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SponsoringPrograms

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Outreachy

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2015-05

Introduction

FFmpeg is the universal multimedia toolkit: a complete, cross-platform solution to record, convert, filter and stream audio and video. It is used by a number of media players (including VLC, MPlayer, and Totem through GStreamer), video distribution websites (including YouTube and Vimeo), Internet browsers (including Google Chrome/Chromium), and lots of other software projects in the multi-media field and beyond.

Outreachy is a program that helps underrepresented people to get involved in free and open source software. Through the guidance of mentors, interns gain valuable experience interacting with and coding for open source projects like FFmpeg. Additionally, the project and its users benefit from code created from applicants who often continue contributing as developers.

This is our landing page for the current round of the program, which will formally start in May, 2015. Please also see our Google Summer of Code Page for ideas, they are all also eligible and not duplicated here


Information for Applicants

Getting Started

  1. Get to know FFmpeg. If you are an applicant interested in contributing to FFmpeg, it is recommended to start by subscribing to the ffmpeg-devel mailing-list, visiting our FreeNode IRC channels (#ffmpeg-devel and #ffmpeg although you will find most developers on the first one), and exploring both 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 un-mentored projects. Mentored projects are well-defined and mentor(s) have already volunteered. Un-mentored projects are additional ideas you may want to consider, but you will have to contact us to find a mentor. You can also propose your own project, if you can think of one that better fits your interest and skill level. If a project description is unclear or you have any questions, please get in touch with its mentor and/or send an email to the program admins at [opw@ffmpeg.org].
  1. Contact us. If you decide on a project, get in touch with the community and let us know. If you want to work on a qualification task, let the respective mentor know so we can avoid duplicated efforts.
  1. Apply. Interns should apply by April 7 at the very latest. The "work" period begins May 25 and ends the same day in August. Take a look at https://gnome.org/outreachy/#apply for additional information.

Note: A friendly reminder that while the application to Outreachy is important for you and Outreachy, FFmpeg mentors will not base their decision solely on the Outreachy application. We will judge the applicant based on their abilities in coding, learning the tools, communication skills etc. So please do not worry about your application being perfect for us. Although it is very important to follow Outreachy's application rules so they can pay you.

Qualification Tasks

In order to get accepted you normally have to complete a small qualification task. FFmpeg development can be quite challenging and the qualification task helps us figure out whether you are motivated enough and have the potential to deliver successfully.

The qualification tasks are usually shown in the project description. Contact the respective mentor(s) for assistance on getting a related qualification task or if you want to propose your own. You can also browse the FFmpeg Bug Tracker for qualification task ideas. In general qualification tasks should include submitting a patch to the ffmpeg-devel mailing list which passes review and is accepted into the FFmpeg codebase. It will be common for such patches to need multiple iterations of submissions and reviews, so dont wait too long with the first submission!

Note: Assigned qualification tasks are being tracked here.

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 Outreachy admins:

  • Mailing-list: ffmpeg-devel
  • IRC: #ffmpeg-devel on Freenode
  • FFmpeg Outreachy Admin: Michael Niedermayer (michaelni in #ffmpeg-devel on Freenode IRC, michaelni@gmx.at)
  • FFmpeg Outreachy Backup Admins: Stefano Sabatini (saste in #ffmpeg-devel on Freenode IRC, stefasab AT gmail DOT com. ), Reynaldo Verdejo (reynaldo in #ffmpeg-devel on Freenode IRC, R Verdejo on g mail)

You may 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 respective mentor(s) to get more information about the project and the requested qualification task.

