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 and MPlayer), video websites (including YouTube and Vimeo), web browsers (including Google Chrome/Chromium and Firefox), social media (including Facebook and Twitter) and countless other software projects in the multimedia field and beyond.

This is our ideas page for ​Google Summer of Code 2016. See the ​GSoC Timeline for important dates.

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Information for Students

Getting Started

1. Get to know FFmpeg. If you are a student 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. Also do not hesitate to answer questions from other students on our IRC channel if you know the answer to something.

2. 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 join our IRC channel at #ffmpeg-devel.

3. 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.

4. Apply. Students should apply by March 25 at the very latest. The "work" period begins on May 23 and ends in August. Take a look at ​GSoC timeline for additional information. Note, make sure you apply to Google before the 25th even if you have not yet finished your qualification task. And please apply as soon as possible: Applications can be improved until the 25th but not afterwards!

Note: A friendly reminder that while the application to GSoC is important for you and GSoC, FFmpeg mentors will not base their decision solely on the GSoC 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 GSoC'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, please avoid picking a qualification task which another student is already working on, each student should work on a different qualification task.

Note: The running status of this term's qualification tasks is 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 GSoC admins:

• Mailing-list: ​ffmpeg-devel
• IRC: #ffmpeg-devel on Freenode
• FFmpeg GSoC Admins: Michael Niedermayer (michaelni in #ffmpeg-devel on Freenode IRC, ​michaelni@gmx.at), Reynaldo Verdejo (reynaldo in #ffmpeg-devel on Freenode IRC, R Verdejo on g mail), Carl Eugen Hoyos (cehoyos in #ffmpeg-devel on Freenode IRC, cehoyos at ag dot or dot at)

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

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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.

Create a fuzzing testsuite for FFmpeg

Description: Fuzzing is the process of using random or specially crafted junk input to make programs crash or exploit security vulnerabilities. Many organisations such as Google have fuzzed FFmpeg and found and fixed many issues. The problem is FFmpeg moves so quickly that often new commits expose other problems. We need a way of automatically assessing whether commits have exposed bugs. At the same time we don't want to fuzz parts of the codebase that we know haven't changed because this just wastes CPU cycles.

Expected results:

• Add an existing specialised fuzzing test application to main repository
• Create a corpus of small test files that exercise code paths likely to crash for a selection of decoders or demuxers
• Build a web interface able to extract information from each commit and run against an appropriate fuzz corpus.

Prerequisites: Knowledge of the command line and program compilation. Knowledge of a web programming language (python, node.js etc). Useful to have C experience.

Qualification Task: Compile and run ​fffuzz and report and (possibly fix) a crash using zzuf or afl-fuzz.

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

Backup Mentor: Timothy Gu (Timothy_Gu in #ffmpeg-devel, ​timothygu99@gmail.com), Thilo Borgmann (thilo DOT borgmann AT mail DOT de)

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. Also see the ​spec

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 frame.

Alternative 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

Alternative Qualification Task2: Add support for bayer pixel formats to FFV1, update the context model and predictor to work well with bayer formats, and provide some evidence that shows that your choice for how bayer would be handled is good.

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

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

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)

Hardware Acceleration API Software / Tracing Implementation

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.

Note: You should find out which hardware acceleration APIs are available on hardware you have access to before applying. Most common are VDPAU (Linux), VA-API (Linux), DXVA (Windows). I will be able to help most with VDPAU, if you want to work on DXVA you should be confident that you can resolve issues not related to FFmpeg mostly on your own as my ability to help will be limited and you will encounter additional issues. If you have access to none, we need to find a solution for that early on.

Prerequisites: C coding skills, basic familiarity with git, knowledge of how dynamic linking works will help.

Qualification Task: Anything related to the hardware acceleration code, though producing first ideas and code pieces for this task would also be reasonable. I can suggest something, but please spend a moment trying to come up with an idea that would interest you.

