Developing XBMC for Linux
|Development||Developing XBMC for Linux|
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XBMC is a huge open source project and it takes loads of people working together to maintain it for all platforms, that is why Team XBMC is always on the lookout for C/C++ programmers to volunteer in assisting us with the development of XBMC. Whether you have contributed to The XBMC Project in the past or not, please consider doing so now.
1 What is XBMC and why was it ported to Linux?
For developers who do not know this, XBMC Media Center (formerly named "XBox Media Center", not to be confused with Microsoft's Windows Media Center Extender for the Xbox) is an award-winning free and open source media player, originally designed to run on the Xbox game-console. The GPL/LGPL licensed source code basically consist of a GUI framework that has been written from scratch by Team-XBMC, this GUI acts as a front-end control interface for several audio/video players designed for specific purposes (and those are loaded when needed as DLLs), the GUI is also the user interface to all of XBMC multimedia handling functions such as databases and sorting, etc.. The XBMC Project, (who's members maintain XBMC source code), is a non-profit open source hobby project that is developed by volunteers in their spare-time without any monetary gain. The team of developers working on XBMC have always encouraged anyone to submit their own source code patches for new features or functions, improve on existing ones, or fix bugs.
2 Skill requirements and where to start
2.1 Where do I start on Linux?
The recommended Linux development platform is currently 32-bit Ubuntu Desktop (for x86). The code can be obtained by cloning the xbmc git repository hosted on Github. First use your package manager to install git on your system and then execute the following command to clone your own repository:
git clone git://github.com/xbmc/xbmc.git
After the clone has completed, follow the compilation/development guide in the new repository (README.linux) to setup the required packages and so on. Team-XBMC developers opinion is that the best thing to start with is just to take a look through the source code and try to understand how it all fits together. Test things out, find what works and what does not, then try and track down why.
Alternatively, you can download VirtualBox and follow this guide to install the required software: Ubuntu Desktop (32-bit for x86). Besides from KDevelop, additional development tools that can be useful include Subcommander, Doxygen, Sysprof and PowerTop.
The performance of a virtual machine is not great, as there is no 3D hardware acceleration support under a virtual machine, however it should work good enough to get a lot of development tasks done. Nice is also that you can install/run VirtualBox on Windows, OS X and Linux. The free VirtualBox also enables you to share data seamlessly between the virtual machine and host computer, and also allows you to directly access USB 2.0 devices from within the virtual machine. To improve the performance of your virtual machine, you can increase the number of cores on a multi-core system that is assigned to your virtual machine.
2.1.1 Hardware requirements
- x86-based computer (if you don't know what it means, you probably have one). No special hardware is required for development, as developers can compile using the "make sdl_2d option" (see README.linux). However for end-users the recommended minimum requirement is a 3D GPU (Graphics Processing Unit) that at least supports Shader Model 3.0 and OpenGL 2.0 (that features 24bpp or 32bpp for 3D hardware-acceleration support, which the XBMC GUI needs to run smoothly at an acceptable frame-rate). Graphic adapters that support DirectX version 9.0c or later usually meet all of those mentioned requirements, (Team XBMC recommends NVIDIA GeForce 6150 or later as NVIDIA is currently the manufacturer that offers good device-drivers for Linux (and NVIDIA GeForce 6150 or later supports OpenGL 2.0).
2.2 XBMC Linux port FAQ for developers
2.2.1 Can non-Linux developers also help?
XBMC can also be compiled for many other operating systems, and you can read more information about that here.
2.2.2 Why is OpenGL 2.0 needed for XBMC?
OpenGL 2.0 is not really the current minimum requirement to run XBMC for Linux, as in reality XBMC will today run with only OpenGL 1.3 + GLSL support. Everything else has fall-backs to be run in software on the CPU (which is slower than GPU hardware, though). However, in order to stay future-proof, Team XBMC has decided that the OpenGL 2.0 is the recommended minimum requirement.
- Currently OpenGL 2.0 hardware is only needed for:
- Any deinterlacing that is not linear blending (which FFmpeg does in software)
- Video video post-processing filtering (bicubic upscaling, etc.)
- Non-power of two textures for the GUI (using NPOT saves a lot of texture memory)
- Hardware accelerated YUV 2 RGB conversion (actually GLSL is needed for this, and a few GPU hardware implementations as low as OpenGL 1.3 does provide GLSL as an extension. OpenGL 2.0 guarantees availability of GLSL).
- In the future OpenGL 2.0 might also be needed for:
- More video post-processing filters to improve visual quality perception.
- Hardware Accelerated Video Decoding (using the GPU hardware to assist with video decoding)
2.3 General guidelines
2.3.1 User-friendliness is next to godlyness
One major ongoing goal of Team-XBMC has always been to make XBMC and its user interface feel even more intuitive and user-friendly for its end-users, based on the KISS (Keep It Simple Stupid) principle of simplicity. It is our belief that usability is the most important aspect of a media center like XBMC. Many other media center projects make user interface decisions by developers, who often have little experience in user interface design. In contrast, Team-XBMC does its best to listen to XBMC's end-users to learn how XBMC is actually being used and how we can improve the user experience. We also aim to do regular overhauls, improving existing features/functions, and scrapping outdated code and features/functions (as "too much stuff" adds unnecessary complexity and can thus also be a bad thing). Everything should be made as simple as possible, but no simpler.
2.3.2 XBMC as a whole must...
- First and foremost be aimed at a large-screen (28" or more) 10-foot user interface for the living-room experience.
- Large menus, text/fonts and buttons that is designed to be navigated by a hand-held remote-control.
- Be focused around the main features of playing music, watching movies, recorded television broadcasts, and viewing pictures.
- XBMC may be capable of converging other things but those things should never take over the main focus in the interface.
- Be easy to install, set up and maintain (so that our valuable end-users do not get fed up with it and quit).
- Have an user interface that is simple and intuitive enough so that less tech-savvy people are not intimidated by it.
- Make common usage easy, simple 'Human–Computer Interaction (HCI)', from the viewpoint of an ordinary user.
- Be able to play audio and video files that have been encoded using DivX, XviD, etc. directly out-of-the-box.
- Be able to organize audio and video files in an easy and user-friendly way.
- Use standards and be consistent, (the Music section can for example not use completely different controls from the Video section).
- Perform actions in the GUI with as few 'clicks' as possible.
- Be aimed at an international audience, internationalization and localization by supporting different languages, timezones and other regional differences
- Require little to no non-GUI configuration (and all such non-GUI configuration should be done in just one file: advancedsettings.xml).
- Be beautiful to look at, after all we hope you will be using it a lot!
2.3.3 Team-XBMC members should always strive to
- Promote open source - XBMC is based on the ideas of FOSS (free open source software), licensed under the GPL and builds partly on other open source projects which we do our best to support. The GPL should be respected at all times. All code should be committed to the XBMC project’s git repo before any public binaries are released.
- Promote the sharing of knowledge and collaboration - Through the use of information sharing tools and practices XBMC is a collaborative environment.
- Understand that development is a team effort - Treating our users as co-developers has proven to be the most effective option for rapid development. Always strive to work as a team at all times. Actively promote discussion on new features and bug fixes, and respect others comments and criticisms with replies in a timely fashion.
- Apply the Law of Diminishing Return - The majority of the effort should be invested in implementing features which have the most benefit and widest general usage by the community.
- Try to make all code, feature, and functions to be platform agnostic - XBMC is a multi-platform software, thus any single platform specific features should be discussed with other team members before implemented. Major features should be developed in a separate branch or committed in small increments so that other members have the opportunity to review the code and comment on it during development.