SpritesMind.Net

I'm currently having problems emulating audio for Comix Zone. Samples (DAC) playback appears to be really slow and the music is all kinds of off tempo. Does anyone know what drives the music for this game as far as timings/interrupts etc?

cheers,
Steve.

From the tests I've done, it appears that each entry in the per line hscroll table covers 2 screen lines when in double interlace mode.

Thanks for the help guys.

Since I only have to display either the top or bottom half of the interlace display (stretched to full screen), my solution was to parse and save off the sprite table at the beginning of the frame for top half, or at end of line 112 for the bottom half. I then render this ...

With this method for Sonic2 I'm only able to see sprites if I subtract 224 from their y position - and I mainly see the sprites of the bottom half of the interlace display (Tails' screen).

For the normal and single density interlace modes bits 8-0 of the sprite Y coordinate are used. In the ...

I'm currently working on Sonic2 double resolution interlace mode emulation, and I'm seeing some weirdness with sprite rendering.

My current emulation does not perform per scan line sprite table query rendering, but rather at the end of the frame just parses the current sprite table and renders each ...

I got it guys and it all makes sense given your info Snake.

My problem was simply for PAL I was still doing an NTSC inner loop (262 lines) so playback was stretching 262 samples instead of 313 samples over 1/50 sec (so it slowed the sample down compared to NTSC playback).

cheers,
Steve

Ok - I think I'm going crazy. Extra lines or no extra lines 50hz is 50hz. So if a game ROM is for both NTSC and PAL, sample play back for PAL will be lower pitched unless the z80 code compensates for it.

I might be missing reporting my genesis emulator is in PAL mode correctly (what does the z80 ...

...and checking if something is written to DAC reg of YM2612 on a scanline is lousy... my MD music system will have terrible PCM if things work like that...

Haha..yes it is, but the platform I'm coding on is very slow....

Okay I think I might know what my issue is then. I'm not taking into account that PAL has more scan lines than NTSC.

My current emulation main loop grabs a DAC sample once per NTSC scan line (224 active, 38 vblank = 262). I assume my main loop will need updating to take into account the extra PAL ...

I'm looking into an issue where I've setup the emulated IO system VMOD and MODE into I'm running a PAL rom:

PSG/YM2612 music tempo and frequency is playing at the correct speed, but YM2612 DAC sample playback is pitched down. The DAC is being driven by the Z80 which for my current PAL ...

Okay - so after looking over my int code very closely I found the real problem (ignore my last posts) and your info confirms this Eke.

My previous 68k frame execute loop only checked for handling ints at the beginning of every scan line. I updated the code so that a check for ints is handled ...

thanks guys - yes that was a typo, but (luckily) it didn't caused any problems.

anyway, now that I've fixed that, I think I've cracked the golden axe problems:

1) I do not trigger 68k vbl interrupts when the vdp display is disabled (happens when the screen is black just before a level starts in ...

Okay so I've found a solution and was wondering if anyone else is doing the same:

Basically golden axe turns off the display during level initialization (when the bottle graphic is written to vram). Disabling vbl triggering when the display is turned off fixes the problem.

I also implemented ...

thanks for pointing out the small errors. they didn't actually solve the problem but that's because that was not the cause.

I tracked down the issue to the main loop performing vram writes (for the bottle graphic), but it gets interrupted by a 68k vbl which performs a mem->cram dma. this trashes ...

A bit more info:

From debugging I can see the bottle graphics being downloaded into cram instead of vram. (this would explain the missing bottle, and the corrupt palette).

Can you spot anything wrong with my code register update? This is the only function where I update it:

cheers,
Steve


void ...