[MEncoder-users] output to 3gp with amr_nb

[David Wadler]

I'm having some difficulty generating a 3gp file with amr_nb audio.  From
what I understand, 3gp/mp4 muxing has progressed a bit with mencoder,and it
seems that once I figure out the audio piece, I'll be able to generate a
valid file.  (Please correct me if I'm wrong about this. My plan is to use
lavf.)

Anyway, a problem similar to the one that I'm encountering was raised a few
months ago and apparently solved:
http://lists.mplayerhq.hu/pipermail/mencoder-users/2007-July/006490.html

However, this doesn't seem to work.  The latest build of mencoder has
slightly different syntax -- libamd_nb instead of amr_nb -- which I've
corrected.  I am always gettings errors like this:
[libamr_nb @ 00C97EA0]bitrate not supported: use one of 4.75k, 5.15k, 5.9k,
6.7k, 7.4k, 7.95k, 10.2k or 12.2k
Couldn't open codec libamr_nb, br=8

Here is an example command line:
.\mencoder  -oac lavc -ovc lavc -lavcopts
vcodec=h263p:vbitrate=10:acodec=libamr_nb:abitrate=10 -of lavf -vf
scale=160:120 -srate 8000 -af lavcresample=8000,channels=1  um.mov -o
um-menc.3gp

I've tried many values for the audio bitrate, but with no luck.  I can't
pass in one of the recommended values as the "k" syntax for 1000s and the
decimal throw it off.  (Mencoder expects an integer.)  For what it's worth,
I'm working on Windows and Linux.

Thanks,
David