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pydvbcss is a library implementing DVB "CSS" protocols for Companion Screen Synchronisation.

Project description

# Python DVB Companion Screen Synchronisation protocol library

  • [How to install](#install)
  • [Read the documentation](
  • [Run the examples](#run-examples)

pydvbcss is a set of Python 2.7 libraries that implement some of the protocols defined in the DVB CSS specification (published as [ETSI 103-286 part 2]( These protocols enable synchronisation of media presentation between a TV and Companion devices (mobiles, tablets, etc).

This library includes simple to use high level abstractions that wrap up the server or client behaviour for each protocol as well as low level code for packing and unpacking messages sent across the protocols. There are also objects that work with the rest of the library to represent clocks and timelines.

This code is intended as an informal reference and is suitable for building prototypes and testing tools that implement TV (server) or Companion (client) behaviour. It is not considered production ready or suitable for integration into consumer products.

The code does not implement media playback functionality and this is not a planned feature.

_The DVB CSS specification was formerly published as [“DVB Bluebook A167-2”]( This is deprecated in favour of the [ETSI spec](

## Getting started

pydvbcss requires [ws4py]( for use in clients and servers, and also [cherrypy]( for server implementations. The steps below describe how to install these.

pydvbcss has been developed on Mac OS X 10.10 but has also been used successfully on Microsoft Windows 7 and Ubuntu 14.04.

### Read the Documentation (online)

The latest docs for the library [can be read online here](

<a name=”install”></a> ### Install the code …

The [master branch]( is the latest state of the code, including any recent bugfixes. It is mostly stable but might have occasional small API changes. Alternatively you can download a [release snapshot](

On Mac OS X and Linux you may need to run one or more of the commands as root.

We recommend using [pip]( to install dependencies from the Python Package Index [PyPI](

$ pip install cherrypy $ pip install ws4py

Then take (or update) your clone of the repository master branch, or download and unzip a snapshot release and run the script to install:

$ python install

This will install all module packages under ‘dvbcss’.

There is a limited test suite (it only tests certain classes at the moment). Run it via

$ python test

This checks some timing sensitive implementation issues, so ensure you are not running any CPU intensive tasks at the time.

<a name=”run-examples”></a> ### Run the examples

There is a set of examples demonstrating simple servers and clients for the protocols included with the library. See the [quick start guide]( in the documentation to see how to run them.

They demonstrate simple clients and servers. As appropriate, they pretend that there is content playing and that it has a progressing timeline. These examples serve to demonstrate how to use the library. They are not intended as finished and useful tools.

## Super-quick introduction to the protocols

DVB has defined 3 protocols for communicating between a companion and TV in order to create synchronised second screen / dual screen / companion experiences (choose whatever term you prefer!) that are implemented here:

  • CSS-CII - A WebSockets+JSON protocol that conveys state from the TV, such as the ID of the content being shown at the time. It also carries the URLs to connect to the other two protocols.
  • CSS-WC - A simple UDP protocol (like NTP but simplified) that establishes a common shared clock (a “wall clock”) between the TV and companion, compensating for network delays.
  • CSS-TS - Another WebSockets+JSON protocol that communicates timestamps from TV to Companion that describe the current timeline position.

The TV implements servers for all 3 protocols. The Companion implements clients.

There are other protocols defined in the specification (CSS-TE and CSS-MRS) that are not currently implemented by this library.

## Building the documentation for yourself

You can also build the documentation yourself. It is written using the [sphinx]( documentation build system.

Building the documentation requires [sphinx]( and the sphinx “read the docs” theme. The easiest way is using PyPI:

$ pip install sphinx $ pip install sphinx_rtd_theme

The docs directory contains the configuration and main documentation sources that descibe the structure. Most of the actual words are in the inline docstrings in the source code. These structural pages pull these in.

To build docs in HTML format, either:

$ python build_sphinx


$ cd docs $ make html

## Contact and discuss

Discuss and ask questions on the [pydvbcss google group](<!forum/pydvbcss>).

The original author is Matt Hammond ‘at’

## Licence

All code and documentation is licensed under the Apache License v2.0.

## Contributing

If you would like to contribute to this project, see [CONTRIBUTING]( for details.

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