[MEncoder-users] mencoder to generate mp4 files for Motorola A1200

[Etienne Buira]

On Fri, Oct 23, 2009 at 07:58:29AM +0800, Zhang Weiwu wrote:
> Hi. To let you get update of what I achieved and for other who followed 
> this thread from Google, here is my "solution".
> 
> On Sun, 18 Oct 2009, Zhang Weiwu wrote:
> 
> > Hello. I am trying to convert DVD to be playable on Motorola A1200.
> >
> > A1200 can see the video format: default support RM, 3gp, MP4.
> >
> > According to the spec,
> > MPEG4 video files： can support 320 to X240, 30fps, 350kbps.
> > 3GP and rm video file to support the 320 X240, 15fps, 350kbps.
> 
> I tried the following can create video playable on the device.
> $ mencoder dvd://01 -endpos 1800 -nosound -ovc lavc -lavcopts vcodec=mpeg4 -vf scale=320:240 -o movie.avi -ofps 25
> $ mplayer -vo null -endpos 1800 -ao pcm -af resample=8000 dvd://01
> $ ffmpeg -i movie.avi -i audiodump.wav -b 48 -ac 1 -ab 12200 -map 0.0 -map 1.0 movie.mp4
> 
> However I am afraid I compressed the video twice, once with mencoder, 

Indeed, you are encoding twice.

A way to avoid that is to specify the appropriate bitrate at the
mencoder step, "-lavcopts vcodec=mpeg4:vbitrate=48".
To get a better quality, you can also use two-pass encoding (one pass
with -lavcopts vpass=1, discard output, second pass with -lavcopts
vpass=2) if your player supports it (you might also want to look at
vrc_maxrate if you go 2 pass).

Also, please check ffmpeg's output, as -b option takes a number in
bits/s, not kbits/s.

> once with ffmpeg. If I use 'ffmpeg -vcodec copy' to avoid second round 
> compression, the resulting .mp4 file is big, 150MB for 1800 seconds, 
> which is okay to me, but not possible to playback on mobile phone. The 
> realone player simply say something like parameter is not ok. (in 
> Chinese)
> 
> This doesn't look like a perfect solution, I might follow up with a 
> better one when I have.

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