See also: IRC log
<trackbot> Date: 09 July 2013
<paulc> Good morning
<paulc> I will need a scribe today.
<adrianba> ScribeNick: markw
<adrianba> Scribe: Mark Watson
<paulc> Agenda: http://lists.w3.org/Archives/Public/public-html-media/2013Jul/0008.html
<Michael_Thornburgh> you're typing aaac instead of aacc
<paulc> Usual pattern: "Topic: xxxxx"
paulc: Propose to note previous minutes
paulc: Embedded in agenda
<paulc> Latest Ed draft: http://dvcs.w3.org/hg/html-media/raw-file/tip/media-source/media-source.html
<paulc> MSE bugs: http://tinyurl.com/6pdnzej
<paulc> Bug 22148 - Request that we reconsider adding jitter to video quality metrics
https://www.w3.org/Bugs/Public/show_bug.cgi?id=22148
paulc: This is open, assigned to Aaron
acolwell: This this is answered. I will try to get this implemented this week.
paulc: If this is the only open one, we could go to LC before implementing it
Bug 22137 - changes in number of audio tracks during advert insertion
https://www.w3.org/Bugs/Public/show_bug.cgi?id=22137
<adrianba> ACTION-21?
<trackbot> ACTION-21 -- Adrian Bateman to work with Jerry to review bug 22137 and provide feedback -- due 2013-07-02 -- PENDINGREVIEW
<trackbot> http://www.w3.org/html/wg/media/track/actions/21
<paulc> See latest comment at https://www.w3.org/Bugs/Public/show_bug.cgi?id=22137#c5
jdsmith: We had some discussion
and comments are in the bug. Some aspects tricky. Trade-off
between throwing an error if track numbers are reduced vs
trying to play.
... Trying to play is a good goal
... Local language might be preferred for example
adrianba: Aaron's compromise
proposal was what the original bug was asking for. In summary
the difference between what the current spec says (prohibit
track changes) and coming up with heuristics for deciding on
which track to continue with when available tracks change
... not obvious we have a clear answer
... in out media engine we look at languages, formats and pick
default track. Other media engines might do something
different. Getting interop might be hard.
... Is this something we really need to solve now ?
... If yes, how precisely should heuristics be defined and does
it need to be repeatable ?
Michael_Thornburgh: I'll add a
note today to eb bug about the main usecase: separate video and
audio tracks coming in separately and then switch to an add
which is multiplexed
... so you are going from 0 to 1 track of a particular type or
1 to 0
BobLund: Issues adrianba raised are independent of MSE and apply to any media resource where the set of tracks changes. There's a resolved bug in the HTML5 spec on this.
<paulc> What is the HTML5 bug number?
BobLund: There is some ambiguity
about how applications should respond, but it's not just an MSE
issue
... MSE issue is whether we want to allow those track changes
at all - a separate issue from how you deal with them when the
happen
... Should just discuss whether we allow track changes in
MSE
<paulc> Is this a case where the spec should say the choice of text track is "implementation-defined"?
paulc: adrianba, is this a case
where we should just say "implementation defined" ?
... if we did this and got into Last Call it could be a source
of objections
acolwell: First on
Michael_Thornburgh's use case, those transitions would actually
introduce new tracks
... if one of the source buffers suddenly had an extra track,
then that should introduce a new track in HTML5 and you ought
to actually select that new track
... not clear that UA could automatically detect that it should
switch just based on the absence of data in the old source
buffer and the appearance of the new track
<BobLund> http://www.w3.org/TR/2012/CR-html5-20121217/embedded-content-0.html#audiotracklist, http://www.w3.org/TR/2012/CR-html5-20121217/embedded-content-0.html#texttracklist
acolwell: Second, on BobLund's
comment, I think HTML has language about tracks coming and
going which is fine but the concern is whether the media
engines can actually support that and what bar do we want to
set for minimal client implementations
... seems to me it is more in the scope of MSE than HTML5
pal: There is already in HTML5 a means of selecting which track should be played, correct ?
acolwell: yes
pal: so for this use-case with an ad insertion the app can select which track will start playing
acollwell: when they append the new data they should get a notification of the new track on the HTMLMediaElement and the app could select then. But there is no implicit way for the track selection to happen automatically
pal: would seem dangerous to have
a track selected automatically
... another thing is whether we should impose constraints on
track switching
... perhaps requires multiple decoders etc.
acolwell: current text does not
allow track count or codecs to change exactly for that
reason
... my comment was just to define minimal behaviour so that if
the track counts do change the behaviour is deterministic, but
don't require the UA to actually handle the new tracks
BobLund: links above are to the
HTML IDL that provide add/remove track capability
... app can select the tracks - no ambiguity there - I agree
with acolwell that the issue for MSE is whether or not to
support these track changes
... if we do support them the UA behaviour is clear in HTML
adrianba: in response to BobLund,
HTML5 is clear what event should be fired in response to track
add/remove.
... what's missing is what to do if the track that you are
playing disappears. Should you enable another track
automatically ?
... and how do you decide which one ?
... alternatives are to give an error and stop playing or to
continue playing
... ideally we would have the ability to schedule a track
change at some time in the future
... so for example when appending the new track you could let
the media element know that you will want to change at some
future point
... might not be able to do this right away, but seems like a
long-term goal
... propose converting this to an HTML5 bug
<BobLund> +1 to moving this to an HTML5 bug
adrianba: proposing future scheduling of track changes
acolwell: agree with adrianba
that providing information about how to switch tracks at a
particular point in the timeline
... immediate problem is whether to trigger an error (which is
what is says now) or whether to change that to say it's allowed
but may not be exposed by the UA
... so then this new future spec can be used to control the
changes
<paulc> Mark: A simple suggestion is to possibly mark one of the tracks as the default if one of the tracks goes away.
