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Old 06 April 2012, 02:01   #2
Amiga will never die!
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Join Date: Nov 2004
Location: Gold Coast, Australia
Age: 37
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Those Sega CD videos were limited to 16 colours I'm pretty sure. You could make a 16 colour CDXL almost full screen and have it playing at the same speed on a CDTV or CD32 too. The reason so many CDXLs are a lot smaller than Sega CD videos is because they're spooling 4,096 colours per frame. You can make and play CDXLs in any Amiga colour depth except 18bit, so with a bit of playing around you could maybe get a full screen video playing at a decent framerate at around 16-32 colours. I've always wanted to experiment with converting a Simpsons episode or something. You can also use the Copper to double the height of a CDXL video. I've made example CDXLs using 4,096 and 256 colours which are 320x80, and are played at 320x160 making them roughly the same aspect ratio as a widescreen movie, and they fill the screen (apart from overscan areas). I've tested them on a real CD32 and they play fine, and I calculated you could fit around 45 minutes of video on a CD if you used this format. So an hour and a half long film could be divided onto two CDs similar to a Video CD, but would be playable on all CD32s, but the film would have to be in 2.35:1 roughly to start with unless you want to crop or shrink the video... or reduce the colours to less than 256.

A colour-mapped CDXL can use a different palette for each frame, so you might get nice results from 128 colours using a good image processing program to convert all the frames with a smart colour-reduction and dithering routine.

I don't know if the 68EC020 would be fast enough to deal with any kind of compression for a streaming video either, but it would be interesting to know if the frames or audio could be compressed slightly if a new format was created.
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