Summer of Code 2009

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This is our ideas page for Google Summer of Code 2009 projects with and Annodex. The two projects participate jointly this year under Xiph's name.

Students please use the template at Summer of Code Applications when applying for a GSoC position.

Mentors please visit Summer of Code Mentoring and help us prepare our application as a mentoring organization.

General Ideas


  • OpenMAX IL components for Ogg codecs
  • Get skeleton patches upstream so players stop choking on it.
  • Portable listening application for codec MOS/MUSHRA comparisons (Win32, MacOS, Linux; FF3.1 web application?).

Web Video

  • Proof of concept liboggplay-based media patch for Google's Chrome browser.
  • Metavid improvements
  • Kate to HTML & CSS overlay library in javascript.
  • Firefox extension to record locally and stream to icecast.
  • Firefox extension to support RTP for conferencing.
  • mod_duration apache module to generate X-Content-Duration headers for Ogg files. (We should get people to use oggz_chop instead ... oggz_chop provides this functionality and more, is already relatively lightweight.) Perhaps this project could be more focused on packaging oggz_chop for other web servers like lightpd and maybe a fastCGI version and or maybe push for an mod_ogg to be adopted upstream in apache to improve distribution.

Detailed Project Descriptions

These ideas were suggested by various members of the developer community as projects that would be beneficial and which we feel we can mentor. Students should feel free to select one of these, develop a variation, or propose their own ideas. Here, ideally.

Proof of Concept liboggplay (html5 video) support in Chromium Browser

This project would focus on integrating support for liboggplay into chrome. This project would only need to be a proof of concept with the end result being some frames decoded in the browser. We have some direct contacts with people on the Chromium project in Google, but would expect the student mostly to work through the Xiph on Chromium online communities.

Chromium Home Page

Metavid related projects

see full page on

  • Improve transcript import / export system:
    • Wiki to SRT
    • SRT to Wiki
    • CMML to Wiki
    • Extend oggz_chop or other tool for exporting transcript encapsulated in the ogg file.

Javascript Library for Subtitles, Captions and other time-aligned text

The main focus of the project is on enabling video accessibility for Ogg in Firefox.

Problem / Intro

Captions, subtitles and other categories of time-aligned text are starting to become relevant to HTML5. In Ogg, we currently encapsulate such data in OggKate and can use SRT or Kate as input formats. Display of OggKate is currently supported in VLC and there are patches for various other media players. We now want to enable Web browsers to also deal with these time-aligned text tracks in those Web Browsers that support the HTML5 video tag.

Solution / Task

There is a proof of concept patch for Firefox 3.1 (now called 3.5) and liboggplay through which Firefox is capable of decoding Ogg Kate tracks and either overlay them onto the video, or handing the raw text to the browser (eg, for text to speech). However, there is no display of OggKate in Firefox 3.5 using HTML5. This can be fixed through the creation of a javascript library that can deal with Kate output and convert it to HTML and CSS. Example libraries exists for displaying SRT for HTML5 video, but they will need to be extended to Kate in this project.

This project includes the creation of example files for different types of time-aligned text. These are then encapsulated into Ogg through Kate encoding. Firefox 3.5 with the applied OggKate patch can decode these files and hand the textual data to the Web browser. It will be necessary to extend liboggplay to pass non textual Kate data (eg, styling, etc) to the browser, as currently the only two ways of dealing with a Kate track is to render it, or pass raw text, ignoring extra styling information. This could be part of the project, or done before the GSoC projects begins. The browser receives the text and styling information, and a javascript library implemented by the student will take care of the display. This will include an implementation of default display mechanisms for the different types of time-aligned text that we decide to deal with.


The project requires a student with experience in javascript development, HTML and CSS, but also with some understanding of C for liboggplay and libkate, and of C++ for Firefox. The student will learn how to deal with Ogg and Ogg tracks, including Ogg Kate. He/she will also get some insight into Firefox development. He/she will work with the developer of Ogg Kate and the video accessibility expert of Xiph, as well as having access to the whole Xiph community including the core developer of Ogg support in Firefox.

The project is adaptable to the qualifications of the student - it may consist in simply implementing a tool-chain for handling srt through OggKate, or it may go much further and include richer forms or time-aligned text such as audio annotations, Karaoke, ticker text, clickable text etc.


  • Silvia Pfeiffer (nessy / ginger)
  • ogg.k.ogg.k

OpenMAX IL components for Ogg codecs

OpenMAX is a set of low-level C APIs for media codecs. It is used by many mobile devices, in platforms like Maemo and Android. As we'd like to encourage the use of free codecs on mobile and embedded devices, we want to develop a set of components using our codec libraries.

For details, including the motivation for this project and links to related projects, see Is OpenMAX important for Free Software?

XSPF-related projects

XSPF import and export for Songbird

  • Songbird cannot read XSPF playlists
  • Songbird cannot write XSPF playlists
  • Extend the development line of Songbird by XSPF read and write support.
  • Read support should be able to tolerate most above-XML-level errors so users don't get frustrated with XSPF. That's the short version :-)
  • Communication with upstream will be needed
  • Solution should use whatever solution upstream is likely to accept as a patch. If you get them to accept a libxspf-based solution it's C++, otherwise probably JavaScript.
  • Sebastian Pipping (sping)

Python library / Online validator refactoring

  • The Online XSPF Validator's code (Python >=2.4) is a procedural spaghetti mix of logic and presentation.
  • There is no Python XSPF library around.
  • Refactor the current validator code and separate it into a OOP XSPF reading library/API
  • Adapt the validator to use former library
  • Separate presentation and logic in validator code possibly involving a popular light-wight LGPLv3-compatible Python framework of your choice
  • Sebastian Pipping (sping)

CELT-related projects

Conference bridge using CELT

When a conference takes place, the voice from all participants is often decoded, mixed together, and re-encoded. The goal of this project is to do better. We would like to have only partial decoding and re-encoding and reuse as much as possible from the already-encoded streams. This not only decreases the CPU load but also improves quality.

Reference SIP client for CELT

See Also