Video Streams for 8-bit Commodores
Date: 2001-08-20 06:51:21

Hi All,

Ever since I built Nate Dannenburg QuickCam64 project I've been impressed by
the concept of Video on the C64.

As a result, I looked into ways of enhancing the 80x50 multi-colour
character mode Nate used so that it facilitated greater colour choice whilst
keeping bandwidth low. 

After working on this for about a year now (in the background to other
projects) I'm releasing both the proposed format specification and a MSDOS
tool for converting and displaying AVI files in the new Commodore video

The lowest spec video mode has a bandwidth of 1kb per frame and has a
palette of 4 fixed colours - ideal for greyscale as Nate did. The highest
spec video modes that I think can be generated provides 3 colours fixed for
each "row" and another colour per 2x2 region (one colour RAM location).
Using raster based changes to the $D021-$D023 registers and interlacing the
colour palette is increased. The high spec mode would need 2.2kb per frame.
In both cases the video data could be streamed using a parallel file system
or REU (for short animations).

I'm proposing that audio is handled as CD-Audio streams using mixed mode
CD-ROMs so as to avoid bandwidth problems with a 1MHz machine having to
process both audio and video. This should work with CD-ROMs fitted to CMD's
HardDisk, IDE64 and 64HDD. One CD should hold about an hour of video/audio
data. The video stream includes single channel SID sound data and some
control coding.

I would appreciate comments regarding the format specification. If anyone is
interested in assisting in writing the playback software for a C64 or any
other CBM machine, your help would be greatly appreciated. 

I'm not a C64 graphics expert so any help in identifying where I've
stretched the capabilities of the C64 "too far" would be appreciated.



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