See also: IRC log
<trackbot> Date: 16 February 2012
<davidmays> scribe: Dave_Mays
<davidmays> scribe: davidmays
Clarke: welcome Joe Steele from Adobe
… Joe is a content protection expert
… describing agenda
<joesteele> thanks! I am still trying to dial in -- bad phone setup on my side
… asking Mark Watson about updated content protection proposal
Mark Watson: will be updating sometime next week, working offline with other companies
Clarke: next week's main topic will be content protection
Bob Lund: I was asked by Ian to provide pointer to a spec for LC13357
… I posted a spec for AC3 audio that matches this
… no response from Ian yet
… LC13359 - long discussion thread, I supplied some more detailed information. Ian thinks this is complicated. The ball is in Ian's court
Clarke: need to add LC13358. Maybe it's already resolved?
… asking for other comments on the rest of the bugs
Clarke: mentions that Kilroy was going to summarize comments from last week's call, will follow up with Kilroy.
… any other comments on Chromium WIP proposal?
Mark Watson: if people have comments on chrome media extension, they should contact the author
Clarke: let's look at Adaptive Bitrate control section and get feedback
… Video tag makes it easy to discern what's in the HTML, instead of using something like <OBJECT>
… proposal from Chromium meets this criteria
Bob Lund: couple of comments
… 1 issue is whether the tag is video/object
… 2 whether the solution needs to support <video>
… strongly supporting the use of <video> element, rather than <object> due to all the HTML5 work that has already been done
Clarke: common time reference
… kilroy brought up overlapping tracks need to be handled
… any disagreement on the common time reference requirement?
Glenn: in trick modes (play speed !=1) is there a good model for time for this in HTML or is it left to the underlying protocol and layers
Bob Lund: there is a definition for playspeed in HTML5. pretty clear cut what UA behavior should be for different playback rates
… similarly for seeking within stream - also well defined using seekable range objects or attributes
Clarke: what is the range relative to?
<glenn> +q glenn
<Juhani> I am on the call
Bob Lund: it's sourced off the video, complicated with multiple videos. base ref defined from one of the videos in HTML5 spec
Mark Watson: it would depend on protocol using to retrieve the video - no server involvement on HTTP streaming, but with RTSP there is server involvement
Clarke: HTML5 spec does not say if you change play speed, how to make use of underlying protocols
… other specs may cover it, but not HTML5
Glenn: the spec *could* say that resolution of play-time is governed by protocol in use by the referenced URI
Mark Watson: it's mainly up to client capability to support FF/RW
… depends how it interprets the media data from the server
glenn: i have concerns about a lack of any language in this area in the spec
… e.g. if the server is delivering video over HTTP and it is performing trick-play on the server, does the client know that?
MW: that's a media protocol/format issue, not an HTML5 issue
Bob Lund: HTML5 API is agnostic to that. just use the specified attributes to specify play speed
… haven't seen a deficiency in that area
Clarke: to double play speed in HTTP, specify in HTML that you want a play speed of 2. presumably the UA would issue the correct requests
… after that the HTML doesn't need to know
Glenn: b/c HTML5 defines a playspeed attribute that is mutable, JS can change that value
… any server-initiated change handler is unspecified
… should HTML5 provide a mapping that gives guidance to implementors
Bob Lund: in DLNA we saw that it was necessary to provide that
… in HTTP adaptive, the goal has been to make use of standard HTTP without any further mapping
… does not seem to be a part of the HTML5 spec
glenn: not suggesting that it should be, but HTML5 leaves it blank as to how mutations of play speed should be mapped
Clarke: try to come up with a use case where there is ambiguity in HTML
MW: HTML5 doesn't specify protocols, so this isn't the right place for that kind of thing
… should be included in the protocol specification instead
Clarke: mixing of tracks with different time references - does HTML5 specify anything like a "master" track?
