On this page https://kdenlive.org/en/2020/05/kdenlive-20-04-1-released/?unapproved=3668&moderation-hash=ccd40a2c8cb321e6d29602f2042884e2#comment-3668 people (including me) have a problem creating proxy files from .MTS sources.
Here is a quick workaround:
I stumbled across this too these days and as an intermediate workaround I created a file with the line

Code: Select all

#!/bin/bash
ffmpeg -sn “$@”
exit $?


Make sure you chmod +x /path/to/script

In the setting of kdenlive, under “Environment”, you replace the value for ffmpeg (which should read like “/usr/bin/ffmpeg”) by the full name of your file (i.e. /path/to/script )

Worked for me.