[MPlayer-users] Re: best encoder ?

Karsten Müller kmu at ratio.de
Tue Jul 23 08:36:02 CEST 2002


On Tuesday 23 July 2002 07:14, D Richard Felker III wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]

> If you're going to scale, you *must* deinterlace or you'll get
> *horrible* artifacts. Unfortunately I've seen way too many movies
> encoded this way -- please don't make the situation even worse. If

Ok, I'll try to keep my encoded movies from you ;-)

> you'd like to see a sample movie or even just a screenshot from one,
> let me know. Perhaps this can be fixed with a scaler that treats both
> fields separately, but I've never heard of one of these, especially
> not in mplayer, and I'm not sure the scaler would do a good job
> keeping the image smooth with only every other line to work with.
> Personally I would just recommend scaling down vertically by about
> 1/2, then there's no reason not to deinterlace since you're losing
> half the lines anyway -- no additional "blurring" as you claim.

But scaling down means (visible) losses, right ?

> > > > So, cropping is heard to do automatically, since i have no way to
> > > > analyze pictures :-( Rescaling could be added depending on
> > > > wanted_size and length of
> > >
> > Is the size gain really that much by cropping the bars ? I always thought
> > this would not be much gain ...
> Yes, it's huge. The sharp border between solid black and the natural
> image makes lots of coefficients that shouldn't be there blow up huge
> when you transform to frequency space, and then lots of space is
> wasted on them to keep the border sharp. Technically, if the black
> border starts/stops exactly on a 16 pixel boundary you should be safe,
> but it's much better to crop it.

Oh, *thats* a good explanation... I thought about the "why does it safe
so much space and time" myself without getting to a solution :)

> Also, black borders make it impossible to play the movie on slow
> computers since lots of memory bandwidth is wasted copying nothing.

Agree. And since Mplayer automagically recenters the cropped movie,
there's no problem at all with cropping...

> Rich
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> RTFM!!!  http://www.MPlayerHQ.hu/DOCS
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- -- 
with best regards
- ---
Karsten Mueller
Softwaredevelopment / Keyaccount Manager
RATIO Entwicklungen GmbH
Admiralitaetstr. 59
20459 Hamburg
Email: mailto:kmu at ratio.de

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