• Andre Pang's avatar
    * Added HACKING file to CMML codec plugin directory, which includes · 6a0e132d
    Andre Pang authored
      description of what it does and how it's implemented.
    * Overview of the CMML codec:
      This is an implementation of the Continuous Media Markup Language
      (CMML) for VideoLAN.  In short, CMML is a (XML) markup language for
      time-continuous data, which of course includes multimedia such as
      video and audio.  It allows one to annotate a media file with both
      structured and unstructured textual data, but one of its distinguishing
      features--and what this code implements--is its support for embedding
      hyperlinks in media files.
      So, while viewing some media (e.g. a radio interview with a band),
      you could provide a hyperlink to any URL, including a standard web
      page or other media (e.g. the band's home page).  The hyperlinks
      are active only for specific intervals of time while the media is
      playing, so for example during a radio interview, the hyperlinks
      can change depending on what questions the interviewer is asking
      and topic is being discussed.
      For more general information on CMML and its role in the bigger
      picture of extending the World Wide Web to properly support multimedia,
      see <http://www.annodex.net/overview.html>.  For specifications of
      CMML, see <http://www.annodex.net/specifications.html>.
    * CMML codec usage:
      Once you have hyperlinking capability, you take on some of the
      capabilities of a web browser, in particular following hyperlinks,
      and also maintaining a browsing history where you can go backwards
      and forwards between pieces of media you've linked to.  So, if you
      are viewing a file with CMML markup:
      * Hyperlinks are displayed as a subtitle track
      * Hyperlinks are followed with the VLC "activate" hotkey (by default,
        this is just the Enter key)
      * Going back and forward are done with the "history-back" and
        "history-forward" keys, by default Cmd-[ and Cmd-] on Mac OS X,
        and Ctrl-[ and Ctrl-] on all other platforms.
      Until the media browsing history features are made available outside
      of the CMML plugin, you can only use the history features while
      viewing a file that contains CMML markup: e.g. you cannot navigate
      backwards or forward in the history while viewing a standard MPEG
      video.  This is a limitation which may be removed if the media
      browsing code is merged into the VLC core.