[olofsonprojects] Re: kobodeluxe in OpenEmbedded
- From: David Olofson <david@xxxxxxxxxxx>
- To: olofsonprojects@xxxxxxxxxxxxx
- Date: Sun, 10 Feb 2008 18:26:17 +0100
On Sunday 10 February 2008, Robert Schuster wrote:
> Hi David.
>
> David Olofson schrieb:
> > Unless the rotation is implemented in hardware, I'd think it's SDL
> > that does the rotation. If so, that would mean SDL uses an
> > internal shadow surface, and that may well mean that you get a
> > different pixel format or something.
> It is done in HW I think. They support this through xrandr.
Ok... Not sure if SDL can use that, though.
> > Or perhaps there is something wrong with alpha blending in that
> > SDL version...? (That would likely be disabled when a shadow
> > surface is used, as many APIs only accelerate blits to the
> > screen.)
> Looks like it. By using "noalpha" text display worked nicely on the
> Nokia as well as the Neo1973. However it is much slower now.
How much?
Obviously, there is going to be some extra load when the text is
actually rendered, but one would think that disabling alpha would
pretty much make up for it, unless the alpha blending is h/w
accelerated. (It isn't with any commonly used SDL backends.)
Note: Normally, there will be alpha blending on pretty much
everything. All graphics is antialiazed, so there are translucent
pixels around the edges. Filtered scaling adds more of those. Thus,
disabling alpha (uses colorkeying instead) can speed things up quite
a bit in some cases. However, if you're on an API that supports alpha
but *not* colorkey, I suppose it could actually slow things down...
(glSDL translates colorkey to alpha "off-line", but maybe the backend
you're using doesn't do that?)
> > Does it attempt to use hardware acceleration for the blits?
> How can I find this out?
Well, one would have to study the code of the SDL backend you're
using, and then try to find out what the underlying API is doing.
> Now that I changed it to "noalpha" one time, I wanted to make a log
> with alpha and therefore switched back. Interestingly it now paints
> characters. At least somewhat:
> http://scap.linuxtogo.org/files/25385fcb760b269ce797d5e43b67b6c1.png
Interesting... :-D
It sort of looks like what you see there is old garbage or something -
but at least the big font appears to have alpha...
I'm pretty much out of ideas, and I can't seem to make anything like
that happen here. :-/
[...memory mapped audio...]
> On the Neo this may be possible since they have a proper ALSA driver
> for their Wolfson chip. However on the Nokia all sound output is
> done through gstreamer. They patched sdl to do this, too. Their
> reason is that as a gstreamer plugin (which is LGPLed) they could
> keep the codec proprietary ... :(
Ok... :-(
//David Olofson - Programmer, Composer, Open Source Advocate
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