I am trying to speed up the video on a 17 minute (2.1GB) clip I recorded on my phone (29.97 FPS, 1920x1080, total bitrate >17000 kbps in case it matters).
I selected the video strip, then did
Effect Strip ->
Speed Control, and from the speed strip's
Effect Strip configuration, I have tried both leaving
Stretch to input strip length checked and setting
Multiply Speed: 10.0 and I have tried unchecking the checkbox and setting
Speed factor: 1.0,
Multiply Speed: 10.0. In both cases, when I preview my updated settings and when I try to render a portion of it (around 30 seconds) to a video, the output is still the original speed.
However, I tried doing the exact same process on a different video clip (same framerate, resolution, and bitrate) that is only ~30 seconds long (50MB), and it works as I expect.
Using Blender v2.79 on Windows, is there something I need to do differently to edit larger files like this? Or is there some preprocessing I need to do to the file?