Mailing List Archive: 49091 messages
  • Home
  • Script library
  • AltME Archive
  • Mailing list
  • Articles Index
  • Site search

[REBOL] Multimedia quality (was) One disk OS + REBOL Re:(8)

From: holger::rebol::com at: 25-Aug-2000 16:42

On Fri, Aug 25, 2000 at 08:03:16PM +0200, [g--santilli--tiscalinet--it] wrote:
> That's platform dependance. If REBOL/View was designed with the > Amiga chipset in mind, it would probably be quite different and > would be fast on the Amigas, but not really fast on the other > systems. It was instead designed with an abstact system in mind; > probably that was too abstract, and /View is using only a little > of the power of our computers.
REBOL internally keeps data in 32-bit chunky format (image! datatype). This is efficient on pretty much every hardware architecture, with the exception of the somewhat obsolete planar bitmap format the Amiga chipset uses. Planar bitmaps were great in the late 80's when it was important to use as few bits as possible per pixel (fewer than 8 typically), in order to achieve high resolutions with little memory. Things have changed since then though, and today everyone is using 8, 16, 24 or 32 bits per pixel. For that chunky formats are more efficient, in particular when manipulating individual pixels. What makes REBOL/View relatively slow on Amigas with the native graphics chipset is the necessary chunky-to-planar conversion. We are using optimized Assembler code for that, but it is still a bottleneck. On Amigas with graphics boards REBOL/View is reasonably fast (often faster than under Unix/X running on the same hardware). REBOL/View cannot directly use planar bitmaps for its internal images, not only because that would require some rewrites, but also because the up to 8 planes the Amiga hardware supports would not be sufficient to support the various effects View provides (blending, colorization etc.). Those effects need to operate on 32-bit images throughout, and quantize colors down to the requirements of the display hardware only as the last step. This makes chunky-to-planar conversion inevitable. If REBOL stored all internal bitmaps in 8 or fewer bits then errors would add up when processing effects and the resulting images would look "ugly". -- Holger Kruse [holger--rebol--com]