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[XaraXtreme-dev] Moview replay progress

It has been decided that the movies should be encoded as h264\vorbis\ogg (i.e. h264 for the video, vorbis for the audio in a ogg format file). A means is needed to replay these movies, which allowed the user to pause and skip forward and back to allow performing operations along with the movie.

We identified 2 possible ways of approaching the replay of the help movies:
1) Use a mplayer executable. Currently we try running a native copy and if that fails a shipped version is tried.
2) Use wxMediaCtrl (which uses gstreamer on Linux, http://en.wikipedia.org/wiki/Gstreamer).

Neither solution is ideal and both have pros and cons:


  • Does not need serious amounts of work on mplayer source code to produce working executable. The only work that was needed was witting a script to automate the build with the right options.
  • Possible to produce a stripped version without the overhead of the mplayer, just by removing the executable.
  • Easy to produce a standalone installation just by the inclusion of a pre-built mplayer.
  • Will not work on a non-x86\x86_64 platform if a native mplayer not present
  • Control of replay is not as easy. In order to pause or skip forward or back commands must be sent on stdin, also current location has to be read from the application stdout.

  • Cross platform. wxMediaCtrl uses DirectShow on windows and Quciktime on mac, which means exactly same code will work on all platforms.
  • Plugin based. This means it's possible to produce a minimal install that contains just the plugins that are needed (but see static issues below)
  • Easy to write the user interface to control replay, since this can be achieved by just calling functions.
  • A statically linked gstreamer seems unable to load plugins. Instead the plugins must be linked into the application, which means changing the plugin source so they can be correctly registered. This may cause problems with licenses.
  • If linked dynamically the application will not load on a machine that doesn't have the basic gstreamer code installed.
  • Error reporting leaves much to be desired if a plugin that is needed to replay the movie is not present. This may well be more lack of decent handling within wxMediaCtrl than an inherent limitation of gstreamer.
At the moment using mplayer is looking like the better method for movie replay, since it makes producing a static release executable much easier. An other possible solution is to use mplayer for the static release build and use wxMediaCtrl for user built executables (and version built by distributions). It's probable that other platforms could also use wxMediaCtrl even for static builds since the media replay components are a standard part of the OS. They problem with this middle way is it means an other bit of code needs writing and maintaining.

Part of the reason that this document was produced now was to get feedback from the community about which direction looks like its best (or even if you can think of a better way). So we'd very much like to hear your comments.