ZOOM H4n Material lost on SD Card

[Adam Bankhead]

OK- it SEEMS like (and I have almost no idea what I’m talking about) if I can figure out HOW MANY bytes my TASCAM DR-40 records the channels sequentially, and if I could find the EXACT START of that data, I could use the split option in HXD to split the data accordingly, and save as a new file. Forget about rewriting the header- now that I have the data in one continuous STEREO stream, I can import THAT into Audacity and recover it using the method that everyone knows how to do (above). Right?!

If I only knew how to do this!!!!!!!

[Karl Chelette]

Hi Adam, yes, I can do this for you. The first time I spent more than 40 hours to figure it out and this is after tech support at Zoom said it’s not possible! The hardest part is to find where the data starts because there is no header written. Any headers you find are old file headers. Is this an H4n? If it is, I’ll need a disk image of your test recording. If it’s a R16/R24 won’t need it. And of course a disk image of the sd card. Are you able to load it into Audacity as raw and hear the interleaved recording?

[Karl Chelette]

Hi Adam, yes, I can do this for you. The first time I spent more than 40 hours to figure it out and this is after tech support at Zoom said it’s not possible! The hardest part is to find where the data starts because there is no header written. Any headers you find are old file headers. Is this an H4n? If it is, I’ll need a disk image of your test recording. If it’s a R16/R24 won’t need it. And of course a disk image of the sd card. Are you able to load it into Audacity as raw and hear the interleaved recording?

[Karl Chelette]

Adam, ok, dr-40. What I would do to find the data block size is make a test recording with channel 1-pink or white noise, channel 2- silence. Load into audacity as raw, find the section where the silence begins, expand out the timeline and trim off the excess noise leaving very little before the silence starts. Then stretch out the timeline to the very max and you can find the last byte of noise before the silence byte, a diagonal line coming down to the center line. Trim off the noise. Do the same thing at the end of the silence. Save as wav file, load into hxd, trim off the 44 byte header and do a byte count. It should line up symmetrically, the first byte starting at byte 0 and the last one ending at byte F. Use “goto” to change the hex number to decimal for chunk size. Load the lost file section in audacity and hopefully you’ll be able to figure out the start of data byte, which is where the recorder started recording at, trim off the excess. Save as wav file, load into hxd, save the 44 byte header into a separate file or write it down, delete the header, split file with hxd into chunks of the right size, combine every other chunk and you’ll end up with 2 mono files. Copy the wave header you saved earlier and paste onto the beginning of each file. Done. Headache yet?

[Rod Smith]

Karl – could you or anyone else help me with restoring audio from a TASCAM DR-701D that lost power? I read through your methods, but it is way over my head. Any help is appreciated. I have an image file of the SD card.

[Karl Chelette]

Are you able to load the file as raw in audacity and hear bits of the music? Besides the disk image will need a sample recording in the same format. Same number of channels, bit rate, sample rate, etc and it would be helpful if you would write zeros to the SD card first, so I don’t have to search so hard. I would like you to record on the first channel, silence, the second channel, loud noise. Repeat for the remaining channels. Need 1-2 minutes only.

Karl

[Rod Smith]

Thanks so much, Karl. How do I write zeros to the SD card?
The audio is an interview. When I play it back RAW, I hear digital noise and then intermittent very high speed voice.

We recorded about 20-30 minutes of interview – lost power – then restarted and recorded 8 minutes of interview that is on the card. So, I’m assuming 8 minutes of the first interview was erased over.

[Karl Chelette]

Rod, sorry, been busy working on taxes. Get me the sd card image and image of the test recording and I’ll see what I can do. The first eight minutes aren’t necessarily gone, but might be. You can email me at karlc37@dslextreme.com

[Adam Sewell]

Hey Karl.
Is it possible that I could send you a file to take a look at? I have a similar problem to what you were talking about earlier with the echo.
Battery died on my tascam dr-60D mkII during recording and I lost the whole audio track. I have created a new image of the SD card and was able to bring that into Audacity to find the lost audio. The track however has an embedded echo to the track and I am unable to correct that. I’m not sure if there is a simple fix or if the only way to fix it is to do what you mentioned above. I don’t think I can do that without messing it up even more. If there is a way you could fix that, it would be much appreciated!!

Thanks so much,
Adam

[Tucker Tangeman]

Could some one help me with the conversion here.. I had the Zoom plugged into the mains via an faulty extension cable.. it powered on but I have 3 fils reading 0kb. I have made a disk image of the card (it was clean before I started) and am ready to try to convert it using audacity. Only every time I try different variation I just get interference.. The file is the right length for my recordings around (1 hour). I was recording MP3 320kbps I just need the right combination if some one could help that would be amazing!