Some features of existing multimedia languages such as BIFS or SVG may be tricky to understand, especially when dealing with media control and interaction. These case studies are an attempt at clarifying the way they work.

Stream Selection

This movie shows the power of MPEG-4 regarding media stream selection. With very few scripting you can dynamically switch languages or subtitles while ensuring a proper synchronization between the streams. In this sequence, the user can switch between english and japanese sound tracks and french and spanish subtitles. The video material used is the introduction of “The Second Renaissance Part I” from the animatrix series, freely available on their web site.

The content also features an animated, embedded skin providing media control (play/pause/stop/ffw) and a link to an internet web page.

Movie playing with japanese audio and spanish subtitles.

Movie playing with english audio and french subtitles.

Download this sample file or View the sample embedded in a web page.

Quality Selection

This movie shows another usage of MPEG-4 stream selection, this time based on quality switching rather than language switching. In this movie you may choose two different qualities for audio and video, and still ensure a proper synchronization between the streams. The interesting aspect of this demonstration is its use of MPEG-4 Object Clock Reference stream, which acts as a virtual clock other streams synchronize to, rather than synchronizing media streams on eachother such as video on audio. Of course such a selection of streams would usually be made at the server side, but this nonetheless shows the ease and feasability of stream switching in MPEG-4.

This content was designed by Mr Mollet from UGent.

High quality version of both audio and video streams, with spanish subtitles.

Low quality version of both audio and video streams, with english subtitles.

Download this sample file or View the sample embedded in a web page.