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Re: [Bug 25275] VideoTrackList.selectedIndex initialization confilicts with HTML5 spec, "if no track is selected".

From: Steev James <steev.a.james@gmail.com>
Date: Wed, 16 Apr 2014 22:19:05 +0530
Message-ID: <CAB1_PA7EdL9QvoZuhdsAVFDLOez1Q0Apszkt-K2WNTRAwcSQkw@mail.gmail.com>
To: Stefan Håkansson LK <stefan.lk.hakansson@ericsson.com>
Cc: Adam Bergkvist <adam.bergkvist@ericsson.com>, "kiran.guduru@samsung.com" <kiran.guduru@samsung.com>, "public-media-capture@w3.org" <public-media-capture@w3.org>
+1
This change seems to be fine for me.


On Wed, Apr 16, 2014 at 7:27 PM, Stefan Håkansson LK <
stefan.lk.hakansson@ericsson.com> wrote:

> 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 16:49:33 UTC

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