Compressing Data with Audio

You can record/extract a .wav in a CD and play it in almost every CD/DVD player...

To write a .WAV file you need to know the .wav structure.

Here's what maybe you'll need:

struct WAVEFMT {
    char signature[4];  // must contain 'RIFF'
    long RIFFsize;      // size of file (in bytes) minus 8
    char type[4];       // must contain 'WAVE'
    char fmtchunk[4];   // must contain 'fmt ' (including blank)
    long fmtsize;       // size of format chunk, must be 16
    int  format;        // normally 1 (PCM)
    int  channels;      // number of channels, 1=mono, 2=stereo
    long samplerate;    // sampling frequency: 11025, 22050 or 44100
    long average_bps;   // average bytes per second; samplerate * channels
    int  align;         // 1=byte aligned, 2=word aligned
    int  bitspersample; // should be 8 or 16
    char datchunk[4];   // must contain 'data'
    long samples;       // number of samples
  };

You can record/extract a .wav in a CD and play it in almost every CD/DVD player...

To write a .WAV file you need to know the .wav structure.

Here's what maybe you'll need:

struct WAVEFMT {
    char signature[4];  // must contain 'RIFF'
    long RIFFsize;      // size of file (in bytes) minus 8
    char type[4];       // must contain 'WAVE'
    char fmtchunk[4];   // must contain 'fmt ' (including blank)
    long fmtsize;       // size of format chunk, must be 16
    int  format;        // normally 1 (PCM)
    int  channels;      // number of channels, 1=mono, 2=stereo
    long samplerate;    // sampling frequency: 11025, 22050 or 44100
    long average_bps;   // average bytes per second; samplerate * channels
    int  align;         // 1=byte aligned, 2=word aligned
    int  bitspersample; // should be 8 or 16
    char datchunk[4];   // must contain 'data'
    long samples;       // number of samples
  };

Hello Alex,

Thanks for the information on .WAV files.
Can you make the datachunk array any size you like?
The application I had in mind requires regular data elements so that the embedded side syncs with the music. Can I do this with the .WAV format?

Thanks again

Mark.

Can you make the datachunk array any size you like?

I think so Mark, I don't know how much is the size limit ( if it really exist ) but, remember that you can have just one track of music inside a CD, it means 74 seconds, something around 650MB of data in just one WAV file, so I'm not sure about a limit.


I also think that these regular elements can be put inside the file without problems.

the data on an audio CD isn't a WAV file; when you burn an audio CD (ie, one you can play on an audio CD player) your burner performs the conversion.

BTW: that's 74 minutes, not seconds!

that's 74 minutes, not seconds!

Thanks Andrew.

the data on an audio CD isn't a WAV file

Oh that's why I didn't found the WAV structure inside the binary image of my Audio CD... hummmm..

I really wasted a lot of time dumping 473MB of binary numbers in my hex editor...