Question

I need to perform FFT and I have a sound sample .wav format.
The function needs double[] xRe, double[] xIm, REAL PART and imaginary part How to convert the sound file into double[]?
I have never seen something like that. Could not find in the internet that kind of operation.
This is this sound sample:
http://www.speedyshare.com/fFD8t/e.wav

Please help, cause I used Pascal and now don’t know what to do here.

Answer 1

It’s a simple stream operation.

1. You have to read wav file header.
2. You have to read data bytes.

Paste from MSDN:

BinaryReader reader = new BinaryReader(waveFileStream);

//Read the wave file header from the buffer. 

int chunkID = reader.ReadInt32();
int fileSize = reader.ReadInt32();
int riffType = reader.ReadInt32();
int fmtID = reader.ReadInt32();
int fmtSize = reader.ReadInt32();
int fmtCode = reader.ReadInt16();
int channels = reader.ReadInt16();
int sampleRate = reader.ReadInt32();
int fmtAvgBPS = reader.ReadInt32();
int fmtBlockAlign = reader.ReadInt16();
int bitDepth = reader.ReadInt16();

if (fmtSize == 18)
{
    // Read any extra values
    int fmtExtraSize = reader.ReadInt16();
    reader.ReadBytes(fmtExtraSize);
}

int dataID = reader.ReadInt32();
int dataSize = reader.ReadInt32();


// Store the audio data of the wave file to a byte array. 

byteArray = reader.ReadBytes(dataSize);

// After this you have to split that byte array for each channel (Left,Right)
// Wav supports many channels, so you have to read channel from header

Here this is more detailed explanation:

http://msdn.microsoft.com/en-us/library/ff827591.aspx

And here you can read about WAV file format:

https://ccrma.stanford.edu/courses/422/projects/WaveFormat/

And something about WAV as complex numbers and FFT:

How to convert wave data into Complex numbers