- From: Stefan Håkansson LK <stefan.lk.hakansson@ericsson.com>
- Date: Wed, 16 Apr 2014 13:57:10 +0000
- To: Adam Bergkvist <adam.bergkvist@ericsson.com>, "kiran.guduru@samsung.com" <kiran.guduru@samsung.com>, Steev James <steev.a.james@gmail.com>
- CC: "public-media-capture@w3.org" <public-media-capture@w3.org>
On 16/04/14 09:51, Adam Bergkvist wrote: > OK, let's try to get this into the spec. > > Since the media element resource load algorithm says that a media > resource can indicate a set of audio and/or video tracks to enable, > perhaps that's what we should do and nothing more. Then we would leave > it up to the media element spec take care of the rest (setting > AudioTrack.enabled, VideoTrack.selected and VideoTrackList.selectedIndex). I agree, the only thing we should change is the section: "Set the VideoTrackList.selectedIndex to the index of the first VideoTrack, in the VideoTrackList, that corresponds to a MediaStreamTrack that has readyState 'live'. If no such VideoTrack exists, set the selectedIndex attribute to -1." The rest seem OK IMO. > > /Adam > > On 2014-04-16 07:42, Stefan Håkansson LK wrote: >> On 16/04/14 06:03, Kiran Kumar Guduru wrote: >>> Samsung Enterprise Portal mySingle >>> >>> Some more comments regarding relation between "live" and "muted" state >>> of a MediaStreamTrack. >>> >>> This has been discussed earlier in [1] and concluded that "muted" and >>> "disabled" tracks should be considered as "live". >>> >>> [1] https://www.w3.org/Bugs/Public/show_bug.cgi?id=22259 >>> >> OK, so we should be able to use "live". >>> ------- *Original Message* ------- >>> >>> *Sender* : Kiran Kumar Guduru<kiran.guduru@samsung.com> Lead >>> Engineer/SRI-Bangalore-TZN/Samsung Electronics >>> >>> *Date* : Apr 16, 2014 12:32 (GMT+09:00) >>> >>> *Title* : Re: Re: [Bug 25275] VideoTrackList.selectedIndex >>> initialization confilicts with HTML5 spec, "if no track is selected". >>> >>> Yes It is done by modifying the statement. >>> >>> I agree that the relation between 'live' and 'muted' is not defined in >>> the spec. Since muted is not present in the readyState of the >>> MediaStreamTrack, I thought that "muted" and "disabled" are part of >>> "live" state only. >>> >>> ------- *Original Message* ------- >>> >>> *Sender* : Stefan Håkansson LK<stefan.lk.hakansson@ericsson.com> >>> >>> *Date* : Apr 15, 2014 22:12 (GMT+09:00) >>> >>> *Title* : Re: [Bug 25275] VideoTrackList.selectedIndex initialization >>> confilicts with HTML5 spec, "if no track is selected". >>> >>> On 2014-04-15 14:36, Kiran Kumar Guduru wrote: >>>> +1 for "not take the muted/disabled of the MediaStreamTrack into >>> account". >>>> I would like to polish this "just select one of the video tracks >>>> regardless of it being muted/disabled or not" with >>>> >>>> "First available MediaStreamTrack with MediaStreamTrack.readyState >>>> "live", (Since live includes muted and disabled), If no such track >>>> available set it to -1. >>> This would work for me. That would mean that we replace the sentences >>> >>> "Set the VideoTrackList.selectedIndex to the index of the first >>> VideoTrack, in the VideoTrackList, that corresponds to a >>> MediaStreamTrack that is not muted or disabled. If no such VideoTrack >>> exists, set the selectedIndex attribute to 0." >>> >>> with >>> >>> "Set the VideoTrackList.selectedIndex to the index of the first >>> VideoTrack, in the VideoTrackList, that corresponds to a >>> MediaStreamTrack that has readyState 'live'. If no such VideoTrack >>> exists, set the selectedIndex attribute to -1." >>> >>> and we're done? >>> >>> (The caveat seem to be that the relation between 'live' and 'muted' is >>> not defined.) >>> >>> >>>> ------- *Original Message* ------- >>>> >>>> *Sender* : Stefan Håkansson LK >>>> >>>> *Date* : Apr 15, 2014 20:20 (GMT+09:00) >>>> >>>> *Title* : Re: [Bug 25275] VideoTrackList.selectedIndex initialization >>>> confilicts with HTML5 spec, "if no track is selected". >>>> >>>> On 2014-04-15 11:33, Kiran Kumar Guduru wrote: >>>> > It is true that MediaElement spec is not specifying anything about >>>> > initialization of selectedIndex. >>>> > >>>> > In MediaStreams spec, we will come across this scenario, "if no >>> track is >>>> > selected", after removing the selected track from VideoTracks >>> (and when >>>> > not selecting any other tracks in the list). >>>> >>>> Re-reading the html draft, I get to the following understanding: >>>> >>>> * For audio, any new tracks (tracks that are added to a MediaStream that >>>> is being played in a media element) gets status disabled in the media >>>> element's AduioTrackList. I.e. the application has to enable them >>>> (enabled=true) to have their audio played (mixed in with the other audio >>>> tracks). >>>> * For video, any new track (tracks that are added to a MediaStream that >>>> is being