Pelican-dashify

Pelican-dashify let you convert proper MPEG-DASH content generated from your videos with Pelican.

Features

• Support for MPEG-DASH live and on-demand profiles, and even more.
• Transcode a video stream in multiple qualities, customizable with settings.
• Callable from any article or page metadata, by using the tag {dashify}.
• Seamless integration with Pelican, dashify does not include any HTML or JS extra code.

DASHwhat?

Many notable streming providers uses this standard, like YouTube or Netflix. MPEG-DASH let client adapt to changing network conditions and provide high quality playback with fewer stalls or re-buffering events. He is widely used on devices like Internet-connected televisions, TV set-top boxes, desktop computers, smartphones, tablets, etc. to consume multimedia content (video, TV, radio, etc.) delivered via the Internet.

Installation

Under the hood, dashify call for external binaries, which are ffprobe to get input file info like resolution and metainfo. ffmpeg is used to transcode the representations and MP4Box to pack everything for delivery. Tests will be added to cover supported versions list, for now 4.x of ff[mpeg/probe] and 0.7.x of GPAC are fine.

Install the latest release from PyPi :

pip install pelican-dashify

Quickstart

Enable dashify for your Pelican project into the pelicanconf.py config file :

PLUGINS = ('pelican_dashify',)

Download a video like the Big Bunny into the content directory, assuming path to be content/videos/BigBuckBunny.mp4.
Edit a dummy article, with a "DASHified" version of the BigBuckBunny.mp4 attached :

Big Buck Bunny
==============

:date: 2018-11-12 23:00
:summary: This is a MPEG-DASH compliant sample of the Big Buck Bunny
:video: {dashify}videos/BigBuckBunny.mp4

That's it, the site can be generated.

make html

Generated files

Transcoded representations are stored in a cache-like directory to avoid a re-transcoding on every site generation.

output/videos/BigBuckBunny.mp4/.cache/1280x720_2211k.mp4
output/videos/BigBuckBunny.mp4/.cache/640x360_552k.mp4
output/videos/BigBuckBunny.mp4/.cache/320x180_138k.mp4
output/videos/BigBuckBunny.mp4/.cache/audio_128k.mp4

Since these files are stored in the Pelican output directory by default, they will be removed on cleaning, which leads to re-transcode. To avoid this behavior, set DASHIFY_CACHE_PATH outside the output scope.

Just after, on packing phase, representations are segmented by MP4Box and placed in the output directory. From BigBuckBunny.mp4, using the default DASH profile 'onDemand', following files have been generated :

output/videos/BigBuckBunny.mp4/manifest.mpd
output/videos/BigBuckBunny.mp4/1280x720_2211k_dash_track1_init.mp4
output/videos/BigBuckBunny.mp4/640x360_552k_dash_track1_init.mp4
output/videos/BigBuckBunny.mp4/320x180_138k_dash_track1_init.mp4
output/videos/BigBuckBunny.mp4/audio_128k_dash_track1_init.mp4

To serve representations using the onDemand profile, the HTTP server must support range requests. As a workaround, the live profile can be used.

Video displaying

Now the content has been generated, but Pelican doesn't know how and where to display the video. To do this, a modification of your template is required. You can use any DASH player to read your converted video, for this example, we choose video.js for less code as possible.

Into article.html :

{% extends "base.html" %}
...

{% block content %}
<section id="content" class="body">
  ...
  <div class="entry-content">
    {% if article.video %}
    <video data-dashjs-player autoplay src="{{ SITEURL }}/{{ article.video.url }}" controls></video>
    <div class="video-duration">{{ article.video.duration|timedelta_as_string }}</div>
    {% endif %}

    {{ article.content }}
  </div><!-- /.entry-content -->
</section>
<script src="https://cdn.dashjs.org/latest/dash.all.min.js"></script>
{% endblock %}

The timedelta_as_string are provided by Pelican-dashify.

Settings

Settings can be defined globaly into pelicanconf.py or per video using a specific JSON file. To define a video configuration, like a custom DASH profile for BigBuckBunny.mp4, create a file named BigBuckBunny.mp4.dashify.config with the following content :

{
	"DASHIFY_DASH_PROFILE": "live"
}

General

DASHIFY_EXTRACT_TAGS : Inject the original video tags into the template variable {{ <metaname>.tags }}. Default to False.

DASHIFY_CACHE_PATH : Use a custom path to store the representations transcoded from the original video. By default, dashify will store them into the content directory. Default to None.

DASHIFY_FFMPEG_BIN : Specific path to use for the ffmpeg binary, libav can be used. Default to ffmpeg.

DASHIFY_FFPROBE_BIN : Specific path to use for the ffprobe binary. Default to ffprobe.

DASHIFY_MP4BOX_BIN : Specific path to use for the MP4Box binary. Default to MP4Box.

DASHIFY_METATAG : Tag used to prefix video to be DASHified. Default to {dashify}.

Transcoding

DASHIFY_RESOLUTION_DIVISOR : The divisor used to downscale the resolution of representations. Default is 2.
For a 720p formatted input, the 1280x720, 640x360 and 320x180 will be generated with DASHIFY_VIDEO_REPRESENTATIONS set to 3.

DASHIFY_VIDEO_REPRESENTATIONS : How many representations to generate. Default to 3.

DASHIFY_SEGMENT_DURATION : The time of a DASH segment in seconds, used to switch between the different video/audio qualities.
Dashify will compute the ffmpeg keyint accordingly. Default to 4.

DASHIFY_BITS_PER_PIXEL : The BPP used to compute the bitrate for a given resolution. Default to 0.1.

DASHIFY_DASH_PROFILE : Choices are : onDemand, live, main, simple, full, dashavc264:live, dashavc264:onDemand.
Default to onDemand.

Video

DASHIFY_FRAMERATE : The frames per second to use on representations. Default to 24fps.

DASHIFY_X264_PRESET : Preset used by ffmpeg on transcoding. Default to slow for a better rendering.
Choices are : ultrafast, superfast, veryfast, faster, fast, medium, slow, slower, veryslow.
For more info check the ffmpeg wiki.

DASHIFY_VIDEO_STREAM_INDEX : Select a given stream from the input container. Default to 0 for the first available one.

DASHIFY_VIDEO_MAX_WIDTH : Skip representation if computed width is greater then value. Default to 7680 (8K).

DASHIFY_VIDEO_MAX_HEIGHT : Skip representation if computed height is greater then value. Default to 4320 (8K).

DASHIFY_VIDEO_MAX_BITRATE : Skip representation if computed bitrate is greater then value. Default to 79626 (8K w/ 0.1 BPP @ 24fps).

DASHIFY_VIDEO_MIN_WIDTH : Skip representation if computed width is lower then value. Default to 128.

DASHIFY_VIDEO_MIN_HEIGHT : Skip representation if computed height is lower then value. Default to 72.

DASHIFY_VIDEO_MIN_BITRATE : Skip representation if computed bitrate width is lower then value. Default to 22.

Audio

DASHIFY_AUDIO_STREAM_INDEX : Select a given stream from the input container. Default to 0 for the first available one.

DASHIFY_AUDIO_CODEC : Codec to use on audio transcoding. Default to aac.

DASHIFY_AUDIO_CHANNELS : Number of audio channels. Default to 2.

DASHIFY_AUDIO_BITRATE : Default to 128k.

DASHIFY_AUDIO_DISABLE : Disable audio. Default to False.