Fixing corrupted 3GP with AMR audio file

[Alonshow]

I have some corrupted audio recordings which use the 3GP container and the AMR codec. I have googled for hours for a tool that can fix them, but none has worked. What does work, however, is the website mp4repair.org. I uploaded one of my corrupted files there and their software does fix it. However, they charge 90 bucks just to repair a single file, which I find excessive and unfair.

Do you know of a cheaper (or free) alternative?

I have plenty of other recordings from the same source which are fine. I think this can help to repair the bad ones.

[Baldrick]

Have you tried open them with any audio editor like goldwave, audacity and see if they can read them at all?

[Alonshow]

Yes, I tried both, but they can't read the files. Actually, I asked for help in the Audacity forum and the people there have been so helpful. They suggested a tool (MP4 Fix) which did fix a similar problem with files encoded with AAC. Unfortunately that tool doesn't work with AMR files.

[Baldrick]

If mp4repair.org works might graus video repair tool work. Try the free trial and see if it can open the 3gp and repair half the audio. I have the full version so I can test also...

[Alonshow]

I tried Video repair and some other tools I found in Google, but none has worked. Unfortunately I didn't keep a list of the tools I tried. Among those I remember are All media fixer and the ffmpeg command line.

By the way, I've heard that this can be fixed with an hex editor. I have already used hex editors in the past, so it might be worth giving it a shot, but I think I would need at least some basic guidance on how to go about it.

[Adithya]

Can you please upload a sample of the corrupted file?

[Alonshow]

Sure. There you go:

Sample

[Adithya]

EDIT: I Fixed your sample!!! (Duration: 1h 33m 34s)

Here you go!

[Adithya]

I will post a guide on hex editing the corrupt 3gp files soon. But if you are in a hurry you can upload your files to some file sharing account and please send that link to me.

[Alonshow]

Thank you so much, Adithya, that was awesome. Looking forward to that hex editing guide. I'm sure it will be very useful.

[flintstone2]

Hallo Adithya,

I am still looking forward to your guide on hex editing corrupt 3gp files with AMR audio

Flintstone2

[testerics]

Adithya, please make some of us happy with your work! Could you offer a short tutorial about HEX editing the 3gp corrupted files?
Thank you very much!

[testerics]

I see in Adithya fixed 3gp rthe following in the header:
amr - Imported with GPAC 0.5.0-rev4065

The file is ended with:
7freeIsoMedia File Produced with GPAC 0.5.0-rev4065

So it looks like the damaged file was converted using GPAC..
Somebody knows the command to make this import/conversion possible?
Thanks!

[Baldrick]

GPAC = mp4box.

Have you tried open the video with a multiplexer like mp4boxgui or mkvtoolnix and then output a new mp4 or mkv video.

[flintstone2]

I would suggest that anybody who has an idea for a solution first try that solution on the example .3gp file mentioned above, and only post it if the solution actually works. At the moment, it looks like Adithya is the only person who knows how to fix the corrupted file, and we are eagerly waiting to see how he did it. As concerns GPAC, it seems that this was merely used to create a 3gp file from an AMR file that was already fixed. As indicated by Adithya, the actual fixing can probably only be done with a HEX editor.

[prad]

I have recorded an audio call in 3GP format. After recording, the recorded file is displayed as Video file(3GP) which cannot be played on the mobile or using VLC player. The file size shows as 30 Mb and I can open the file using Goldwave although I cannot hear anything. How can I repair this file? Please help.

[testerics]

Ok, after 1 week of testing a lot of programs and solutions I found the way to listen a corrupted (interrupted) 3gp file

What I used: HxD hex editor (free) and a good 3gp file, BIGGER (longer) than corrupted one!
If somebody is trying to modify the header or footer of the good 3gp, the file is unredable (you can see in explorer that the lenght of the file is missing..).
So my ideea was to take a part from the broken file and PASTE WRITE in the good file.
The content on my 3gp is looking like this (can be seen on HxD), always strting with "<":

<.1d>3â.!-O¯´ÖyD½è‡Ùò…¦..Æ…Ø#.±à
<..W·æ.4.‡P[ëßW.MÑ,E $Q.$˜°GÖÎ"Ð
<..c6Ññ(@-.¯8.㺌6ˆËì.ùƒTþ–Ñ.¡.€
<.$[†.¸vÀSòÛm±L–a£´s.•nÕ,PÇ”.œµ€

So you need to copy the part that you need and PASTE WRITE (not INSERT) in the good file, over the body part. The ideea is to keep the dimension of the good file untouched (because of this the good file should be bigger than corrupted). One bit in plus or minus and the file is unredable.. I think the header or footer of the file has the information about this and has some internal checksum.
After this operation you need to save the file (don't worry, HxD it wil automatically create a backup of the original file, with .bak extension).
You need only to play the new file in the same player where the good 3gp can be listen. You will hear even the sounds from the good 3gp, but if you PASTE WRITE the part that you want to listen at the begining of the body you will hear first the sounds that you need and after this the sounds from the good original file.
I prefer to insert SILENCE after the part that I need (for example, if you have good 3gp only with SILENCE recorded, after the recovered part the SILENCE will begin) so after I save the file I have the part that I want and SILENCE till the end

I hope this could be usefull even from other type of corrupted audio or video file.
And.. happy holidays from Romania!

