Apple Lossless audio, or ALAC, is a modern audio encoding format. As its name indicated, it is lossless: encoding and re-encoding doesn't degrades quality.
ALAC is not difficult to repair.
ALAC can be found in audio files, usually in QuickTime and MP4 containers with the following extensions: .m4a .mp4a .mov
ALAC is sometimes found in movie files.
iPhone application Voice Memos records .mp4a files containing ALAC audio.
Detection
Treasured can detect ALAC in damaged audio files, but it doesn't "preview" it.
How to repair a damaged ALAC file?
The easiest way is certainly to ask your Movie Repair Service to help you recover the unplayable audio file.
But for those who can program, here you have a few tips:
Pattern matching: Simple bitstream properties allow to accurately find ALAC frames.
A simple 60 bits pattern/mask checking 54 bits identifies the beginning of a frame:
00x0 0000 0000 0000 0000 0000 0000 0x00 0000 0xx0 0001 0011 000x x000 0000 xxxx
Then we create a QuickTime audio file by reindexing those ALAC frames.