tree fdb28b01ba751593ba642aab563eed793873cf3e
parent 98faa17f139b1c280fbea40563078b1fcb438aa5
author Vignesh Venkatasubramanian <vigneshv@google.com> 1663693078 -0700
committer Vignesh Venkatasubramanian <vigneshvg@users.noreply.github.com> 1663713253 -0700

Write 'auxv' as handler_type for alpha channel track

For animated AVIF sequences, alpha channel track has to have the
handler_type set to 'auxv'.

This is mentioned in Section 7.5.3.1 of the HEIF specification.

libavif's parser ignores the 'hdlr' box that occurs inside the
'mdia' box. So this change is backward compatible (i.e.) files
produced after this change will still be parse'able by earlier
libavif versions.