public void WavReaderMakeMultiChannelWav()
{
const double Tau = 2 * Math.PI;
var a = new double[22050].Select((v, i) => Math.Sin(Tau * i * 500 / 22050)).ToArray();
var b = new double[22050].Select((v, i) => Math.Sin(Tau * i * 1500 / 22050)).ToArray();
var c = new double[22050].Select((v, i) => Math.Sin(Tau * i * 2500 / 22050)).ToArray();
var d = new double[22050].Select((v, i) => Math.Sin(Tau * i * 3500 / 22050)).ToArray();
var multiplexed = new double[22050 * 4].Select(
(v, i) =>
{
switch (i % 4)
{
case 0: return(a[i / 4]);
case 1: return(b[i / 4]);
case 2: return(c[i / 4]);
case 3: return(d[i / 4]);
}
return(double.NaN);
});
var reader = new WavReader(multiplexed.ToArray(), 4, 16, 22050);
CollectionAssert.AreEqual(a, reader.GetChannel(0));
CollectionAssert.AreEqual(b, reader.GetChannel(1));
CollectionAssert.AreEqual(c, reader.GetChannel(2));
CollectionAssert.AreEqual(d, reader.GetChannel(3));
}
public void WavReaderChannelOutOfBoundsFails()
{
var source = PathHelper.GetTestAudioFile("different_channels_tone.wav");
var reader = new WavReader(source);
Assert.ThrowsException <IndexOutOfRangeException>(() => { reader.GetChannel(-1); });
Assert.ThrowsException <IndexOutOfRangeException>(() => { reader.GetChannel(5); });
Assert.ThrowsException <IndexOutOfRangeException>(() => { reader[0, -1].ToString(); });
Assert.ThrowsException <IndexOutOfRangeException>(() => { reader[0, 5].ToString(); });
}
public void WavReaderReadsSamplesAccurately24bit()
{
// 11025Hz fake array
var a = new double[44100 * 5].Select((v, i) => i % 4 == 3 ? -1 : i % 2).ToArray();
var source = PathHelper.GetTestAudioFile("11025Hz-24bit.wav");
var info = this.audioUtility.Info(source);
var reader = new WavReader(source);
TestHelper.WavReaderAssertions(reader, info);
Assert.AreEqual(5.0M, reader.ExactDurationSeconds);
var mono = reader.GetChannel(0);
Assert.AreEqual(a.Length, reader.Samples.Length);
Assert.AreEqual(a.Length, mono.Length);
for (int i = 0; i < a.Length; i++)
{
Assert.AreEqual(a[i], reader.Samples[i], double.Epsilon);
Assert.AreEqual(a[i], mono[i], double.Epsilon);
}
}
private static void DoFrequencyAnalysis(
AudioUtilityInfo expected,
int[][] expectedFrequencies)
{
var reader = new WavReader(expected.SourceFile);
TestHelper.WavReaderAssertions(reader, expected);
for (var channel = 0; channel < expectedFrequencies.Length; channel++)
{
var samples = reader.GetChannel(channel);
TestHelper.AssertFrequencyInSignal(reader, samples, expectedFrequencies[channel]);
}
}
public void WavReaderGetChannel()
{
var source = PathHelper.GetTestAudioFile("4channelsPureTones.wav");
var info = this.audioUtility.Info(source);
var reader = new WavReader(source);
TestHelper.WavReaderAssertions(reader, info);
var channels = new double[4][];
var expectedFrequencies = new int[] { 4000, 3000, 2000, 1000 };
for (int c = 0; c < channels.Length; c++)
{
channels[c] = reader.GetChannel(c);
TestHelper.AssertFrequencyInSignal(reader, channels[c], new[] { expectedFrequencies[c] });
}
}
public void WavReaderReadsSamplesAccuratelytMultiChannelRandom(int bitDepth, int sampleRate, int channels)
{
const int testSampleCount = 500;
// generate some fake data
// generates a repeating saw wave of 0, 1, 0 -1
var a = new double[testSampleCount].Select((v, i) => i % 4 == 3 ? -1.0 : i % 2).ToArray();
// random data
var random = TestHelpers.Random.GetRandom();
double Clamp(double value)
{
return(Math.Max(Math.Min(value, 1.0), -1.0));
}
var b = new double[testSampleCount].Select(v => Clamp(random.NextDouble() * 2.0 - 1.0)).ToArray();
// now write the file
var temp = PathHelper.GetTempFile("wav");
var signals = new double[channels][];
switch (channels)
{
case 4:
signals[0] = a;
signals[1] = b;
signals[2] = b;
signals[3] = a;
break;
case 2:
signals[0] = a;
signals[1] = b;
break;
case 1:
var c = new double[a.Length + b.Length];
a.CopyTo(c, 0);
b.CopyTo(c, a.Length);
signals[0] = c;
break;
default:
throw new InvalidOperationException();
}
WavWriter.WriteWavFileViaFfmpeg(temp, signals, bitDepth, sampleRate);
// verify file written correctly
var info = this.audioUtility.Info(temp);
var reader = new WavReader(temp);
// verify the writer wrote (the header) correctly
TestHelper.WavReaderAssertions(reader, new AudioUtilityInfo()
{
BitsPerSample = bitDepth,
BitsPerSecond = channels * bitDepth * sampleRate,
ChannelCount = channels,
Duration = TimeSpan.FromSeconds(testSampleCount * (channels == 1 ? 2 : 1) / (double)sampleRate),
MediaType = MediaTypes.MediaTypeWav1,
SampleRate = sampleRate,
});
// verify the wav reader read correctly
TestHelper.WavReaderAssertions(reader, info);
// our ability to faithfully convert numbers depends on the bit depth of the signal
double epilson = reader.Epsilon;
for (int c = 0; c < channels; c++)
{
double[] expected;
double e;
switch (c)
{
case 0 when channels == 1:
var ex = new double[a.Length + b.Length];
a.CopyTo(ex, 0);
b.CopyTo(ex, a.Length);
expected = ex;
e = epilson;
break;
case 0:
expected = a;
e = 0.0;
break;
case 1:
expected = b;
e = epilson;
break;
case 2:
expected = b;
e = epilson;
break;
case 3:
expected = a;
e = 0.0;
break;
default:
throw new InvalidOperationException();
}
var mono = reader.GetChannel(c);
Assert.AreEqual(expected.Length, mono.Length);
for (int i = 0; i < a.Length; i++)
{
Assert.AreEqual(expected[i], mono[i], epilson, $"failed at index {i} channel {c}");
}
}
}