[FFmpeg-user] Question about audio

[Stan Defawes]

Hello,
Is it possible to convert à video stream (an mpeg1 stream in this case) and exclude the right audio canal ?
I would like to conserve only  the left  audio canal and put it on the two canals in the result stream ??
I search in -map direction but with no result and i'm not a specialist of ffmpeg command's line :)
Thanks a lot for your help and all apologizes for my bad english

Stanislas