WP42 STREAMING MEDIA SPOTLIGHT SERIES APRIL/MAY 2018 SPONSORED CONTENT
... with Just-In-Time Packaging
One technology used to minimize these costs is called Just-in-Time (JIT) or dynamic packaging. Briefly, JIT packaging
refers to server-based technologies that work from a single
set of live or VOD MP4 streams, and packages and encrypts
these streams according to the unique requirements for the
endpoint requesting playback. This is shown in Figure 3.
Specifically, you see a common set of files on the left
packaged into multiple groups for different protocols and
DRMs. As previously discussed, since the container format
is determined by just a few bits of data contained in the file
header, JI T technologies can convert to the proper format on
the fly and cater to the specific needs of the client requesting
the video. At a high level, JI T technologies allow producers to
store a single format at the origin server, saving the costs of
packaging and storing multiple formats.
In addition to packaging, JI T technologies can customize
the segment size for different protocols. Some can also manage
blackout periods, or apply rules-based logic to perform
operations like limiting stream quality to mobile devices
where the costs of delivering 1080p streams makes little sense
because viewers can’t see the improvement over 720p video.
The Common Media Application Format (CMAF)
To recount, prior to June 2016, Apple’s HLS only supported
files packaged in the MPEG- 2 container format. Then, at its
2016 Worldwide Developers Conference, Apple announced
that newer versions of iOS, tv OS, and macOS would support
f MP4 files within HLS via a specification called the Common
Media Application Format (CMAF).
What exactly is CMAF? In MPEG-speak, it’s a standard for
segmented media delivery formalized as MPEG-A Part 19,
or ISO/IEC 23000-19. Specifically, CMAF uses the ISO Base
Media File Format (ISOBMFF) container and can support
H.264, HEVC, and other codecs. CMAF defines the media
format only, not the structure or content of the manifest files,
and CMAF-formatted content can be retrieved by both HLS
playlists (.m3u8 files) and DASH manifest files (.mpd files).
Figure 3. JIT packaging customizes container format and DRM for each endpoint