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Google Summer of Code Advice

This page has some general advice for people thinking about applying for Summer of Code with Mixxx. If you wish to apply for the program then you will need to visit the official Google Summer of Code website.

What Project Should I Work On?

In general, your project proposal can be inspired by any of the following:

How Do I Contact Mixxx?

You are more than welcome to contact us before submitting your application, we will be happy to advise on most aspects of the process. Getting in touch first is especially recommended if you are planning to apply to work on an original idea, rather than one of our suggestions from the ideas page.

So if you'd like to discuss your application, your ideas or just introduce yourself, then feel free to get in touch in one of the following ways:

  1. Send an email to our public developers' mailing list: mixxx-devel
  2. Contact our GSoC administrators directly via email:
    1. gsoc2017-mentors -A-T-
  3. Hop on our IRC channel (#mixxx on Freenode) and see if our mentors are around.
    1. We encourage idling in our IRC channel to get acquainted with the wider Mixxx community as well.

What Would Working On Mixxx Be Like?

The Mixxx development environment is cooperative and relatively informal. Our community is small but unusually diverse. Working on Mixxx you would have an opportunity to interact with a unique mixture of programmers, artists and DJs. Mixxx as a piece of software also offers some unique challenges, we are both cross-platform and (soft) real-time and support a huge range of MIDI and audio hardware devices. Students with Mixxx will have an opportunity to learn advanced skills like low-latency programming and cross-platform application deployment which will look great on your resumé.

We also very much value the contributions students make. Because Mixxx is relatively small, students' work often makes a large impact. During and after your Summer of Code project you will have the opportunity to put your work in the hands of real DJs and hear how they've used it. Past students have had a lot of fun working on Mixxx and learned a lot at the same time. If you want challenging problems, freedom to develop your ideas, interesting people and an all-round brilliant Summer, then apply to work on Mixxx.

Am I Experienced Enough?

This is a common question asked by prospective students, the answer is generally: “Yes”. The Mixxx Summer of Code team value intelligence and enthusiasm above specific knowledge of the libraries or algorithms we use. We have found in the past that an interested and motivated student who is willing to learn is more valuable than anything else.

We also value general software design and development experience above specific knowledge of a library or API. For example, if you've never used Qt before but have done lots of Java and Gtk+ UI development then you should make sure you let us know about it in your application.

Of course if you do have direct experience with the tools we use, you should definitely tell us about that too. The main external tools we rely on are Qt, scons, portaudio and git.

Our expectations from students


  • write a weekly report on your progress
    • This can be delivered via mailing list message, blog post, or email to the mentors list.
  • commit early commit often and push to github so that we can see it
  • actively work on your project plan and communicate with us during the community bonding period
  • Communicate every working day with your mentor. Just say “hello” If you like. It can be via email,IRC or github comments.
  • If there are good reasons, for not communicating please announce them early.
  • If you don't communicate with us regularly we will fail you.

Midterm and Final evaluations

  • set a realistic goal for mid-term. If you fail to meet your own goal we are more likely to fail you in the evaluations.
  • have some code merged into master at the end of the summer to pass the final evaluation.
  • The later is a hard requirement so make sure that your time plan includes it.

How Do I Write A Great Application?

Firstly, think about your choice of project carefully, you're going to be doing it for a couple of months, so it's important that you choose something you're going to enjoy. Once you've made your mind up:

  1. Make sure you've thought about the project and understand what it entails
  2. Don't be afraid to come up with original solutions to the problem
  3. Don't be afraid to give us lots of detail about how you would approach the project
    1. Things like UI mockups are very much encouraged where appropriate
  4. Consider how much time you need for each part of the project

Overall, your application should make us believe that you are capable of completing the project and delivering the functionality to our users. If you aren't sure about anything, get in touch with us, we're happy to advise you.

Splitting up your project into smaller pieces

We require our students to merge some of their code into our master branch before the end of the summer. The best way to achieve this is to divide your project into small self contained subprojects and plan to merge at least one of them around midterm.

A good example for this is 'Improve our track managment':

  1. handle property changes for a selection of tracks
  2. add a custom editor for cue points
  3. add an editor for the BPM-grid
  4. build an editor to comment time slices of a track

Another approach is to analyze what the absolute minimal requirements are and then adding features on top of that. eg 'implement cover art in mixxx':

  1. handle reading/storing covers in the database and application
  2. Show the cover next to the track name in a deck
  3. display the covers in the library view
  4. add picture flow

During your summer you'll encounter bugs in mixxx or find code that can be refactored to help you implement your ideas. You can also immediately fix them in the master branch and help us all out. This has several advantages. All your pull request will only concentrate on specific features and are much better to review. And you'll also get direct feedback from other devs and user during the summer.

Since this is a hard requirement we as mentors will also have an eye on that and check if your proposal incorporates it and also warn you ahead of time during the summer if we see that you might not make it. Communicating with us on a regular basis is vital for that though.

Having good time estimates

To get a feeling for the code and get some experience with our code you can go and tackle some of our easy bugs. Look at the code that you want to change, check if it follows our coding guidelines. Do some research on the API's you want to use, plan what classes you will add and how their public API will look. Write down your algorithms in pseudo code. The better your research is and the better you plan ahead the easier it will be to judge how long a given task will take. For your time estimates you should also consider that you can do less stuff during exams and try to be a bit conservative. If you have never done anything like GSoC before you will tend to underestimate the time to complete a task. I know that giving these estimates is not easy and that also professionals have problems with it. Having a good plan, knowing its weak and strong points are can help a lot.

Some other (entirely optional) things you might consider doing

  1. Why not introduce yourself on the mailing list? Even just to say hello, your name and what you're applying to work on
  2. If you don't have Mixxx already, download it, play around with it for a while, let us know what you like or don't like
  3. For lots of bonus points:
    1. Check out the source and compile it, play around with the code a little
      1. Be sure to write about what you did in your application
      2. If you can't get it to compile, it's probably our fault not yours, don't be embarrased to ask for help
    2. Check out our Wishlist bugs and Easy Bugs lists.
      1. Try picking something on the list and tackling it as a starter project!
  4. As mentioned in the contact section above, hang around on IRC at #mixxx
  5. Sign up for the forums

We look forward to your application :) - The Mixxx Development Team

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gsocadvice.txt · Last modified: 2017/02/08 13:10 by rryan