For sjovs skyld skrev jeg dette eksempel på en WavFile klasse:
public class WavFile : IDisposable
{
private const string FormatRiff = "RIFF";
private const string FormatWave = "WAVE";
private const string SubchunkData = "data";
private const string SubchunkFmt = "fmt ";
private readonly Stream source;
public WavFile(Stream source)
{
if ( source == null )
throw new ArgumentNullException("source");
this.source = source;
SamplePosition = 0;
ReadHeader();
}
public short NumChannels { get; private set; }
public uint SampleRate { get; private set; }
public short BitsPerSample { get; private set; }
public long TotalSamples { get; private set;}
public uint SamplePosition { get; private set; }
/// <summary>
/// Reads the Wav file header and positions the stream at first data sample.
/// </summary>
private void ReadHeader()
{
if (ReadString(4) != FormatRiff)
throw new ApplicationException("Not a RIFF file");
Read(4);
if (ReadString(4) != FormatWave)
throw new ApplicationException("Not a WAVE file");
if (ReadString(4) != SubchunkFmt)
throw new ApplicationException("fmt subchunk not found");
if (ReadInt() < 16)
throw new ApplicationException("Unexpected format");
if (ReadShort() != 1)
throw new ApplicationException("Only PCM supported");
NumChannels = ReadShort();
SampleRate = ReadInt();
ReadInt(); // Byterate, ignored
ReadShort(); // block-align, ignored
BitsPerSample = ReadShort();
if ( BitsPerSample % 8 != 0 || BitsPerSample > 32)
throw new ApplicationException(String.Format("{0} bps not supported.",BitsPerSample));
if(ReadString(4) != SubchunkData)
throw new ApplicationException("Data chunk not found");
uint size = ReadInt();
TotalSamples = (uint)(BitsPerSample/8)*NumChannels;
}
/// <summary>
/// Reads the next sample.
/// </summary>
/// <returns></returns>
public int ReadSample()
{
switch(BitsPerSample)
{
case 8:
return Read(1)[0];
case 16:
return ReadShort();
case 32:
return (int)ReadInt();
default:
throw new ApplicationException("Sample format unsupported");
}
}
/// <summary>
/// Skips the specified samples.
/// </summary>
/// <param name="samples">The samples.</param>
public void Skip(int samples)
{
Read((BitsPerSample*samples*NumChannels)/8);
}
/// <summary>
/// Skips the specified seconds.
/// </summary>
/// <param name="seconds">The seconds.</param>
public void Skip(double seconds)
{
Skip((int) (seconds*SampleRate));
}
/// <summary>
/// Reads the string.
/// </summary>
/// <param name="byteCount">The byte count.</param>
/// <returns></returns>
private string ReadString(int byteCount)
{
var buffer = Read(byteCount);
return Encoding.ASCII.GetString(buffer);
}
private uint ReadInt()
{
var b = Read(4);
uint v = BitConverter.ToUInt32(b, 0);
return v;
}
private short ReadShort()
{
var b = Read(2);
short v = BitConverter.ToInt16(b,0);
return v;
}
private byte [] Read(int byteCount)
{
byte [] buffer = new byte[byteCount];
if (source.Read(buffer,0,byteCount)!=byteCount)
throw new IOException("Unable to read from file");
return buffer;
}
public void Dispose()
{
source.Dispose();
}
}
Som kan bruges f.eks. sådan:
using(var file = new WavFile(new FileStream(args[0],FileMode.Open,FileAccess.Read)))
{
Console.WriteLine("Reading file:\t\t{0}", args[0]);
Console.WriteLine("Number of channels:\t{0}", file.NumChannels);
Console.WriteLine("Samplerate\t\t{0} Hz",file.SampleRate);
Console.WriteLine("Bits per sample:\t{0}", file.BitsPerSample);
// Skip 5 seconds.
file.Skip(5d);
// Print 10 samples from left and right channel.
int c = 0;
while(c++ < 10)
{
Console.WriteLine("Sample {0}\tL: {1}\tR:{2}",c,file.ReadSample(),file.ReadSample());
}
}
Ny bruger
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