/// <summary>
/// Creates a new <see cref="Waveform"/> containing a specific number of data points by selecting the average value of each sampled group.
/// </summary>
/// <param name="pointCount">The number of points the resulting <see cref="Waveform"/> should contain.</param>
/// <param name="cancellationToken">The token to cancel the task.</param>
/// <returns>An async task for the generation of the <see cref="Waveform"/>.</returns>
public async Task <Waveform> GenerateResampledAsync(int pointCount, CancellationToken cancellationToken = default)
{
if (pointCount < 0)
{
throw new ArgumentOutOfRangeException(nameof(pointCount));
}
if (readTask == null)
{
return(new Waveform());
}
await readTask;
return(await Task.Run(() =>
{
var generatedPoints = new List <WaveformPoint>();
float pointsPerGeneratedPoint = (float)points.Count / pointCount;
for (float i = 0; i < points.Count; i += pointsPerGeneratedPoint)
{
if (cancellationToken.IsCancellationRequested)
{
break;
}
int startIndex = (int)i;
int endIndex = (int)Math.Min(points.Count, Math.Ceiling(i + pointsPerGeneratedPoint));
var point = new WaveformPoint(channels);
for (int j = startIndex; j < endIndex; j++)
{
for (int c = 0; c < channels; c++)
{
point.Amplitude[c] += points[j].Amplitude[c];
}
point.LowIntensity += points[j].LowIntensity;
point.MidIntensity += points[j].MidIntensity;
point.HighIntensity += points[j].HighIntensity;
}
// Means
for (int c = 0; c < channels; c++)
{
point.Amplitude[c] /= endIndex - startIndex;
}
point.LowIntensity /= endIndex - startIndex;
point.MidIntensity /= endIndex - startIndex;
point.HighIntensity /= endIndex - startIndex;
generatedPoints.Add(point);
}
return new Waveform
{
points = generatedPoints,
channels = channels
};
}, cancellationToken));
}
/// <summary>
/// Constructs a new <see cref="Waveform"/> from provided audio data.
/// </summary>
/// <param name="data">The sample data stream. If null, an empty waveform is constructed.</param>
public Waveform(Stream data = null)
{
if (data == null)
{
return;
}
readTask = Task.Run(() =>
{
var procs = new DataStreamFileProcedures(data);
int decodeStream = Bass.CreateStream(StreamSystem.NoBuffer, BassFlags.Decode | BassFlags.Float, procs.BassProcedures, IntPtr.Zero);
ChannelInfo info;
Bass.ChannelGetInfo(decodeStream, out info);
long length = Bass.ChannelGetLength(decodeStream);
// Each "point" is generated from a number of samples, each sample contains a number of channels
int sampleDataPerPoint = (int)(info.Frequency * resolution * info.Channels);
points.Capacity = (int)(length / sampleDataPerPoint);
int bytesPerIteration = sampleDataPerPoint * points_per_iteration;
var dataBuffer = new float[bytesPerIteration / bytes_per_sample];
while (length > 0)
{
length = Bass.ChannelGetData(decodeStream, dataBuffer, bytesPerIteration);
int samplesRead = (int)(length / bytes_per_sample);
// Process a sequence of samples for each point
for (int i = 0; i < samplesRead; i += sampleDataPerPoint)
{
// Process each sample in the sequence
var point = new WaveformPoint(info.Channels);
for (int j = i; j < i + sampleDataPerPoint; j += info.Channels)
{
// Process each channel in the sample
for (int c = 0; c < info.Channels; c++)
{
point.Amplitude[c] = Math.Max(point.Amplitude[c], Math.Abs(dataBuffer[j + c]));
}
}
for (int c = 0; c < info.Channels; c++)
{
point.Amplitude[c] = Math.Min(1, point.Amplitude[c]);
}
points.Add(point);
}
}
channels = info.Channels;
}, cancelSource.Token);
}
/// <summary>
/// Constructs a new <see cref="Waveform"/> from provided audio data.
/// </summary>
/// <param name="data">The sample data stream. If null, an empty waveform is constructed.</param>
public Waveform(Stream data)
{
if (data == null)
{
return;
}
readTask = Task.Run(() =>
{
// for the time being, this code cannot run if there is no bass device available.
