BizHawk/BizHawk.Client.Common/movie/PlatformFrameRates.cs

using System;
using System.Collections.Generic;

namespace BizHawk.Client.Common
{
	public class PlatformFrameRates
	{
		// these are political numbers, designed to be in accord with tasvideos.org tradition. they're not necessarily mathematical factualities (although they may be in some cases)
		// it would be nice if we could turn this into a rational expression natively, and also, to write some comments about the derivation and ideal values (since this seems to be where they're all collected)
		// are we collecting them anywhere else? for avi-writing code perhaps?

		// just some constants, according to specs
		private static readonly double PALCarrier = (15625 * 283.75) + 25; // 4.43361875 MHz
		private static readonly double NTSCCarrier = 4500000 * 227.5 / 286; // 3.579545454... MHz
		private static readonly double PALNCarrier = (15625 * 229.25) + 25; // 3.58205625 MHz

		private static readonly Dictionary<string, double> Rates = new Dictionary<string, double>
		{
			["NES"] = 60.098813897440515532, // discussion here: http://forums.nesdev.com/viewtopic.php?t=492 ; a rational expression would be (19687500 / 11) / ((341*262-0.529780.5)/3) -> (118125000 / 1965513) -> 60.098813897440515529533511098629 (so our chosen number is very close)
			["NES_PAL"] = 50.006977968268290849,
			["FDS"] = 60.098813897440515532,
			["FDS_PAL"] = 50.006977968268290849,
			["SNES"] = 21477272.0 / (4 * 341 * 262), // 60.098475521
			["SNES_PAL"] = 21281370.0 / (4 * 341 * 312), // 50.0069789082
			["SGB"] = 21477272.0 / (4 * 341 * 262), // 60.098475521
			["SGB_PAL"] = 21281370.0 / (4 * 341 * 312), // 50.0069789082
			["PCE"] = (7159090.90909090 / 455 / 263), // 59.8261054535
			["PCECD"] = (7159090.90909090 / 455 / 263), // 59.8261054535
			["SMS"] = (3579545 / 262.0 / 228.0), // 59.9227434043
			["SMS_PAL"] = (3546893 / 313.0 / 228.0), // 49.7014320946
			["GG"] = (3579545 / 262.0 / 228.0), // 59.9227434043
			["GG_PAL"] = (3546893 / 313.0 / 228.0), // 49.7014320946
			["SG"] = (3579545 / 262.0 / 228.0), // 59.9227434043
			["SG_PAL"] = (3546893 / 313.0 / 228.0), // 49.7014320946
			["NGP"] = (6144000.0 / (515 * 198)), // 60.2530155928
			["VB"] = (20000000.0 / (259 * 384 * 4)),  // 50.2734877735
			["Lynx"] = 16000000.0 / (16 * 105 * 159), // 59.89817310572028
			["WSWAN"] = (3072000.0 / (159 * 256)), // 75.4716981132
			["GB"] = 262144.0 / 4389.0, // 59.7275005696
			["GBC"] = 262144.0 / 4389.0, // 59.7275005696
			["GB_Clock"] = 2097152.0,
			["GBA"] = 262144.0 / 4389.0, // 59.7275005696 
			["GEN"] = 53693175 / (3420.0 * 262),
			["GEN_PAL"] = 53203424 / (3420.0 * 313),

			// while the number of scanlines per frame is software controlled and variable, we
			// enforce exactly 262 (NTSC) 312 (PAL) per reference time frame
			["A26"] = 315000000.0 / 88.0 / 262.0 / 228.0, // 59.922751013550531429197560173856
			// this pal clock ref is exact
			["A26_PAL"] = 3546895.0 / 312.0 / 228.0, // 49.860759671614934772829509671615

			["A78"] = 59.9227510135505,
			["Coleco"] = 59.9227510135505,

			// according to http://problemkaputt.de/psx-spx.htm
			["PSX"] = 44100.0 * 768 * 11 / 7 / 263 / 3413, // 59.292862562
			["PSX_PAL"] = 44100.0 * 768 * 11 / 7 / 314 / 3406, // 49.7645593576

			["C64_PAL"] = PALCarrier * 2 / 9 / 312 / 63,
			["C64_NTSC"] = NTSCCarrier * 2 / 7 / 263 / 65,
			["C64_NTSC_OLD"] = NTSCCarrier * 2 / 7 / 262 / 64,
			["C64_DREAN"] = PALNCarrier * 2 / 7 / 312 / 65,
			["INTV"] = 59.92,

			["ZXSpectrum_PAL"] = 50.080128205,
			["AmstradCPC_PAL"] = 50.08012820512821,

			// according to ryphecha, using
			// clocks[2] = { 53.693182e06, 53.203425e06 }; //ntsc console, pal console
			// lpf[2][2] = { { 263, 262.5 }, { 314, 312.5 } }; //ntsc,pal; non-interlaced, interlaced
			// cpl[2] = { 3412.5, 3405 }; //ntsc mode, pal mode
			// PAL PS1: 0, PAL Mode: 0, Interlaced: 0 --- 59.826106 (53.693182e06/(263*3412.5))
			// PAL PS1: 0, PAL Mode: 0, Interlaced: 1 --- 59.940060 (53.693182e06/(262.5*3412.5))
			// PAL PS1: 1, PAL Mode: 1, Interlaced: 0 --- 49.761427 (53.203425e06/(314*3405))
			// PAL PS1: 1, PAL Mode: 1, Interlaced: 1 --- 50.000282(53.203425e06/(312.5*3405))
		};

		public double this[string systemId, bool pal]
		{
			get
			{
				var key = systemId + (pal ? "_PAL" : "");
				return Rates.ContainsKey(key) ? Rates[key] : 60.0;
			}
		}

		public TimeSpan MovieTime(IMovie movie)
		{
			var dblSeconds = GetSeconds(movie);
			var seconds = (int)(dblSeconds % 60);
			var days = seconds / 86400;
			var hours = seconds / 3600;
			var minutes = (seconds / 60) % 60;
			var milliseconds = (int)((dblSeconds - seconds) * 1000);
			return new TimeSpan(days, hours, minutes, seconds, milliseconds);
		}

		private double Fps(IMovie movie)
		{
			var system = movie.HeaderEntries[HeaderKeys.Platform];
			var core = movie.HeaderEntries[HeaderKeys.Core];
			var pal = movie.HeaderEntries.ContainsKey(HeaderKeys.Pal)
				&& movie.HeaderEntries[HeaderKeys.Pal] == "1";

			if (movie.HeaderEntries.ContainsKey(HeaderKeys.CycleCount) && core == "Gambatte")
			{
				system = "GB_Clock";
			}

			return this[system, pal];
		}

		private double GetSeconds(IMovie movie)
		{
			double frames = movie.TimeLength;

			if (frames < 1)
			{
				return 0;
			}

			return frames / Fps(movie);
		}
	}
}