Summer of Code 2008

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Revision as of 21:32, 8 March 2007 by Jmspeex (talk | contribs) (some speex projects)
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This is our ideas page for Google Summer of Code projects with and Annodex. The two projects are participating jointly this year under Xiph's name.

We need a primary and backup mentor volunteer for any project that is to become an official proposal, but submit something and we'll see who we can round up. :)

note: Google Summer of Code 2007, mentoring organizations to apply between March 5 and March 12, students March 14 - March 24

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

Mentors for details of our mentor application and plan, please see Summer of Code 2007.

Students should also check out projects related to the Elphel Open Source cameras.

Optimize Theora encoding/decoding speed, SSE/SSE2

Work on MMX, SSE/SSE2 implementations of the crucial encoding and decoding elements in libtheora and/or theora-exp. This could include porting the vp3 mmx and altivec code to the libtheora decoder, and writing sse improvements on the mmx work that has already been done. The results must still build cleanly on other archs and do run-time capability detection.

You could start improving this MMX loop filter patch for theora-exp that was never completed nor merged in current theora-exp (see all list thread).

Mentor: Ralph Giles, Timothy Terriberry, backup: Jan Gerber, Mike Smith

Encode support in theora-exp

Implement a rate-distortion optimized encoding mode for theora-exp, including R-D optimzed mode decision and quantization (e.g., constant lambda). Then, use the above routines to implement a medium-latency ABR encoding mode (e.g., varying lambda), with a default target buffer size of approximately 2 seconds.

Mentor: Timothy "Derf" Terriberry, backup: Mike Smith, Ralph Giles

Development assistant for the "Ghost" audio codec

Designing a cutting edge perceptual codec is a very daunting task. Xiph is in the research stage on a new low-latency, general purpose audio codec, code-named "Ghost". This is basically a "code assistant" position, where you will be asked to implement, test, and give feedback on ideas from Christopher Montgomery, designer of the Ogg Vorbis format. Be prepared to learn a lot about audio coding, or apply what you already know. While there's less "ownership" potential in this project proposal, it will be a great opportunity to learn about compression algorithm design, practice your programming chops, and learn to work in team.

Mentor: Christopher "Monty" Montgomery, backup: Jean-Marc Valin

OggMNG implementation

Implement the OggMNG decode support in gstreamer and/or illi's dshow filters. Implement encoding support in based on byzanz or Istanbul. Bonus points for overlay support. Details on the OggMNG specifications here

Mentors: Mike Smith, Ralph Giles

Theora reference encoder quality optimization

The libtheora encoder could make more use of some features present in the spec but not currently implemented in the encoder. This is a little open ended, but suggestions are: quant matrix tuning, per-block qi choice, 4:2:2 and 4:4:4 chroma support.

Mentor: Ralph Giles, backup: Timothy Terriberry

Subtitle Editor

this project would also consolidate the various proposals for subtitles. from what i saw on #annodex, using CMML might be the way to go. Coordinate with

another option is to pick an existing format (e.g. srt) and get a gui mockup done. It should: give you playback with scrubbing, let you set in and out points, and write out the results in an Ogg File.

OggSkeleton tool support

Implement OggSkeleton production in various xiph tool packages, e.g. oggenc, vorbisenc, speexenc, theora encoder_example or ffmpeg2theora. Possibly also implement support for the QuickTime media framework (most other media frameworks already support OggSkeleton e.g. gstreamer, xine, vlc, DirectShow). It may be interesting to do these as a general library, e.g. on top liboggz. This was a successful project in 2006.

Mentor: Conrad Parker, backup: Silvia Pfeiffer

Theora support in ekiga

Implement support for Theora as a video codec in the ekiga chat application. Overlaps with GNOME.

Mentor: Ralph Giles

MXF support in gstreamer

Implement an MXF mux/demux for gstreamer, with mappings for Vorbis and Theora.

Mentors: Christian Schaller, Mike Smith

Hardware implementation of Theora decoding

Working on a hardware theora decoder, that can be used in embedded devices, dvd players and video pods. Presumedly GPL verilog source to run on an FPGA. See for a rough encoder implementation. This was a successful project in 2006.

