Development Notes

From XBMC4Xbox
Jump to navigation Jump to search

XBMC4Xbox is a third-party developer spin-off project of XBMC for Xbox, with still active development and support of the Xbox. This project was created as a fork of XBMC for Xbox as a separate project to continue having a version of XBMC for the Xbox hardware platform, and was initially started by a few members from the original XBMC project in order to fully breakout the removed Xbox branch support from the official XBMC project and let it continue as a totally separate project.

Contributing to the XBMC project

Third-party developers/programmers can make and submit source code patches/modules with new features, functions, or bug-fixes to us via our Tracker (Trac) on this site.

The XBMC source code structure uses a fairly modular design (with libraries and DLL files), the structure is large, though relatively easy to grasp by most programmers. XBMC's source code is predominantly written in the C++ programming-language, though there is a small splattering of C libraries and assembler for good measure. XBMC uses the Microsoft DirectX multimedia framework (Direct3D) on the Xbox.

The main XBMC program is developed using Microsoft Visual Studio for the Xbox builds of XBMC. For the Xbox version a copy of the latest Microsoft Xbox SDK (a.k.a. XDK) and DirectX 9.0 SDK Update (Summer 2004) is also required.

XBMC's code also contains three player cores: One core based on MPlayer that is only available to the Xbox version of XBMC, another in-house developed (FFmpeg-based) dedicated video-player core that is used for video playback on all other platforms, and an in-house developed dedicated music-player core which works on all platforms.

Some of the XBMC libraries are in the C programming-languages but those then uses a C++ wrapper and are loaded via XBMC's own DLL loader. The Xbox Operating-System/BIOS is kind of Win32-based however it does not have all of the resources or capabilities of a full Microsoft Windows Operating-System, (for example: DirectShow, registry, nor DLL are nativly supported on the Xbox). Because of the constraints on the hardware (like only 64MB shared memory and a 733Mhz PIII CPU) and the XDK environment of the Xbox, all software development for XBMC is highly focused on reserving the limited resources that exist, the main hindrance of which is the amount of available random access memory at any one time, (which is why XBMC code structure is built so modular, enabling libraries to be unloaded when they are not in active use). For more detailed information about XBMC inner working please follow these links and the categories at the end of this article:

Development Catagory Sections

Development HOW-TO

XBMC inner working and platform-independent HOW-TO guides

XBMC for Xbox

XBMC programming and code formatting convention guidelines

Note! More specifics to come based on ongoing discussions, see Proposed code formatting conventions for XBMC

General coding guidelines

  • Code documentation (DocBook, rst, or doxygen for the code documentation steps, preferably the latter, doxygen).
    • Like for example every field of public API structures should have a doxygen comment.
  • Self-containment - XBMC should be as little dependent as possible on operating-system and third-party services/deamons/libraries
    • XBMC should for example contain all file-system and network-client (like samba) support built-into the XBMC package
  • Modular design - independent modules made up by localized/isolated code libraries without dependencies
    • XBMC should still compile and run if a non-essential module/library is disabled or removed
  • Aim for the GUI/interface to run smoothly on a low spec computer (less than 1Ghz)
    • 3D graphic controller (GPU) will always be required hardware for XBMC so try to utilize the GPU as much as possible
  • Avoid harddisk trashing (excess read/write/erase cycles), so no harddrive paging, (utilize RAM memory intead).
    • End-users will be running XBMC and the operating-system on Solid-State memory as a Live CD (LiveDistro) of a USB-key
  • Fast load and boot times for end-user perception (other thing can still run/start in the background without the user knowledge)

The code of conduct guidelines all XBMC developers is expected to abide by is

  • Promote open source - XBMC is based on the ideas and spirit of FOSS (free open source software) , licensed under the GPL and builds partly on other open source projects which we too do our best to support. The GPL should be respected at all times, and all code should be committed to the XBMC project’s SVN 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.
  • All code should strive 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, and software portability should always be kept in mind. All major code changes and new features and functions should be developed in a separate branch or committed in small increments so that other members have the opportunity to review the code on other platforms and be able to give feedback during development.===

User-friendliness is next to godliness

One of Team-XBMC major ongoing goal have always been to make XBMC and its user interface even more intuitive and user-friendly for its end-users, based on the KISS (Keep It Simple Stupid) philosophy. We think that usability is very important for media players like XBMC. Many user interface decisions are being made by developers who often have little experience in user interface design, in order to improve this, we try to listen to XBMC's end-users for 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 "to much stuff" can also be a bad thing).

XBMC as a whole must...

  • Be easy to install, set-up, configure, and maintain, (so that the end-users do not get fed up with it and quit).
  • Have an user interface simple and intuitive enough so that less geek-savvy people are not intimidated by it.
  • Be able to play audio and video files that have been compressed using divx, xvid, etc. directly out-of-the-box
  • Be able to and 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
  • Require little to none non-GUI configuration (and all such non-GUI config should be via advancedsettings.xml)
    • There is still a little work to be done here, for example RSS-feeds settings need to moved to the GUI
  • Look nice.