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| Genesis Overclock without changing timings. [message #4121] | Wed, 29 July 2015 04:54  |
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Hello all, I need some help with overclocking Genesis core in Mednafen. So if I change cpus table then I break timings and some games (like a Road Rush 3) became broken. I did it in Nes core, so I want to implement it to genesis too. 1) Increase lines per frames in vdp_run.inc - 262 -> 524 example (x2 overclock) So I got 30 fps with overclock. There is four ways(or more) return 60 fps. 1.1) decrease FrameCount in sound.cpp, then I got 60 fps, but sounds are really bad with distortion. Also DMC channel is have x2 speed. 1.2) decrease zebuf.end_frame(md_timestamp / 15); to zebuf.end_frame(md_timestamp / 30). Result is same. 1.3) change zebuf.set_sample_rate. Same. 1.4) NTSC_CLOCK x2. So... Well now there is no distortion and sound is clear. But now sounds are have wrong tone. 1.4.1)If I change "ret = (z80_tstates - last_z80_tstates)" to int ret = (z80_tstates - last_z80_tstates) * 2.17, then I get normal speed for DMC channel and tone is good. In early versions "Gens" there was changed scanlines per frame and increased sound buffer. It was enough for overclock. I think true way is strings 1 and 1.1. How I can remove distortion and get normal speed for DMC channel? [Updated on: Wed, 29 July 2015 04:55] | ||||
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| Re: Genesis Overclock without changing timings. [message #4124 is a reply to message #4121 ] | Fri, 31 July 2015 03:39  |
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| I need to delete sync between Z80 and c68k without crashing. | ||||
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