Hello,
On 31-May-01 Ben Bridgwater wrote:
> Actually I've already implemented such a beast. I have no objection to
> GPLing it
> (that was my general intent), other than the fact that I'm too lazy to
> create a
> web page or put much effort into support. You've shamed me - I'll
> release it.;-)
*heh* Not my intention. But it did wake you up :)
> What I have does pretty much all RGB<->YUV conversions, but all in C
> at this
> point. I define an "Image Descriptor" data structure which defines the
> representation (packed/planar YUV or packed RGB with appropriate
> paramaters such
> as chroma subsampling and r/g/b bpp and component masks) and includes
> pointers
> to the data (with row stride for flexibility). This data structure can for
> example describe all V4L and AVI RGB/YUV formats as well as a TrueColor
> XImage (packed RGB).
Interesting; that´s a bit more information than my proposal has.
>
> The way I've structured it is to allow for individual optimized
> conversions, so
> any of my C implementations could be individually replaced with
> MMX/whatever
> implementations). Since this is intended for use with repeated (video)
> conversions, you first request a converter function (converter =
> GetConverter(imageDesc1, imageDesc2), which internally does a table lookup
> for a corresponding converter), and then use it to perform conversions
> (converter(imageDescIn, imageDescOut).
A few questions beforehand:
- does your library have a dynamic list of convertors, or just a huge matrix?
- can you query all available convertors?
- how difficult would it be to make the selection of the optimized assembly
routines dynamic? That is, during initialization the right code for that
processor is put in the list; I would not want to build different libraries
for different processor subtypes (MMX, SSE, 3Dnow, etc), but rather one x86
library that can be installed on all system.
I picked the x86 platform because that´s where I work on (and program in
assembly as well), but is this the only one that has these kind of
extensions? Maybe the 68000 CPUs have this?
> Gimme a week to procastinate, and I'll release the thing.
I´ll be looking forward to it. In the mean time I´ll try to find out how one
compiles a .so library anyway :)
- Nemosoft
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