Green screen processing speed

Support Compositing and Post Processing
1

I love to use Blender for VFX stuff (spare time / hobby level).

But when for example doing a greenscreen keying, it can take very long time to “render” the movie->node->movie process, where node is just the keying node and there is no 3D rendering at all.

Im not sure where the bottle neck is or if its just the way “it is”. I know keying from other video editor software is a pretty fast realtime process, but it takes ~3-4 sec / frame on my setup (very much depending on output format).

Is there any speed tips I can use, to make the compositor run faster ? Or maybe just to profile witch stage takes most of the time to process.

Sincerely Per

2

There are ways to optimize the compositor’s processing. But keying should not be very slow. If your source is a movie file try converting it to an image sequence first. As the movie decompressing can take memory and time. Also play with the Properties window Project > Performance panel. Tile size can have a significant impact on render speed (multiples of 64).

3

I do work on the .MOV or .MP4 directly but export as .png image sequence. I will try the sequence as input.

with size, do you mean frame size ? … its 1080p (which is not divideable with 64)

4

Oh ok, the tile size in the render panel. Perhaps divisible by render output might be better? Sometimes a larger compositor tile works faster.

5

I did some more experimenting. Most of the time is actually spend on writing output files. I turned compression of PNG to 0 and that really sped up the processing. I get around 1 fps processing now, which is acceptable.