4 ms·
Choosing 50 FPS instead of 60 was because needing to dedicate more CPU to each frame, or because another reason? P.S. Impressive demo, kudos :-)
by faragon 9y ago
Choosing 50 FPS instead of 60 was because needing to dedicate more CPU to each frame, or because another reason?
P.S. Impressive demo, kudos :-)
- shinymark 9y agoPAL vs NTSC perhaps?
- jix 9y agoFor the Mega Drive/Genesis the framerate depends on the region, matching the local video standard. The European Mega Drive uses PAL with 50Hz. As the biggest part (but not all) of the demoscene is based in Europe, most demos target PAL hardware. The same is true for our demo group. NTSC ports can be very difficult if not impossible as PAL often does have a slight advantage in CPU cycles per frame. This is also the case on the Mega Drive. Porting the polygon renderer shouldn't be a problem as it renders in an off-screen CPU RAM buffer. In the worst case it would have to skip more frames, having a lower effective framerate. A lot of the other effects have very critical timing though. I've been told that porting some of them to NTSC is just impossible.
- mikejmoffitt 9y agoThere is a little more CPU time, but the extended vertical blanking interval means there is a huge difference in video memory bandwidth, which is critical for a long DMA transfer from 68000-bus memory to VRAM through the Mega Drive's VDP. 60Hz V-blank DMA: 7524 50Hz V-blank DMA: 17622 That's at 320x224 resolution for both. I don't know how much this affects this one demo in particular, but for other things it can be a little annoying sometimes to be bandwidth-starved.
- faragon 9y agoThank you very much, with the available DMA bandwidth figures during V-blank you gave, I've found some VDP documentation: http://md.squee.co/VDP http://md.squee.co/VDP