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

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: Paul B Mahol (durandal_1707 in #ffmpeg-devel on Freenode IRC, ​onemda@gmail.com)

Backup Mentor: TBA

VDPAU filter

Description: VDPAU is not only about hardware-accelerated decoding but also allows some postprocessing - most notably deinterlacing. Other features of the API include scaling, noise removal, and a sharpening filter. See the ​VDPAU API documentation for more information on some of the features.

Expected results: Implement a filter that allows usage of the postprocessing features as defined by the VDPAU API. This should particularly include the deinterlacer, and ideally all features should be usable to allow comparing the quality and performance of different hardware and hardware vs. software.

Prerequisites: C coding skills, and you will need hardware that allows VDPAU post-processing.

Qualification Task: Find the bug using one of the options of the detelecine filter and fix it. Once this is done, find a very simple filter that is missing from FFmpeg and implement it or port an existing filter from another application. Don't forget to tell us on which filter you are working!

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

Backup Mentor: Reimar Doeffinger (reimar in #ffmpeg-devel on Freenode IRC, Reimar.Doeffinger [at] gmx.de), Thilo Borgmann (thilo DOT borgmann AT mail DOT de)

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: Rostislav Pehlivanov (atomnuker in #ffmpeg-devel on Freenode IRC, atomnuker AT gmail DOT com)

Backup mentor: TBA

Improve Selftest coverage

Description: FFmpeg contains many self-tests, 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 libraries (libavcodec, libavformat, libavdevice, libavfilter, libavutil, libswresample, libswscale) as listed at ​coverage.ffmpeg.org.

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

Backup mentor: Reynaldo Verdejo (reynaldo in #ffmpeg-devel on Freenode IRC, R Verdejo on g mail), Thilo Borgmann (thilo DOT borgmann AT mail DOT de)

Improve and Cleanup Swscale

Description: Swscale is the part of FFmpeg responsible for scaling pictures, fields, slices of videos and converting colorspace and pixelformats. The code has a long history and grew alot. It is in need of some cleanup, it has been improved significantly in GSoC 2015, but there is a large number of possibly cleanups and improvments remaining. This is not a simple task. It requires to quickly learn and understand what the existing code does and how it can be restructured to be clearer and more modular without making it slower or otherwise worse in a practically relevant way.

Expected results: A subset of: significantly improve clarity of the code, add features like multithreaded scaling, internal floating point support (swscale is largey integer only). The expected results for this task can also very easily be adjusted during the summer depending on how the work is progressing. Quality code is preferred over quantity!

Prerequisites: Good C coding skills, basic familiarity with git, ability to quickly understand existing code.

Qualification Task: Something that proofs that you understand the existing code and can manipulate it as you need to. A specific possibility would be to move some cases which are handled as cascaded contexts to run as part of the filters from ff_init_filters() wthout using cascaded contexts.

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

Backup Mentor: Paul B Mahol (durandal_1707 in #ffmpeg-devel on Freenode IRC, ​onemda@gmail.com), Pedro Arthur (​bygrandao@gmail.com)

Motion interpolation in libavfilter

Description: Libavfilter is missing motion estimation and interpolation filters.

Expected results: State of the art frame interpolation in the libavfilter.

Prerequisites: Very good C coding skills, familiarity with git, ability to very quickly understand existing code.

Qualification Task: Basic but working motion estimation filter.

Mentor: Paul B Mahol (durandal_1707 in #ffmpeg-devel on Freenode IRC, ​onemda@gmail.com)

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

DICOM support

Description: FFmpeg currently does not support DICOM files although this is a widely used image format that is often passed to patients who have no access to DICOM equipment.

Expected results: Support reading as many features of the format as possible.

Prerequisites: Good C coding skills, basic familiarity with git

Qualification Task: Write a simple demuxer for a format currently unsupported by FFmpeg. The following tickets contain possible tasks, not all of them are equally simple / difficult, some may turn out to be less useful: #5154, #4748, #4519, #3986 (this may be too difficult or impossible), #3720, #2956, #2662 and #2176. Not all possible features of a demuxer have to be implemented (the more the better) but at least auto-detection and video decoding (and remuxing) should be possible to implement for all of them.

