private static Bitmap DrawSpectrogram(int nfft, double[] samples, Fourier f, Color[] palette)
{
const int overlap = 0;
int numSamples = samples.Length;
int colIncrement = nfft * (1 - overlap);
int numcols = numSamples / colIncrement;
// make sure we don't step beyond the end of the recording
while ((numcols - 1) * colIncrement + nfft > numSamples)
{
numcols--;
}
double[] real = new double[nfft];
double[] imag = new double[nfft];
double[] magnitude = new double[nfft / 2];
var bmp = new Bitmap(numcols, nfft / 2);
for (int col = 0; col <= numcols - 1; col++)
{
// read a segment of the recorded signal
for (int c = 0; c <= nfft - 1; c++)
{
imag[c] = 0;
real[c] = samples[col * colIncrement + c] * Fourier.Hanning(nfft, c);
}
// transform to the frequency domain
f.FourierTransform(real, imag);
// and compute the magnitude spectrum
f.MagnitudeSpectrum(real, imag, Fourier.W0Hanning, magnitude);
// Draw
for (int newY = 0; newY < nfft / 2 - 1; newY++)
{
int colorIndex = MapToPixelIndex(magnitude[newY], 100, 255);
bmp.SetPixel(col, (nfft / 2 - 1) - newY, palette[colorIndex]);
}
}
return(bmp);
}
private static Bitmap DrawSpectrogram(int nfft, double[] samples, Fourier f, Color[] palette)
{
const int overlap = 0;
int numSamples = samples.Length;
int colIncrement = nfft * (1 - overlap);
int numcols = numSamples / colIncrement;
// make sure we don't step beyond the end of the recording
while ((numcols - 1) * colIncrement + nfft > numSamples)
numcols--;
double[] real = new double[nfft];
double[] imag = new double[nfft];
double[] magnitude = new double[nfft / 2];
var bmp = new Bitmap(numcols, nfft / 2);
for (int col = 0; col <= numcols - 1; col++)
{
// read a segment of the recorded signal
for (int c = 0; c <= nfft - 1; c++)
{
imag[c] = 0;
real[c] = samples[col * colIncrement + c] * Fourier.Hanning(nfft, c);
}
// transform to the frequency domain
f.FourierTransform(real, imag);
// and compute the magnitude spectrum
f.MagnitudeSpectrum(real, imag, Fourier.W0Hanning, magnitude);
// Draw
for (int newY = 0; newY < nfft / 2 - 1; newY++)
{
int colorIndex = MapToPixelIndex(magnitude[newY], 100, 255);
bmp.SetPixel(col, (nfft / 2 - 1) - newY, palette[colorIndex]);
}
}
return bmp;
}
//////////////////////////////////////// SPECTRUM ///////////////////////////////////////////////////////////
public List <Bitmap> GenerateFourierData(int nfft, string spectrogramDirectory, int delayInMilliseconds)
{
const int bitmapWidth = 1024;
var bitmaps = new List <Bitmap>();
// setup fourier transformation
var f = new Fourier(nfft, true);
double divider = 2.0;
for (int k = 0; k < Header.BitsPerSample - 2; k++)
{
divider *= 2;
}
// determine how to read sample values
ReadSampleDataValueDelegate readSampleDataValue = GetSampleDataRerader();
// set up one column of the spectrogram
var palette = new Color[nfft];
if (Configuration.Settings.VideoControls.SpectrogramAppearance == "Classic")
{
for (int colorIndex = 0; colorIndex < nfft; colorIndex++)
{
palette[colorIndex] = PaletteValue(colorIndex, nfft);
}
}
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++)
{
palette[i] = list[i];
}
}
// read sample values
DataMinValue = int.MaxValue;
DataMaxValue = int.MinValue;
var samples = new List <int>();
int index = 0;
int sampleSize = nfft * bitmapWidth;
int count = 0;
long totalSamples = 0;
// write delay (if any)
int delaySampleCount = (int)(Header.SampleRate * (delayInMilliseconds / TimeCode.BaseUnit));
for (int i = 0; i < delaySampleCount; i++)
{
samples.Add(0);
if (samples.Count == sampleSize)
{
var samplesAsReal = new double[sampleSize];
