public void TestWindowing()
{
float[] samples = new float[] {
1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1
};
byte[] samplesAsBytes = new byte[samples.Length * 4];
Buffer.BlockCopy(samples, 0, samplesAsBytes, 0, samplesAsBytes.Length);
var source = new MemorySourceStream(new System.IO.MemoryStream(samplesAsBytes), new AudioProperties(1, 44100, 32, AudioFormat.IEEE));
var windower = new StreamWindower(source, 10, 10);
float[] frame = new float[10];
// Read first 10 items that are 1
windower.ReadFrame(frame);
CollectionAssert.AreEqual(frame, Enumerable.Repeat(1f, 10).ToArray());
// Read next 10 items that are 0
windower.ReadFrame(frame);
CollectionAssert.AreEqual(frame, Enumerable.Repeat(0f, 10).ToArray());
// Read last 10 items that are -1
windower.ReadFrame(frame);
CollectionAssert.AreEqual(frame, Enumerable.Repeat(-1f, 10).ToArray());
}
public void MonoOverlapAddRectangle()
{
var properties = new AudioProperties(1, 44100, 32, AudioFormat.IEEE);
var sourceStream = new SineGeneratorStream(44100, 440, TimeSpan.FromSeconds(1));
var targetStream = new MemoryWriterStream(new System.IO.MemoryStream(), properties);
// Rectangular window (samples unchanged) with no overlap should just reconstruct the original stream
int windowSize = 100;
int hopSize = 100;
var window = WindowType.Rectangle;
var sw = new StreamWindower(sourceStream, windowSize, hopSize, window);
var ola = new OLA(targetStream, windowSize, hopSize);
var frameBuffer = new float[windowSize];
while (sw.HasNext())
{
sw.ReadFrame(frameBuffer);
ola.WriteFrame(frameBuffer);
}
ola.Flush();
Assert.AreEqual(sourceStream.Length, targetStream.Length);
// Validate ola target stream content
sourceStream.Position = targetStream.Position = 0;
long similarFloats = StreamUtil.CompareFloats(sourceStream, targetStream);
Assert.AreEqual(sourceStream.Length / sourceStream.SampleBlockSize, similarFloats);
}
public void MonoOverlapAddHann()
{
var properties = new AudioProperties(1, 44100, 32, AudioFormat.IEEE);
IAudioStream sourceStream = new SineGeneratorStream(44100, 440, TimeSpan.FromSeconds(1));
IAudioWriterStream targetStream = new MemoryWriterStream(new System.IO.MemoryStream(), properties);
// 50% overlap with a Hann window is an optimal combination, Hann window is optimally uneven with a 1 as middle point
int windowSize = 21;
int hopSize = 11;
var window = WindowType.Hann;
// Adjust source length to window/hop size so no samples remain at the end
// (a potential last incomplete frame is not returned by the stream windower)
// With remaining samples, the source and target length cannot be compared
sourceStream = new CropStream(sourceStream, 0,
sourceStream.Length
- (sourceStream.Length - windowSize * sourceStream.SampleBlockSize)
% (hopSize * sourceStream.SampleBlockSize));
var sw = new StreamWindower(sourceStream, windowSize, hopSize, window);
var ola = new OLA(targetStream, windowSize, hopSize);
var frameBuffer = new float[windowSize];
while (sw.HasNext())
{
sw.ReadFrame(frameBuffer);
ola.WriteFrame(frameBuffer);
}
ola.Flush();
Assert.AreEqual(sourceStream.Length, targetStream.Length);
// Validate ola target stream content
// Crop the streams to ignore windowed start and end when no overlap-add is performed and content definitely differs
var sourceStreamCropped = new CropStream(sourceStream,
hopSize * sourceStream.SampleBlockSize * 2,
sourceStream.Length - hopSize * sourceStream.SampleBlockSize);
var targetStreamCropped = new CropStream(targetStream,
hopSize * sourceStream.SampleBlockSize * 2,
sourceStream.Length - hopSize * sourceStream.SampleBlockSize);
sourceStreamCropped.Position = targetStreamCropped.Position = 0;
long similarFloats = StreamUtil.CompareFloats(sourceStreamCropped, targetStreamCropped);
Assert.AreEqual(sourceStreamCropped.Length / sourceStreamCropped.SampleBlockSize, similarFloats);
}