FFMPEG: get right-channel audio out of both speakers?

[Coruscant]

About two or three months ago, the left-channel audio input cable slipped out of my capture card and I didn't notice until yesterday. That means quite a few recordings have audio coming out of just the right-hand speakers. The left channel is completely silent.

Is there a command line in FFMPEG that would, without having to re-encode the AAC audio, make right audio channel (0.1.1) sound come out of both left and right speakers?

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'recording.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
encoder : Lavf56.15.102
Duration: 00:24:42.74, start: 0.000000, bitrate: 10144 kb/s
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 9951 kb/s, 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc (default)
Metadata:
handler_name : VideoHandler
Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 185 kb/s (default)
Metadata:
handler_name : SoundHandler

[Baldrick]

I'm pretty sure you must reconvert the audio.

See https://trac.ffmpeg.org/wiki/AudioChannelManipulation

Maybe just right channel to left

ffmpeg -i video.mp4 -c:v copy -c:a libfdk_aac -b:a 128k -map_channel 0.0.1 newvideo.mp4

[jack616]

I dont know if this is any help but I worked it out lastyear (dont ask me to explain I totally forget how I did it except I read the docs for ffmpeg!)
It is a .bat file for dos - you would need to adjust the path setting and codec.

@echo off
echo .
echo path to ffmpeg is set 
echo enter .MKV file name containing single mono audio track and video track
echo  this will duplicate the audio track allowing winff to convert to ac3 audio
set path=%PATH%;n:\dlprograms\ffmpeg\bin;

ffmpeg -i %1 -f lavfi -i " amovie=%1:si=1 [a1]; amovie=%1:si=2 [a2]; [a1][a2] amerge" -c:a pcm_s16le -c:v copy dualmono.mkv 
echo .
echo done
echo.