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Old 26 June 2013, 11:46   #38
pandy71
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Join Date: Jun 2010
Location: PL
Posts: 1,546
Quote:
Originally Posted by kovacm View Post
nice. did not know that it use only 2 bitplanes. we should made one nice site about all this stuff!...
Hmmm i think that ST has only 3 video modes, 4 bpl 16 colors, 2 bitplanes 4 colors and mono - 1 bpl? So direct mode corespond to Atari ST 640x200 4 colors is Amiga Hires No Lace ie 640x200(256 on PAL) with 2 bitplanes and CPU have all own cycles available.

Quote:
Originally Posted by kovacm View Post
on ST there is no CPU time left (almost) while displaying Spectrum512 images. you are saying that same thing is with Amiga?
Same on Amiga. Same CPU, same bus limitations, slightly lower clock compensated by less power hungry tasks performed by HW.

Quote:
Originally Posted by kovacm View Post
btw this is offtopic but: what about PCHG animation/video? is anybody done this on Amiga?
Possible technically, probably no one is even interested as we can use HAM (at worst case SHAM or PCHG HAM).

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But as there is no good conversion software then HAM is far from perfect. On AGA all efforts was made to make real time transcoding ie not preconverted but convert on the fly (with decoding) video from different formats (such as MPEG and similar).

Quote:
Originally Posted by kovacm View Post
on Atari STe, Mr. Petari made 50fps video playback from CF Card connected to ROM port.
Video is up to 416x228px, 48 colors per scanline, 50fps for flickering and additional perceptual colors (30000). Speed of CF card ROM port adapter is more than 3.5MB/s(!) but for video and sound 2.4MB/sec is enough.


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Same rule as previously and obviously when you use temporal dithering there is no 50fps also cinema source (film) is 24 fps - no reason to push over this especially that Amiga can change vertical frequency easily and create 24/48 fps modes to render such video without time jitter.
In case of Amiga - CHIP BUS seem to be limit - absolute maximum is hires 4 bpl, AGA is much better on this.

Quote:
Originally Posted by kovacm View Post
btw2 do you have some reference that palette changing trick for displaying images are made on XL or C64 prior 1987.?
Not sure - probably on those time people was focused on different aspects, later temporal dithering and similar tricks was introduced - i think break trough was related to widely variable high quality pictures (scans) mostly as GIF and JPG.

Last edited by pandy71; 26 June 2013 at 11:56.
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