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I'm attempting to use Blender as a precision video editing tool. I have a few dozen short videos recorded with NVidia's screen recording software. Ostensibly (according to NVidia), they are all recorded at 30 FPS, and each one plays back correctly in VLC.

About half of these videos behave correctly in the video sequence editor of my 30 FPS project. I can scrub from one frame to the next in Blender, and each frame of the video clip appears correctly in the preview (and when rendered).

The other half behave quite oddly when scrubbing and rendering. It's as if every even frame appears twice, and the odd frames are skipped.

This is not exactly what's happening, but that's what it seems like. Certain frames are duplicated, while adjacent frames are skipped.

This causes the affected clips to render out slow and choppy. Anyone have any suggestions for a remedy?

My sincere thanks for any insight,

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  • $\begingroup$ I'm willing to bet that the faulty half of the videos are on another frame rate. Sounds like they were recorded at 24 fps. $\endgroup$
    – LetTheWritersWrite
    May 23, 2017 at 3:51
  • $\begingroup$ Thanks for the idea! Tried this out, but got the same issue. Exacerbated, if anything.. Again, ostensibly, they should all be the same (recorded with identical parameters), but who knows what NVidia's up to behind the scenes. $\endgroup$
    – AlwaysSunny
    May 23, 2017 at 4:14

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Blender is very picky about source codecs. Try creating a proxy with timecode (bottom VSE Clip menu). You could also try turning on MPEG preseek in the Strip Properties menu by entering a frame value higher than 0. This enables Blender to cache a portion of the source making it easier to decode. It may slow performance of playback

If that doesn't work try converting the media to a codec that Blender prefers. Make sure that the codec that you use has a fixed frame rate. Variable frame rate screen captures will fail.

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  • $\begingroup$ Thanks a ton for the quick reply! No dice, unfortunately. Can you elaborate on the idea of a superior / preferred codec? Windows properties says the files are mp4's, though I'll go on a limb to assume that may not tell the whole story. Hopefully Handbrake can rescue me. $\endgroup$
    – AlwaysSunny
    May 23, 2017 at 4:09
  • $\begingroup$ Screen captures are often recorded at a variable frame rate which Blender does not like. Try converting it to a fixed bitrate fixed frame rate mp4. The file will probably get a fair bit larger. $\endgroup$
    – 3pointedit
    May 23, 2017 at 4:25
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    $\begingroup$ I was made a fool of by NVidia's FPS selection dropdown of lies. Enforced a fixed framerate in handbrake and it's working like a charm. What a happy trip to Stack Exchange this has been. You're my hero, stranger! $\endgroup$
    – AlwaysSunny
    May 23, 2017 at 4:32
  • $\begingroup$ MP4 can be encoded in a multitude of ways, problems in blender can be caused by variable framerates or using Long GOP (as opposed to intra- frame). $\endgroup$
    – user1853
    May 23, 2017 at 4:49

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