<paulc> Mark: If the audio track goes away maybe the UA will stall and we don't want the UA arbirtarily picking tracks.
markw: perhaps allow a track to be flagged from the MSE side as the default track to be used if the currently playing track ends
<paulc> Aaron: There is currently no way for the applications to know the track ids.
acolwell: that could be tricky because There is currently no way for the applications to know the track ids
Michael_Thornburgh: provding
information for track switches at append time would unify the
append time behaviour with the rendering behavior
... would also solve the stall problem when there were suddenly
zero tracks
... I'll add this to my comment on the bug
pal: acolwell, when you said the MSE had no concept of trackid, what did you mean
acolwell: track selection is abstracted away from track ids in the media itself. There is just a track list and you can select from that. You can't use track id on that side.
pal: There are attributes like kind, which you can use, but there's no id on the media element side, right ?
acolwell: yes, there's no id which is guaranteed to be the id from the container
pal: ?
acolwell: may be benefits of exposing the track ids, but that's not this particular issue
pal: application should be able to select which track to play from what it has inserted and wants to play the French track or track id 5
<adrianba> We had MSE bugs for this issue
acolwell: you can't select by
track id but you can select by language etc.
... underlying container id is not exposed. it can change
adrianba: this topic is the
subject of MSE bugs, we discussed a long time ago that mapping
from track id to HTML track lists is tricky. Thought we had
resolved that
... should check in time as there's another issue
... summary: propose to move this to be solved in HTML5 in a
broader way
paulc: in 5.0, the CR ?
adrianba: no, 5.1
... feature request
acolwell: would that HTML5 proposal remove the current resriction in MSE ?
<paulc> Move to HTML5 -> create a new 5.1 bug that references this bug
adrianba: right, I'm proposing we make no change to MSE now and potentially change that in future
paulc: this means creating a new
HTML5 bug referring to this one
... is there consensus today to do that ?
... not today
<adrianba> Bug 22136 - Inband Storage for SPS/PPS in ISO BMFF
<adrianba> https://www.w3.org/Bugs/Public/show_bug.cgi?id=22136
<adrianba> ACTION-22?
<trackbot> ACTION-22 -- Adrian Bateman to work with jerry to confirm the proposal in 22136 is acceptable -- due 2013-07-02 -- PENDINGREVIEW
<trackbot> http://www.w3.org/html/wg/media/track/actions/22
jdsmith: There's an MPEG DASH
specification that requires inband SPS/PPS support
... for ISO BMFF part 15. Currently in draft state
... hard to require support when it is not yet stable
paulc: what is the exact
status
... ?
jdsmith: don't know exact status
paulc: we should find that out first
http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=62115
DIS ballot, close of voting
adrianba: can we close ACTION-21
and ACTION-22 ?
... if we identify status of ISO spec as unstable, then what
?
paulc: markw identified status as DIS, which is pretty stable
The status is at: http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=62115
Getting the actual document is a different matter
paulc: looks like it when into
DIS in April
... suggest adrianba looks at how stable this is
Note this is just from searching for 14496-15 amendment 2 which is HEVC support. I am not *certain* this contains the SPS/PPS thing
though that would make sense
<adrianba> ACTION-21: need to confirm exact status of the proposal for SPS/PPS
<trackbot> Notes added to ACTION-22 Work with Jerry to review bug 22137 and provide feedback.
Bug 22117 - Add a conformance section
paulc: asked Cyril what he want
to do about this item
... waiting for response
Bug 22112 - Merge appendBuffer and appendStream text
https://www.w3.org/Bugs/Public/show_bug.cgi?id=22112
paulc: This is resolved, fixed
<paulc> https://www.w3.org/Bugs/Public/show_bug.cgi?id=22112 is resolved fixed
paulc: those were the 5 bugs
blocking LC. One is resolved. The first one Aaron will
implement in the next two weeks
... 22137 and 22136 need more work and we have action items for
those
... 22117 is on Cryil
https://www.w3.org/Bugs/Public/show_bug.cgi?id=22432
(scribe missed that)
https://www.w3.org/Bugs/Public/show_bug.cgi?id=22371
paulc: Aaron offered to respond at the Jul 2 meeting
acolwell: yep, will do that
acolwell: fixed the statistics to
return an object, instead of a method
... this applies to buffered attribute as well
... it returns a new object every time
... which was identified as a problem for the video playback
quality
... curious whether we should also change buffered
adrianba: stick with what we have got as it's the same as the HTML5 buffered attribute
acolwell: ok, fine
This is scribe.perl Revision: 1.138 of Date: 2013-04-25 13:59:11 Check for newer version at http://dev.w3.org/cvsweb/~checkout~/2002/scribe/ Guessing input format: RRSAgent_Text_Format (score 1.00) Succeeded: s/objectiosn/objections/ Succeeded: s/woudl/would/ Succeeded: s/ACTION-21/ACTION-22/ Succeeded: s/tha/that/ Found ScribeNick: markw Found Scribe: Mark Watson WARNING: No "Present: ... " found! Possibly Present: ACTION-21 Aaron Aaron_Colwell BobLund Mark Mark_Watson MartinSoukup Michael_Thornburgh Microsoft P21 ScribeNick aa aaaa aabb aacc acollwell acolwell adrianba davide glenn html-media https jdsmith joined markw pal paulc pladd trackbot wseltzer You can indicate people for the Present list like this: <dbooth> Present: dbooth jonathan mary <dbooth> Present+ amy Agenda: http://lists.w3.org/Archives/Public/public-html-media/2013Jul/0008.html Found Date: 09 Jul 2013 Guessing minutes URL: http://www.w3.org/2013/07/09-html-media-minutes.html People with action items:[End of scribe.perl diagnostic output]