This section documents the track-reference types, which link tracks with relationships between them. The link is typed with a code. These codes are documented here.

ISO Family code points (see below for QuickTime code points)
Code Abstract Defined in/by
avcp AVC parameter set stream link AVC
cdsc this track describes the referenced track. MPEG-4
dpnd this track has an MPEG-4 dependency on the referenced track MPEG-4
hind Hint dependency ISO
hint links hint track to original media track ISO
ipir this track contains IPI declarations for the referenced track MPEG-4
mpod this track is an OD track which uses the referenced track as an included elementary stream track MPEG-4
sbas Scalable base AVC
scal Scalable extraction AVC
swfr AVC Switch from AVC
swto AVC Switch to AVC
sync this track uses the referenced track as its synchronization source. MPEG-4
tmcd Time code. Usually references a time code track. Apple
vdep Auxiliary video depth ISO
vplx Auxiliary video parallax ISO

QuickTime code-points

Code Abstract Defined in/by
chap Chapter or scene list. Usually references a text track. QT
scpt Transcript. Usually references a text track. QT
ssrc Nonprimary source. Indicates that the referenced track should send its data to this track, rather than presenting it. QT
tmcd Time code. Usually references a time code track. QT