sample_number
marking of the sync samples within the stream [...] If the sync sample box is not present, every sample is a sync sample
(content element) is (content element value for independent) but (container element for IPF) or (container element for IF) does not indicate this frame is independent.
usacIndependencyFlag is 1 but MP4 stts or (container format) (container element for independent frame (IF)) does not indicate this frame is independent
(container format) (container element for immediate play-out frame (IPF)) or (container format) (container element for independent frame (IF)) does not indicate this frame is independent but (content format) (content element) (content field) (value) indicates this frame is independent
(container format) (container element for immediate play-out frame (IPF)) indicates this frame is an immediate play-out frame (IPF) but (content format) (content element) (content field) (value) indicates this frame is not an immediate play-out frame (IPF)
(container format) (container element for immediate play-out frame (IPF)) does not indicate this frame is an immediate play-out frame (IPF) but USAC AudioPreRoll is present
(container format) (container element for immediate play-out frame (IPF)) indicates this frame is an immediate play-out frame (IPF) but USAC AudioPreRoll is not present