Instead of the nal_prefix, this profile inside wraps the RPU inside an
EMDF container, as specified in ETSI TS 102 366. However, this
DV-specific EMDF container is restricted (by the specification) to
a fixed set of hard-coded parameters, which we can effecitvely treat as
a magic byte sequence.

Validated and tested using official Dolby sample files, which
I unfortunately cannot share. However, there are public sample files
available at the merge request link below.

Relevant links:
- https://www.etsi.org/deliver/etsi_ts/102300_102399/102366/01.04.01_60/ts_102366v010401p.pdf
- https://patentimages.storage.googleapis.com/8a/0b/da/28294acaed2182/EP3588964A1.pdf
- https://www.etsi.org/deliver/etsi_ts/103500_103599/103572/01.03.01_60/ts_103572v010301p.pdf
- https://gitlab.com/mbunkus/mkvtoolnix/-/merge_requests/2254