On Thursday, April 24, 2014 12:42:35 AM UTC+8, Martin Thomson wrote: > On 2014-04-23, at 04:39, Marco Chen <mc...@mozilla.com> wrote: > > > > > 2. Then there are multiple MediaStreamTrack to represent multiple > > audio/video tracks in TV stream. > > > > I don't know if this is a problem here, or whether it's just a > misunderstanding, but the structure of MediaStream is actually three-deep: > > > > MediaStream is a synchronisation container > > MediaStreamTrack describes a single type of related content (e.g., audio, or > video) > > channels are not visible in the DOM, but they correspond to a single piece of > a track (e.g., the left speaker channel in multi-channel audio) > > > > When you say that there are multiple MediaStreamTrack instances, do you mean > to say that there is media from multiple sources (e.g., separate cameras, > different translations), or are you talking about media with multiple parts > (e.g., 5.1 channel audio)? >
The former is closer. A stream can contain multiple tracks, for example, a DTV channel provides a program with selection of multiple languages, in this case, it is a MediaStream with one VideoSteramTrack and multiple AudioStreamTrack, all tracks are from one source. The case with front/back camera would be one MediaStream, two VideoStreamTrack, but two sources though. > > > Why is it necessary for MediaStreamTrack to carry tags that identify things > as (for example) English or Mandarin? Is it not possible for this labelling > to occur in the application? At a second discuss, i don't think there is a need for MediaStreamTrack to carry such tags. Nevertheless, the VideoTrack of media elements will carry those tags (provided by content provider), in order to let application (e.g. a player menu) to display these information for users to select. _______________________________________________ dev-media mailing list dev-media@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-media
