, 1:11 PM

There are couple of things which leads to slow playback in this file:

  • Color management set to Filmic
  • Time sync to set to something different from No-sync.

The former one requires extra processing power to convert sequencer result to a correct display space. The latter one makes it hard for frame cache to hit same frame again after the full playback was done.

We've now changed color management to default view for video editing workspace, which should solve performance for the newly created files. For the existing ones either disable Filmic or set Image Display Method in viewport settings to GLSL (this will work fine for your configuration, but will cause slowdown when high-res HDR images are used).

Surely, there are a lot of optimization we can do here, but it is not considered a bug. So thanks for the report, but closing it now.

This comment was removed by Brecht Van Lommel (brecht).