Bad Apple demos

[mk79]

Can you play chip choons???

Choons? I've got a player for most popular Spectrum file formats if that's what you're asking. Will make a video some day.

[vanpeebles]

That video player looks amazing!

[vanpeebles]

Can you play chip choons???

Choons? I've got a player for most popular Spectrum file formats if that's what you're asking. Will make a video some day.

Will you be doing a kit with the AY setup and software?

[stephen_usher]

OK, I think I can probably say that a "Bad Apple" demo is impossible on a stock QL with memory and disk expansion, the memory sub-system is just too slow.

Even after halving the resolution (reducing the number of pixels by 3/4trs), doing a little more optimisation in the decoder and simplifying the dithering I get this:

QL + Trump Card: https://youtu.be/m58G923zU0I

Compare that to:

QL + Super Gold Card (clone): https://youtu.be/If0SXsOCFA0

Which is six times as fast. (3x clock speed plus twice the memory bus width on the CPU?)

[Cristian]

Here's a larger (and better rendered) version of test_m4v: http://www.lingula.org.uk/~steve/share/test_m4v

I could run the first version (named "testm4v.img") with QemuLator, but I can't open this new one.
I tried also to rename it as "test_m4v.img" but I get a "not a QDOS disk" error.
Where am I wrong?

Anyway, I've just seen the SGC youtube version, and it's impressive! Great job!

[stephen_usher]

Here's a larger (and better rendered) version of test_m4v: http://www.lingula.org.uk/~steve/share/test_m4v

I could run the first version (named "testm4v.img") with QemuLator, but I can't open this new one.
I tried also to rename it as "test_m4v.img" but I get a "not a QDOS disk" error.
Where am I wrong?

Anyway, I've just seen the SGC youtube version, and it's impressive! Great job!

It's just the video file, not a disk image. You'll need to use qltools to copy it onto one.

[stephen_usher]

OK, I've given up on the development of this, but I've packaged up everything so if anyone else would like to continue playing with this stuff they can.

You can download the gzipped tar file here: http://www.lingula.org.uk/~steve/share/ ... dec.tar.gz

I've written some very basic documentation so it shouldn't be difficult to someone to understand the code and continue on and I've placed the code into the public domain so everyone is free to do with it what they will.

Have fun!

[mk79]

I really shouldn't be doing this because I don't have the time for it right now, but it was intriguing enough that I had a short stab at the problem while watching a movie with my wife...

Here are the first 500 frames of the video running at max speed on a SGC, which in this case is about 150 frames per second: https://www.kilgus.net/videos/ba_test150.mov (my iPhone doesn't play well with the CRT, sorry). Mind you that in this quick&dirty implementation everything has to fit into RAM, so there is no disc penalty (that's why there are only 500 frames, which in my case is currently about 3MB).

Here's the same movie synchronized to 25 frames per second: https://www.kilgus.net/videos/ba_test25.mov. Here you can see that the loading time for the 3MB exe from QL-SD is approximately 6 seconds for a video that lasts about 17 seconds, so streaming the whole video on a SGC shouldn't be a problem. I'm still not sure how an unmodified QL would keep up, but with some further tricks I guess it's possible.

Now off to bed. Enjoy, Marcel

[mk79]

Will you be doing a kit with the AY setup and software?

The software will be free and QPC will have AY support built in. I don't intend to build any hardware, this was strictly a proof of concept.

[stephen_usher]

Now off to bed. Enjoy, Marcel

That's absolutely amazing!

What sort of algorithm are you using for that?

By the way those speckles in the images are probably from diffusion dithering on too small an image, I got that once and had to swap to a different dithering algorithm for the small version of the video.

At that speed it might just work on a stock QL, which seems to be about 1/6th the speed of the SGC.

P.S. With my compression algorithm I was getting 150 frames (full screen) down to 1MB, so maybe that would be useful to use?