Atoms mvex, mehd, trex and sdtp are found at least in PIFF (isml) files.
This a first step towards Smooth Streaming support in VLC.
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>
(cherry picked from commit 789ea42038c632d67f4752d9755c6155f10765eb)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>