asc_len == 0 and end > b.len() reject for different reasons - a useless
zero-length ASC, and a truncated one - and nothing distinguished the || from
an && that would only reject when both are true simultaneously, or the >
from a < that would reject the common case of an esds with bytes after the
ASC (more child boxes, padding) instead of only a genuine truncation.
Documented the | in read_descriptor_len's accumulator as the same
shift-then-mask equivalent already recorded in audio.rs's BitReader::read:
the shift always vacates exactly the bits the mask fills, so | and ^ can't
disagree.
Matthew Jackson
39d9714ae7