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Topic: Can ALAC/m4a detect file corruption? (Read 81 times) previous topic - next topic
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Can ALAC/m4a detect file corruption?

I have found amount of article, and know that flac/ape/tak can check audio integrity with inner crc info and outter md5.
ALAC/m4a is also open. But its format is so complicated (so many "box" type with different meta info), and I try to find crc or md5
in the format  structure detail description, and cant find them.

I have tried use an hex editor directly change some random bytes in middle of the alac file.
First time I change 2 position, [foobar 2000 - verify integrity] says it's ok. So the check tool cant detect this change.
Second time I change 2 more position, and this time the tool report :
"Reported length is inaccurate : 4:25.653333 vs 4:25.560454 decoded
Error: Decoding error: Unsupported format or corrupted file, frame: 2112 of 2861".

May there anyone know much about ALAC/m4a structure could tell me :
Can ALAC/m4a detect file corruption? (with inner metadata like crc/md5?or other mechanism?) O:)