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Topic: Need some m4a audio guru assistance (Read 10160 times) previous topic - next topic

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  • tazdevl
  • [*]
Need some m4a audio guru assistance
Need some assitance.  Have a m4a file that appears to be corrupted.  Happy to pp some scratch to whoever can fix it.

http://www.box.com/s/fthemrn4x153cjsf0pyy

  • tazdevl
  • [*]
Need some m4a audio guru assistance
Reply #1
If you've got it working, post a message on the thread and we can work through logistics via PM.

  • db1989
  • [*][*][*][*][*]
  • Global Moderator
Need some m4a audio guru assistance
Reply #2
I trust this is not copyrighted material, as per #9 of the Terms of Service.

  • tazdevl
  • [*]
Need some m4a audio guru assistance
Reply #3
I trust this is not copyrighted material, as per #9 of the Terms of Service.


Nope.  Just need to pull some meeting notes from it.  I'm thinking the metadata is jacked up.
  • Last Edit: 06 March, 2012, 07:24:31 PM by tazdevl

  • nu774
  • [*][*][*][*][*]
  • Developer
Need some m4a audio guru assistance
Reply #4
Seems just moov box missing. Probably file was not finalized properly, due to premature termination of writing software or hardware. The following worked. If you want rescued file, I can upload it and will let you know.
Code: [Select]
$ dd ibs=1 skip=44 if='your broken file.m4a' of=raw.aac
$ faad -a adts.aac raw.aac


  • teemuek
  • [*]
Need some m4a audio guru assistance
Reply #5
Hey!

I'm having corrupted m4a file issue as well. I recorded an interview today with iPhone 4's Voice Memo app and the recorded file won't play. I'd be very thankful if someone could take a look at it

Link to the file: https://dl.dropbox.com/u/50308108/haast.m4a

  • psycho
  • [*][*][*]
Need some m4a audio guru assistance
Reply #6
teemuek, by using the method described by nu774, I managed to get the following result.
lame -V 0

  • teemuek
  • [*]
Need some m4a audio guru assistance
Reply #7
teemuek, by using the method described by nu774, I managed to get the following result.


Thank you so much! It seems to miss about 12 minutes from the end but i'm very happy anyway. Thanks!!

  • psycho
  • [*][*][*]
Need some m4a audio guru assistance
Reply #8
You're welcome.
lame -V 0

  • nu774
  • [*][*][*][*][*]
  • Developer
Need some m4a audio guru assistance
Reply #9
Since my post seems to be occasionally referred to....
- This method only works for a single track file. If more than two tracks are multiplexed, there's no way to rescue it.
- Basically, you have to cut mdat content out of the broken MP4 first. However, mdat location is not always the same. 44 bytes skip in my previous post is only for the OP's specific file.
- To find mdat location, just open the file with a hex editor, and search for the string "mdat". Bytes that follows "mdat" are the actual contents, and you have to cut them out.
- When you feed the resulting raw (headerless) AAC to faad command, you may additionally have to specify samplerate by -s option if it is not 44.1kHz.

  • enry2k
  • [*][*]
Need some m4a audio guru assistance
Reply #10
You can also try the Federico Ponchio's code:http://vcg.isti.cnr.it/~ponchio/untrunc.php
It worked great for a file of mine.

Regards
Enrico