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Last pushed: 2 years ago
Short Description
A MPEG-DASH packaging SDK and application with Common Encryption support
Full Description

Media packaging SDK intended for C++ programmers writing DASH packager applications with common encryption support, Widevine DRM support, Live, and Video-On-Demand.

This document provides the information needed to create a DASH packager that is able to remux and encrypt a video into fragmented ISO BMFF format with common encryption (CENC) support. The DASH packaging API is also designed in such a way for easy extension to more source and destination formats.

Current supported codecs:

H264 (AVC) I / O - I I
H265 (HEVC) I / O - I -
VP8 I / O I / O - -
VP9 I / O I / O - -
AAC I / O - I I
Dolby AC3/EAC3 I / O - - -
DTS I / O - - -
Opus - I / O - -
Vorbis - I / O - -

I for input and O for output. We will update this table once new formats are supported.

Right now this project is supported directly on Linux and MacOSX platforms only. One option to run edash-packager on other platforms is using [docker] (#Using docker for testing /development).

Mailing list

We have a public mailing list for discussion and announcements. To receive notifications about new versions, please join the list. You can also use the list to ask questions or discuss eDash Packager developments.

Setting up for development

  1. Packager source is managed by Git at We use gclient tool from Chromium to manage third party libraries. You will need Git (v1.7.5 or above) installed on your machine to access the source code.

  2. Install Chromium depot tools which contains gclient and ninja

    See for details.

  3. Get the source

    mkdir edash_packager
    cd edash_packager
    gclient config --name=src
    gclient sync

    To sync to a particular commit or version, use 'gclient sync -r \<revision>', e.g.

    # Sync to commit 4cb5326355e1559d60b46167740e04624d0d2f51
    gclient sync -r 4cb5326355e1559d60b46167740e04624d0d2f51
    # Sync to version 1.2.0
    gclient sync -r v1.2.0
  4. Build

    We use ninja, which is much faster than make, to build our code:

    cd src
    ninja -C out/{Debug,Release} [Module]

    Module is optional. If not specified, build all, e.g.

    ninja -C out/Debug                     # build all modules in Debug mode
    ninja -C out/Release                   # build all modules in Release mode
    ninja -C out/Release mp4               # build mp4 module in Release mode

    Refer to ninja manual for details.

    We also provide a mechanism to change build configurations, for example, developers can change build system to “make” by overriding GYP_GENERATORS.

    GYP_GENERATORS='make' gclient runhooks

    Another example, developers can also enable clang by overriding GYP_DEFINE.

    GYP_DEFINES='clang=1' gclient runhooks
  5. Updating the code

    Update your current branch with git pull followed by gclient sync. Note that if you are not on a branch, git pull will not work, and you will need to use git fetch instead.

  6. Contributing

    See for details.

Using docker for testing / development

Docker is a tool that can package an application and its dependencies in a virtual container to run on different host operating systems.

  1. Install Docker.

  2. Pull prebuilt image from Dockerhub or build an image locally

    2.a. Pull prebuilt image from Dockerhub

     docker pull google/edash-packager

    2.b. Build an image locally

     docker build -t google/edash-packager
  3. Run the container (your_media_path should be your media folder)

    docker run -v /your_media_path/:/media -it --rm google/edash-packager
  4. Testing

    # Make sure you run step 3 and you're inside the container.
    cd /media
    # VOD: mp4 --> dash
    packager input=/media/example.mp4,stream=audio,output=audio.mp4 \
            input=/media/example.mp4,stream=video,output=video.mp4 \
            --profile on-demand --mpd_output example.mpd
    # Leave the container.

    Outputs are available in your media folder your_media_path.

Design overview

Major modules are described below:

Demuxer is responsible for extracting elementary stream samples from a multimedia file, e.g. an ISO BMFF file. The demuxed streams can be fed into a muxer to generate multimedia files. An optional KeySource can be provided to Demuxer to decrypt CENC and WVM source content.

Demuxer reads from source through the File interface. A concrete LocalFile class is already implemented. The users may also implement their own File class if they want to read/write using a different kinds of protocol, e.g. network storage, http etc.

Muxer is responsible for taking elementary stream samples and producing media segments. An optional KeySource can be provided to Muxer to generate encrypted outputs. Muxer writes to output using the same File interface as Demuxer.

Demuxer and Muxer are connected using MediaStream. MediaStream wraps the elementary streams and is responsible for the interaction between Demuxer and Muxer. A demuxer can transmits multiple MediaStreams; similarly, A muxer is able to accept and mux multiple MediaStreams, not necessarily from the same Demuxer.

MpdBuilder is responsible for the creation of Media Presentation Description as specified in ISO/IEC 23009-1 DASH MPD spec.

