[FFmpeg-user] Split convert MOV files to left and right wav files.

Tim Nicholson tim.nicholson at bbc.co.uk
Thu Dec 8 13:08:11 CET 2011

On 08/12/11 04:02, Ron Novy wrote:
> Hello, my name is Ron.  I'm new to FFmpeg and the mailing list and I've been having a little trouble.  I've been trying to split audio out of some MOV files using the latest windows version of FFmpeg.exe, but it is not working.  Can someone tell me if I'm doing something wrong or if it's a bug or something that just isn't implemented?
> It works with WAV files like this...
> ffmpeg -i "0001f3.wav" -map_channel 0.0.0 "0001f3-0.wav" -map_channel 0.0.1 "0001f3-1.wav"
> But when I use a MOV file instead I get two stereo wav files where the left and right input were mixed together into both channels (also tried with -ac 1 but that just mixed both channels into one).
> ffmpeg -i "0001f3.mov" -map_channel 0.1.0 "0001f3-0.wav" -map_channel 0.1.1 "0001f3-1.wav"

Hmmm I think you need the -ac 1 to get a mono wav otherwise you will get 
stereo as indicated by:-
> [...]
> Output #0, wav, to '0001f3-0.wav':
>    Metadata:
>      major_brand     : qt
>      minor_version   : 512
>      compatible_brands: qt
>      creation_time   : 1970-01-01 00:00:00
>      encoder         : Lavf53.24.0
>      Stream #0:0(eng): Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, 2 chan
> nels, s16, 1536 kb/s

However I agree that what you seem to get is a mono mix of both channels 
instead of the expected.

As a work around you could try:-

ffmpeg -i "0001f3.mov" "stereo.wav"

followed by

ffmpeg -i "stereo.wav" -map_channel 0.1.0 -ac1 "0001f3-0.wav" 
-map_channel 0.1.1 -ac 1 "0001f3-1.wav"


This e-mail (and any attachments) is confidential and may contain personal views which are not the views of the BBC unless specifically stated.
If you have received it in error, please delete it from your system.
Do not use, copy or disclose the information in any way nor act in reliance on it and notify the sender immediately.
Please note that the BBC monitors e-mails sent or received.
Further communication will signify your consent to this.

More information about the ffmpeg-user mailing list