Setting up FATE automated testing system on various platforms

Description: Set up virtalboxes with various OSs inside them as well as various qemu based non x86 clients, which run our FATE testset and submit results to fate.ffmpeg.org

Docs: https://ffmpeg.org/fate.html

Expected results:

Prerequisites: POSIX and command line knowledge sufficient to install and setup various odd and obscure operating systems, building and using cross compilers

Qualification Task: create one or 2 working images with fate clients inside them for platforms not yet listed on http://fate.ffmpeg.org

Mentor: Ramiro Polla (ramiro in #ffmpeg-devel on Freenode IRC, ramiro DOT polla AT gmail DOT com)

Backup mentor: Michael Niedermayer (michaelni in #ffmpeg-devel on Freenode IRC, michaelni@gmx.at)

Creating fate tests / finding sample files to improve fate test coverage

Description: Many of our decoders and demuxers are tested but some are not and many are tested incompletely. The goal of the task would be to find small multimedia files which improve this test coverage and add them to the fate tests. Also encoding / muxing / filtering tests can be added to improve coverage

Docs: https://ffmpeg.org/fate.html

Expected results: Significantly improved coverage on http://coverage.ffmpeg.org/, and new tests integrated in "make fate"

Prerequisites: Good knowledge of the Makefile syntax as its used in our fate tests.

Qualification Task: add 3 or 4 fate tests which improve the code coverage of "make fate"

Mentor: Carl Eugen Hoyos (ce at hoyos dot ws)

Backup mentor: Michael Niedermayer (michaelni in #ffmpeg-devel on Freenode IRC, michaelni@gmx.at)

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 with motion compensation and motion estimation support (the existing motion estimation code in libavcodec can be reused here). Then fine-tune it until the best compression rate is achieved. This will make FFv1 competitive with existing I+P frame lossless codecs like lossless H.264.

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: Improve the compression of the existing FFV1 Intra frames, you can change any part of the algorithm but it must be practical, the more improvement you can achieve, the better

Mentor: Michael Niedermayer (michaelni in #ffmpeg-devel on Freenode IRC, michaelni@gmx.at)

Backup mentor: Derek Buitenhuis (Daemon404 in #ffmpeg-devel on Freenode IRC, derek.buitenhuis ut gmail)

API regression testing

Description: FATE is FFmpeg's automated testing suite. However, it only covers users of the ffmpeg executable, and not API users. This means that library users can often have bugs which the ffmpeg executable may hide.

Expected results: Build a suite of tests for API users, including advanced options such as draw_horiz_band

Prerequisites: Good C coding skills, basic familiarity with git

Qualification Task: Write a test for a libavcodec decoder using the API

Mentor: Kieran Kunhya(kierank in #ffmpeg-devel on Freenode IRC, kieran[at]kunhya.com)

Backup Mentor:

Postproc optimizations

Postproc optimizations

Description: FFmpeg contains libpostproc, which is used to postprocess 8x8 DCT-MC based video and images (jpeg, mpeg-1/2/4, H.263 among others). Postprocessing removes blocking (and other) artifacts from low bitrate / low quality images and videos. The code though has been written a long time ago and its SIMD optimizations need to be updated to what modern CPUs support (AVX2 and SSE2+).

Expected results:

  • Convert all gcc inline asm in libpostproc to YASM.
  • Restructure the code so that it works with block sizes compatible with modern SIMD.
  • Add Integer SSE2 and AVX2 optimizations for each existing MMX/MMX2/3dnow optimization in libpostproc.

Prerequisites: C coding skills, good x86 assembly coding skills, basic familiarity with git.

Qualification Task: convert 1 or 2 MMX2 functions to SSE2 and AVX2.

Mentor: Michael Niedermayer (michaelni in #ffmpeg-devel on Freenode IRC, michaelni@gmx.at)

Backup Mentor:

MPEG-4 Audio Lossless Coding (ALS) encoder

Description: A MPEG-4 ALS decoder was implemented several years ago but an encoder is still missing in the official codebase. A rudimentary encoder has already been written and is available on github. For this project, that encoder is first to be updated to fit into the current codebase of FFmpeg and to be tested for conformance using the reference codec and specifications. Second, the encoder is to be brought through the usual reviewing process to hit the codebase at the end of the project.

Expected results:

  • Update the existing encoder to fit into the current codebase.
  • Ensure conformance of the encoder by verifying using the reference codec and generate a test case for FATE.
  • Ensure the FFmpeg decoder processes all generated files without warnings.
  • Enhance the rudimentary feature set of the encoder.

Prerequisites: C coding skills, basic familiarity with git. A certain interest in audio coding and/or knowledge about the FFmpeg codebase could be beneficial.

