Rework aspect ratio calculations.
They are now based on signal timings rather than pixels, as it didn't make a lot of sense to do things with pixels. Now handles all 240i/240p/480i/480p modes without any special casing. Despite the diffrent equaions, this should result in the exact same aspect ratio as the previous code.
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@ -472,34 +472,90 @@ static u32 GetTicksPerOddField()
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return GetTicksPerHalfLine() * GetHalfLinesPerOddField();
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return GetTicksPerHalfLine() * GetHalfLinesPerOddField();
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}
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}
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// Get the aspect ratio of VI's active area.
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float GetAspectRatio()
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float GetAspectRatio()
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{
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{
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u32 multiplier = static_cast<u32>(m_PictureConfiguration.STD / m_PictureConfiguration.WPL);
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// The picture of a PAL/NTSC TV signal is defined to have a 4:3 aspect ratio,
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int height = (multiplier * m_VerticalTimingRegister.ACV);
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// but it's only 4:3 if the picture fill the entire active area.
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int width = ((2 * m_HTiming0.HLW) - (m_HTiming0.HLW - m_HTiming1.HBS640)
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// All games configure VideoInterface to add padding in both the horizontal and vertical
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- m_HTiming1.HBE640);
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// directions and most games also do a slight horizontal scale.
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float pixelAR;
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// This means that XFB never fills the entire active area and is therefor almost never 4:3
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if (m_DisplayControlRegister.FMT == 1)
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// To work out the correct aspect ratio of the XFB, we need to know how VideoInterface's
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// currently configured active area compares to the active area of a stock PAL or NTSC
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// signal (which would be 4:3)
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// This function only deals with standard aspect ratios. For widescreen aspect ratios,
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// multiply the result by 1.33333..
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// 1. Get our active area in BT.601 samples (more or less pixels)
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int active_lines = m_VerticalTimingRegister.ACV;
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int active_width_samples = (m_HTiming0.HLW + m_HTiming1.HBS640 - m_HTiming1.HBE640);
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// 2. TVs are analog and don't have pixels. So we convert to seconds.
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float tick_length = (1.0f / SystemTimers::GetTicksPerSecond());
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float vertical_period = tick_length * GetTicksPerField();
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float horizontal_period= tick_length * GetTicksPerHalfLine() * 2;
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float vertical_active_area = active_lines * horizontal_period;
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float horizontal_active_area = tick_length * GetTicksPerSample() * active_width_samples;
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// We are approximating the horizontal/vertical flyback transformers that control the
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// position of the election beam on the screen. Our flyback transformers create a
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// perfect Sawtooth wave, with a smooth rise and a fall that takes zero time.
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// For more accurate emulation of video signals out of the 525 or 625 line standards,
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// it might be necessary to emulate a less precise flyback transformer with more flaws.
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// But those modes aren't officially supported by TVs anyway and could behave differently
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// on different TVs.
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// 3. Calculate the ratio of active time to total time for VI's active area
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float vertical_active_ratio = vertical_active_area / vertical_period;
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float horizontal_active_ratio = horizontal_active_area / horizontal_period;
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// 4. And then scale the ratios to typical PAL/NTSC signals.
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// NOTE: With the exception of selecting between PAL-M and NTSC color encoding on Brazilian
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// GameCubes, the FMT field doesn't actually do anything on real hardware. But
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// Nintendo's SDK always sets it appropriately to match the number of lines.
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if (m_DisplayControlRegister.FMT == 1) // 625 line TV (PAL)
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{
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{
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//PAL active frame is 702*576
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// PAL defines the horizontal active area as 52us of the 64us line.
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//In square pixels, 1024*576 is 16:9, and 768*576 is 4:3
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// BT.470-6 defines the blanking period as 12.0us +0.0 -0.3 [table on page 5]
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//Therefore a 16:9 TV would have a "pixel" aspect ratio of 1024/702
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horizontal_active_ratio *= 64.0f / 52.0f;
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//Similarly a 4:3 TV would have a ratio of 768/702
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// PAL defines the vertical active area as 576 of 625 lines.
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pixelAR = 768.0f / 702.0f;
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vertical_active_ratio *= 625.0f / 576.0f;
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// TODO: Should PAL60 games go through the 625 or 525 line codepath?
