- From: Bryan Sullivan <blsaws@gmail.com>
- Date: Mon, 10 Oct 2011 19:44:47 -0700
- To: 이현재 <hj08.lee@lge.com>
- Cc: public-web-and-tv@w3.org
In the recent F2F (http://www.w3.org/2011/09/22-webtv-minutes.html), I
noted that there was consensus on these "items to standardize" related
to adaptive streaming:
1) the ability for the Web app to specify ABR parameters ("The video
element interface must support specification of adaptive bit rate
parameters, e.g. maximum bit rate to be used for playback.")
2) the ability for the Web app to receive events/errors about the
status of ABR streams, e.g.:
"jan: the statistics could be very critical based on the algorithms"
...
"clarke: will add statistics point as the third item here. any objections?"
"all: agree"
I believe these needs are basic to support for adaptive streaming,
which should survive the choice for an underlying facility e.g. DASH.
In order for the user (through the app, or by the app on the user's
behalf) to be able to make choices about quality/compatibility, there
needs to be awareness that an adaptive facility is in use, and some
degree of control/visibility to it.
I believe these are important requirements, and I suggest to retain
them for further discussion, as we consider what adaptive streaming
facilities can be specified in a W3C profile.
Bryan Sullivan | AT&T
2011/10/10 이현재 <hj08.lee@lge.com>:
> Hi all,
>
> Might I ask a question or give my opinion regarding R6?
> According to the meeting minutes, Adaptive bitrate format is dropped out.
> Does it mean we no more discuss on the format, so called manifest? I'm
> confused that dropping off is equivalent to there being no discussion
> anymore on this. we don't have to start from the scratch as some candidate
> formats are available outside W3C, for example, the famous DASH, and even
> some proprietary solutions. we can adapt video tag to support adaptive
> streaming without making new one.
> I guess some discussion is necessary such as what technology will be the
> main framework of video tag extension. Manifest could be represented by xml
> format or JavaScript friendly JSON or whatever. To what extent the manifest
> should support is also a good discussion topic.
>
> What we want to achieve here in W3C is to have browser based single
> streaming solution that is available to TV platform. The keyword here is
> browser and single. From the standpoint of TV manufacturers and content
> owners, we need single solution because we are strayed among too many
> seemingly same solutions.
>
> As a start, it does not necessarily to have complicated use cases. Starting
> from the very small, very fundamental thing is reasonable. For example,
> free VOD content will be a good starting point. After successful migration
> from normal video tag to adaptive streaming video tag, we can add more rich
> features to the media.
>
> Can I hear from other's viewpoint? I would like to listen to other's
> opinion as much as possible.
>
> Best regards,
> HJ
>
>
> -----Original Message-----
> From:
> Sent: 없음
> To: public-web-and-tv@w3.org
> Subject: [MEDIA_PIPELINE_TF] Minutes teleconference call 2011-10-06
>
> Hi,
>
> The minutes of yesterday's Media Pipeline Task Force call are available at:
> http://www.w3.org/2011/10/06-webtv-minutes.html
>
> ... and copied as raw text below.
>
> Discussions covered requirements R3 to R9, both included. A possible quick
> summary:
> - R6 and R9 are already covered with existing technologies, so are probably
> going to be dropped.
> - R10/R11, R7/R8, and R4/R5 would benefit from parallelization. Clarke will
> work on it.
>
> Please check minutes for details I managed to capture.
>
> Thanks,
> Francois.
