FFmpeg imports mono tracks as stereo[SOLVED]

Audacity Help Forum Windows
1

for saving space and before conversion to AAC by FFMPEG. very easy in principle, looking here http://wiki.audacityteam.org/wiki/Talk:Mixing_stereo_tracks_to_mono_in_your_Project
still, if I save the mono track and re-open it I still se two channels. I cannot fine any oprion which sets the mono bit in the AAC file
If i do the same using the mp3 lame encoder I can see just one track in audacity when re-reading the saved fil
thanks for your help
I am 2.x and W7

2

To convert a stereo track to mono in Audacity 2.x,
Select the track, then “Tracks menu > Stereo Track to Mono”
http://manual.audacityteam.org/o/man/tracks_menu.html#Stereo_to_Mono

3

…for saving space and before conversion to AAC by FFMPEG.

I wouldn’t want a “fake” stereo file, but I don’t think you’ll save space by saving a mono file as mono AAC. AAC uses [u]Joint Stereo[/u] by default, which encodes the L+R & L-R signals separately. With mono, there is no sound in the L-R “channel”, and AAC (and MP3) are “smart enough” not to waste space when there is nothing to encode, so you are only encoding one channel’s worth of information.

4

Update to the currently recommended FFmpeg 0.6.2 ( http://manual.audacityteam.org/o/man/faq_installation_and_plug_ins.html#ffdown ) then it will import mono AAC files as mono.


Gale

5

thanks, it works! and yes, saving mono files will save 50% of space approx (as expected)