[FFmpeg-devel] Suggestion of append alternative when partial result file already exists

[LinAdmin]

Unless you have a very powerful machine, encoding a 2 hour 
film may take 40 hours. It must run continuously and in case 
you are forced to interrupt the process, it becomes 
difficult to append to the work already done.

When you start encoding using something like
    ffmpeg -i input.mp4 -map 0:0 -map 0:1 -c:v libx265 -c:a 
copy output.mp4
and reuse that same command when part of output.mp4 is 
already present, ffmpeg asks the question
"output.mp4 already present, overwrite y/n".

It would be helpful if the question could be improved to:

"output.mp4 already present, append or overwrite a/o".

It is evident that appending would only success if creation 
of the existing partial file was stopped in a 'normal' way, 
e.g. by pressing CtrlC for the encoding process.

I am convinced that many users of ffmpeg would be very happy 
about this possibility.
Many thanks for your good work with ffmpeg!

LinAdmin