[FFmpeg-devel] Ableton live aiff file

[Adam Johnson]

Carl pointed me at an 'abledecoder' repository he found on GitHub. I forked
it and added a very basic compile script that works on my machine (I'm not
a C(++) developer by day): https://github.com/adamchainz/abledecoder . The
decryption there works. It seems there's a key in one of the AIFF chunks
that can be used to decrypt the sound chunks. The key itself is encrypted
with another hardcoded key. The current code depends on OpenSSL's blowfish
implementation.

Not sure if this would be easy to merge into ffmpeg's AIFF decoder. But at
least I can solve my immediate problem.

On Thu, 26 Sep 2019 at 11:08, Paul B Mahol <onemda at gmail.com> wrote:

> On 9/20/19, Adam Johnson <me at adamj.eu> wrote:
> > I have some aiff files in my music production library that I'd like to
> > convert to flac. However they aren't recognized by ffmpeg:
> >
> > $ ffmpeg -i Raylon-190-Full.aif
> > ...
> > [aiff @ 0x7fc3ce800000] unknown or unsupported codec tag: able is not
> > implemented. Update your FFmpeg version to the newest one from Git. If
> the
> > problem still occurs, it means that your file has a feature which has not
> > been implemented.
> > [aiff @ 0x7fc3ce800000] If you want to help, upload a sample of this file
> > to ftp://upload.ffmpeg.org/incoming/ and contact the ffmpeg-devel
> mailing
> > list. (ffmpeg-devel at ffmpeg.org)
> > [aiff @ 0x7fc3ce800000] could not find COMM tag or invalid block_align
> value
> > Raylon-190-Full.aif: Operation not permitted
> >
> > These files can only be decoded by Ableton Live. Quicktime, VLC, MPlayer,
> > and ffmpeg can't read them. I believe the 'able' tag is Ableton's
> > proprietary format. I know it's 24 bit but no more.
> >
> > I exported one through Ableton to a 44.1khz 24 bit wav and the filesize
> > comes out exactly the same so I know the format is not compressed. Also
> the
> > exported wav matches the waveform precisely since if I add it back  with
> > inverted phase I hear nothing.
> >
> > Here is a sample file, in aif format and wav format:
> >
> > https://files-adamj-eu.s3.amazonaws.com/ffmpeg-devel/Raylon-190-Full.aif
> > https://files-adamj-eu.s3.amazonaws.com/ffmpeg-devel/Raylon-190-Full.wav
> >
> > (I tried uploading to the ftp server as per debug message but couldn't
> > connect.)
> >
> > Thanks for any help reverse engineering this format!
>
> Looks like encrypted, need binary responsible for encryption.
>
> >
> > --
> > Adam
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> >
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-- 
Adam