if (Bass.CurrentDevice <= 0)
{
return;
}
procedures = CreateDataStreamFileProcedures(data);
if (!RuntimeInfo.SupportsIL)
{
pinnedProcedures = GCHandle.Alloc(procedures, GCHandleType.Pinned);
}
int decodeStream = Bass.CreateStream(StreamSystem.NoBuffer, BassFlags.Decode | BassFlags.Float, procedures.BassProcedures,
RuntimeInfo.SupportsIL ? IntPtr.Zero : GCHandle.ToIntPtr(pinnedProcedures));
Bass.ChannelGetInfo(decodeStream, out ChannelInfo info);
long length = Bass.ChannelGetLength(decodeStream);
// Each "point" is generated from a number of samples, each sample contains a number of channels
int samplesPerPoint = (int)(info.Frequency * resolution * info.Channels);
int bytesPerPoint = samplesPerPoint * bytes_per_sample;
points.Capacity = (int)(length / bytesPerPoint);
// Each iteration pulls in several samples
int bytesPerIteration = bytesPerPoint * points_per_iteration;
var sampleBuffer = new float[bytesPerIteration / bytes_per_sample];
// Read sample data
while (length > 0)
{
length = Bass.ChannelGetData(decodeStream, sampleBuffer, bytesPerIteration);
int samplesRead = (int)(length / bytes_per_sample);
// Each point is composed of multiple samples
for (int i = 0; i < samplesRead; i += samplesPerPoint)
{
// Channels are interleaved in the sample data (data[0] -> channel0, data[1] -> channel1, data[2] -> channel0, etc)
// samplesPerPoint assumes this interleaving behaviour
var point = new WaveformPoint(info.Channels);
for (int j = i; j < i + samplesPerPoint; j += info.Channels)
{
// Find the maximum amplitude for each channel in the point
for (int c = 0; c < info.Channels; c++)
{
point.Amplitude[c] = Math.Max(point.Amplitude[c], Math.Abs(sampleBuffer[j + c]));
}
}
// BASS may provide unclipped samples, so clip them ourselves
for (int c = 0; c < info.Channels; c++)
{
point.Amplitude[c] = Math.Min(1, point.Amplitude[c]);
}
points.Add(point);
}
}
Bass.ChannelSetPosition(decodeStream, 0);
length = Bass.ChannelGetLength(decodeStream);
// Read FFT data
float[] bins = new float[fft_bins];
int currentPoint = 0;
long currentByte = 0;
while (length > 0)
{
length = Bass.ChannelGetData(decodeStream, bins, (int)fft_samples);
currentByte += length;
double lowIntensity = computeIntensity(info, bins, low_min, mid_min);
double midIntensity = computeIntensity(info, bins, mid_min, high_min);
double highIntensity = computeIntensity(info, bins, high_min, high_max);
// In general, the FFT function will read more data than the amount of data we have in one point
// so we'll be setting intensities for all points whose data fits into the amount read by the FFT
// We know that each data point required sampleDataPerPoint amount of data
for (; currentPoint < points.Count && currentPoint * bytesPerPoint < currentByte; currentPoint++)
{
points[currentPoint].LowIntensity = lowIntensity;
points[currentPoint].MidIntensity = midIntensity;
points[currentPoint].HighIntensity = highIntensity;
}
}
channels = info.Channels;
}, cancelSource.Token);
}
/// <summary>
/// Creates a new <see cref="Waveform"/> containing a specific number of data points by selecting the average value of each sampled group.
/// </summary>
/// <param name="pointCount">The number of points the resulting <see cref="Waveform"/> should contain.</param>
/// <param name="cancellationToken">The token to cancel the task.</param>
/// <returns>An async task for the generation of the <see cref="Waveform"/>.</returns>
public async Task <Waveform> GenerateResampledAsync(int pointCount, CancellationToken cancellationToken = default)
{
if (pointCount < 0)
{
throw new ArgumentOutOfRangeException(nameof(pointCount));
}
if (readTask == null)
{
return(new Waveform(null));
}
await readTask;
return(await Task.Run(() =>
{
var generatedPoints = new List <WaveformPoint>();
float pointsPerGeneratedPoint = (float)points.Count / pointCount;
// Determines at which width (relative to the resolution) our smoothing filter is truncated.
// Should not effect overall appearance much, except when the value is too small.
// A gaussian contains almost all its mass within its first 3 standard deviations,
// so a factor of 3 is a very good choice here.
const int kernel_width_factor = 3;
int kernelWidth = (int)(pointsPerGeneratedPoint *kernel_width_factor) + 1;
float[] filter = new float[kernelWidth + 1];
for (int i = 0; i < filter.Length; ++i)
{
filter[i] = (float)Blur.EvalGaussian(i, pointsPerGeneratedPoint);
}
for (float i = 0; i < points.Count; i += pointsPerGeneratedPoint)
{
if (cancellationToken.IsCancellationRequested)
{
break;
}
int startIndex = (int)i - kernelWidth;
int endIndex = (int)i + kernelWidth;
var point = new WaveformPoint(channels);
float totalWeight = 0;
for (int j = startIndex; j < endIndex; j++)
{
if (j < 0 || j >= points.Count)
{
continue;
}
float weight = filter[Math.Abs(j - startIndex - kernelWidth)];
totalWeight += weight;
for (int c = 0; c < channels; c++)
{
point.Amplitude[c] += weight *points[j].Amplitude[c];
}
point.LowIntensity += weight *points[j].LowIntensity;
point.MidIntensity += weight *points[j].MidIntensity;
point.HighIntensity += weight *points[j].HighIntensity;
}
// Means
for (int c = 0; c < channels; c++)
{
point.Amplitude[c] /= totalWeight;
}
point.LowIntensity /= totalWeight;
point.MidIntensity /= totalWeight;
point.HighIntensity /= totalWeight;
generatedPoints.Add(point);
}
return new Waveform(null)
{
points = generatedPoints,
channels = channels
};
}, cancellationToken));
}