[prad]

Thanks a lot for the help from Romania (testerics)! I was desperate to recover the 3GP file and I could do it following the steps you mentioned. Thanks to you and the forum.

[flintstone2]

Ok, after 1 week of testing a lot of programs and solutions I found the way to listen a corrupted (interrupted) 3gp file

What I used: HxD hex editor (free) and a good 3gp file, BIGGER (longer) than corrupted one!
If somebody is trying to modify the header or footer of the good 3gp, the file is unredable (you can see in explorer that the lenght of the file is missing..).
So my ideea was to take a part from the broken file and PASTE WRITE in the good file.
The content on my 3gp is looking like this (can be seen on HxD), always strting with "<":

<.1d>3â.!-O¯´ÖyD½è‡Ùò…¦..Æ…Ø#.±à
<..W·æ.4.‡P[ëßW.MÑ,E $Q.$˜°GÖÎ"Ð
<..c6Ññ(@-.¯8.㺌6ˆËì.ùƒTþ–Ñ.¡.€
<.$[†.¸vÀSòÛm±L–a£´s.•nÕ,PÇ”.œµ€

So you need to copy the part that you need and PASTE WRITE (not INSERT) in the good file, over the body part. The ideea is to keep the dimension of the good file untouched (because of this the good file should be bigger than corrupted). One bit in plus or minus and the file is unredable.. I think the header or footer of the file has the information about this and has some internal checksum.
After this operation you need to save the file (don't worry, HxD it wil automatically create a backup of the original file, with .bak extension).
You need only to play the new file in the same player where the good 3gp can be listen. You will hear even the sounds from the good 3gp, but if you PASTE WRITE the part that you want to listen at the begining of the body you will hear first the sounds that you need and after this the sounds from the good original file.
I prefer to insert SILENCE after the part that I need (for example, if you have good 3gp only with SILENCE recorded, after the recovered part the SILENCE will begin) so after I save the file I have the part that I want and SILENCE till the end

I hope this could be usefull even from other type of corrupted audio or video file.
And.. happy holidays from Romania!

Many thanks for this; I now finally can recover my corrupted audio file, after having looked for a solution for more than 3 years! As a tip: I found it easiest to copy the whole content of the bad file starting with "mdat" to the part of the good file which also starts with "mdat". And now I will look for some way to cut off the excess audio at the end of the recovered file without re-encoding; I expect that this will be a much easier process

[barlycrn]

Hi all, I have what I hope is a recoverable .amr file, a storycorps interview with my dying father (not a (fake) sob story, you are welcome to listen if you can fix it). Any help would be appreciated. My attempts to upload it here produce and invalid file error, so can anyone accept an email attachment? Wow. This whole thing sounds like a Nigerian phishing scam, but really I just want to hear and share this file.

Eric

[testerics]

@barlycrn, upload your file to https://wetransfer.com and give me the download link in my e-mail

[barlycrn]

Thank you for the reply. wetransfer.com does not pass security muster on my network. anyplace else to sit a 3 meg file?

[barlycrn]

sorry, different issue... will get the link out soon!

[Baldrick]

Thank you for the reply. wetransfer.com does not pass security muster on my network. anyplace else to sit a 3 meg file?

You can attach files when you post. Under Upload files/Manage attachments.

[testerics]

For .mp4 repair, use the instructions from here: http://slydiman.me/eng/mmedia/recover_mp4.htm

[lcapellaro]

Hey, @testerics. I was able to recover some .amr files by editing the hex, but I could not find a pattern like you showed. I saw that the normal file has nothing before #! In hex, then I recovered 4 audios by removing what there is before that. But 3 even removing audio still does not play. I'll post the audio link here on onedrive, if you can help me with this! Thank you!

Https://1drv.ms/u/s!Agbyu4vkkajhgapwZIgxvAhxo7YOEg

[testerics]

@lcapellaro, please upload even a good audio AMR file and bigger than 9MB to be possible to compare and recover. The good file should be generated with the same source.

[lcapellaro]

@testerics Follows the link of corrupted audios: https://1drv.ms/u/s!Agbyu4vkkajhgapwGYOQzL5XtYXm4A

and follows the link of good audio with 9,7mb: https://1drv.ms/u/s!Agbyu4vkkajhgatLcz32AqBkr9g_Jw

Thanks for listening!

[testerics]

@lcapellaro, your corrupted audios are too corrupted even for me..
Sorry, maybe someone else could help you with this

[lcapellaro]

@testerics No problem, thanks for your kindness and help! o/