/// <summary>
/// Reads a single sample from a wav stream.
/// </summary>
/// <param name="wavStream">Wave Stream.</param>
/// <param name="wavInfo">Wave Info.</param>
/// <returns>Sample read from stream.</returns>
private static double ReadSample(Stream wavStream, WavAudioInfo wavInfo)
{
double sample;
switch (wavInfo.BitsPerSample)
{
case 8:
sample = wavStream.ReadByte() / 128.0;
int remainingChannels8 = wavInfo.Channels - 1;
wavStream.Skip(remainingChannels8);
break;
case 16:
var buffer = new byte[2];
wavStream.Read(buffer, 0, 2);
var value = BitConverter.ToInt16(buffer, 0);
sample = value / 32768.0;
// two bytes per sample
int remainingChannels16 = wavInfo.Channels - 1;
wavStream.Skip(remainingChannels16 * 2);
break;
default:
throw new NotSupportedException("Bits per sample other than 8 and 16.");
}
return(sample);
}
/// <summary>
/// Get samples from the wav stream. Start from <paramref name="firstSampleIndex"/> (zero indexed),
/// and read <paramref name="numberOfSamplesToRead"/>.
/// </summary>
/// <param name="firstSampleIndex">
/// The first Sample Index.
/// </param>
/// <param name="numberOfSamplesToRead">
/// The number Of Samples To Read.
/// </param>
/// <returns>
/// <paramref name="numberOfSamplesToRead"/> starting from <paramref name="firstSampleIndex"/>.
/// </returns>
public double[] GetSamples(long firstSampleIndex, long numberOfSamplesToRead)
{
var dataChunk = this.GetDataChunk;
var sampleLength = (int)numberOfSamplesToRead;
var samples = new double[sampleLength];
WavAudioInfo wavInfo = this.AudioInfo;
using (Stream fileStream = this.GetFileStream)
{
// set stream to correct location
fileStream.Position = GetCalculatedPosition(wavInfo, dataChunk.Position, firstSampleIndex);
for (var index = 0; index < sampleLength; index++)
{
samples[index] = ReadSample(fileStream, wavInfo);
}
}
// if samples is odd, padding of 1 byte
////if (sampleLength % 2 != 0)
////{
//// fileStream.Position++;
////}
return(samples);
}
/// <summary>
/// Get position (number of bytes from start of file) in wav stream of <paramref name="sampleIndex"/>.
/// </summary>
/// <param name="wavInfo">Wave Info.</param>
/// <param name="dataChunkPosition">Data Chunk Position.</param>
/// <param name="sampleIndex">Index of Sample.</param>
/// <returns>Position of <paramref name="sampleIndex"/>.</returns>
private static long GetCalculatedPosition(WavAudioInfo wavInfo, long dataChunkPosition, long sampleIndex)
{
// each sample takes wavInfo.BytesPerSample, want to skip sampleIndex samples.
var amountToSkip = wavInfo.BytesPerSample * sampleIndex;
// position = start of datachunk + start of sample
var newPosition = dataChunkPosition + amountToSkip;
return(newPosition);
}
/// <summary>
/// Get samples per channel. The first channel (mono if it is the only channel) is usually the left.
/// </summary>
/// <param name="wavSource">
/// The wav Source.
/// </param>
/// <param name="wavInfo">
/// The wav Info.
/// </param>
/// <param name="duration">
/// The duration.
/// </param>
/// <exception cref="NotSupportedException">
/// Bits per sample other than 8 and 16.
/// </exception>
/// <returns>
/// Samples divided into channels.
/// </returns>
public static double[][] SplitChannels(this Stream wavSource, WavAudioInfo wavInfo, TimeSpan?duration)
{
short numberOfChannels = wavInfo.Channels;
short bitsPerSample = wavInfo.BitsPerSample;
long numberOfFrames = wavInfo.Frames;
var sampleLength = (int)wavInfo.Frames;
var samples = new double[sampleLength][];
if (duration.HasValue)
{
var sampleRate = (double)wavInfo.SampleRate;
double givenDuration = duration.Value.TotalSeconds;
var framesForDuration = (long)Math.Floor(sampleRate * givenDuration);
numberOfFrames = Math.Min(framesForDuration, numberOfFrames);
}
for (int channel = 0; channel < numberOfChannels; channel++)
{
samples[channel] = new double[numberOfFrames];
}
for (int frame = 0; frame < numberOfFrames; frame++)
{
for (int channel = 0; channel < numberOfChannels; channel++)
{
switch (bitsPerSample)
{
case 8:
samples[channel][frame] = wavSource.ReadByte() / 128.0;
break;
case 16:
var buffer = new byte[2];
wavSource.Read(buffer, 0, 2);
var value = BitConverter.ToInt16(buffer, 0);
samples[channel][frame] = value / 32768.0;
break;
default:
throw new NotSupportedException("Bits per sample other than 8 and 16.");
}
}
}
return(samples);
}
/// <summary>
/// Get a single sample. Do not use this method in a loop.
/// </summary>
/// <param name="sampleIndex">
/// The sample index (zero-based).
