QuickTime Streaming

Track Reference Atom (`'tref'` )

Each hint track refers to a media track. The hint track contains a track reference atom ('tref' ) containing a child atom of type 'hint' which holds the track ID of the media track. There is a diagram of a hint track reference atom below.

Atom/Field	Bytes	Description
Track Reference Atom		Contains a `'hint'` atom
Size	4	Size of track reference atom (including `'hint'` atom). 32-bit integer.
Type	4	`'tref'`
..Track Reference Ty pe Atom		Contains the track ID of the media track being hinted
..Size	4	Size of this child atom. 32-bit integer.
..Type	4	`'hint'`
..Track ID	4	Track ID of the media track being hinted. 32-bit integer.

The Track ID field of the 'hint' atom contains the track ID of the media track being hinted. The target track ID can be found in the media track's track header atom ('tkhd' ). All media sample data should be taken from the specified media track.

There could theoretically be a list of track ID's, for a hint track that hinted multiple media tracks, but the current hinter only references one media track per hint track.

Track Reference Atom ( 'tref' )

Track Reference Atom (`'tref'` )