[MEncoder-users] ffmpeg vs. mencoder with libavcodec

[Gary Steele]

On Sat, 17 Dec 2005, Oded Shimon wrote:

> Uhh, that can't be right...
>
> $ mencoder tv:// -lavcopts vcodec=mpeg4v2:vbitrate=50
> ...
> Cannot find codec 'mpeg4v2' in libavcodec...
>
> Either way, you should use 'mpeg4', I find it very odd that the ffmpeg site
> reccommends otherwise. 'msmpeg4' and 'msmpeg4v2' are crippled, lower
> quality versions of mpeg4. You should never use them.
>
> P.S. Please don't top-post
>
> - ods15

To clarify the issue a bit, I'm stating that this is _not_ a codec 
issue: if I use the _same_ codec with the same settings with mencoder 
and ffmpeg, I get vastly different outputs. This is not particular to 
a given codec: it happens at least with both the mpeg4 and msmpeg4v2 
codecs. For example:

MPEG4 codec:

ffmpeg -r 25 -b 50 -i %03d.jpg -vcodec mpeg4 output_ffmpeg.mp4
ffmpeg -r 25 -b 50 -i %03d.jpg -vcodec mpeg4 output_ffmpeg_mpeg4.avi
mencoder "mf://*.jpg" -mf fps=25 -o output_mencoder_mpeg4.avi -ovc lavc -lavcopts vcodec=mpeg4:vbitrate=50

msmpeg4v2 codec:

mencoder "mf://*.jpg" -mf fps=25 -o output_mencoder_msmpeg4v2.avi -ovc lavc -lavcopts vcodec=msmpeg4v2:vbitrate=50
ffmpeg -r 25 -b 50 -i %03d.jpg -vcodec msmpeg4v2 output_ffmpeg_msmpeg4v2.avi

For the mpeg4 codec with ffmpeg, I used both the avi container 
(incompatible with windows media player on my install: probably a 4cc 
issue, see http://ffmpeg.sourceforge.net/compat.php), and in the 
quicktime mp4 container.

The output files are available here:

http://electron.mit.edu/~gsteele/encode_test/tmp/

In all of the files encoded by ffmpeg, _regardless_ of the codec, 
there are bad blockyness issues that I mentioned in my earlier 
(type-ridden) post. I just want to know why.

I am sorry for the typos in my previous posts: I was mistakenly cut 
and pasted the wrong command line ito the email, and then when I 
replied to correct myself, I made a typo. Sorry.

Regards,
Gary.