[MPlayer-users] setting aspect after encoding

[Corey Hickey]

D Richard Felker III wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> On Tue, Jun 10, 2003 at 02:31:40AM -0400, j.a.l wrote:
> 
>>[Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
>>while encoding i screewed up, setting aspect=1.33 instead of 1.78.
>>is there a way to set the correct aspect ( perhaps by direct write on 
>>.avi offset ) but encoding it again ?????? ;
> 
> 
> What you want is possible, but the work involved in making such a
> program is significantly more than just re-encoding your movie. :)
> 
> BTW, in the future, run your output thru mplayer right after encoding
> begins to make sure you haven't made any obvious errors like this...
> That's what I do, and I catch myself making stupid mistakes all the
> time (and then I get the chance to correct them).
> 
> Rich
> 

To the original poster:
In the future you might want to just rescale the video so it has the
correct aspect without modification. As far as I know, mplayer is the
only player that recognizes the aspect setting on AVI files, and in many
cases compressing a DVD can benefit in quality from the downscaling.

There are two reasons for this. First, if you crop the black borders,
you'll often end up with resolutions that aren't multiples of 16. MPEG-4
encoding works best with multiples of 16 (read
DOCS/tech/encoding-tips.txt), so you'll get a quality increase there.
Second, depending on your bitrate, the resulting encode might be
"bandwidth-starved" and look ugly unless you scale down to values your
bitrate can gracefully handle.

To Rich:
Once I transposed the width and height for -vf scale=, and didn't
notice until my machine had already finished both passes. :)

-Corey