Splitting and regrouping stereo's right and left channels (Stereo to Mono) I have several (rather old) videos of which probably due to an encoding error by their original creator, sound is in stereo, but only coming out of the left side, while the right side stays silent.

I want to split the audio and then copy the left side to the right side (basically turn the whole thing into mono).

I'm using pitivi, but I'm open to suggestions of using another software, as long as it's free and have a Linux version.
Using ffmpeg, a free command-line tool,

ffmpeg -i input.mov -c:v copy -af "pan=1c|c0=c0" out.mov


This copies the video over, and the audio is mono with the first channel of the input mapped for export.

Some players may not be setup to default to a stereo matrix. In which case, you can generate a faux stereo stream.

ffmpeg -i input.mov -c:v copy -af "pan=stereo|c0=c0|c1=c0" out.mov