/// </param>
/// <returns>
/// Read sample.
/// </returns>
public double GetSample(long sampleIndex)
{
WavAudioInfo wavInfo = this.AudioInfo;
var dataChunk = this.GetDataChunk;
using (Stream fileStream = this.GetFileStream)
{
// set stream to correct location
fileStream.Position = GetCalculatedPosition(wavInfo, dataChunk.Position, sampleIndex);
double sample = ReadSample(fileStream, wavInfo);
return(sample);
}
}
/// <summary>
/// Read first channel samples as doubles.
/// Set the SampleStream position before using this method.
/// </summary>
/// <param name="wavSource">
/// The wav source.
/// </param>
/// <param name="wavInfo">
/// The wav info.
/// </param>
/// <returns>
/// Samples of first channel.
/// </returns>
/// <exception cref="NotSupportedException">
/// </exception>
public static double[] ReadSamples(this Stream wavSource, WavAudioInfo wavInfo)
{
var sampleLength = (int)wavInfo.Frames;
var samples = new double[sampleLength];
switch (wavInfo.BitsPerSample)
{
case 8:
for (int i = 0; i < sampleLength; i++)
{
samples[i] = wavSource.ReadByte() / 128.0;
int remainingChannels = wavInfo.Channels - 1;
wavSource.Skip(remainingChannels);
}
break;
case 16:
for (int i = 0; i < sampleLength; i++)
{
var buffer = new byte[2];
wavSource.Read(buffer, 0, 2);
var value = BitConverter.ToInt16(buffer, 0);
samples[i] = value / 32768.0;
// two bytes per sample
int remainingChannels = wavInfo.Channels - 1;
wavSource.Skip(remainingChannels * 2);
}
break;
default:
throw new NotSupportedException("Bits per sample other than 8 and 16.");
}
// if samples is odd, padding of 1 byte
if (sampleLength % 2 != 0)
{
wavSource.Position++;
}
return(samples);
}
/// <summary>
/// Get samples from the wav stream. Start from <paramref name="firstSampleIndex"/> (zero indexed),
/// and read <paramref name="numberOfSamplesToRead"/>.
/// </summary>
/// <param name="wavStream">
/// The wav Stream.
/// </param>
/// <param name="dataChunk">
/// The data Chunk.
/// </param>
/// <param name="wavInfo">
/// The wav Info.
/// </param>
/// <param name="firstSampleIndex">
/// The first Sample Index.
/// </param>
/// <param name="numberOfSamplesToRead">
/// The number Of Samples To Read.
/// </param>
/// <returns>
/// <paramref name="numberOfSamplesToRead"/> starting from <paramref name="firstSampleIndex"/>.
/// </returns>
public static double[] GetSamples(Stream wavStream, WavChunk dataChunk, WavAudioInfo wavInfo, long firstSampleIndex, long numberOfSamplesToRead)
{
var samples = new double[numberOfSamplesToRead];
// set stream to correct location
wavStream.Position = GetCalculatedPosition(wavInfo, dataChunk.Position, firstSampleIndex);
for (long index = 0; index < numberOfSamplesToRead; index++)
{
samples[index] = ReadSample(wavStream, wavInfo);
}
// if samples is odd, padding of 1 byte
////if (sampleLength % 2 != 0)
////{
//// fileStream.Position++;
////}
return(samples);
}
/// <summary>
/// Reads the wave header and stores info in WavAudioInfo.
/// </summary>
/// <param name="stream">
/// The stream.
/// </param>
/// <exception cref="InvalidDataException">
/// <c>InvalidDataException</c>.
/// </exception>
private void ReadHeader(Stream stream)
{
var wavInfo = new WavAudioInfo();
const string ChunkIdRiff = "RIFF";
const string ChunkIdData = "data";
const string ChunkIdFormat = "fmt ";
int chunkDataSizeData = 0;
var chunks = new List <WavChunk>();
using (var reader = new BinaryReader(new NonClosingStreamWrapper(stream)))
{
long streamLength = reader.BaseStream.Length;
long streamPosition = reader.BaseStream.Position;
try
{
while (streamPosition < streamLength)
{
// deal with next chunk
var chunkName = new string(reader.ReadChars(4));
int chunkSize = reader.ReadInt32();
chunks.Add(new WavChunk {
Position = reader.BaseStream.Position, Name = chunkName, Length = chunkSize
});
switch (chunkName)
{
case ChunkIdRiff:
ReadRiffChunk(reader);
break;
case ChunkIdFormat:
ReadFmtChunk(reader, wavInfo, chunkSize);
break;
case ChunkIdData:
// chunk name: "data"
// chunk size: size of audio data.
chunkDataSizeData = chunkSize;
// skip over data chunk
reader.Skip(chunkSize);
break;
default:
// skip over chunk
reader.Skip(chunkSize);
break;
}
streamPosition = reader.BaseStream.Position;
}
}
catch (EndOfStreamException)
{
}
// make sure riff,format and data chunks were found
if (chunks.Where(c => c.Name == ChunkIdRiff || c.Name == ChunkIdFormat || c.Name == ChunkIdData).Count() != 3)
{
throw new InvalidDataException("Did not find one or more required chunks.");
}
// frames and sample count are the same thing?