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

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

Improve the tee muxer

Description: FFmpeg contains a tee muxer, which is capable of writing the same coded packets to multiple outputs. However, if one of the outputs blocks or fails for any reason, the other outputs will block or fail too. Also there is no built-in support for gracefully restarting an output in case of a failure. Lacking these two features makes the tee muxer unsuitable for redundancy or high availability purposes especially on networked outputs.

Expected results:

• Add a non-blocking mode with a configurable maximum packet queue size where one output does not block the others
• Add a graceful restart mode where a failed output can transparently automatically restart its operation

Prerequisites: C coding skills, understanding of threading primitives, basic familiarity with git.

Qualification Task: Add a per-output option to the tee muxer which allows an output to fail

Mentor: Marton Balint (​cus@passwd.hu)

Backup Mentor: Nicolas George (​george@nsup.org)

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.

Improve Closed Caption support

Description: FFmpeg contains some support for Closed Captions, the goal of this project would be to improve the support.

Expected results: To be defined

Qualification Task: Not yet defined, a starting point would be to look at ​https://trac.ffmpeg.org/query?status=new&status=open&status=reopened&keywords=~+cc&order=priority related tickets].

Mentor: TBA

Missing AAC decoder features

Description: FFmpeg contains an AAC decoder which is missing some features. The task is to implement them in FFmpeg, and make sure they work by extensively testing them.

• AAC BSAC decoder: This has already been started, but the existing BSAC decoder contains non free reference source and can thus not be used
• AAC SSR decoder
• AAC 960/120 MDCT window

Qualification Task: See the ​FFmpeg bug tracker for AAC issues, fixing one of them is a possible qualification task.

Prerequisites: C coding skills, basic familiarity with git, knowledge about transform based audio coding would be useful.

Mentor: TBA

Backup Mentor: Reynaldo Verdejo (reynaldo in #ffmpeg-devel on Freenode IRC, R Verdejo on g mail), Sascha Sommer (saschasommer at freenet de)

VC-1 interlaced

Description: The FFmpeg VC-1 decoder has improved over the years, but many samples are still not decoded bit-exact and some real-world interlaced streams show artefacts. This task is difficult.

Expected results:

• Implement missing parts of interlacing
• Make more reference samples bit-exact

Prerequisites: C coding skills, basic familiarity with git, ability to read and understand the vc1 specification and align that knowledge with the existing code

Qualification Task: Find a bug in the current decoder implementation and fix it.

JPEG 2000

Description: FFmpeg contains a native JPEG 2000 encoder and decoder. Both are missing many features, see also the FFmpeg bug tracker for some unsupported samples. This task is difficult

Expected results: A jpeg 2000 decoder which can decode more samples and / or an encoder that achieves higher compression.

Qualification Task: Fix an issue (for example from the bug tracker) to show that you are capable of improving the codec implementation.

Prerequisites: C coding skills, basic familiarity with git, good knowledge of Jpeg-2000

H.264 Multiview Video Coding (MVC)

Description: MVC samples exist and the codec is used on Blu-ray media, but FFmpeg is missing a decoder. Since this project also consists of some changes in the current architecture, it is especially important that this project is discussed on the ffmpeg-devel mailing list.

Expected results: Create MVC decoder and add a test for ​FATE.

Prerequisites: C coding skills, familiarity with git/source code control systems. Knowledge of H.264 and MPEG-TS would be helpfull

Qualification Task: Perform work that demonstrates understanding of MVC and that is a subpart of the whole MVC implementation.

Mentor: TBA

Backup mentor: TBA

Subtitles

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.

Expected results:

• Add support for new subtitles formats. Example: a VobSub muxer, a demuxer and decoder for EBU-TT, or even Kate subtitles (Xiph).
• Improve text subtitles decoders. Typically, this can be supporting advanced markup features in SAMI or WebVTT.
• 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.

Prerequisites: C coding skills, basic familiarity with git. 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: TBA

Backup Mentor: TBA, possibly Nicolas George (Cigaes in #ffmpeg-devel on Freenode IRC)

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: TBA

Backup Mentor: TBA

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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 internship 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.