[Scummvm-devel] BS2 cutscenes

LavosSpawn LavosSpawn at scummvm.org
Tue Jan 6 05:06:00 CET 2004


whoups. just noticing I sent a mail to andreas mail account instead of the
mailing list.
well, again.

as mpeg is a lossy compression, based on YCbCr color space and discrete
cosine transformation, it outputs a variety of different colors which are
more or less close to the original ones.
It'd take a hell of arithmetics to force a given decompressed image into a
256 color palette again. I think it's impossible and those handheld devices
are nowhere near the necessary CPU time.
Besides, it's taking the point out of using mpeg compression from the
beginning.
We'd even have to use very high bitrates for the mpeg encoding to have the
playback colors accurate enough to do a transformation back to 256 colors.

----- Original Message ----- 
From: "Andreas Röver" <andreas_roever at web.de>
To: <scummvm-devel at lists.sourceforge.net>
Sent: Tuesday, January 06, 2004 1:42 PM
Subject: Re: [Scummvm-devel] BS2 cutscenes


> I've been thinking about this problem a bit:
>
> You have to convert the pixels from the mpeg color space to RGB anyway. So
you could instead
> directly convert to a palette index. Using predefined lookups this should
be just as fast, or even
> faster then converting to RGB. The palette must be predefined for each
movie. It should even be
> possible to change the palette in the middle of the movie. I need to have
a look at them to see if
> this is necessary.
>
> Anyway: this way you have the advantages of mpeg: one can treat quality
for size very easily. And still use the normal backends without a change.
>
> I'm currently trying to write some proof of concept code to see what it
looks like. I'll mail again once it's finished and looks ok.
>
> Andreas
>
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