// they should be equal
long calc1 = chunkDataSizeData * (long)WavUtils.BitsPerByte;
long calc2 = wavInfo.Channels * (long)wavInfo.BitsPerSample;
long calc3 = calc1 / calc2;
wavInfo.Frames = calc3;
double sampleCount = chunkDataSizeData / (double)wavInfo.BytesPerSample;
wavInfo.Duration = TimeSpan.FromSeconds(sampleCount / wavInfo.SampleRate);
// verify frame/sample count
if (wavInfo.Frames != sampleCount)
{
throw new InvalidDataException(string.Format(ErrorMsg, wavInfo.Frames, sampleCount, "frames and samples"));
}
}
this.AudioInfo = wavInfo;
this.Chunks = chunks;
this.SampleStream = stream;
}
/// <summary>
/// Read format chunk. Assumes <paramref name="reader"/> is correctly positioned.
/// </summary>
/// <param name="reader">
/// Binary Reader.
/// </param>
/// <param name="wavInfo">
/// Wav audio info.
/// </param>
/// <param name="chunkSize">
/// The chunk Size.
/// </param>
/// <exception cref="InvalidDataException">
/// <c>InvalidDataException</c>.
/// </exception>
private static void ReadFmtChunk(BinaryReader reader, WavAudioInfo wavInfo, int chunkSize)
{
/*
* chunk name: "fmt " - the chunk ID string ends with the space character (0x20).
* chunk size: size of format data (16 bytes for compression code 1).
*/
// the size of the standard wave format data (16 bytes)
// plus the size of any extra format bytes needed for
// the specific Wave format, if it does not contain
// uncompressed PCM data.
const int ChunkDataSizeFormat = 16;
int chunkDataSizeFormatRead = chunkSize;
// The first word of format data specifies
// the type of compression used on the Wave
// data included in the Wave chunk found in this "RIFF" chunk.
// 1 for PCM/uncompressed
const short CompressionCode = 1;
wavInfo.CompressionCode = reader.ReadInt16();
if (wavInfo.CompressionCode != CompressionCode)
{
throw new InvalidDataException(string.Format(ErrorMsg, CompressionCode, wavInfo.CompressionCode, "compression code"));
}
// how many separate audio signals that are
// encoded in the wave data chunk. A value of
// 1 means a mono signal, a value of 2 means a stereo signal.
wavInfo.Channels = reader.ReadInt16();
// The number of sample slices per second.
// This value is unaffected by the number of channels.
wavInfo.SampleRate = reader.ReadInt32();
// Average Bytes Per Second
// This value indicates how many bytes of wave
// data must be streamed to a D/A converter per
// second in order to play the wave file. This
// information is useful when determining if
// data can be streamed from the source fast
// enough to keep up with playback. This value
// can be easily calculated with the formula:
// AvgBytesPerSec = SampleRate * BlockAlign
wavInfo.BytesPerSecond = reader.ReadInt32();
// Block Align / bytes per sample. (frame)
// The number of bytes per sample slice. This value
// is not affected by the number of channels and can be
// calculated with the formula:
// BlockAlign = SignificantBitsPerSample / 8 * NumChannels
// or
// short frameSize = (short)(channels * ((wavInfo.BitsPerSample + 7) / 8));
wavInfo.BytesPerSample = reader.ReadInt16();
// Significant Bits Per Sample
// This value specifies the number of bits used to define each sample.
// This value is usually 8, 16, 24 or 32. If the number of bits is not
// byte aligned (a multiple of 8) then the number of bytes used per sample
// is rounded up to the nearest byte size and the unused bytes are set to 0 and ignored.
wavInfo.BitsPerSample = reader.ReadInt16();
var remainder = WavUtils.MaxBitsPerSample % wavInfo.BitsPerSample;
if (remainder != 0)
{
throw new InvalidDataException(
"The input stream uses an unhandled SignificantBitsPerSample parameter. " +
string.Format(ErrorMsg, "0 (" + WavUtils.MaxBitsPerSample + ")", remainder + "(" + wavInfo.BitsPerSample + ")", "bits per sample"));
}
// extra format bytes
reader.ReadChars(chunkDataSizeFormatRead - ChunkDataSizeFormat);
// verify bytes per second
int checkBytesPerSecond = wavInfo.SampleRate * wavInfo.BytesPerSample;
if (wavInfo.BytesPerSecond != checkBytesPerSecond)
{
throw new InvalidDataException(string.Format(ErrorMsg, wavInfo.BytesPerSecond, checkBytesPerSecond, "bytes per second check"));
}
// verify bytes per sample
int checkBytesPerSample = wavInfo.BitsPerSample / WavUtils.BitsPerByte * wavInfo.Channels;
if (wavInfo.BytesPerSample != checkBytesPerSample)
{
throw new InvalidDataException(string.Format(ErrorMsg, wavInfo.BytesPerSample, checkBytesPerSample, "bytes per sample check"));
}
}
