- From: Harald Alvestrand <harald@alvestrand.no>
- Date: Wed, 22 Apr 2015 11:41:30 +0200
- To: Adam Bergkvist <adam.bergkvist@ericsson.com>, "public-media-capture@w3.org" <public-media-capture@w3.org>
Den 22. april 2015 11:31, skrev Adam Bergkvist: > On 2015-04-15 15:11, Harald Alvestrand wrote: >> In the current specification, we have two concepts related to sources >> and tracks: >> >> - A track can be stop()ed, in which case it is ended. >> - A track can be detached from its source. >> >> The text says: >> >> A) in terminology for "source", we have: >> >> Sources are detached from a track when the track is ended for any reason. >> >> B) Under "Life-cycle and Media Flow", we have: >> >> A MediaStreamTrack can be detached from its source. It means that the >> track is no longer dependent on the source for media data. If no other >> MediaStreamTrack is using the same source, the source will be stopped. >> MediaStreamTrack attributes such as kind and label must not change >> values when the source is detached. >> >> C) Under the "enabled" attribute of a track, we have: >> >> On getting, the attribute must return the value to which it was last >> set. On setting, it must be set to the new value, regardless of whether >> the MediaStreamTrack object has been detached from its source or not. >> >> Under the "stop" function for a track, we have: >> >> 3. Set track's readyState attribute to ended. >> >> 4. Detach track's source. >> >> It seems to me that this is one concept more than we need. >> Whether there is a relationship between a stopped track and its source >> or not is an implementation detail, and we shouldn't be constraining it >> in our API description. >> >> So my suggestion: >> >> In A, C and D, simply remove the text that refers to "Detach". >> >> In B, instead say: >> >> If all MediaStreamTracks that are using the same source are ended, the >> source will be stopped. >> >> I think that simplifies the terminology, and doesn't change any >> observable property of the API. >> >> What do people think? >> (If others like it, I'll file a bug for it.) > > I think this is a simplification worth doing. > > This will let us refer to properties on the source without having to > verify that the track has a source attached. A new thing, however, is > that a track can have a stopped source (attached). Is this an issue? I think only stopped tracks can have stopped sources, since a source is only stopped if all the tracks have been stopped. So we can't have a live track sourced from a stopped source (which would indeed be a bit strange). We do have the concept of a source ending by itself (someone removed the camera?), which causes all the attached tracks to stop.
Received on Wednesday, 22 April 2015 09:42:00 UTC