[MPlayer-users] advice on mencoder options

[D Richard Felker III]

On Tue, Nov 18, 2003 at 06:31:11PM +1300, anton wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> 
> Thanks heaps so far, just a few more qs...
> OK, so lets say I'm a stingy B'stard and I want to scale. What is the 
> best scaling to use? I see there is -vf scale=... but there is also -x, 
> -y and -xy, and afaict this can be used in tandem -zoom. The Digilander 
> artiticle also mentions that -sws should be used to improve the quality 
> of the scale. Frankly I'm lost. I would have thought that there would 
> have been a good reason to keep the aspect ratio, but that is on the 
> assumption that a movie is just frames full of pixels one after another, 
> which .avi and .mpeg are clearly not. I used to use vidomi and that had 
> an option of scaling by percent. I thought that that is what the -xy 
> did, but that was from reading the man pages from 0.90 or 0.91. 1.0pre2 
> baffles me! Is there an equivalent to scaling by percent? If so is there 
> any point? Can I just scale to 640:360, regardless of whether the source 
> is 4:3 or widescreen? I realise I can show the movie in other aspects so 
> maybe I should just do my own percent scale? (remembering to leave it at 
> /16...)
> This is genuinely a case of me being a dumbarse newbie, and not lazy. I 
> have read all I can find...

You should always crop all black borders _entirely_ and scale the
movie so that the final dimension are both multiples of 16 and so that
pixels are close to square (i.e. so width:height ratio in pixels is
close to the actual width:height ratio). Use -vf scale rather than the
weird -zoom/-xy syntax because it gives you more control.
DOCS/tech/encoding-tips.txt may be helpful, but some of it is
inaccurate or outdated. I'd especially recommend ignoring the parts I
wrote about vlelim/vcelim, or at least using much lower values than I
suggested there...

Rich