Reads the tracks an init segment declares. null when the piece holds no moov box, when a box's size runs past
what holds it, or when a track lacks the tkhd or hdlr box that identifies it. A track whose sample entry this
reader does not know is still listed, without a codec. Parameter sets and the AudioSpecificConfig are copied, so the
result outlives the piece's buffer (which a caller may transfer to another thread).
Reads the tracks an init segment declares.
nullwhen the piece holds nomoovbox, when a box's size runs past what holds it, or when a track lacks thetkhdorhdlrbox that identifies it. A track whose sample entry this reader does not know is still listed, without a codec. Parameter sets and the AudioSpecificConfig are copied, so the result outlives the piece's buffer (which a caller may transfer to another thread).