I think that a WAV file can really have several formats. If you take a look
at

http://www.wotsit.org

you will probably find some pretty good documents describing WAV files.
Many WAV files are totally uncompressed, and are just either offset or
plain 8-bit or 16-bit data. However, there are options for other formats
and ADPCM is one of them.

There is a part of the win95/98 API (PlaySnd or PlayWAV, IIRC) which allows
you to play WAV files by just one line of C code (one function call).
However, it gives you no ability to stop the WAV file while it is playing,
etc. There are lower level calls which allow you to feed the samples to a
buffer and tell windows to send that to a sound card. You can tell that
win95's Sound Recorder does this because if you click on the window and
move it and then hold the mouse button down, it will play the sound for a
few seconds and then stop until you release, presumably giving it a chance
to reload the buffer.

The first of these two calls deals with the different WAV formats itself
(although I don't know if it is compatible with them all). I think the
second function only works with raw samples, so you would need to extract
them from the WAV file.

As I say, WAV file can actually mean many things. I once tried to write a
DOS program to read WAV files, and it worked fine with a large number of
WAVs but I would have problems with others (which Sound Recorder could
still read) so that clued me in to the fact that they vary a alot in their
exact format and that many simple, three page explanations of them will not
get you all the info you need to be compatible with all formats.

Hope this helps,

Sean


At 02:00 PM 2/4/00 +1200, Lance Allen wrote:
>All I really know is that WAV is a windows label of ADPCM which
>is a lossless compression standard.
>Elektor (www.elektor-electronics.co.uk) ran a stand alone wav file
>player (Feb 1999) that is an ATMEL AT90S2313 with a EEPROM
>and DAC hanging off it. So obviously it can be done on a PIC.
>
>
>
>_____________________________
>
>Lance Allen
>Technical Officer
>Uni of Auckland
>Psych Dept
>New Zealand
>
>www.psych.auckland.ac.nz
>
>_____________________________
>
|
| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
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