[MEncoder-users] How to get ".mp3" audio rather than "mp4a" audio?

[Reimar Döffinger]

On Wed, Nov 17, 2010 at 02:58:37PM +0000, Sheppard, Mark wrote:
> On 16 November 2010 19:58 Reimar Döffinger wrote:
> > On Tue, Nov 16, 2010 at 11:12:28AM +0000, Sheppard, Mark wrote:
> > > mencoder 588.wmv -o 588.mp4 -oac mp3lame -lameopts cbr:br=128 -
> > channels 2 -srate 44100 -ofps 25 -of lavf -ovc x264 -x264encopts
> > bitrate=1500:subq=5:8x8dct:frameref=2:threads=auto:global_header:nocaba
> > c:nob_adapt:bframes=0:keyint=50 -lavfopts format=mp4 -vf
> > harddup,scale=1280:720
> > 
> > I can't see any way that would result in a video with mp4a audio.
> > I don't have an mencoder with lame/x264, but
> > -ovc lavc -oac lavc -of lavf -lavfopts format=mp4
> > for me results in a file with mp2 audio.
> 
> The output of the mp4info utility (from http://packages.ubuntu.com/lucid/mpeg4ip-utils) shows the following information for a file that works (i.e. produced before the upgrade):
> 
> Track   Type    Info
> 1       video   H264 High at 3.1, 223.720 secs, 1446 kbps, 1280x720 @ 25.000000 fps
> 2       audio   .mp3, 223.921 secs, 128 kbps, 44100 Hz
> 
> And this for a file that doesn't work (i.e. produced after the upgrade):
> 
> Track   Type    Info
> 1       video   H264 High at 3.1, 201.680 secs, 1422 kbps, 1280x720 @ 25.000000 fps
> 2       audio   MPEG-1 Audio (11172-3), 200.359 secs, 0 kbps, 44100 Hz
>  Tool: Lavf52.64.2
> 
> So my guess is that the "mp4a" bit reported by mp4dump is some extra/diiferent chunk description thing, but the audio is still in MP3 format, which is officially called "MPEG-1 Audio (11172-3)".  It's just that the flash player doesn't understand that and needs the old behaviour of having a file which has a ".mp3" chunk/header/tag/whatever.  Which is why I tried adding the " -fafmttag 0x55" option mentioned in the mencoder man page.  But that didn't help.

Ok, that confirms the suspicion I have from the start.
Flash player obviously does not support the mp4 container format but
only QuickTime/mov. If you use format=mov instead of format=mp4
you should get .mp3 again.