[FFmpeg-user] Optimized workflow to create video from blender output ?

[tuxic at posteo.de]

Hi,

I have a longish animation, which - when rendered - a great amount of
*.pmg images.
In a second step with ffmpeg I create a mp4 video from those images.

When I correct - say - the video sequence of frame 1000 ... 1120
nonetheless I need to recreate the video from _all_ images and not 
only from those, which I recently rerendered.

Is the following possible - and if yes - how:

Suppose I have rerendered frame n to m.

Take the previous and cut in in three parts:

Part 1 consists of frame 1 - (n-1)
Part 2 consists of frame n - m
Part 3 consists of frame (m+1) - last frame

Create part 2* from the newly randered images (frame n - m) 

Join Part 1, Part 2* and part 3.

Is this possible and how is this possible with ffmpeg?

Cheers!