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Palette indexes are not actually related to the FFT length.

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This commit is contained in:
J.D. Purcell 2015-09-03 10:52:47 -04:00
parent d5fa8fbe3c
commit 0e9a416a7a
1 changed files with 14 additions and 13 deletions
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27
libse/WaveToVisualizer.cs
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@ -504,6 +504,7 @@ namespace Nikse.SubtitleEdit.Core
private class SpectrogramDrawer
{
private const double raisedCosineWindowScale = 0.5;
private const int magnitudeIndexRange = 256;
private readonly int _nfft;
private readonly MagnitudeToIndexMapper _mapper;
@ -516,9 +517,9 @@ namespace Nikse.SubtitleEdit.Core
public SpectrogramDrawer(int nfft)
{
_nfft = nfft;
_mapper = new MagnitudeToIndexMapper(100.0, 255);
_mapper = new MagnitudeToIndexMapper(100.0, magnitudeIndexRange - 1);
_fft = new RealFFT(nfft);
_palette = GeneratePalette(nfft);
_palette = GeneratePalette();
_segment = new double[nfft];
_window = CreateRaisedCosineWindow(nfft);
_magnitude = new double[nfft / 2];
@ -582,20 +583,20 @@ namespace Nikse.SubtitleEdit.Core
return a * a + b * b;
}
private static FastBitmap.PixelData[] GeneratePalette(int nfft)
private static FastBitmap.PixelData[] GeneratePalette()
{
var palette = new FastBitmap.PixelData[nfft];
var palette = new FastBitmap.PixelData[magnitudeIndexRange];
if (Configuration.Settings.VideoControls.SpectrogramAppearance == "Classic")
{
for (int colorIndex = 0; colorIndex < nfft; colorIndex++)
palette[colorIndex] = new FastBitmap.PixelData(PaletteValue(colorIndex, nfft));
for (int colorIndex = 0; colorIndex < magnitudeIndexRange; colorIndex++)
palette[colorIndex] = new FastBitmap.PixelData(PaletteValue(colorIndex, magnitudeIndexRange));
}
else
{
var list = SmoothColors(0, 0, 0, Configuration.Settings.VideoControls.WaveformColor.R,
Configuration.Settings.VideoControls.WaveformColor.G,
Configuration.Settings.VideoControls.WaveformColor.B, nfft);
for (int i = 0; i < nfft; i++)
Configuration.Settings.VideoControls.WaveformColor.B, magnitudeIndexRange);
for (int i = 0; i < magnitudeIndexRange; i++)
palette[i] = new FastBitmap.PixelData(list[i]);
}
return palette;
@ -669,16 +670,16 @@ namespace Nikse.SubtitleEdit.Core
return list;
}
/// Maps magnitudes in the range [-decibelRange .. 0] dB to palette index values in the range [0 .. indexRange-1]
/// Maps magnitudes in the range [-decibelRange .. 0] dB to palette index values in the range [0 .. indexMax]
private class MagnitudeToIndexMapper
{
private readonly double _minMagnitude;
private readonly double _multiplier;
private readonly double _addend;
public MagnitudeToIndexMapper(double decibelRange, int indexRange)
public MagnitudeToIndexMapper(double decibelRange, int indexMax)
{
double mappingScale = indexRange / decibelRange;
double mappingScale = indexMax / decibelRange;
_minMagnitude = Math.Pow(10.0, -decibelRange / 20.0);
_multiplier = 20.0 * mappingScale;
_addend = decibelRange * mappingScale;
@ -690,11 +691,11 @@ namespace Nikse.SubtitleEdit.Core
}
// Less optimized but readable version of the above
public static int Map(double magnitude, double decibelRange, int indexRange)
public static int Map(double magnitude, double decibelRange, int indexMax)
{
if (magnitude == 0) return 0;
double decibelLevel = 20.0 * Math.Log10(magnitude);
return decibelLevel >= -decibelRange ? (int)(indexRange * (decibelLevel + decibelRange) / decibelRange) : 0;
return decibelLevel >= -decibelRange ? (int)(indexMax * (decibelLevel + decibelRange) / decibelRange) : 0;
}
}
}