8 hour recording... lost?

I’m not sure if this has come up before, as I can’t seem to find it in the forum. I use Audacity to record my scanner. I had an 8 hour recording of a house fire the other day that saved to approx. 4Gb “wav”. When I went to access it today, it only reads as 18 minutes. I’m assuming, being as the file is still 4Gb, the information is there. Can the full 8 hours be recovered? I’ve tried opening it with several different programs and players but have had no luck. This is an important file… please, if anyone can offer advice, I would be extremely greatful.

Audacity version: 2.2.1
OS: Windows 10, 64 bit

Try importing as Raw Data. You’ll have to know (or guess) the encoding (16-bits, etc.) and the sample rate.

it only reads as 18 minutes. I’m assuming, being as the file is still 4Gb,

There is a 4GB WAV file size limit due to a 32-bit file-size field in the WAV header. That value can “roll over” (loosing the most significant bits) if you exceed the limit, incorrectly giving a file size that’s too small. If that’s the only problem you can recover by importing the raw data.

If that works, re-export as FLAC or some other format.

Thank you for your quick reply. Using the media info from the large file (matches other files I’ve exported): 1411.2 kb/s, 44.1 kHz, 16 bits, 2 channels, PCM, (Little / Signed). This imports as a 14 second recording. The only thing I don’t know is the offset. Should I experiment with that? This is all new to me.

The offset is usually just a few samples, that appear as a bit of noise at the start. I usually import with offset set to zero, then when it has imported, zoom in on the first few samples and delete the noise.

The above may not work in the case of 24-bit PCM, in which case you would need to try offsets of 8 and 16 bits to see which works. This is not likely to be the case for you.

Got it! Thank you so much for your help! My video editor doesn’t accept FLAC files for some reason, so I’ll save it in smaller chunks. That’s what I normally do anyway… and why this issue has likely never come up before. Again, thank you.