Search found 349 matches

by ulfalizer
Fri Nov 15, 2013 10:36 pm
Forum: NESemdev
Topic: APU triangle emulation question
Replies: 24
Views: 5311

Re: APU triangle emulation question

What you should be doing is checking whether the period of the channel generates a waveform that completes a full oscillation in less than 2 samples. So in other words, if you're emulating the sound and outputting at 44100hz, then a triangle wave (or any wave, really) that is higher pitched than 22...
by ulfalizer
Fri Nov 15, 2013 9:18 pm
Forum: NESemdev
Topic: APU triangle emulation question
Replies: 24
Views: 5311

Re: APU triangle emulation question

Hmm, bubble bobble is unusual. It uses halts properly in the intro, but the short bass notes are terminated by setting the period to 1. Thanks for the tip, I'd never noticed anything using 1 to silence the triangle before. Kinda bizarre. Maybe they noticed that 0 sounded bad, switched to 1 and noti...
by ulfalizer
Tue Nov 12, 2013 11:50 pm
Forum: NESdev
Topic: Several Famicom Nes Documents... in Japanese
Replies: 96
Views: 42214

Re: Several Famicom Nes Documents... in Japanese

I have to admit that as a newbie, the term "mirroring" has always confused me to no end. I don't say that the term "scrolling" makes me any wiser though. When you see "mirroring", think mapping from addresses to nametable locations. At the conceptual level you have four screens arranged in a square...
by ulfalizer
Tue Nov 12, 2013 7:23 pm
Forum: NESdev
Topic: Making a mapper that detects BG vs Sprite tiles
Replies: 12
Views: 3036

Re: Making a mapper that detects BG vs Sprite tiles

Certainly for the real NES PPU, the second fetch is always from the not-attribute-part of the nametables, and not from the attribute tables. Did someone actually discover and/or document this behavior According to ulfalizer's post above, which cites Visual 2C02, the signal to fetch attributes is ac...
by ulfalizer
Mon Nov 11, 2013 4:20 pm
Forum: NESemdev
Topic: DMC pops
Replies: 10
Views: 3388

Re: DMC pops

Do people really find the pops in e.g. Castlevania II annoying? If you remove them, the drums seem to lose a lot of their "punch". With headphones on, yes, I very much dislike the Konami bass drum pops, and I am glad when I have the option to turn them off. Over a loudspeaker they don't bother me. ...
by ulfalizer
Sun Nov 10, 2013 11:51 pm
Forum: NESemdev
Topic: DMC pops
Replies: 10
Views: 3388

Re: DMC pops

Do people really find the pops in e.g. Castlevania II annoying? If you remove them, the drums seem to lose a lot of their "punch".
by ulfalizer
Sun Nov 10, 2013 11:12 pm
Forum: NESdev
Topic: Making a mapper that detects BG vs Sprite tiles
Replies: 12
Views: 3036

Re: Making a mapper that detects BG vs Sprite tiles

Poked around a bit in Visual 2C02, and it looks like attribute fetches are indeed only done for BG tiles. The "fetch attribute byte" signal is +hpos_eq_0-255_or_320-335_and_hpos_mod_8_eq_2_or_3_and_rendering , i.e. "fetching background tile and in the attribute byte position". Need to fix this is in...
by ulfalizer
Sun Nov 10, 2013 10:28 pm
Forum: NESdev
Topic: Making a mapper that detects BG vs Sprite tiles
Replies: 12
Views: 3036

Re: Making a mapper that detects BG vs Sprite tiles

An interesting note is that the MMC5 can determine the absolute screen position of fetched BG tiles, as that's how the split position is specified in vertical split mode. The coarse x and y scroll can be set to whatever, and the split still ends up in the same location. That alone would make me susp...
by ulfalizer
Sun Nov 10, 2013 11:07 am
Forum: NESemdev
Topic: APU triangle emulation question
Replies: 24
Views: 5311

Re: APU triangle emulation question

In the low frequency case you're not getting more accurate emulation OR sound, so both of those goals are defeated. Maybe it sounds nicer though for games that do it. What games are these, btw? I haven't run into that problem yet. Yeah, the only point would be "nicer" sound for games that attempt t...
by ulfalizer
Sat Nov 09, 2013 8:16 pm
Forum: NESemdev
Topic: APU triangle emulation question
Replies: 24
Views: 5311

Re: APU triangle emulation question

The MM2 triangle popping is really easy to hear in Crash Man's stage: https://dl.dropboxusercontent.com/u/20047039/poppycrash.mp3. Here's a version with the triangle isolated: https://dl.dropboxusercontent.com/u/20047039/trianglepops.mp3. The period is set to 0 to "silence" the triangle. Those sampl...
by ulfalizer
Mon Oct 21, 2013 9:00 am
Forum: NESemdev
Topic: Original Mario Bros bug on my emulator?
Replies: 141
Views: 28675

Re: Original Mario Bros bug on my emulator?

Yeah, you need to keep your target system in mind. At least the case of running several instances is embarrassingly parallel though, so if your emulator is single-threaded you can scale it up to at least the number of available cores (just experimented with 10 or so instances, and they ran fine unti...
by ulfalizer
Mon Oct 21, 2013 8:30 am
Forum: NESemdev
Topic: Original Mario Bros bug on my emulator?
Replies: 141
Views: 28675

Re: Original Mario Bros bug on my emulator?

Ulfalizer - So what you're saying, is that the norm for today's emulators is to have a CPU, which makes the PPU and APU tick for every single one of its cycles? I thought that was the slow way to do things. Not sure how much of the norm it is, but today's desktop computers seem fast enough at least...
by ulfalizer
Mon Oct 21, 2013 7:41 am
Forum: NESemdev
Topic: Original Mario Bros bug on my emulator?
Replies: 141
Views: 28675

Re: Original Mario Bros bug on my emulator?

Wait a minute. If I understand correctly, the catch-up method is used to run the CPU for X amount of cycles, and while that is happening, if the instruction writes to the PPU, you let the PPU run until it "catches up" with the CPU before doing the actual write (or read or whatever). What is conside...
by ulfalizer
Sun Oct 20, 2013 2:52 am
Forum: NESemdev
Topic: Video encoding formats/libraries
Replies: 7
Views: 2873

Re: Video encoding formats/libraries

I'll look into gstreamer first. Having a choice between encodings and having formats available that work well with various filters applied would be nice. I'm guessing DOSBox's format is most suited for when you keep the native color range.
by ulfalizer
Sat Oct 19, 2013 11:32 am
Forum: NESemdev
Topic: Video encoding formats/libraries
Replies: 7
Views: 2873

Video encoding formats/libraries

Got tired of messing around with screen capture in X11 and thought I might as well add video encoding to my emulator. Unfortunately I'm very much a beginner when it comes to video. What formats and/or libraries would you recommend? At the moment I could go with something lossless for further process...