// Note: Actually no longer used because instead of disabling playback with no music,
// we load an EmptySampleProvider instead.
public void Clear()
{
Stop();
this.sampleProvider = null;
lastKnownSeekSample = 0;
continuationOnStoppedHook = null;
}
public void Init(ISeekableSampleProvider sampleProvider)
{
Stop();
EnsureDeviceCreated();
this.sampleProvider = sampleProvider;
lastKnownSeekSample = sampleProvider.Position;
playbackDevice.Init(sampleProvider);
}
public static Task <Waveform> CreateWaveformAsync(ISeekableSampleProvider sampleProvider, float scaleInPixelsPerSecond,
double fromTime, double toTime,
CancellationToken cancellation = default(CancellationToken))
{
if (scaleInPixelsPerSecond <= 0)
{
throw new ArgumentOutOfRangeException(nameof(scaleInPixelsPerSecond), scaleInPixelsPerSecond, "must be positive");
}
if (fromTime < 0)
{
throw new ArgumentOutOfRangeException(nameof(fromTime), fromTime, "must be non-negative");
}
return(Task.Run(() => CreateWaveform(sampleProvider, scaleInPixelsPerSecond, fromTime, toTime, cancellation), cancellation));
}
private static Waveform CreateWaveform(ISeekableSampleProvider sampleProvider, float scaleInPixelsPerSecond,
double fromTime, double toTime,
CancellationToken cancellation = default(CancellationToken))
{
var sw = new Stopwatch();
sw.Start();
int channels = sampleProvider.WaveFormat.Channels;
float sampleRate = sampleProvider.WaveFormat.SampleRate;
scaleInPixelsPerSecond /= WAVEFORM_PIXEL_INTERVAL;
// It does not make sense to have more pixels than samples.
if (scaleInPixelsPerSecond > sampleRate)
{
scaleInPixelsPerSecond = sampleRate;
}
List <float> minValues = new List <float>();
List <float> maxValues = new List <float>();
// the first sample to include in the waveform - aligned with the pixel interval to prevent jittering when scrolling
long alignIntervalFactor = (long)Math.Round(sampleRate / scaleInPixelsPerSecond);
long firstSample = (long)(fromTime * sampleRate) / alignIntervalFactor * alignIntervalFactor;
long lastSample = (long)Math.Ceiling(toTime * sampleRate);
sampleProvider.Seek((int)firstSample * channels);
long c = firstSample; // global sample counter (for all channels)
int lastX = 0; // current render position
float currentMin = float.PositiveInfinity;
float currentMax = float.NegativeInfinity;
float[] buffer = new float[READ_BUFFER_SIZE];
int numRead;
do
{
cancellation.ThrowIfCancellationRequested();
numRead = sampleProvider.Read(buffer, 0, READ_BUFFER_SIZE);
for (int i = 0; i < numRead && c <= lastSample; i++)
{
float renderPosition = (c - firstSample) / sampleRate * scaleInPixelsPerSecond;
int x = (int)renderPosition;
if (x > lastX)
{
// we advanced a pixel, add new values with aggregate
minValues.Add(currentMin);
maxValues.Add(currentMax);
lastX++;
// reset
currentMin = float.PositiveInfinity;
currentMax = float.NegativeInfinity;
}
// aggregate
float value = buffer[i];
currentMin = Math.Min(currentMin, value);
currentMax = Math.Max(currentMax, value);
// only count up total when we cycled through all channels
if ((i + 1) % channels == 0)
{
c++;
}
}
} while (numRead > 0 && c <= lastSample);
double actualFromTime = (double)firstSample / sampleRate;
double timePerSample = 1.0 / scaleInPixelsPerSecond;
var wf = new Waveform(actualFromTime, timePerSample, minValues.ToArray(), maxValues.ToArray());
sw.Stop();
Debug.WriteLine($"generated waveform with {minValues.Count} data points for {toTime - fromTime} s in {sw.ElapsedMilliseconds} ms");
return(wf);
}