for (int k = 0; k < sampleSize; k++)
{
samplesAsReal[k] = 0;
}
var bmp = DrawSpectrogram(nfft, samplesAsReal, f, palette);
bmp.Save(Path.Combine(spectrogramDirectory, count + ".gif"), System.Drawing.Imaging.ImageFormat.Gif);
bitmaps.Add(bmp);
samples = new List <int>();
count++;
}
}
// load data in smaller parts
_data = new byte[Header.BytesPerSecond];
_stream.Position = Header.DataStartPosition;
int bytesRead = _stream.Read(_data, 0, _data.Length);
while (bytesRead == Header.BytesPerSecond)
{
while (index < Header.BytesPerSecond)
{
int value = 0;
for (int channelNumber = 0; channelNumber < Header.NumberOfChannels; channelNumber++)
{
value += readSampleDataValue.Invoke(ref index);
}
value = value / Header.NumberOfChannels;
if (value < DataMinValue)
{
DataMinValue = value;
}
if (value > DataMaxValue)
{
DataMaxValue = value;
}
samples.Add(value);
totalSamples++;
if (samples.Count == sampleSize)
{
var samplesAsReal = new double[sampleSize];
for (int k = 0; k < sampleSize; k++)
{
samplesAsReal[k] = samples[k] / divider;
}
var bmp = DrawSpectrogram(nfft, samplesAsReal, f, palette);
bmp.Save(Path.Combine(spectrogramDirectory, count + ".gif"), System.Drawing.Imaging.ImageFormat.Gif);
bitmaps.Add(bmp);
samples = new List <int>();
count++;
}
}
bytesRead = _stream.Read(_data, 0, _data.Length);
index = 0;
}
if (samples.Count > 0)
{
var samplesAsReal = new double[sampleSize];
for (int k = 0; k < sampleSize && k < samples.Count; k++)
{
samplesAsReal[k] = samples[k] / divider;
}
var bmp = DrawSpectrogram(nfft, samplesAsReal, f, palette);
bmp.Save(Path.Combine(spectrogramDirectory, count + ".gif"), System.Drawing.Imaging.ImageFormat.Gif);
bitmaps.Add(bmp);
}
var doc = new XmlDocument();
doc.LoadXml("<SpectrogramInfo><SampleDuration/><TotalDuration/><AudioFormat /><AudioFormat /><ChunkId /><SecondsPerImage /><ImageWidth /><NFFT /></SpectrogramInfo>");
double sampleDuration = Header.LengthInSeconds / (totalSamples / Convert.ToDouble(nfft));
doc.DocumentElement.SelectSingleNode("SampleDuration").InnerText = sampleDuration.ToString(CultureInfo.InvariantCulture);
doc.DocumentElement.SelectSingleNode("TotalDuration").InnerText = Header.LengthInSeconds.ToString(CultureInfo.InvariantCulture);
doc.DocumentElement.SelectSingleNode("AudioFormat").InnerText = Header.AudioFormat.ToString(CultureInfo.InvariantCulture);
doc.DocumentElement.SelectSingleNode("ChunkId").InnerText = Header.ChunkId.ToString(CultureInfo.InvariantCulture);
doc.DocumentElement.SelectSingleNode("SecondsPerImage").InnerText = ((double)(sampleSize / (double)Header.SampleRate)).ToString(CultureInfo.InvariantCulture);
doc.DocumentElement.SelectSingleNode("ImageWidth").InnerText = bitmapWidth.ToString(CultureInfo.InvariantCulture);
doc.DocumentElement.SelectSingleNode("NFFT").InnerText = nfft.ToString(CultureInfo.InvariantCulture);
doc.Save(Path.Combine(spectrogramDirectory, "Info.xml"));
return(bitmaps);
}
//////////////////////////////////////// SPECTRUM ///////////////////////////////////////////////////////////
public List<Bitmap> GenerateFourierData(int nfft, string spectrogramDirectory, int delayInMilliseconds)
{
const int bitmapWidth = 1024;
var bitmaps = new List<Bitmap>();
// setup fourier transformation
var f = new Fourier(nfft, true);
double divider = 2.0;
for (int k = 0; k < Header.BitsPerSample - 2; k++)
divider *= 2;
// determine how to read sample values
ReadSampleDataValueDelegate readSampleDataValue = GetSampleDataRerader();
// set up one column of the spectrogram
var palette = new Color[nfft];
if (Configuration.Settings.VideoControls.SpectrogramAppearance == "Classic")