Intel to AT&T x86 assembly translation

There is a general need for cross platform projects to be able to compile the same asm accelleration code on both GCC and MSVC. Unfortunately, at least of x86, they have incompatible assembly formats. Currently people either convert one to the other by hand (a maintenance nightmare) or require an external compile/assemble step on one or the other platform.

Start with the (unmaintained?) intel2gas script. Spruce it up to support all of recent MMX, SSE, SSE2, SSE3 instructions. Then implement the reverse translation. Once both are working, write some glue code so it can be easily used as part of a GNU autotools build to derive one set of source from the other at build or package time.

Theora encoder and Ogg exporter/muxer QuickTime components

QuickTime is a major multimedia framework, used in many professional audio and video applications. The framework is flexible and its functionality can be extended by means of plugins - components. While the number of existing tools able to export video in Theora format is still limited, Theora encoder/exporter components would somewhat improve the situation allowing applications based on QuickTime to produce content in Theora format.

The project idea is to implement two QuickTime components: Theora encoder and Ogg exporter. In the Theora encoder component libtheora should be used for the encoding functionality and focus here is on integrating that functionality with the rest of the QuickTime framework. Ogg file exporter would be built around libogg for transfering internal QuickTime movie structures into physical ogg streams. The component would also need to support concurrent multiplexing and Ogg Theora mapping (Theora spec, appendix A). Sequential multiplexing and possibly OggSkeleton support would be a plus.

QuickTime is extensively documented including component creation and example components. The old qtcomponents project also contains an Ogg/Vorbis exporter component.

Mentor: Arek Korbik

Audio encoders in QuickTime/CoreAudio

This is a complementary idea to the Theora and Ogg QuickTime components above, adding audio format support to the Ogg exporter component.

Implement Vorbis, Speex and possibly FLAC encoders as Core Audio AudioCodecs.

Besides documentation, Core Audio SDK includes an example AudioCodec implementation.

Mentor: Arek Korbik

New vocoder for Speex

Speex currently has a very low bit-rate (2.15 kbps) mode that is implemented as a trivial vocoder. This mode has four "reserved" bits per frame, which means it would be possible to transmit more information. The idea of this project would be to make use of these bits to improve the quality of the 2.15 kbps mode. Changes to both the encoder and the decoder are allowed, provided that they are compatible with older version. This means that the new bit-stream should be decodable by the old decoder with only minor loss in quality. This still leaves plenty of room for improvement. Requires signal processing knowledge.

Mentor: Jean-Marc Valin

New Speex VAD/VBR code

The current Speex VAD/VBR code is a quick hack, put together a long time ago. This project would consist of rewriting it to perform much better under all kinds of conditions. Requires signal processing knowledge.

Mentor: Jean-Marc Valin

rehuff: a tool to losslessly compress Vorbis files

Would be nice to have an updated version of "rehuff", a tool to losslessly compress Vorbis files. There were an experimental version of it (see rehuff status), but had some limits:

  • it's not free software;
  • it has a bug causing the rehuffed file can't correctly seek;
  • it works only with stereo files.

Would be nice to have an updated rehuff, without the previous limits, and with a library part that will be included in libvorbisenc, so all encoders could use it (rehuff binary, oggenc, ...).

Not an official project, only a user proposed idea.


Remember that many people will apply to work on the Summer of Code.

Keep in mind that those of us evaluating your application do not know you, we do not know what kind of experience you have, we do not know what you have done in the past and we have to pick the best people suited for a particular task.

Hence, it is very important that you tell us in your email why you should be considered to implement a particular project. Projects with one line applications will probably get discarded so don't make an application like this:

I would like to work on project XYZ

Do not cut-and-paste the text from this page in your application. We know full well what the text here is. Instead explain to us your take on the problem "I could implement this using this and that", "I would need to research these areas", "I might need help sorting this out", etc.

Explain to us why you are a good candidate, also explain which projects interest you (in case that there is more than one) and why.

During the summer of code, we will invest significant resources from existing team members to guide you, answer your questions, and help you architect the software in a way that is acceptable to and that has a high chance of having an impact on the larger community works with.

Note that if you are a student that want to apply for the Summer of Code, you should go through the standard Google process.

If you have questions about these projects you can for instance come to the #theora channel on

(thanks to the Mono project for these general guidelines)