Having fun with HAM8 videos @ 25 FPS for 3+ minutes

[Hans_]

I'm not convinced it is legitimate but it depends on the resolution. At 320*256@25fps would need around 2MB/s sustained write to chip ram. The footage looked rather higher resolution than this.

The video says it's 640x180 so the bandwidth is similar to 320x256@25fps. However, he played it on FS-UAE, and I doubt that it's emulating the chip RAM bandwidth limitations too.

I totally agree that HAM8 videos will playback on a reasonably powerful Amiga. Even 25 FPS is possible. But that original video was not on an unexpanded A1200 for sure. There was not even one single artifact that I could see from a HAM8 video. I have no idea why the original author of the post would be interested in lying about it.

The description of his last video says playback is in FS-UAE, so it's emulated hardware. From memory, HAM8 artifacts can be avoided/minimised via intelligent use of dithering. I can't remember what tools generated the highest quality HAM8 images, though. Added to that, it's clear that each anim frame has its own base colour palette; just look at the mouse pointer flashing different colours in the bottom right. That means that the colours of each frame have been optimized for that frame.

It would be nice if we could play the anim itself on our own hardware.

Hans

[Hans_]

@Dynamic_Computing

Nicely done. Looks like atron has better tools for the conversion, because your video has definite HAM artifacting along the left edge. That's avi4hc/avi4aga's fault, unless you're cropping the HAM8 images that they produce. A better HAM6/8 encoder wouldn't generate those.

I wonder if it would be possible to come up with a better compression scheme for HAM6/8 to make streaming them from disk less taxing. There might be a way of doing motion compensation to reduce the size further beyond the basic compression CDXL and anim formats used. I'm too busy with AmigaOS 4.x graphics to try that out myself, though.

Hans

[Hans_]

I wonder if it would be possible to come up with a better compression scheme for HAM6/8 to make streaming them from disk less taxing. There might be a way of doing motion compensation to reduce the size

So I once thought about this back in the day when I had the blizzardppc but not the Bvision to go with it. The biggest problem is that you can't readily do simple change application to HAM frames as they just get messed up for all the classic reasons. With modern hardware however it ought to be possible to develop an encoder that can perform HAM simulation from RGB and generate differential frames within some sort of error limit. If playback is all we care about, it might not matter if we need a core i7 to do the encoding.

Hehe, so you also thought about it until you had newer hardware. I wanted to create a more capable HAM8 video player when I still had my A1200. Back then I lacked the expertise needed to pull it off. Now I could probably figure it out, but am too busy with other stuff.

Your idea of doing HAM simulation from RGB is interesting. That should allow you to do lossy compression, trading image quality for smaller file size.  I was thinking of a simpler method where you'd search for blitter ops that reduce the compressed size of the residual image. Preferably with a method that the AGA blitter units could handle (assuming they're fast enough to handle it).

Hans