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// The resulting aspect ratio is close, but not identical.
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}
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}
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else // 525 line TV (NTSC or PAL-M)
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{
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// The NTSC standard doesn't define it's active area very well.
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// The line is 63.55555..us long, which is derived from 1.001 / (30 * 525)
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// but the blanking area is defined with a large amount of slack in the SMPTE 170M-2004
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// standard, 10.7us +0.3 -0.2 [derived from table on page 9]
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// The BT.470-6 standard provides a different number of 10.9us +/- 0.2 [table on page 5]
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// This results in an active area between 52.5555us and 53.05555us
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// Lots of different numbers float around the Internet including:
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// * 52.655555.. us -- http://web.archive.org/web/20140218044518/http://lipas.uwasa.fi/~f76998/video/conversion/
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// * 52.66 us -- http://www.ni.com/white-paper/4750/en/
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// * 52.6 us -- http://web.mit.edu/6.111/www/f2008/handouts/L12.pdf
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//
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// None of these website provide primary sources for their numbers, back in the days of
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// analog, TV signal timings were not that precise to start with and it never got standardized
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// during the move to digital.
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// We are just going to use 52.655555.. as most other numbers on the Internet appear to be a
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// simplification of it. 53.655555.. is a blanking period of 10.9us, matching the BT.470-6 standard
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// and within tolerance of the SMPTE 170M-2004 standard.
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horizontal_active_ratio *= 63.555555f / 52.655555f;
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// Even 486 active lines isn't completely agreed upon.
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// Depending on how you count the two half lines you could get 485 or 484
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vertical_active_ratio *= 525.0f / 486.0f;
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}
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// 5. Calculate the final ratio and scale to 4:3
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float ratio = horizontal_active_ratio / vertical_active_ratio;
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if (std::isnormal(ratio)) // Check we have a sane ratio and haven't propagated any infs/nans/zeros
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return ratio * (4.0f / 3.0f); // Scale to 4:3
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else
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else
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{
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return (4.0f / 3.0f); // VI isn't initialized correctly, just return 4:3 instead
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//NTSC active frame is 710.85*486
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//In square pixels, 864*486 is 16:9, and 648*486 is 4:3
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//Therefore a 16:9 TV would have a "pixel" aspect ratio of 864/710.85
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//Similarly a 4:3 TV would have a ratio of 648/710.85
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pixelAR = 648.0f / 710.85f;
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}
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if (width == 0 || height == 0)
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{
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return 4.0f / 3.0f;
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}
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return ((float)width / (float)height) * pixelAR;
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}
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}
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// This function updates:
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// This function updates:
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@ -561,9 +617,14 @@ void UpdateParameters()
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TargetRefreshRate = lround(2.0 * SystemTimers::GetTicksPerSecond() / (GetTicksPerEvenField() + GetTicksPerOddField()));
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TargetRefreshRate = lround(2.0 * SystemTimers::GetTicksPerSecond() / (GetTicksPerEvenField() + GetTicksPerOddField()));
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}
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}
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u32 GetTicksPerSample()
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{
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return 2 * SystemTimers::GetTicksPerSecond() / s_clock_freqs[m_Clock];
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}
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u32 GetTicksPerHalfLine()
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u32 GetTicksPerHalfLine()
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{
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{
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return 2 * SystemTimers::GetTicksPerSecond() / s_clock_freqs[m_Clock] * m_HTiming0.HLW;
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return GetTicksPerSample() * m_HTiming0.HLW;
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}
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}
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@ -330,9 +330,11 @@ union UVIHorizontalStepping
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// Change values pertaining to video mode
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// Change values pertaining to video mode
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void UpdateParameters();
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void UpdateParameters();
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u32 GetTicksPerSample();
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u32 GetTicksPerHalfLine();
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u32 GetTicksPerHalfLine();
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u32 GetTicksPerField();
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u32 GetTicksPerField();
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//For VI Scaling and Aspect Ratio Correction
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// Get the aspect ratio of VI's active area.
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// This function only deals with standard aspect ratios. For widescreen aspect ratios, multiply the result by 1.33333..
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float GetAspectRatio();
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float GetAspectRatio();
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}
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}
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