Refer to Design, API for details.

DASH-IF IOP Compliance

We try out best to be compliant to Guidelines for Implementation: DASH-IF Interoperability Points.

We are already compliant to most of the requirements specified by the document, with two exceptions:

  • ContentProtection elements are still put under Representation element instead of AdaptationSet element;
  • Representations encrypted with different keys are still put under the same AdaptationSet.

We created a flag '--generate_dash_if_iop_compliant_mpd', if enabled,

  • ContentProtection elements will be moved under AdaptationSet;
  • Representations encrypted with different keys will be put under different AdaptationSets, grouped by @group attribute.

Users can enable the flag '--generate_dash_if_iop_compliant_mpd' to have these features. This flag will be enabled by default in a future release.

Please feel free to file a bug or feature request if there are any incompatibilities with DASH-IF IOP or other standards / specifications.

Driver Program Sample Usage

Sample driver programs packager and mpd_generator are written using the SDK.

Some sample usages:

Run the program without arguments will display the help page with the list of command line arguments:


Dump stream info:

packager input=sintel.mp4 --dump_stream_info

Demux audio from the input and generate a fragmented mp4:

packager input=sintel.mp4,stream=audio,output=fragmented_sintel.mp4

Demux streams from the input and generates a mpd with on-demand profile along with fragmented mp4:

packager \
  input=sintel.mp4,stream=audio,output=sintel_audio.mp4 \
  input=sintel.mp4,stream=video,output=sintel_video.mp4 \
--profile on-demand \
--mpd_output sintel_vod.mpd

Includes a subtitle input from webvtt:

packager \
  input=sintel.mp4,stream=audio,output=sintel_audio.mp4 \
  input=sintel.mp4,stream=video,output=sintel_video.mp4 \
  input=sintel_english_input.vtt,stream=text,output=sintel_english.vtt \
--profile on-demand \
--mpd_output sintel_vod.mpd

You may also generate mpd with live profile. Here is an example with IPTV input streams:

packager \
  'input=udp://,stream=audio,init_segment=live-audio.mp4,segment_template=live-audio-$Number$.mp4,bandwidth=130000'  \
  'input=udp://,stream=video,init_segment=live-video-sd.mp4,segment_template=live-video-sd-$Number$.mp4,bandwidth=2000000' \
  'input=udp://,stream=video,init_segment=live-video-hd.mp4,segment_template=live-video-hd-$Number$.mp4,bandwidth=5000000' \
--profile live \
--mpd_output live.mpd

Demux video from the input and generate an encrypted fragmented mp4 using Widevine encryption with RSA signing key file widevine_test_private.der:

packager input=sintel.mp4,stream=video,output=encrypted_sintel.mp4 \
--enable_widevine_encryption \
--key_server_url "" \
--content_id "3031323334353637" \
--signer "widevine_test" \
--rsa_signing_key_path "widevine_test_private.der"

The program also supports AES signing. Here is an example with encryption key rotates every 1800 seconds:

packager \
  'input=udp://,stream=audio,init_segment=live-audio.mp4,segment_template=live-audio-$Number$.mp4,bandwidth=130000'  \
  'input=udp://,stream=video,init_segment=live-video-sd.mp4,segment_template=live-video-sd-$Number$.mp4,bandwidth=2000000' \
  'input=udp://,stream=video,init_segment=live-video-hd.mp4,segment_template=live-video-hd-$Number$.mp4,bandwidth=5000000' \
--profile live \
--mpd_output live.mpd \
--enable_widevine_encryption \
--key_server_url "" \
--content_id "3031323334353637" \
--signer "widevine_test" \
--aes_signing_key "1ae8ccd0e7985cc0b6203a55855a1034afc252980e970ca90e5202689f947ab9" \
--aes_signing_iv "d58ce954203b7c9a9a9d467f59839249" \
--crypto_period_duration 1800

Note that key rotation is only supported for live profile.

Demux and decrypt video from a WVM container, and generate encrypted fragmented mp4 using Widevine encryption with RSA signing key file widevine_test_private.der:

packager input=sintel.wvm,stream=video,output=encrypted_sintel.mp4 \
--enable_widevine_decryption \
--enable_widevine_encryption \
--key_server_url "" \
--content_id "3031323334353637" \
--signer "widevine_test" \
--rsa_signing_key_path "widevine_test_private.der"

The program can be told to generate MediaInfo files, which can be fed to mpd_generate to generate the mpd file.

packager \
  input=sintel.mp4,stream=video,output=sintel_video.mp4 \
  input=sintel.mp4,stream=audio,output=sintel_audio.mp4 \

mpd_generator \
--input "sintel_video.mp4.media_info,sintel_audio.mp4.media_info" \
--output "sintel.mpd"
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