WP26 STREAMING MEDIA SPOTLIGHT SERIES JUNE 2017 SPONSORED CONTENT
Until recently, H.264 (also known as AVC) was the best
codec for optimizing quality and reducing file sizes, and many
content publishers still use it today. But it’s slowly giving way
to HEVC, which stands for High Efficiency Video Coding. (It’s
also referred to as H.265; different standards groups employ
different designations to refer to the same standard.) HEVC
requires more computing power than H.264, but it’s also
more efficient (Figure 8). Because AWS Elemental writes all
of its encoding software from scratch, rather than relying on
off-the-shelf encoding software, it is able to take the efficiency
gains in each new generation of codec and adjust the software
accordingly in order to get the best quality and/or smallest file
sizes along with the shortest encoding times.
Now that we’ve covered video compression, let’s take a
look at video delivery. In the first decade of the millennium,
most video content was downloaded rather than streamed.
This was pioneered by Apple and its i Tunes store, but of course
quickly became available from
other video download services.
And even though the majority of
VOD content is streamed today,
downloading is still relevant;
Amazon Video, for instance,
offers downloads of much of its
content. The upside is that, once a
file is downloaded to a device, the
consumer can watch it anytime,
any where, sometimes even without
an internet connection.
The downside is that the device
needs to download the entire file
before it can be watched. Progressive
downloading is one step better than regular downloading. It
allows viewers to start watching a video before the entire file is
downloaded—provided the device and network keep up with
the playback location in the video. If the device or net work has
issues, the viewer can experience buffering where the video
pauses, and study after study shows that consumers do not
like this experience. Progressive download, though popular
in the early 2000s, was an imperfect solution to the problem of
consumers having to wait to begin viewing their content, and
so it is used infrequently today.
Streaming—where video is delivered consistently to the
viewing device as the consumer is watching—can also face
the same buffering issues as progressive download. If you
recall trying to watch streaming video a decade ago, you surely
remember the video might take 10 or even 30 seconds to start,
and then might pause mid-stream if the internet connection
became congested (say, if another device on the same network
was also trying to stream video) or if the device’s processor
couldn’t keep up with the decoding.
The most recent delivery evolution is adaptive bitrate
(ABR) streaming, which for the most part solves the buffering
challenge. In adaptive streaming, each video file contains
multiple streams encoded at different bitrates and resolutions;
in the case of the video shown above in Figure 4, the adaptive
bitrate stream would include both the high bitrate stream and
the low bitrate version—as well as streams at other bitrates
and resolutions in between—and adjusts what bitrate is
actually delivered to the viewing device based on the speed
of the network connection (Figure 9). If you’re watching
Figure 8. High Efficiency Video Coding (HEVC), or H.265, requires more computational power to
process, but is also much more efficient than its predecessors, AVC and MPEG- 2.
Figure 9. While single bitrate streams deliver video to the viewing device at a single, consistent bitrate, adaptive bitrate streams include
multiple bitrates, and the device or player will choose the best stream in real time.