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Topic: How see data inside WAV file? (Read 6251 times) previous topic - next topic
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How see data inside WAV file?

I use XP.  I have some WAV files on my PC which were created by my Olympus voice recorder.  How do I access the special Olympus date-stamp in one of these files?

(A) When I view the files on the PC using Olympus's Digital Wave Player software then the files have a date-stamp of the time of the actual *original* recording.

(B)  By contrast, WinXP just shows date-time of when the file was modified or created but neither of those match the recording date shown.

Is there a area in WAV's for storing the date-stamp? Or does the existence of such an area depend on what format the WAV contains?  A hex dump I took of the WAV file shows a few characters at the beginning which refer to TIF.  dB Poweramp's popup utility says the format is:  IMA ADPCM.

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As background, I understand that my Olympus VN-2100PC records in CELP.  The transfer of audio files to a PC can only be performed by Olympus's proprietary software Digital Wave Player and maybe during transfer the original CELP file is converted into a WAV.

But where is the date-time stamp?  I want to access it and then put that info into the file name so that I can transport the file between devices and still preserve that date-stamp info.

Thanks for any info.
Moonshot

How see data inside WAV file?

Reply #1 –
Quote from: moonshot on
But where is the date-time stamp?  I want to access it and then put that info into the file name so that I can transport the file between devices and still preserve that date-stamp info.

There is no official place to store a timestamp in a WAV file. It's probably in a proprietary chunk that Olympus have added.

The basic format of a WAV file is as follows:

1. The first 12 bytes are the characters "RIFF", then a 32 bit integer giving the file length in bytes (minus 8), then the characters "WAVE".

2. The rest of the file is a sequence of "chunks". Each chunk consists of a four character chunk identifier, followed by an unsigned 32 bit integer giving the length of the chunk in bytes (excluding the identifier and the length word itself, ie. the value is 8 less than the entire size of the chunk).

The only chunks that are required in a WAVE file are the format chunk (identifier is "fmt ") and the data chunk (identifier is "data"). Extra chunks may be added at the whim of the software that creates the file. My guess is that there are one of more extra chunks added by Olympus. So, go through your dump looking for chunks that do not start "fmt " or "data". The timestamp will probably be in there.

Alternatively, it's possible that they've just added the timestamp at the very end of the file. There is no rule which says a WAVE file has to end when the data chunk finishes - software is free to tack on extra data afterwards. So add up the sizes of all the chunks (including the data chunk), compare that to the file size specified just after the starting "RIFF" identifier (remembering that the value there is actually 8 less than the true file size), and if the file seems to be bigger than is needed for all the chunks, there is extra stuff at the end. The Olympus software could easily seek to the end of the file to read the timestamp from there.

Note that even if you find the timestamp, there's no knowing what format it's in. It could be text, or some sort of numeric representation (eg. if it's fixed point  then it might be the number of seconds since some base date/time which you don't know; if it's floating point it might be the number of days since a base date, and you also may not be able to tell the relative sizes of mantissa and exponent). So even if you find the timestamp, deciphering it might still be a challenge.