pub fn read_structure_from<R: Read + Seek>(
r: &mut R,
file_len: u64,
) -> Result<Mp4Scan, Mp4ScanError>Expand description
Read the structural boxes (ftyp, moov, and the mdat header) by seeking,
never reading the mdat payload — for audiobooks that payload is hundreds
of MB and is served from the backing file at read time. Produces an Mp4Scan
byte-identical to read_structure on the same file, so synthesis is unchanged.
The header walk reads only 8 bytes per top-level box (16 for a 64-bit
largesize), so it skips over the mdat payload to reach a trailing moov.