Bob Lund: don't know enough details about time management to answer that
Clarke: let's see if we can resolve time reference issues
Bob: kilroy should bring up some use cases to illustrate this problem
MW: multi-track support in HTML, each element has a timeline from start to zero, and all those need to be aligned
… if multiple inbound tracks from a media format, we depend on the format to provide alignment
… if switching between bitrates, need to make sure that segments are aligned.
… just need to be clear about where the timelines need to be aligned.
Clarke: i will open an issue on this and we can put up some use cases
… anything more about search and trick-play to talk about?
… want to determine ASAP if a UA can handle a type of content
… let's come to a consensus on this
… does this req't need restatement
… no different wording proposed
… how do we best resolve this?
Dave Mays: reading the requirement from the wiki - "The ability of the user agent to play a piece of content must be determined quickly and with reasonable accuracy (e.g. using CanPlayType(codec, level, profile) or other means)"
Clarke: the less we have to process before getting an answer, the better
… if you can get it from mime type or canPlayType() that's better than going into the UA and getting an error
Bob: may want to restate it a little bit
… "what in the various adaptive formats needs to be reflected in the mime type to support the existing HTML5 spec behaviors"
… need to talk about specifics in the protocols/formats that would identify this
… we need to get down to specifics
*problems with Bob's audio*
Jason Lewis: we have apps where we need to find out whether we *can* use the Video tag on a particular device
… want to get a list of supported playback types from the UA
… maybe inject flash instead, or no video container at all
Bob: in HTML5 today there is fallback to object element
… need more than that?
Jason: wrapping in objects until one succeeds works, but rather query an API for supported types
… want the application to make an active decision rather than use fallbacks
… want to query the UA somehow
Bob: do that with a JS function and call canPlayType() to query now
Glenn: that means you have to have a list in mind first
Clarke: is there a precedent for anything similar?
Dave Mays: does that expose an information security issue? "what do you handle" vs "do you handle x"
Jason: does that try to download content at all?
Jason: comfortable with this requirement now
Clarke: point about sniffing may also be relevant. most things in HTML are asked in the form of "do you support x" rather than "what are all the things you support"
… asking for other requirements that should be in this list
… talk about procedure
… when something gets listed in req'ts list, i'll put an indication whether it's "OPEN" issue or not
… will link to an actual Wiki ISSUE
… leave open until we get resolved
… keep dashboard relevant for current topics
… any other topics for today?
… dive into content protection next week, hope to see netflix proposal
<kaz> [ adjourned ]
This is scribe.perl Revision: 1.136 of Date: 2011/05/12 12:01:43 Check for newer version at http://dev.w3.org/cvsweb/~checkout~/2002/scribe/ Guessing input format: RRSAgent_Text_Format (score 1.00) Succeeded: s/Web and TV Interest Group Teleconference/Media Pipeline Task Force Teleconference/ Found Scribe: Dave_Mays Found Scribe: davidmays Inferring ScribeNick: davidmays Scribes: Dave_Mays, davidmays Default Present: glenn, Clarke, Dave_Mays, Kazuyuki.a, MarkW, Kazuyuki.b, Duncan, Narm_Gadiraju, Kazuyuki, Philipp, Mark_Vickers, Bob_Lund, John_Simmons, Jason, +1.503.705.aabb, +1.925.984.aacc, joesteele, Juhani, giuseppe Present: Clarke glenn Dave_Mays MarkW Juhani Bob_Lund John_Simmons Duncan Kazuyuki Philipp Mark_Vickers Jason Narm_Gadiraju Joe_Steele Giuseppe Agenda: http://www.w3.org/2011/webtv/wiki/MPTF/Agenda_Telco_16th_February_2012 Found Date: 16 Feb 2012 Guessing minutes URL: http://www.w3.org/2012/02/16-webtv-minutes.html People with action items: WARNING: Input appears to use implicit continuation lines. You may need the "-implicitContinuations" option.[End of scribe.perl diagnostic output]