Correctly parse MP4 non-full meta atoms (#1041)

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There are m4a files with regular (non-full) meta atoms. When such
a meta atom is not correctly parsed, the subsequent atoms are not
recognized and offsets will not be adjusted when atoms are added,
which will corrupt the MP4 file.

This change will look behind the meta atom to check if the next
atom follows directly, i.e. without the four bytes with version
and flags as they exist in full atoms. In such a case, these
four bytes will not be skipped.

Witnesses of this strange format specification are
https://leo-van-stee.github.io/
https://github.com/axiomatic-systems/Bento4/blob/v1.6.0-639/Source/C%2B%2B/Core/Ap4ContainerAtom.cpp#L60

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This commit is contained in:

Urs Fleisch

2022-03-03 21:03:48 +01:00

parent e255e749e8

commit 197d2a684b

3 changed files with 41 additions and 1 deletions

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tests/data/non-full-meta.m4a Normal file

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