>
> -----
> Media Pipeline Task Force Teleconference
>
> 06 Oct 2011
>
> See also: [2]IRC log
>
> [2] http://www.w3.org/2011/10/06-webtv-irc
>
> Attendees
>
> Present
> John_Simmons, Franck_Denoual, Eric_Winkelman, Hiroyuki_Aizu,
> Clarke_Stevens, Jan_Lindquist, Duncan_Rowden, Kaz_Ashimura,
> Francois_Daoust, Mark_Watson, Mark_Vickers, Bob_Lund,
> Russell_Berkoff, Steven_Wright, Paul_Caporn
>
> Regrets
> Chair
> Clarke
>
> Scribe
> francois
>
> Contents
>
> * [3]Topics
> 1. [4]R3. Midstream Modification of Track Elements
> 2. [5]R4. Content Authorization Parameters
> 3. [6]R5. Content Authorization Failure
> 4. [7]R6. Adaptive Bit Rate Format Support
> 5. [8]R7. Adaptive Bit Rate Parameters (and R8. Adaptive Bit
> Rate Feedback)
> 6. [9]R9. Security and Digital Rights Management
> Identification
> * [10]Summary of Action Items
> _________________________________________________________
>
> Clarke: got to requirement 2 last week. Let's move on from there.
> ... We can get through the rest of the less controversial ones
> today.
> ... Next week, we can get to adaptive streaming, then the week after
> that to the digital rights requirements.
> ... Then that's TPAC.
> ... Less concerned that we're not ready by TPAC. We want to show
> that we have requirements at TPAC. From the F2F, we do have general
> agreement about use cases and requirements even it not perfect.
> ... Main goal of TPAC is to bring these to WG.
>
> John: is the intent to take all of them to TPAC or some of them?
>
> Clarke: We only want to have standardized those things that can't be
> done today.
>
> R3. Midstream Modification of Track Elements
>
> <Clarke> R3:
> [11]http://www.w3.org/2011/webtv/wiki/MPTF/MPTF_Requirements#R3._Mid
> stream_Modification_of_Track_Elements
>
> [11]
> http://www.w3.org/2011/webtv/wiki/MPTF/MPTF_Requirements#R3._Midstream_Modif
> ication_of_Track_Elements
>
> Clarke: ability to change, add, remove track element in the middle
> of a stream.
> ... From some discussion, maybe removing them is not necessary.
>
> Bob: Changes are going into HTML5 spec as we speak to add this
> capability.
> ... Ian Hickson is leaving the door open to track removal if a use
> case comes for that.
> ... We agree that it's difficult to a) know when a track is gone,
> and b) do something useful with it.
>
> markW: Potential problem if a track comes back?
>
> Bob: It wouldn't get added as a new one.
>
> markW: How would you know it's come back?
>
> Bob: you'd look at cues.
>
> markW: What about audio?
> ... [example with English track]
> ... Was planning to comment to HTML WG about that.
>
> Russell: Similar comment, if you don't know when a track's gone,
> hard to see when a track comes back.
> ... The argument goes that in order for you to rewind, you need to
> have them available. Broadcast does not support rewind, so they
> should reflect what is available.
>
> Bob: Didn't see anything in the bug's response that it was
> specifically about seeking.
>
> Russell: maybe I read through the lines here.
> ... How do I have my default language, and over time want to switch
> to another default. If I don't know when a track is removed, I can't
> implement a selection mechanism based on preferences.
>
> MarkW: valid points. Not quite sure what Ian proposes works in the
> end.
> ... What about track numbers when you remove a track?
> ... It has to be treated in a different way. A track that gets
> removed has to remain in the list.
>
> Bob: I think that's right, otherwise you can't reorder track.
>
> Russell: dealt with in OIPF, whether array of tracks is dynamic.
> Ended up with a static array parsed again and again.
>
> Clarke: in the user agent, you then have to "track" which track maps
> to which index.
>
> Russell: Yes.
>
> Clarke: We don't need to change the requirement here necessarily.
> Checking that Jan and Mark's comments are recorded in that bug seems
> the appropriate way to go.
>
> R4. Content Authorization Parameters
>
> R4:
> [12]http://www.w3.org/2011/webtv/wiki/MPTF/MPTF_Requirements#R4._Con
> tent_Authorization_Parameters
>
> [12]
> http://www.w3.org/2011/webtv/wiki/MPTF/MPTF_Requirements#R4._Content_Authori
> zation_Parameters
>
> Clarke: Does this one have a bug?
>
> Bob: No. It is my opinion that this can already be done.
