[MPlayer-users] probably my usual stupid question of the week

[D Richard Felker III]

On Fri, Apr 16, 2004 at 12:13:31AM -0400, Aaron Peterson wrote:
> well, i think i'm catching on to using mencoder a little bit better the
> more I stay at it.  All the documentation I read says the elequent aspect
> preservation method for mpeg4s only to be used with mplayer is autoaspect
> (-lavcopts).  I haven't explicit instructions anywhere for how to preserve
> aspect for other players.  I'm guessing that -vf scale has something to do
> with that, but I an official recommendation on that one.  I have
> previously used -vf scale -zoom -xy 640 to scale down the size of videos
> i'm encoding, but perhaps I just want to preserve aspect without changing
> sizes?  do i just make the -xy XXX equal whatever the normal width of the
> movie is?  i generally crop as well, and understand that the order of the
> filters for -vf matters.  should crop go before or after scale?

Crop should probably go first. No need to use -xy and -zoom. They're
rather strange. Just use -vf crop=...,scale=w:h and fill in the width
and height to use. There are tricks to get mencoder to compute them
for you, but it won't align them at multiple-of-16 boundaries so
you're best to just figure out the right size yourself. Normally it's
640x272 (2.35:1), 640x288, 640x352 / 640x368 (16:9), or 640x480 (4:3).

Rich