I've been working all the day long on a video project using the VSE. I am using very low def footage (720 x 406). The editing was mainly finished and Blender was working fast (playback 24fps).

Then, suddenly, it became incredibly slow (4 sec for one frame). I saved, reboot, open it again but still the same. When I open an other project, even an heavy one, everything's fine. But this one keep bugging the rendering.

Any idea why ? A solution ? Thank you very much !

  • $\begingroup$ Actually, it's not the rendering that is slow. Even when I don't have any preview area, moving the green bar on the VSE timeline take hours... $\endgroup$ – Nikos_VSE Sep 14 '14 at 17:25
  • $\begingroup$ I am rendering the movie now, the CPU is working at 25% only and I still have plenty of memory available... yet... slow like hell ! $\endgroup$ – Nikos_VSE Sep 14 '14 at 17:42
  • $\begingroup$ What steps did you do before it started slowing down? Did you add an effects strip? another video track? $\endgroup$ – sambler Sep 15 '14 at 11:19

Try the button refresh sequencer at the bottom of the vse timeline. Otherwise it maybe a curruption of a strip or its animation? Are you using fcurve key frames as they might have gone wrong.

Could you try copy and paste out sections of your edit to another scene. Then save it without the other scene. Maybe you can isolate the offending strip?

edit: my suggestion assumes external source media.

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  • $\begingroup$ Well I tried copy past small amount of strips to an other scene, but i took hours and crash half the time... but I finally succeed in confronting the offender ! It was a corrupted color strip ! Can u believe it ? Thanks for your suggestion, it solved the issue ! $\endgroup$ – Nikos_VSE Sep 16 '14 at 3:53
  • $\begingroup$ @Nikos_VSE If you think that is a bug, please consider report it here, so that devs can help to fix it. $\endgroup$ – Leon Cheung Sep 16 '14 at 4:10

Some other suggestions for VSE performance enhancement:

  • Convert your video into image sequence (e.g. PNG), then reload them to VSE to replace the original video strip, which can solve many unknown problems caused by codecs.

  • Use Proxy to speed up even further.

  • If you are using scene strips, it is highly recommended to toggle Open GL Preview (from the properties of the preview) for faster real-time preview.

  • You can also consider setting priority for Blender process (e.g. in the task manager / resources monitor utility of your OS), which is generally not recommended unless necessary.

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  • $\begingroup$ Thanks for all this smart suggestions Leon. My project is made of hundreds of little pieces of video, so I can't really convert them all without re-editing the whole thing, which is OUT of question ! ;-) $\endgroup$ – Nikos_VSE Sep 16 '14 at 3:45

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