played in a media element) gets status not-selected in the >>>> media element's VideoTrackList. I.e. the application has to select it >>>> (selected=true) to have its video played. >>>> * For audio, removing a track does not affect the remaining tracks >>>> (their enabled property in the AudioTrack of the AudioTrackList of the >>>> media element remains). >>>> * For video, removing a track does not affect the remaining ones, >>>> meaning that if the track being removed is the currently selected one, >>>> then no track will be selected after removal (and selectIndex of the >>>> media elements VideoTrackList will return -1). >>>> >>>> I think there are no ambiguities so far. >>>> >>>> The only outstanding thing would be the resource fetch phase. The >>> text says >>>> "If either the media resource [...] indicate a particular set of audio >>>> or video tracks to enable, or if the user agent has information that >>>> enabled it to select specific tracks for optimal performance, then the >>>> selected audio tracks must be enabled in the element's audioTracks >>>> object, and, of the selected video tracks, the one that is listed first >>>> in the element's videoTracks object must be selected." >>>> >>>> What this means for a MediaStream is up to this group to define. What is >>>> currently said is that for all MediaStreamTracks of kind audio, the >>>> media element's corresponding AudioTrack should be initialised to >>>> "enabled" (and not take the enabled attribute of the corresponding >>>> MediaStreamTrack into account). >>>> >>>> For video, it is said: "Set the VideoTrackList.selectedIndex to the >>>> index of the first VideoTrack, in the VideoTrackList, that corresponds >>>> to a MediaStreamTrack that is not muted or disabled. If no such >>>> VideoTrack exists, set the selectedIndex attribute to 0." I think '0' >>>> should be changed to '-1', but otherwise this is quite clear IMO. We >>>> could consider simplifying by not take the muted/disabled of the >>>> MediaStreamTrack into account, and just select one of the video tracks >>>> regardless of it being muted/disabled or not. >>>> >>>> Stefan >>>> >>>> >>>> >>>> > >>>> > ------- *Original Message* ------- >>>> > >>>> > *Sender* : Steev James >>>> > >>>> > *Date* : Apr 14, 2014 22:24 (GMT+09:00) >>>> > >>>> > *Title* : Re: [Bug 25275] VideoTrackList.selectedIndex initialization >>>> > confilicts with HTML5 spec, "if no track is selected". >>>> > >>>> > Hmm, >>>> > My reay intention is "if none of the tracks are selected" has no >>> room in >>>> > MediaStreams spec. >>>> > >>>> > >>>> > On Mon, Apr 14, 2014 at 6:15 PM, Stefan Håkansson LK >>>> > > > wrote: >>>> > >>>> > On 2014-04-14 14:15, Steev James wrote: >>>> > > Stefan, >>>> > > This link is just specifying that AudioTracks / VideoTracks >>>> can have >>>> > > multiple tracks and, >>>> > > "The|VideoTrackList.selectedIndex|attribute must return >>> the index >>>> > of the >>>> > > currently selected track, if any. If the|VideoTrackList >>>> > > >>>> > |object >>>> > > does not currently represent any tracks, or if none of the >>>> tracks are >>>> > > selected, it must instead return −1." >>>> > >>>> > Hm, we must be talking past each other. I read your comment >>>> > 'MediaElement spec has not mentioned anything about "how" to >>> select a >>>> > track.', and responded to it because I think that is precisely >>>> what you >>>> > _can_ do with the enabled (audio) and selected (video) >>> attributes. >>>> > >>>> > > >>>> > > >>>> > > It is not mandating the default initialization to first >>> track. But >>>> > > MediaStreams is mandating it to initialize it to '0' track >>> of the >>>> > list. >>>> > > So "if none of the tracks are selected" has no room in >>>> > MediaStreams spec. >>>> > > >>>> > > >>>> > > >>>> > > On Mon, Apr 14, 2014 at 5:02 PM, Stefan Håkansson LK >>>> > > > >>>> > > > >> wrote: >>>> > > >>>> > > On 2014-04-14 08:58, bugzilla@jessica.w3.org >>>> > >>>> > > > > wrote: >>>> > > > https://www.w3.org/Bugs/Public/show_bug.cgi?id=25275 >>>> > > > >>>> > > > steev > > >> >>>> > > changed: >>>> > > > >>>> > > > What |Removed |Added >>>> > > > >>>> > > >>>> > >>>> >>> ---------------------------------------------------------------------------- >>>> > > > CC| >>>> > > |steev.a.james@gmail.com >>>> > > >>>> > > > >>>> > > > --- Comment #5 from steev > >>>> > > > >> --- >>>> > > > MediaElement spec has not mentioned anything about >>> "how" to >>>> > > select a track. >>>> > > >>>> > > >>>> > >>>> >>> http://www.w3.org/TR/html5/embedded-content-0.html#media-resources-with-multiple-media-tracks >>>> > > details this. >>>> > > >>>> > > > Is >>>> > > > there any special interst for specifying this in media >>>> > streams spec? >>>> > > > >>>> > > >>>> > > >>>> > > >>>> > >>>> > >>>> >
Received on Wednesday, 16 April 2014 13:57:36 UTC