{
for (int colorIndex = 0; colorIndex < nfft; colorIndex++)
palette[colorIndex] = PaletteValue(colorIndex, nfft);
}
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++)
palette[i] = list[i];
}
// read sample values
DataMinValue = int.MaxValue;
DataMaxValue = int.MinValue;
var samples = new List<int>();
int index = 0;
int sampleSize = nfft * bitmapWidth;
int count = 0;
long totalSamples = 0;
// write delay (if any)
int delaySampleCount = (int)(Header.SampleRate * (delayInMilliseconds / TimeCode.BaseUnit));
for (int i = 0; i < delaySampleCount; i++)
{
samples.Add(0);
if (samples.Count == sampleSize)
{
var samplesAsReal = new double[sampleSize];
for (int k = 0; k < sampleSize; k++)
samplesAsReal[k] = 0;
var bmp = DrawSpectrogram(nfft, samplesAsReal, f, palette);
bmp.Save(Path.Combine(spectrogramDirectory, count + ".gif"), System.Drawing.Imaging.ImageFormat.Gif);
bitmaps.Add(bmp);
samples = new List<int>();
count++;
}
}
// load data in smaller parts
_data = new byte[Header.BytesPerSecond];
_stream.Position = Header.DataStartPosition;
int bytesRead = _stream.Read(_data, 0, _data.Length);
while (bytesRead == Header.BytesPerSecond)
{
while (index < Header.BytesPerSecond)
{
int value = 0;
for (int channelNumber = 0; channelNumber < Header.NumberOfChannels; channelNumber++)
{
value += readSampleDataValue.Invoke(ref index);
}
value = value / Header.NumberOfChannels;
if (value < DataMinValue)
DataMinValue = value;
if (value > DataMaxValue)
DataMaxValue = value;
samples.Add(value);
totalSamples++;
if (samples.Count == sampleSize)
{
var samplesAsReal = new double[sampleSize];
for (int k = 0; k < sampleSize; k++)
samplesAsReal[k] = samples[k] / divider;
var bmp = DrawSpectrogram(nfft, samplesAsReal, f, palette);
bmp.Save(Path.Combine(spectrogramDirectory, count + ".gif"), System.Drawing.Imaging.ImageFormat.Gif);
bitmaps.Add(bmp);
samples = new List<int>();
count++;
}
}
bytesRead = _stream.Read(_data, 0, _data.Length);
index = 0;
}
if (samples.Count > 0)
{
var samplesAsReal = new double[sampleSize];
for (int k = 0; k < sampleSize && k < samples.Count; k++)
samplesAsReal[k] = samples[k] / divider;
var bmp = DrawSpectrogram(nfft, samplesAsReal, f, palette);
bmp.Save(Path.Combine(spectrogramDirectory, count + ".gif"), System.Drawing.Imaging.ImageFormat.Gif);
bitmaps.Add(bmp);
}
var doc = new XmlDocument();
doc.LoadXml("<SpectrogramInfo><SampleDuration/><TotalDuration/><AudioFormat /><AudioFormat /><ChunkId /><SecondsPerImage /><ImageWidth /><NFFT /></SpectrogramInfo>");
double sampleDuration = Header.LengthInSeconds / (totalSamples / Convert.ToDouble(nfft));
doc.DocumentElement.SelectSingleNode("SampleDuration").InnerText = sampleDuration.ToString(CultureInfo.InvariantCulture);
doc.DocumentElement.SelectSingleNode("TotalDuration").InnerText = Header.LengthInSeconds.ToString(CultureInfo.InvariantCulture);
doc.DocumentElement.SelectSingleNode("AudioFormat").InnerText = Header.AudioFormat.ToString(CultureInfo.InvariantCulture);
doc.DocumentElement.SelectSingleNode("ChunkId").InnerText = Header.ChunkId.ToString(CultureInfo.InvariantCulture);
doc.DocumentElement.SelectSingleNode("SecondsPerImage").InnerText = ((double)(sampleSize / (double)Header.SampleRate)).ToString(CultureInfo.InvariantCulture);
doc.DocumentElement.SelectSingleNode("ImageWidth").InnerText = bitmapWidth.ToString(CultureInfo.InvariantCulture);
doc.DocumentElement.SelectSingleNode("NFFT").InnerText = nfft.ToString(CultureInfo.InvariantCulture);
doc.Save(Path.Combine(spectrogramDirectory, "Info.xml"));
return bitmaps;
}
