On Wed, 24 Nov 2010 17:11:02 +0100, Eric Winkelman
<[email protected]> wrote:
I'm investigating how TimedTracks can be used for in-band-data-tracks
within MPEG transport streams (used for cable television).
In this format, the number and types of in-band-data-tracks can change
over time. So, for example, when the programming switches from a
football game to a movie, an alternate language track may appear that
wasn't there before. Later, when the programming changes again, that
language track may be removed.
It's not clear to me how these changes are exposed by the proposed Media
Element events.
The thinking is that you switch between different streams by setting the
src="" attribute to point to another stream, in which case you'll get an
emptied event along with another bunch of events. If you have a single
source where audio/video/text streams appear and disappear, there's not
really any way to handle it.
The "loadedmetadata" event is used to indicate that the TimedTracks are
ready, but it appears that it is only fired before playback begins. Is
this event fired again whenever a new track is discovered? Is there
another event that is intended for this situation?
Similarly, is there an event that indicates when a track has been
removed? Or is this also handled by the "loadedmetadata" event somehow?
No, the loadedmetadata event is only fired once per resource, it's not the
event you're looking for.
As for actual solutions, I think that having loadedmetadata fire again if
the number or type of streams change would make some sense.
--
Philip Jägenstedt
Core Developer
Opera Software
