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  • ZOOM H4n Material lost on SD Card

     Oriol Nieto updated 5 months, 1 week ago 39 Members · 78 Posts
  • Adam Loveday-Brown

    July 31, 2018 at 1:17 pm

    Hi Carlo.

    Sorry for the slow reply. I didn’t get hold of Karl unfortunately.

    I’ve been to so many data recovery companies now it’s getting ridiculous. Zoom UK haven’t been able to help either. They said they would try and put me in contact with Zoom Japan but no dice yet. Zoom UK seemed to think this was a very unusual situation, I pointed out that it’s a common flaw in their systems. For me the unit didn’t loose power, I actually switched the unit off at the end of the recording and it shut down without saving the files properly. This really shouldn’t be physically possible if the files are not written, the unit should either warn you or just take longer to switch off.

    Of about 100 different data recovery companies only one seems to actually understand the issue. They are based here in the UK and are called Ontrack.

    They haven’t been successful yet but they are on the right path. I basically gave them all of the information on this thread and also did some successful recordings for reference.
    We are up to this stage: “It’s more like I have a long audio that’s missing certain intervals, So can hear for 3 seconds then drops for 2 etc, so just need to find out the length in bytes before the next channel is stored, as on disk it’s not sequential.”

    If successful I will post here. Not cheap either, £250. However I really, really need this audio so will keep going no matter what. @ Karl Chelette, there are a few of us out here who would gladly pay for you to work your magic!

    Video production dude, London

  • Carlo Siegfried

    July 31, 2018 at 8:40 pm

    Dear Adam!
    Thankyou for our reply and your findings! I am excited to hear what the company in the UK can do…
    Good luck + best wishes

  • Adam Loveday-Brown

    August 20, 2018 at 11:41 am

    Hi All.

    The company I used in Epsom UK were able to successfully recover all of my lost data! This was for a multitrack recording:
    Stereo LR
    Mono 1
    Mono 2
    Mono 3

    For some reason the Zoom H6 unit shut down without loosing power, but it didn’t correctly finalise the recording.

    This thread has been invaluable in making this happen, and the engineer wouldn’t have gotten there without all the work of everyone on here, so thank you. This has really saved my bacon.

    The company are called OnTrack. It’s a proper company, I went there. It’s all very CSI. They take data protection very seriously:
    I was dealing with a guy called Joe Rogers.

    Good luck!!


    Video production dude, London

  • Michael Angelo

    August 3, 2019 at 7:30 pm

    Had the same issue as everyone here, power cut off, then after putting in new batteries the next recording is corrupt. I used the mac disk image trick with Audacity to access the raw data and reveal the sound is there:

    Unfortunately when Audacity recovers the audio it not only repeats but cuts out every 5 seconds or so on both the originally corrupted audio file but also on all the other previous recorded audio files on the card so hoping there is some way to parse the data correctly and fix this?

    Would be so grateful for any help !

    – MA

    Harvest the compromises…

  • Oriol Nieto

    March 16, 2020 at 4:39 pm

    Hi all,

    I had the same problem (i.e., recovering a raw file with 2 stereo tracks from a Zoom recorder and split it into two different stereo WAVs), and I managed to write a little Python script to successfully do the job.

    You may find it here:

    The trick was that segments alternate in size every two contiguous segments. So, the raw signal looks like this:
    – track1_segmentsize1
    – track2_segmentsize1
    – track1_segmentsize2
    – track2_segmentsize2
    – track1_segmentsize1
    – …

    In my case, where the input was recorded at 44.1kHz, the amount of audio samples for the two segment sizes are:
    segmentsize1 = 131072
    segmentsize2 = 139264

    This will likely be different if you have a 48kHz input signal (might be a matter of multiplying it by the ratio 48 / 44.1).

    Happy to help running the script in case Python is not a language you speak ☺

    Hope this helps!
    Oriol Nieto
    Twitter: @urinieto

  • Lee Nicklen

    August 22, 2021 at 4:26 pm

    This is an old thread, I know. But, there is a solution and it works.

    So, this is for anyone who finds this thread and has lost a recording due to removing power from a Zoom [H2 or any other] recorder without stopping the recording first.

    The program is called TestDisk & PhotoRec. And it’s GNU software license, meaning it’s free. But works on a donation process. So, please donate – if you can! I did!

    Here is the site:

    “TestDisk Download – CGSecurity”


    It recovered my recording (MP3 VBR) automatically without having to do or tell the code anything. It’s very clever, and will automatically be able to find the data file and know that its header/chunk data when it’s save properly is missing and so therefore must be the file that needs recovering.


    I used the Windows 64bit version. No need to install anything, just extract program files and run the program.


    Enjoy! 👍😊

  • Jason Stockton

    October 12, 2022 at 12:13 pm

    How did you figure out the segment size?

  • Oriol Nieto

    October 14, 2022 at 7:06 pm

    By listening to the audio, visualizing the samples in Audition, and by some trial and error 🙂

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