Qualification Task: Add floating point support to MPEG-4 ALS decoder

Mentor: Thilo Borgmann (thilo DOT borgmann AT mail DOT de)

Backup Mentor: Paul B Mahol (durandal_1707 in #ffmpeg-devel on Freenode IRC, onemda@gmail.com), Stefano Sabatini (saste in #ffmpeg-devel on Freenode IRC, stefasab AT gmail DOT com)

Hardware Acceleration API Software / Tracing Implementation

Hardware Acceleration (hwaccel) API v2

Description: Our support for hardware accelerated decoding basically remains untested. This is in part due to FFmpeg only implementing part of the required steps, and in part since it requires specific operating systems and hardware.

The idea would be to start with a simple stub implementation of an API like e.g. VDPAU that provides only the most core functions. These would then serialize out the function calls and data to allow easy comparison and regression testing. Improvements to this approach are adding basic input validation and replay capability to allow testing regression data against real hardware. This would be similar to what apitrace does for OpenGL.

A further step would be to actually add support for decoding in software, so that full testing including visual inspection is possible without the need for special hardware.

Prerequisites: C coding skills, basic familiarity with git

Qualification Task: Anything related to the hardware acceleration code, though producing first ideas and code pieces for this task would also be reasonable

Mentor: Reimar Doeffinger (reimar in #ffmpeg-devel on Freenode IRC, but since I'm rarely there better email me first: Reimar.Doeffinger [at] gmx.de)

Backup Mentor: Stefano Sabatini (saste in #ffmpeg-devel on Freenode IRC, stefasab AT gmail DOT com)

MXF Demuxer Improvements

Description: The MXF demuxer needs a proper, compact way to map EssenceContainer ULs to WrappingKind. See ticket #2776 in our bug tracker, and ticket #1916 contains additional relevant information.

Essence in MXF is typically stored in one of two ways: as an audio/video interleave or with each stream in one huge chunk (such as 1 GiB audio followed by 10 GiB video). Previous ways of telling these apart have been technically wrong, but worked and we lack samples demonstrating the contrary.

Expected results: The sample in ticket ticket #2776 should demux correctly. Add a test case in FATE. The solution should grow libavformat by no more than 32 KiB.

Prerequisites: C coding skills, basic familiarity with git. Knowledge of MXF would be useful

Qualification Task: Investigate if there may be a compact way of representing the UL -> WrappingKind mapping specified in the official RP224 Excel document. The tables takes up about half a megabyte verbatim which is unacceptable in a library as large as libavformat.

Mentor: Tomas Haerdin (thardin in #ffmpeg-devel on Freenode IRC, tomas.hardin a codemill.se)

Backup Mentor: Stefano Sabatini (saste in #ffmpeg-devel on Freenode IRC, stefasab AT gmail DOT com)

Basic servers for network protocols

Description: libavformat contains clients for various network protocols used in multimedia streaming: HTTP, RTMP, MMS, RTSP. Your work will be to implement the server side for one or several of these protocols.

The libavformat framework is not designed to build general-purpose server applications with several clients, and nothing similar to the configuration features of real servers like Apache is expected, but libavformat should be able to stream a single predefined bytestream to/from a single client.

Note: server support is already implemented for the receiving side of RTSP.

Expected results: basic servers for network protocols capable of interoperating with third-party clients.

Prerequisites: C coding skills, basic familiarity with git, network programming.

Qualification Task: proof-of-concept server for one of the protocol, capable of interacting with a particular client in controlled circumstances; or anything network-related, e.g. fixing a ticket in our bug tracker.

Mentor: Nicolas George (george ad nsup dot org)

Backup mentor: Reynaldo Verdejo (reynaldo in #ffmpeg-devel on Freenode IRC, R Verdejo on g mail)

HTTP/2

Description: the final draft for the HTTP/2 protocol has been published. It contains various new features that will probably be used to enhance distribution of multimedia contents. Therefore, FFmpeg needs an implementation.

Expected results: HTTP/2 client over TLS and TCP for reading and writing, capable of interacting with stock servers, including using the same connection for simultaneous requests.

