fixing a wav file
RS
pause to get something, and didn't return to recording. I fell asleep
and forgot to hit save. The battery must have run down and did some
kind of autosave. The file is 8 megs but in using Adobe Audition to
edit it, there
is no wav to display. Does anyone know how to extract that data or
fix the file?
--
Robert Pearson
ParaMind Brainstorming Software http://www.paramind.net
Creative Virtue Press/Telical Books/Regenerative Music
http://www.rspearson.com
Bob Masta
wrote:
>Using an mp3 player with voice recorder, I was reading a book, hit
>pause to get something, and didn't return to recording. I fell asleep
>and forgot to hit save. The battery must have run down and did some
>kind of autosave. The file is 8 megs but in using Adobe Audition to
>edit it, there
>is no wav to display. Does anyone know how to extract that data or
>fix the file?
>
Just a guess, but it's possible the only trouble is in the WAV header.
There is a standard format for this (try Google on "WAV header
format") which includes not only details like number of channels
and sample rate (which are known when the recording starts),
but also includes size information in two places... and that obviously
isn't known until the recording is over. So if there was some sort of
auto-save that just closed the file without going back to fill in
those details in the header, it won't be a valid WAV file.
If you have some sort of binary/hex file viewer that can show the
contents of the start of the file, you'll notice that it starts with
'RIFF'. The next 4 bytes are the size of the remainder of the
file. A little later (40 bytes or so, IIRC) you should see 'data',
and the next 4 bytes are the size of the remainder of the file
after that point. I'm guessing that both of these are still stuck at
zeroes. If you can edit these manually to insert the correct values,
you should be OK. I haven't looked, but there may even be
special utilities to do this just for WAV files.
My Daqarta software will allow you to open the file and view it
as if it were a headerless raw data file, and you can specify how many
channels, sample rate, etc, and skip over the WAV header section.
Alas, that would only allow you to see if there was indeed something
in the file... it would not allow you to re-save it with a patched
header. (Maybe a good idea for a future version...?)
Best regards,
Bob Masta
DAQARTA v3.50
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Signal Generator
Science with your sound card!
Bob Masta
wrote:
<snip>
By the way, note that the values are stored in "little endian"
format. So if your file size is exactly 8000000 bytes, then
the size of the remainder after the 'RIFF' and 4-byte size is
80000000 - 8 = 7999992, which is 007A11F8 in hex.
So the size entry bytes, in the order they appear in the
hex editor, would be F8, 11, 7A, 00.
Hope this helps!