C++ Reading the Data part of a WAV file

Question

I plan to create a program that will visualize the audio waveform of a .wav file.

So far, I have started by properly reading the header part of the said wav file. The code I use would be this:

#include <iostream>
#include <string>
#include <fstream>

using namespace std;
using std::string;
using std::fstream;

typedef struct  WAV_HEADER{
    char                RIFF[4];        // RIFF Header      Magic header
    unsigned long       ChunkSize;      // RIFF Chunk Size  
    char                WAVE[4];        // WAVE Header      
    char                fmt[4];         // FMT header       
    unsigned long       Subchunk1Size;  // Size of the fmt chunk                                
    unsigned short      AudioFormat;    // Audio format 1=PCM,6=mulaw,7=alaw, 257=IBM Mu-Law, 258=IBM A-Law, 259=ADPCM 
    unsigned short      NumOfChan;      // Number of channels 1=Mono 2=Sterio                   
    unsigned long       SamplesPerSec;  // Sampling Frequency in Hz                             
    unsigned long       bytesPerSec;    // bytes per second 
    unsigned short      blockAlign;     // 2=16-bit mono, 4=16-bit stereo 
    unsigned short      bitsPerSample;  // Number of bits per sample      
    char                Subchunk2ID[4]; // "data"  string   
    unsigned long       Subchunk2Size;  // Sampled data length    

}wav_hdr; 

// Function prototypes 
int getFileSize(FILE *inFile); 

int main(int argc,char *argv[]){
    wav_hdr wavHeader;
    FILE *wavFile;
    int headerSize = sizeof(wav_hdr),filelength = 0;

    string answer;

    do{
        string input;
        string answer;

        const char* filePath;

        cout << "Pick wav file from the Windows Media File: ";
        cin >> input;
        cin.get();

        cout << endl;

        path = "C:\\Windows\\Media\\" + input + ".wav";
        filePath = path.c_str();

        wavFile = fopen( filePath , "r" );

        if(wavFile == NULL){
            printf("Can not able to open wave file\n");
            //exit(EXIT_FAILURE);
        }

        fread(&wavHeader,headerSize,1,wavFile);
        filelength = getFileSize(wavFile);
        fclose(wavFile);

        cout << "File is                    :" << filelength << " bytes." << endl;

        cout << "RIFF header                :" << wavHeader.RIFF[0] 
                                                << wavHeader.RIFF[1] 
                                                << wavHeader.RIFF[2] 
                                                << wavHeader.RIFF[3] << endl;

        cout << "WAVE header                :" << wavHeader.WAVE[0] 
                                                << wavHeader.WAVE[1] 
                                                << wavHeader.WAVE[2] 
                                                << wavHeader.WAVE[3] 
                                                << endl;

        cout << "FMT                        :" << wavHeader.fmt[0] 
                                                << wavHeader.fmt[1] 
                                                << wavHeader.fmt[2] 
                                                << wavHeader.fmt[3] 
                                                << endl;

        cout << "Data size                  :" << wavHeader.ChunkSize << endl;

        // Display the sampling Rate form the header
        cout << "Sampling Rate              :" << wavHeader.SamplesPerSec << endl;
        cout << "Number of bits used        :" << wavHeader.bitsPerSample << endl;
        cout << "Number of channels         :" << wavHeader.NumOfChan << endl;
        cout << "Number of bytes per second :" << wavHeader.bytesPerSec << endl;
        cout << "Data length                :" << wavHeader.Subchunk2Size << endl;
        cout << "Audio Format               :" << wavHeader.AudioFormat << endl;
        // Audio format 1=PCM,6=mulaw,7=alaw, 257=IBM Mu-Law, 258=IBM A-Law, 259=ADPCM 


        cout << "Block align                :" << wavHeader.blockAlign << endl;

        cout << "Data string                :" << wavHeader.Subchunk2ID[0] 
                                                << wavHeader.Subchunk2ID[1]
                                                << wavHeader.Subchunk2ID[2] 
                                                << wavHeader.Subchunk2ID[3] 
                                                << endl;

        cout << endl << endl << "Try something else? (y/n)";
        cin >> answer;
        //cin.get();
        cout << endl << endl;

    }while( answer == "y" );


    getchar();
    return 0;
} 
// find the file size 
int getFileSize(FILE *inFile){
    int fileSize = 0;
    fseek(inFile,0,SEEK_END);

    fileSize=ftell(inFile);

    fseek(inFile,0,SEEK_SET);
    return fileSize;
}

I've tried it several times and the data it gives seems consistent through different wav files in the Media folder in the Windows folder.

The next step then would be storing the actual data of the wav file in a vector. However, I'm quite clueless on how to do this. Online solutions that I found only went as far as reading the header file.

Any ideas on how to store (and hopefully display) the actual data of the wav file? Thanks!

Answer 1

This image is taken from a Stanford course

So you can see that the audio data occurs immediately after the headers you already read and there will be Subchunk2Size bytes of audio data.

The pseudocode for this would be

ReadRIFF();
ReadFMT();
int32 chunk2Id = Read32(BigEndian);
int32 chunk2Size = Read32(LittleEndian);
for (int i = 0; i < chunk2Size; i++)
{
    audioData[i] = ReadByte();
}

If the audio is stereo you'll have two audio streams in data. If the audio is compressed (mp3, aac, etc) you'll have to decompress it first.