Of course, this is just little experiment and pushing old HW to limits, not for real usage. Watching movies with 16 or 4096 colors and low resolution  is not exactly what we want in 21st century
8MHz CPU is simple not capable for decoding video of some bigger resolution at decent framerate. But we can achieve smooth motion of 25 frames/sec (PAL) with prepared frames, and just reading them in sequence into video RAM from hard disk with basic sync. and audio.
 
  Hi-color playback:
I currently work on high-color movie playback for Atari STE. By using Photochrome PCS images and displaying code. It allows up to 4096 colors on 1 screen. However, it is very demanding considering data rate needed for fullscreen, 25 fps playback - about 1250 KB/sec is needed. Worse: hi-color displaying occupies CPU 100% during scanlines, so we have only about 35% (max) CPU time available for loading from disk. DMA trasnfers ? Not possible - DMA will destroy accurate timing of hi-color displaying. So, 1250 KB/sec in 1/3 time ? Far from possible with usual disk transfer speeds. Not to mention that FAT16 filesystem adds additional slowdowns.  Still, it is possible, but only with little reduced screen size and CATA IDE adapter + small mod in STE. Reducing line count to 160, what is btw, good for 16:9 AR sources, we will have more CPU time avail. (48%) ane less data rate (1050KB/sec). I will not write here more details for now, because CATA is not yet available. Made some demos, how it looks, and you can try them with Steem or Hatari.
Hard case   Anim   Flying



  16 color playback:

  After couple years from first videos and playing SW I did some major changes, improvements:  changed structure of interleaved LAV (limited audio/video) files. With old format playback was not smooth from hard disk partitions bigger than 128MB, because of AHDI large sectors. New format will play well even from 1GB partitions with sector sizes of 16KB (Falcon). Made new player SW, what works with less CPU load, dropped not really necessary seeking options - there is only abort key. And it works well on Falcon now.

 

  All files are with audio, but audio works only on STE & Falcon (TT ?) machines.

Trailer for well known game  14MB.
The complete gameplay 5MB RAR, LAV is about 100MB, but well packable.


    New playback program

   


 Keys during playback:     Right Shift - abort play & select other LAV or exit   Left Shift - deinterlace

  To have smooth playback without slowdowns, audio repeating and desync  fast hard disk/Flash card and adapter are necessary. Playback program has speed (transfer rate) measuring. Select some file with size of min. 5MB (best some LAV file, of course) for test. It will display after few secs transfer rate in KB/sec. About 1000 KB/sec is usually good enough. So, no Satandisk, but UltraSatan may be OK, however speed depends from used SD card too.  IDE should be about 1200 KB/sec with any decent driver and CF card or drive. Of course when no byte-swap (then may using twisted cable and special driver).  5785 KB/sec is speed in Steem, with emulated ACSI hard disk, just to mention (on real ST not possible). Other requirement is 50 Hz video refresh rate, so PAL only. Falcon not with VGA, but RGB monitor or TV, set to PAL mode.

Guide for creating LAV files, with SW, examples




PP  Jan  2007 - Oct. 2012 .