[MPlayer-DOCS] [PATCH] merge Rich's cropping and scaling tips into mencoder.xml

[Guillaume Poirier]

Hi,

On 4/20/05, The Wanderer <inverseparadox at comcast.net> wrote:
> Only one actual improvement to suggest, but a few other comments.

Hey, that means I'm getting better at this job, doesn't it? :)


> Guillaume POIRIER wrote:
> 
> > +Recall
> > +from the previous section that the final picture size you
> > +encode should be a multiple of 16 (in both width and height). This can
> > +be achieved by cropping, scaling, or a combination of both.
> 
> Random question: is there any particular reason for the linebreak after
> the first word here? It's not actually important, since it'll disappear
> in the *ML rendering, but it seems slightly odd.

Yes, you're right. I'll fix that.


> > +  As you can see, rows and columns of the image naturally come in pairs.
> > +  Thus your crop offsets and dimensions <emphasis>must</emphasis> be
> > +  even numbers.
> > +  If they are not, the chroma will no longer line up correctly with the
> > +  luma.
> > +  In theory, it's possible to crop with odd offsets, but it requires
> > +  resampling the chroma which is potentially a lossy operation and not
> > +  supported by the crop filter.
> 
> Similarly though less strangely here, the line breaks will disappear; I
> wouldn't bother mentioning it anyway, since it looks to be an
> (unnecessary but unobjectionable) extension into the XML docs of the
> man-page technical requirement that sentences begin on new lines, except
> that - as in the place quoted above - there are other places where new
> sentences begin without corresponding line breaks.

Yeah, my understanding of the formating rules in docs doesn't say you
have to start new sentences on a new line. However, I think it looks
better this way (so makes the job of working on the XML doc nicer),
and it should have the merit that if someone reworks just one
sentence, the diff should be smaller than without line breaks after
every sentences.


> > +  Then, test the values you get with <application>MPlayer</application>,
> > +  using the command line <option>cropdetect</option> printed, and
> > +  adjust the rectangle as needed.
> 
> I'd suggest "using the command line which was printed by
> <option>cropdetect</option>", in order to reduce awkwardness.

Ok


> > +  As stated earlier, when cropping, you'll want to increase the y-offset by
> >    half the difference of the old and the new height so that the resulting
> >    video is taken from the center of the frame. And because of the way DVD
> >    video is sampled, make sure the offset is an even number. (In fact, as a
> 
> As a mostly unrelated note, I'd recommend the form "Y offset" in
> instances such as this; it doesn't have to be done simultaneously, but I
> think it works better.

Ok.

Thanks The Wanderer, I'll commit this proofread patch ASAP, at noon probably.

Regards,

Guillaume