Importing Raw Data from Zoom H6 SD card image, recover audio

[jcr5213]

Hi all,

Long story short... my Zoom H6 recorder ran out of batteries while recording. I was able to capture several hours of the recording before the batteries ran out though, which I'm trying to access again. I have used Audacity for years for basic editing and am pretty familiar with the program; but, maybe I'm doing something wrong here.

In my research I found this thread on a Zoom forum, which is exactly the issue I'm having: http://zoomforum.us/viewtopic.php?t=17991. I've followed the instructions, however, when I import the raw data .dmg file into Audacity all I basically get is 2 stereo channels of noise and static. I set the bit depth and sample rate correctly (the same as the recording 24bit/ 44000) in the dialog box when performing the import; but, I notice, on the stereo channel, that it defaults to "32 bit float" once imported into Audacity. When I try to change the bit depth from the drop tab on the channel, Audacity stops responding. Granted, this is quite a large file as I had a to make an image of the entire SD card, I'm guessing that has something to do with the program not responding. Also, please note, there is a lot of audio...approximately 16 hours total, I'm trying to locate some of the last several hours of the recording which is when the batteries ran out.

Has anyone on here experienced something similar? Any help would be very much appreciated.

Thanks in advance.........

[steve]

When I try to change the bit depth from the drop tab on the channel, Audacity stops responding.

I'm guessing that Audacity does not normally do that.
You're aware that with 16 hours of audio, just about everything in Audacity will be slow?

I notice, on the stereo channel, that it defaults to "32 bit float" once imported into Audacity.

That's normal and unrelated to the problem. By default Audacity tries to use 32-bit float tracks whenever it can because that gives best quality when processing, and internally Audacity always works with 32-bit float.

I set the bit depth and sample rate correctly (the same as the recording 24bit/ 44000)

44000 is a totally non-standard sample rate. Do you mean 44100?
Are you certain that your recording was 24-bit WAV and not MP3 or some other format? If it was MP3, then Import RAW won't work - you'll just get noise.

[Gale Andrews]

When I try to change the bit depth from the drop tab on the channel, Audacity stops responding.

I'm guessing that Audacity does not normally do that.
You're aware that with 16 hours of audio, just about everything in Audacity will be slow?

That operation should have a progress dialogue on it, I think. It can take a long time even with more "normal" lengths of audio.


Gale

[jcr5213]

I set the bit depth and sample rate correctly (the same as the recording 24bit/ 44000)

44000 is a totally non-standard sample rate. Do you mean 44100?
Are you certain that your recording was 24-bit WAV and not MP3 or some other format? If it was MP3, then Import RAW won't work - you'll just get noise.

You are correct on the sample rate, that was a typo. I did have it set to 24 bit WAV, but will double check that wasn't changed. In the event that this recording was actually done in MP3 format, is there any way to salvage that audio then with the RAW data whatsoever?

Thanks.

[steve]

In the event that this recording was actually done in MP3 format, is there any way to salvage that audio then with the RAW data whatsoever?

The problem with recovering from MP3 is that MP3 is encoded, whereas "RAW" import is looking for un-encoded "PCM" data, so RAW import is not going to work for MP3.
I had a quick look on Google and saw this application for Mac - note that I've not tried or tested it, so use at your own risk: http://triq.net/articles/mp3-validator-mac-os-x

[cyrano]

Seems to work on Mavericks. Repairs and plays (with the default app for mp3's, usually iTunes.

It also seems abandoned, more or less.