Operating system: Ubuntu 18.04.3 LTS
Graphics card: nVidia GM204GL [Quadro M4000]
Broken: 2.80, downloaded today from blender.org
Short description of error
When rendering a movie strip in the VSE, the render time for each frame gets progressively longer.
Here is a graph of the render time for a simple h264 file loaded in the VSE, and re-exported as another h264 file with some minor transforms (crop and scale)
This pattern seems to indicate a form of reset happens regularly. Upon inspection, these discontinuities happen for each I frame found in the h264 source. Therefore I assume that for each rendered frame, the image is reconstructed from the previous I frame, which requires evaluating each intermediate B and P frames. Is there any way to cache these frames ?
If we can't fix this, we may want to add to the wiki that you can get a very significant speed increase by encoding input files as motion jpegs, or at least reducing the time between I frames.