Version 4 (modified by michael, 5 years ago) (diff)

Misc Libavfilter extension added from gsoc 2013


FFmpeg is the universal multimedia toolkit: a complete, cross-platform solution to record, convert, filter and stream audio and video. It includes libavcodec - the leading audio/video codec library.

Google Summer of Code (GSoC) is a program that offers students stipends to write code for open source projects. Through the guidance of mentors, students gain valuable experience interacting with and coding for open source projects like FFmpeg. Additionally, the project and its users benefit from code created from students who often continue contributing as developers. FFmpeg participated to several past editions (2006, 2007, 2008, 2009, 2010, 2011, 2013), and we are looking forward to being involved this year.

This is our ideas page for Google Summer of Code 2014.

Information for Students

Getting Started

Get to know FFmpeg. If you are a student and interested in contributing to an FFmpeg GSoC project it is recommended to start by subscribing to the ffmpeg-devel mailing-list, visiting our IRC channels (#ffmpeg-devel and #ffmpeg), and exploring the codebase and the development workflow. Feel free to contact us if you have any questions.

  1. Find a project. Listed on this page are mentored and unmentored projects. Mentored projects are well-defined and mentors have already volunteered. Unmentored projects are additional ideas that you may consider, but you will have to contact us to find a mentor. You may also propose your own project that may be a better match for your interest and skill level.
  1. Contact us. If you find a project that you are interested in then get in touch with the community and let us know. In case you want to work on a qualification task, you should ask the appointed mentors so that the task can be claimed.
  1. Apply. Student proposal period begins 10 March 19:00 UTC and ends 21 March 19:00 UTC. See the GSoC timeline for additional information.

Qualification Tasks

In order to get accepted you will be requested to complete a small task in the area you want to contribute. FFmpeg GSoC projects can be challenging, and a qualification task will show us that you are motivated and have the potential to finish a project.

The qualification task is usually shown in the project description. Contact the appointed mentors for assistance on getting a related qualification task or if you want to propose your own. See a list of Small FFmpeg Tasks or browse the FFmpeg Bug Tracker for qualification task ideas.

Contacting FFmpeg

If you have questions or comments feel free to contact us via our mailing list, IRC channel, or e-mail one of the FFmpeg GSoC admins:

  • Mailing-list: ffmpeg-devel
  • IRC: #ffmpeg-devel on Freenode
  • FFmpeg GSoC Admins: TBA

You can also contact a mentor directly if you have questions specifically related to one of the projects listed on this page.

Mentored Projects

This section lists well-defined projects that have one or more available mentors. If you are new to FFmpeg, and have relatively little experience with multimedia, you should favor a mentored project rather than propose your own. Contact the appointed mentor(s) to get more information about the project and the requested qualification task.

FFv1 P frame support

Description: FFv1 is one of the most efficient intra only lossless video codecs, your work will be to add support for P frames, that is for motion compensation and estimation (the existing motion estimation code in libavcodec can be reused here). And finetune it until the best compression rate is achived.

Expected results: state of the art P frame support in the FFv1 encoder and decoder implementation.

Prerequisites: C coding skills, basic familiarity with git, solid understanding of video coding especially with motion compensation.

Qualification Task: Implement support for simple P frames without motion compensation in FFv1. That is so that each frame stores the difference to the previous.

Mentor: Michael Niedermayer (michaelni on IRC)

Backup mentor: TBA

Misc Libavfilter extension


Description: Libavfilter is the FFmpeg filtering library. It currently supports audio and video filtering and generation support. This work may focus on porting, fixing, extending, or writing new audio and video filters from scratch.

Candidate filters for porting may be the remaining MPlayer filters currently supported through the mp wrapper, libaf MPlayer filters, and filters from other frameworks (e.g. mjpegtools, transcode, avisynth, virtualdub, etc.). In case of mp ports, the student should verify that the new filter produces the same output and is not slower.

Some ideas for more filters:

  • a frequency filtering domain filter relying on the FFT utils in libavcodec
  • a controller filter which allows to send commands to other filters (e.g. to adjust volume, contrast, etc.), e.g. like the sendcmd filter but through an interactive GUI
  • a lua scripting filter, which allows to implement filtering custom logic in lua

For more ideas check: trac libavfilter tickets.

Expected results: Write or port audio and video filters and possibly fix/extend libavfilter API and design when required.

Prerequisites: C coding skills, familiarity with git/source code control systems. Some background on DSP and image/sound processing techniques would be a bonus but is not strictly required.

Qualification Task: write or port one or more filters

Mentor: TBA possibly Stefano Sabatini (saste on IRC)

Backup mentor: Clément Bœsch (ubitux on IRC)


Description: FFmpeg has been working on improving its subtitles support recently, notably by adding the support for various text subtitles and various hardsubbing (burning the subtitles onto the video) facilities. While the theme may sound relatively simple compared to audio/video signal processing, the project carries an historical burden not easy to deal with, and introduces various issues very specific to its sparse form. Image:Subtitles-sensei.jpg

Expected results:

  • Add support for new subtitles formats. Example: a demuxer for .SUP files, just like VobSub? but for Blu-Ray, or a VobSub? muxer.
  • Improve text subtitles decoders. Typically, this can be supporting advanced markup features in SAMI or WebVTT.
  • Update the API to get rid of the clumsy internal text representation of styles
  • Proper integration of subtitles into libavfilter. This is the ultimate goal, as it will notably allow a complete subtitles rendering for applications such as ffplay.
  • BONUS: if everything goes well, the student will be allowed to add basic support for teletext

Prerequisites: C coding skills, familiarity with git/source code control systems. Some background in fansubbing area (notably ASS experience) would be a bonus but is not strictly required.

Qualification Task: write one subtitles demuxer and decoder (for example support for Spruce subtitles format). This is in order to make sure the subtitles chain is understood.

Mentor: Clément Bœsch (ubitux on IRC)

Backup Mentor: TBA, possibly Nicolas George (Cigaes on IRC)

Sample Project

Description: Describe the project.

Expected results: Create a foo decoder and add a test for the FFmpeg Automated Testing Environment (FATE).

Prerequisites: C coding skills, basic familiarity with git.

Qualification Task: A task that demonstrates that the student is qualified by skill and determination to proceed with the project.

Mentor: Lou Logan (llogan on IRC)

Backup mentor: TBA

Unmentored Projects

This is a list of projects that students are encouraged to consider if a mentored project is unavailable or not within the students skill or interests. The student will have to find a mentor for the project. A student can also propose their own project.

Your Own Project Idea

A student can propose a project. Ideas can also be found by browsing bugs and feature requests on our bug tracker. The work should last the majority of the GSoC duration, the task must be approved by the developers, and a mentor must be assigned.

Students can discuss an idea in the ffmpeg-devel mailing-list, the #ffmpeg-devel IRC channel, or contact the FFmpeg GSoC admins for more information.

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