> ... There are a bunch of other issues about parental issues that are
> not covered by the use case.
>
> Clarke: could be covered by the requirement 2 on being able to
> distinguish types of metadata
>
> R2:
> [13]http://www.w3.org/2011/webtv/wiki/MPTF/MPTF_Requirements#R2._Key
> _Metadata_Types
>
> [13]
> http://www.w3.org/2011/webtv/wiki/MPTF/MPTF_Requirements#R2._Key_Metadata_Ty
> pes
>
> John: I took an action item to identify ways to document metadata
> conventions. Two options inside W3C for this kind of documentation:
> community and business groups.
>
> [14]Community and Business Groups
>
> [14] http://www.w3.org/community/
>
> John: this could be the way to get together and work on this kind of
> specification.
>
> Clarke: Do people agree that a community/business group would be the
> place to work on metadata mapping?
>
> Bob: I'll be able to share a few things with this group.
>
> R5. Content Authorization Failure
>
> R5:
> [15]http://www.w3.org/2011/webtv/wiki/MPTF/MPTF_Requirements#R5._Con
> tent_Authorization_Failure
>
> [15]
> http://www.w3.org/2011/webtv/wiki/MPTF/MPTF_Requirements#R5._Content_Authori
> zation_Failure
>
> Clarke: There are a number of reasons that could explain why you
> cannot play a content.
>
> MarkW: This seems to be a narrow example of a more generic problem
> for an error reporting mechanism.
> ... It's a real requirement, but I wonder if we could report on the
> generic error reporting mechanism and enumerate the examples we have
> here as part of it.
>
> Clarke: It may just be the addition of an error, or if the error
> reporting mechanism is not efficient enough.
>
> R6. Adaptive Bit Rate Format Support
>
> R6:
> [16]http://www.w3.org/2011/webtv/wiki/MPTF/MPTF_Requirements#R6._Ada
> ptive_Bit_Rate_Format_Support
>
> [16]
> http://www.w3.org/2011/webtv/wiki/MPTF/MPTF_Requirements#R6._Adaptive_Bit_Ra
> te_Format_Support
>
> MarkW: question here is what do we want to normatively specify here?
> That different solutions be supported?
>
> Bob: We had a couple of specific requests (going through)
>
> Clarke: we have to be able to tell when it is an adaptive streaming
> format.
>
> <mav> I don't think R6 is a gap
>
> <mav> Suggest delete R6 & leave R7 & R8
>
> MarkW: We need to be clear what we're requesting. If it is something
> that can already be satisified with no changes, it doesn't make
> sense to list that as a requirement.
>
> JanL: I'm having the same comment as Mark. Could we flag the
> requirement as needed but nothing needs to be done?
>
> MarkW: If there had been a RF codec, then they would have made a
> requirement. The same applies for adaptive streaming format. If we
> can have DASH be that format, then good. Unclear we can, though.
>
> MarkV: I think it's going to evolve in the next couple of years.
> Even if we have a RF format, I don't think we should put it forward
> yet.
>
> John: HTML WG is being format agnostic to let the market decide
> which format to use.
>
> Clarke: I'm not seeing any strong push to keep that requirement in
> there.
> ... I propose to leave it for a few days. If somebody has some
> strong argument, please make them. Otherwise, I propose to drop it.
>
> R7. Adaptive Bit Rate Parameters (and R8. Adaptive Bit Rate Feedback)
>
> R7:
> [17]http://www.w3.org/2011/webtv/wiki/MPTF/MPTF_Requirements#R7._Ada
> ptive_Bit_Rate_Parameters
>
> [17]
> http://www.w3.org/2011/webtv/wiki/MPTF/MPTF_Requirements#R7._Adaptive_Bit_Ra
> te_Parameters
>
> Clarke: Requirement we captured at the F2F.
>
> JanL: I don't believe there's any mechanism today, e.g. to specify
> the max.
>
> Clarke: Could we say we have a preference of a way to do this?
>
> JanL: My preference would be to have a dialog with WG who will pick
> up this requirement.
