SPONSORED CONTENT JUNE 2017 STREAMING MEDIA SPOTLIGHT SERIES WP27
an adaptive bitrate stream on your smart TV and you have
the bandwidth available, you’ll get the highest bitrate—and
highest quality—to watch. Or, if you start watching a video
on your TV, then move to your mobile phone, you’ll get the
lower-bitrate version of the same video on the phone.
Each stream is delivered in chunks lasting a few seconds
long, and the receiving device (or client) chooses the best
chunk based on the current network and device conditions,
with the goal of delivering the highest possible bitrate
and quality at any given time. You may have experienced
this at the beginning of a streamed video when the client
starts out conservatively with the lowest bitrate chunks
and you see softer edges or even pixelation in the picture
until the playback device is able to “move up” to a higher
bitrate and resolution. Then, the device will continue to
select the appropriate chunk every few seconds (Figure 10),
and—best of all—buffering should be eliminated in all but
Of course, adaptive bitrate encoding means that the
encoder needs to generate multiple compressed versions of
any given video file. This is a computationally heavy process,
because of the different bitrates and resolutions.
Adaptive Streaming Formats
Today there are several major types of adaptive bitrate
formats and standards. Microsoft’s Smooth Streaming was
one of the first, but it’s going away as the Silverlight player has
been deprecated. Adobe HT TP Dynamic Streaming (HDS)
is primarily used to deliver Flash Video, but as Flash is being
deprecated, it’s not being used much today, either. Apple has
developed H T TP Live Streaming, which is commonly used to
support iOS devices.
Figure 10. An example of an adaptive bitrate stream. The orange line connecting the video frames represents the viewing device or player selecting
different 10-second chunks based on current network conditions. The manifest lists all the bitrates available in a given adaptive bitrate stream.