Eyevinn / mp4ff / 37015048333

83%

master: 83%

Pull #618

github

fix(mp4): reject sample data stored in other files

A track's sample entries point through data_reference_index to dref entries. A url entry without the self-contained flag puts the data in another file, as in Unified Streaming dref MP4s (mp4split --use_dref, Remix output) and MP4Box -dref files. mp4ff ignored this and read the chunk offsets from the file's own mdat. Without an mdat, mp4ff-crop and the segmenter example panicked. With one, in a file mixing referenced and self-contained tracks, mp4ff-crop wrote the wrong bytes and kept the reference.

Add TrakBox.CheckDataIsSelfContained and call it from File.CopySampleData and from the tools that read progressive sample data. The check reads the self-contained flag from any data entry, since QuickTime alis entries set it too. A url entry without a location, a missing dref, or an index outside it count as self-contained, so files that worked before still do. MdatBox.ReadData and CopyData now return an error for a nil mdat.

prog_8s_dref.mp4 is made with MP4Box -dref -add prog_8s.mp4 and refers to prog_8s.mp4 in the same directory. alis is added to the codespell ignore list as a QuickTime data entry type.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

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