[FFmpeg-devel] Ableton live aiff file

[Carl Eugen Hoyos]

Am Fr., 20. Sept. 2019 um 09:58 Uhr schrieb Adam Johnson <me at adamj.eu>:
>
> 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!

Thank you for posting the samples!
They are "encrypted", I doubt it is a strong encryption (too many
patterns) but I don't know how to undo it.
https://forum.ableton.com/viewtopic.php?p=1100435#p1100435

Carl Eugen