> ... I don't have a solution. Many times, you come to W3C with a
> proposal. Here I don't have that, so that's why I suggest a dialog.
>
> MarkV: R7 and R8 are the counterparts of R4 and R5. Parameters in
> the media pipeline, one way for R4 and R7, or the other way for R5
> and R8
>
> JanL: I note we could change "failure" into "feedback", as we need a
> generic feedback mechanism, not only for failures. I agree with
> MarkV that it's a good parallel.
>
> Clarke: suggest to merge them?
>
> JanL: no.
>
> MarkV: I agree on keeping them separate, just adjust the wording to
> use same words.
>
> Clarke: ok, so we covered R8 as well. Going on to security.
>
> R9. Security and Digital Rights Management Identification
>
> R9:
> [18]http://www.w3.org/2011/webtv/wiki/MPTF/MPTF_Requirements#R9._Sec
> urity_and_Digital_Rights_Management_Identification
>
> [18]
> http://www.w3.org/2011/webtv/wiki/MPTF/MPTF_Requirements#R9._Security_and_Di
> gital_Rights_Management_Identification
>
> Clarke: Parallel with R6. Is the conclusion the same?
> ... For instance, if I am to use UltraViolet, can I do it already?
>
> Bob: I don't know for UltraViolet. I think that, in general,
> anything can be encoded as mime type parameters.
>
> Clarke: Do we have anyone from DECE who knows what we might need?
>
> John: DECE does define a very specific encoding format, not just
> down to the container, also pixel details.
> ... Encoding works fine with downloading and adaptive streaming.
> ... Both DASH on-demand and live demand can be encrypted for
> instance. Not DRM specific.
> ... It's a part 12 compliant encoding (ISO base file format).
> ... I don't see additional requirement for HTML
> ... You may want to know whether the device supports a given
> encryption mechanism.
>
> JanL: I was a bit confused as to how it worked in a streaming world
> where you keep sending authentication information.
>
> John: you can have information in the MPD telling if it's DASH,
> where to get the key.
> ... It's just not a file.
> ... In terms of key rotation and things of that nature, that's also
> supported in adaptive streaming as well.
> ... [example of things to do on the production side]
> ... From a browser's point of view, there are lots of reasons why
> you will fail to play content, in particular while dealing with one
> of the DRM subsystems.
> ... Even if you may be able to require a key, you may still end up
> not being able to play the content.
>
> Clarke: Two basic questions. R9, I haven't heard anything here that
> says we cannot do it today.
> ... Second, I hear more stuff to expose parameters in R10.
>
> Bob: Second point, similar issue as adaptive bitrate, but different
> information that needs to be conveyed.
>
> Clarke: Are there some additional security functionalities that need
> to be added beyond being able to expose parameters and provide
> feedback?
>
> MarkW: [scribe missed that]
>
> John: [missed beginning] It's a piece of piece process. You can pick
> up one, such as device identification we're talking right now.
>
> JanL: I just sent a bug proposal based on Hollywood meeting.
> ... If people can comment. ISSUE-18. I'll pick it up next week in
> any case.
>
> John: We have to be very concise in the requirements for 9 and 10.
> For example, DECE Utlraviolet is too vague, because you might have
> different systems that support different functionalities.
>
> JanL: Points I raised previously, retrieval of ? and device
> identification, are these precise enough?
>
> John: I think so.
> ... For some, it's more a matter of user experience issue, where you
> don't want to discover you cannot play after having tried.
>
> JanL: As I presented in Hollywood, this is something Open IPTV Forum
> touched upon.
>
> Clarke: Any work that we can reference is useful, yes.
> ... I'm going to suggest that R6 and R9 are already covered, and
> then I'll try to parallelize R10/R11 with R7/R8 and R4/R5.
> ... Thanks everyone, be active online and talk to you next week!
>
> [Call adjourned]
>
> Summary of Action Items
>
> [End of minutes]
>
>
>
--
Thanks,
Bryan Sullivan
Received on Tuesday, 11 October 2011 02:45:19 UTC