How to copy audio at a specific interval over and over?

Discussion in 'Digital Audio' started by chirpie, Nov 14, 2016.

  1. chirpie, Nov 14, 2016
    Last edited: Nov 14, 2016

    chirpie macrumors 6502a


    Jul 23, 2010
    So I've got multiple corrupted audio file from a Zoom H6. The data can no longer be read. I was able to do a raw data dump into Audacity and have one giant long audio file. What has happened is the audio has been interlaced. There were originally two or three separate tracks for the recording, but they're now all interwoven. So when someone says, "Hello" you'll hear hello as recorded from all three microphones at their respective distances from the person talking.

    The result is a jarring sort of echo and extension of their talking.

    See here for a sample:

    Is there any way to do an automated copy/paste of intervals of the audio? A logic like, "every .64302 seconds copy the audio for .32156 seconds?

    Thanks for any and all ideas!
  2. BrianBaughn macrumors 603


    Feb 13, 2011
    Baltimore, Maryland
    That sounds like more than microphone distance. What was the procedure you used to get the file into Audacity?
  3. chirpie thread starter macrumors 6502a


    Jul 23, 2010
    I don't think it's more than microphone distance. I carefully cut a 10 second stretch of audio just to see, and it sounds perfectly normal again once you've removed the other two track's audio. The intervals are identical and repeatable as well.

    Here's a similar thread that people had issues with on the Zoom H4.

    To get the audio from the corrupted file into Audacity, I used the steps detailed in one of the posts by using the "Project > Import Raw Data" command.

    In that thread other people had the same issue I'm having...

    "I am having a very similar problem to this, but was recording in four channel mode at the time which is causing a weird echoing / interleaving effect when I pull the audio into into Audacity or Audition."​

    That thread talks about using a Hex Editor, but my raw data file is 32GB and dozens of hours of audio. It'd be a monstrous effort to hunt it all down. It's also beyond my technical capabilities. o_O

    Here's that approach to fixing it...

    "Hi all, I've just cracked the 4 and 8 track corrupt audio file problem, which is a 3 second echo of each track after importing raw into Audacity. This happened from sound guy turning powerstrip off with no batteries in unit. Here are the steps I used: First I made image file of the sd card with the lost files, then I took an old sd card and wrote all zeros to it, formatted it. Then made a short test recording with the same format, saved it and turned it off properly.
    Then I made an image file of the test recording and opened it up in HXD hex editor. I found out that with my zoom r24 recorder, when recording, it records 393216 bytes of each channel sequentially and when done writes the wav header with data location, recording format etc. When turned off improperly the wav header is not written and the data that is there is in alternating blocks of each channel.
    Using HXD hex editor I found the start of the data and saved this as a new file, which I then used the split option in HXD and split the file into chunks of 393216 bytes, named 0001 and up. Then I opened the folder with the file chunks into it and squised the screen down till I could view 2 rows of files, about 4,000 of them. Then I selected the odd row on the left and cut and pasted it into a new folder. Then using HXD, I concatenated (joined) the odd file numbers together, then did the same for the even ones. This left me with in my case, the data for both mono channels. Then I imported the test recording file in HXD and pasted the recovered data into the proper space, which was at 60000 hex location. The next thing I had to alter was the last 4 bytes before the data which tell the file length data. Repeated the same for the other channel then voila, both channels recovered, no echo, synced properly, 3 hours worth back!!!!!"​

    Thanks for the reply!

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