shaka-player/tutorials/intro.html

DASH/EME video player library

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<h3 class="tutorial-heading">
DASH Streams at a High Level
</h3>

<p>
Dynamic Adaptive Streaming over HTTP (DASH) is a technique for adaptive bitrate
streaming of content over the Internet delivered from conventional web servers.
This is a quick overview of DASH for those who are not familiar with it.  For a
more detailed view of DASH, visit {@link http://dashif.org/guidelines/ dashif.org}.
</p>

<p>
Every DASH stream is described by a manifest written in XML.  Within a manifest
file, representation elements describe the DASH stream's audio, video, and text
sources.  There may be more than one representation of the same content.  These
typically differ in terms of bitrate and resolution, although there can be some
other variations as well.
</p>

<p>
Representations are grouped into one or more adaptation sets, and a DASH client
can switch automatically between representations within a set.  Adaptation sets
can differ in codec and language.  DASH streams usually have audio and video in
separate adaptation sets.  Although the DASH specification allows for audio and
video to be multiplexed, the Shaka Player does not support this type of stream.
</p>


<h3 class="tutorial-heading">
Multiple Resolutions and Bitrates
</h3>

<p>
For the Shaka Player to adapt and choose the best representation for the user's
available bandwidth, you must encode your content into more than one resolution
and bitrate.  It is up to you what bitrates and resolutions make sense for your
site.  Note that you can encode at multiple bitrates for a single resolution.
</p>

<p>
Example video encoding scheme:
<ul>
 <li>1920x1080, 5.0 Mbit/s</li>
 <li>1920x1080, 3.0 Mbit/s</li>
 <li>1280x720, 2.0 Mbit/s</li>
 <li>1280x720, 1.0 Mbit/s</li>
 <li>854x480, 750 kbit/s</li>
 <li>640x360, 350 kbit/s</li>
</ul>
</p>

<p>
There are many open-source tools to transcode video, including:

<ul>
 <li>ffmpeg <a href="https://www.ffmpeg.org/">https://www.ffmpeg.org/</a></li>
 <li>DASHEncoder <a href="https://github.com/slederer/DASHEncoder">https://github.com/slederer/DASHEncoder</a></li>
</ul>
</p>


<h3 class="tutorial-heading">
Packaging Content
</h3>

<p>
A DASH packager is required to get your media ready to stream.  There are a few
open-source packagers available for MP4 / ISO BMFF streams, including:

<ul>
 <li>edash-packager <a href="https://github.com/google/edash-packager/">https://github.com/google/edash-packager/</a></li>
 <li>MP4Box <a href="http://gpac.wp.mines-telecom.fr/mp4box/">http://gpac.wp.mines-telecom.fr/mp4box/</a></li>
 <li>DASHEncoder <a href="https://github.com/slederer/DASHEncoder">https://github.com/slederer/DASHEncoder</a></li>
 <li>DASH.encrypt <a href="https://github.com/castlabs/dashencrypt">https://github.com/castlabs/dashencrypt</a></li>
</ul>
</p>

<p>
Your DASH packager will convert your content to a valid, segmented ISOBMFF file
and generate a DASH manifest (MPD file).  Most DASH packagers can not transcode
your media into multiple resolutions and bitrates.  (DASHEncoder does both.)
</p>

<p>
To package WebM streams for DASH, the WebM project provides tools for this:

<ul>
 <li>webm-tools <a href="http://www.webmproject.org/code/">http://www.webmproject.org/code/</a></li>
</ul>

The WebM project also provides <a href="http://goo.gl/cfJ2x3">a tutorial</a> on
encoding WebM content for DASH.
</p>