fixing a corrupt mp4 audio file.

[hsncool]

hi,

I'm trying to fix, or even just play audio from a few files that are corrupted.

they are from a third party android app, that creates an mp4 file from audio recorded.
another app moves the saved files periodically, and can cause the file to be moved while it is being recorded, hence causing a corrupted file.

i have working files, and i was wondering if there was anyway to fix the corrupt files from the information i know of the working ones?
or even if there is any application that can force it to play?
i've searched the forums and tried suggestions for similar problems, such as....

i've tried a range of players, such as mplayerc that usually play anything, but no joy.
i've tried to convert, but all converters i try cant read the input file.
i've tried the same again for just extracting the aac stream from the mp4 container.

following advice found from someone to fix a corrupt video mp4, i even tried hex-editing the files to try and "finish off" the ends of the file from good files i have, but still nothing!

is there any application that can force them to play? or say, a converter where i can state the type of input file so it knows how to read it?

any help would be greatly appreciated.
i will try and simulate a 'bad' file (without the sensitive content) and upload it, so anyone can have a look.

below is the information i have about the type of file, pulled from a 'good' one.

General
Complete name                            : C:\Users\Harmz\Desktop\fix\good1.mp4
Format                                   : MPEG-4
Format profile                           : Base Media
Codec ID                                 : isom
File size                                : 118 KiB
Duration                                 : 20s 736ms
Overall bit rate mode                    : Constant
Overall bit rate                         : 46.6 Kbps
Encoded date                             : UTC 2013-03-16 16:12:18
Tagged date                              : UTC 2013-03-16 16:12:18

Audio
ID                                       : 1
Format                                   : AAC
Format/Info                              : Advanced Audio Codec
Format profile                           : LC
Codec ID                                 : 40
Duration                                 : 20s 736ms
Bit rate mode                            : Constant
Bit rate                                 : 48.0 Kbps
Nominal bit rate                         : 64.0 Kbps
Channel(s)                               : 1 channel
Channel positions                        : Front: C
Sampling rate                            : 8 000 Hz
Compression mode                         : Lossy
Stream size                              : 117 KiB (99%)
Title                                    : SoundHandle
Language                                 : English
Encoded date                             : UTC 2013-03-16 16:12:18
Tagged date                              : UTC 2013-03-16 16:12:18

thanks in advance, any help would be greatly appreciated, this is very important to me.

[Baldrick]

You could try video repair tool. The trial will will try repair half the file and you can see if it works.

[FireRouteR]

Hi hsncool

You could try also MP4repair.org. Diagnostic and preview is free and they do repair Audio files as well. Best of luck!

--Fire

[AlanHK]

Maybe rename it as .m4a (MP4 audio) or .aac

And try MP3DirectCut.
If you get the libfaad2.dll it can also read AAC.
Then open the file and resave it.

This would be lossless, as it doesn't re-eencode.

If that doesn't work, try Audacity.

[hsncool]

You could try video repair tool. The trial will will try repair half the file and you can see if it works.

Amazing! thank you so much! nothing at first, but after fiddling with some settings, worked a treat! it's a shame it costs so much, but a price i will have to pay. thank you!

Hi hsncool
You could try also MP4repair.org. Diagnostic and preview is free and they do repair Audio files as well. Best of luck!
--Fire

had no luck with this website, and it doesnt accept files below 1mb, which many of mine are. but thank you for the suggestion.

Maybe rename it as .m4a (MP4 audio) or .aac
And try MP3DirectCut.
If you get the libfaad2.dll it can also read AAC.
Then open the file and resave it.
This would be lossless, as it doesn't re-eencode.
If that doesn't work, try Audacity.

audacity didnt work. mp3DC only accepted the file if it was renamed to .aac, but then it detected it wrong, interms of the bitrate, Hz...etc. i feel that if there was a way i could manually tell it what kind of file it should be, it might have been perfect, but i didnt seem to find this kind of option.

thank you to all though, it would be nice if there was a free solution, but im glad i have a solution. very happy bunny!

[AlanHK]

audacity didnt work. mp3DC only accepted the file if it was renamed to .aac, but then it detected it wrong, interms of the bitrate, Hz...etc. i feel that if there was a way i could manually tell it what kind of file it should be, it might have been perfect, but i didnt seem to find this kind of option.

If it could play it at all, save it anyway.
Possibly then it could be opened with Audacity or another tool and completed.

Another possibility is ffmpeg, using the "copy" codec.

[Isnard Quintela]

Hi! I am having almost the same problem: got a m4a file that is corrupted and I got some progress using recover_mp4 program http://slydiman.me/eng/mmedia/recover_mp4.htm, but I got some errors in the last step, when I have to use FFMPEG. Could someone please help me with it?
Thanks in advance!