Prerequisites: C coding skills, basic familiarity with git, network programming.

Qualification Tasks:

  • Rework current HTTP/1 client code to make it input-driven and support non-blocking mode.
  • Implement the Websocket protocol on top of the HTTP/1 client code.

Mentor: Nicolas George (george ad nsup dot org)

Backup mentor: TBA

TrueHD encoder

Description: FFmpeg currently does not support encoding to TrueHD, one of the lossless audio formats used on Bluray discs. A nearly functional Meridian Lossless Packing (MLP) encoder has already been written and is available on github. The MLP codec is the basis for TrueHD. For this project, that encoder is first to be updated to fit into the current codebase of FFmpeg and to be tested for conformance against Surcode's MLP encoder. Second, the encoder is to be updated to implement TrueHD functionality, allowing it to losslessly encode audio to play it on hardware devices capable of TrueHD decoding. Finally, the encoder is to be brought through the usual reviewing process to hit the codebase at the end of the project.

Expected results: a TrueHD encoder that allows to losslessly encode audio to play it on hardware devices capable of TrueHD decoding with a competetive compression rate

Prerequisites: C coding skills, basic familiarity with git

Qualification Task: Update the MLP encoder so that it produces a valid bitstream that can be decoded by FFmpeg without errors to silence. Find out how to validate the generated bitstream besides using FFmpeg.

Mentor: Ramiro Polla (ramiro in #ffmpeg-devel on Freenode IRC, ramiro DOT polla AT gmail DOT com)

Backup mentor: Stefano Sabatini (saste in #ffmpeg-devel on Freenode IRC, stefasab AT gmail DOT com)

Implement full support for 3GPP Timed Text (movtext, QuickTime?) subtitles

The standard subtitle format used in MP4 containers is 3GPP timed text, as defined in 3GPP TS 26.245. It is the only subtitle format supported in Apple's media players on OS X and iOS, and the only format that's part of the mpeg4 standard. As such it is important for FFmpeg to support the format as fully as possible. Currently, it supports a limited subset of the format without any rich text formatting or the ability to position text on the screen. For this project, the goal would be to implement complete support for these features and have the implementation fully reviewed and merged into FFmpeg.

Expected Results:

  • A display window for subtitles can be specified by the user when encoding or transcoding subtitles
    • A default window size based on the primary video stream will be implemented
  • As much text formatting metadata as can be expressed in ASS will be supported for both transcoding to and from timed text, including positional metadata
    • The OSX QuickTime? player should be used to evaluate the behaviour of formatting metadata. (This appears to be the most feature complete player with respect to the formatting features of 3GPP Timed Text)
  • Subtitle merging for overlapping subtitles will be implemented

Prerequisites: C coding skills, basic familiarity with git, access to the OS X QuickTime? player for playback verification.

Qualification Task: Implement support for transcoding bold, italic, and underline formatting to and from ffmpeg's internal ASS format. (Will require temporary patches (which already exist) for display window sizing/positioning)

Mentor: Philip Langdale (philipl in #ffmpeg-devel on Freenode IRC, philipl AT overt DOT org)

Backup mentor: Carl Eugen Hoyos (cehoyos in #ffmpeg-devel on Freenode IRC, ce AT hoyos.ws)

Improve Selftest coverage

Description: FFmpeg contains many selftests, still more code is not tested than tested thus more such tests are needed to ensure regressions and platform specific bugs are quickly detected. Examples of existing self tests can be seen under #ifdef TEST in various files

Expected results: Significantly improve selftest code coverage

Prerequisites: Good C coding skills, basic familiarity with git

Qualification Task: Improve selftest code coverage by at least 1% of two of the main libs (libavcodec, libavformat, libavdevice, libavfilter, libavutil, libswresample, libswscale) as listed at http://coverage.ffmpeg.org/index.html

Mentor: Michael Niedermayer (michaelni in #ffmpeg-devel on Freenode IRC, michaelni@gmx.at)

Backup Mentor:

Last modified 21 months ago Last modified on Apr 15, 2015, 6:14:42 PM