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Advances in retro video compression

Posted: Sat Aug 24, 2019 8:48 am
by nollkolltroll
I made a promise when I released the Bad Apple video player that I would enhance it. Since then I've been working hard on upgrading the encoder, both quality- and speed-wise. This morning I made a break-through regarding the quality, so I wanted to show you!

Here is a first preview, a full length rendition of Big Buck Bunny made to run on a ZX81 with a ZXpand classic and UDG128-board.
EightyOne does not work properly, it runs at a lower framerate. ZXpand+ works OK. Chroma instead of UDG128-board does not work yet, but that's only because I haven't gotten around to coding it.

My plan is to finalize the command line encoder and release it with proper documentation regarding the use of it, and the ZX81 player. It is also very easy to render an animated GIF for more modern (pre)viewing.

Some tech:
The format uses 1kb per frame, 768 bytes for the image and 256 bytes for the character set. Every frame gets 32 new character definitions, and pushes out the 32 oldest. 3 frames of old characters plus 1 frame of the current makes for a rather pleasing video.

Re: Advances in retro video compression

Posted: Sat Aug 24, 2019 10:35 am
by RWAP
I wonder how this would compare to the Dragon's Lair encoder....

Re: Advances in retro video compression

Posted: Sat Aug 24, 2019 10:45 am
by nollkolltroll
RWAP wrote:
Sat Aug 24, 2019 10:35 am
I wonder how this would compare to the Dragon's Lair encoder....
I have tested some Dragons Lair material I found online, which was rather crappy to begin with, but this encoder creates OK-ish result. I suspect Jim Bagley has done A LOT of good pre-processing, yielding a very nice result. With the same material, I believe it would look very good in fullscreen.

Re: Advances in retro video compression

Posted: Sat Aug 24, 2019 10:52 am
by nollkolltroll
An update to usage in EightyOne:
I used EightyOne 1.12, and you need the correct settings: 32k RAM, CHR$16, no hires, ZXpand+, PAL. Enabling hires (WRX) will muck up the display, even though it should not. And again: it works in slower frame rate, but the images DO look perfectly fine.

Re: Advances in retro video compression

Posted: Sat Aug 24, 2019 4:14 pm
by olofsen
The movie looks amazing! :)

The slowdown in EightyOne may be caused by emulated delays in the ZXpand code. FileRead sets a delay via COMFUNC(FileRead,100) of 100 units. Roughly every 1 ms the zx81 code decreases this delay with 10 units. The resulting delay of about 10 ms for every 256 bytes may be too large...

Re: Advances in retro video compression

Posted: Sat Aug 24, 2019 9:08 pm
by Moggy
Good grief!

I will never cease to be amazed at what can be done with the zeddy.(When the bird fell out of the tree I nearly choked on my whisky, very funny!)

This is superb work and I cannot wait for the encoder to see the light of day as I will have some serious fun with that.

Once again well done Adam. :ugeek:


Regards.
Moggy.

Re: Advances in retro video compression

Posted: Sat Aug 24, 2019 9:31 pm
by Andy Rea
WOW i am blown away... Fabulous work, this is truly amazing something that was only a dream before today full screen hi-res ( of sorts ) full speed video on ZX81... ARE YOU FREAKING KIDDING ME !!!!

Damn this should win some sort of award.

Running on real hardware B+W CRT monitor viewed from 6 or 7 feet ( ~2 metres ) looks amazing the pixels are just getting small enough to merge together at that distance ( 15 inch monitor BTW )

anyway can't wait to show this to a good friend tomorrow... pretty sure his jaw will do this :-

Image

Anyway yeah.. awesome work

Regards Andy.

Re: Advances in retro video compression

Posted: Sat Aug 24, 2019 9:33 pm
by Andy Rea
Moggy wrote:
Sat Aug 24, 2019 9:08 pm
This is superb work and I cannot wait for the encoder to see the light of day as I will have some serious fun with that.
Do we need to ask the admin for a password protected 18+ area :lol:

Re: Advances in retro video compression

Posted: Sat Aug 24, 2019 9:36 pm
by nollkolltroll
Working hard at the code I now have 4:3 and 16:9 modes of both the encoder and player. It seems possible to do 30fps in widescreen, so all the people in NTSC-land can have some high frame rate fun :)

Re: Advances in retro video compression

Posted: Sat Aug 24, 2019 10:32 pm
by Moggy
Andy Rea wrote:
Sat Aug 24, 2019 9:33 pm
Moggy wrote:
Sat Aug 24, 2019 9:08 pm
This is superb work and I cannot wait for the encoder to see the light of day as I will have some serious fun with that.
Do we need to ask the admin for a password protected 18+ area :lol:
There is absolutely no truth in the rumour that what I have in mind involves a boy scout troop, a cairn terrier called Wilf and a certain shop where I bought the equipment from.
On taking legal advice I will leave it at that! :lol: