W3C

- DRAFT -

Media and Entertainment IG - Cloud Browser TF

28 Jun 2017

See also: IRC log

Attendees

Present
Alexandra, Colin, Kaz, Chris
Regrets
Chair
Alexandra
Scribe
kaz

Contents


alex: during the previous call
... we had a brief chat on the IG Note
... we can start over with the use cases
... have 2 points

colin: updating the wiki page

alex: quality of experience/service
... also MSE stuff
... let's go through the use case wiki

UI scale

colin: not in a formal description yet
... starting with "UI scale"
... resolution like a scroll bar
... could be scaled down in a cloud browser
... what is different with the cloud browser solution?
... that is the first use case

alex: in your view, what would be the impact for APIs?

colin: you could look up device pixel ratio, etc.
... and user resolution
... prefer using guidelines for this

kaz: possible collaboration between a cloud browser and another screen like a smartphone?
... possibly included in "displayed in another way (e.g. in a PiP)"

colin: yes, but Cloud Browser doesn't know how to send that information (at the moment)

kaz: maybe we need another channel or connection for that purpose

coline: yeah
... so would see existing guidelines for that kind of requirements

alex: possible control channel between the cloud browser and the server
... but we also would see guidelines because this need is not the first one

colin: cloud browser and abstract orchestration layer
... two different levels
... same for the devicePixelRatio as well

alex: we can decide use cases and requirements first
... and then think about what kind of APIs are needed

colin: ok
... let's move ahead

UI visibility timing

colin: "UI visibility timing"
... when does the end user sees the UI screen?
... Since the UI is terminated in the cloud it is hard to tell when the user actually sees it.

alex: interesting

Media capabilities

kaz: fine
... but maybe we should call these topics as "difficulties" or "issues" as the starting point of concrete/detailed use case descriptions

colin: ok
... (move ahead)
... on a cloud browser solution you would also like to know which types are played natively on the client device and which are transcoded.
... some examples of codec

[[

var support = videoElement.canPlayType('type=\'video/mp4; codecs="avc1.42E01E, mp4a.40.2"\); if (support == "probably") console.log("natively supported") else if (support == "virtually") console.log("supported by transcoding")

]]

colin: existing APIs could be extended for cloud browser

Identification

colin: identification is also a problem with cloud browser
... for example, with geolocation api
... how to identify the cloud browser and its device?
... also we need a means to analyze the problems

alex: we need to clarify our requirements and also existing APIs (=gap analysis)

colin: and the WG side should make decision about concrete APIs
... will update these description to generate proper use cases

(chris joins)

chris: will check the minutes
... any concrete expectation from me?

colin: now we're talking about Quality of Service/Experience

kaz: "Quality" could include accessibility. right?

colin: right. but we have another separate section for accessibility

chris: what is the difference between QoE and accessibility?

kaz: maybe we could ask Chris to review all the use cases including QoS/QoE, couldn't we?

colin: indeed related to each other

chris: accessibility/usability viewpoint

colin: "usability" has some specific meaning for broadcasting

alex: there is another viewpoint from telecommunication as well
... QoS may include latency issue
... another question is
... have you thought about latency and packet loss?

colin: have not done yet

alex: ITU recommendation on video quality and how to measure it
... also what is important for each user?
... big issue with operation
... big infrastructure for QoS
... the operator sees problems on what QoS is

colin: need to clarify what is expected for cloud browser UI
... would highlight generic problems within this group

kaz: possible intermediate proxy server for identification topic?

colin: have wide channel use case
... you need to add some information if you have multiple cloud browser devices at the same geolocation

kaz: a possible use case is a collaborative game by multiple users at some specific meeting room

colin: need a mechanism of communication with each other for multi-user game

alex: broadcasting vs unicasting

colin: we should clarify delivery mechanism for each specific use case

MSE issues

alex: we have problems with MSE for Cloud Browser
... how we could adapt MSE for Cloud Browser?

MSE use cases

UC3 Cloud-based MSE support

alex: explains the use case
... MSE is complex. Cloud Browser is also complex
... the mixture of them would be more complex
... we have a lot of steps within this UC
... split into 4 sub use cases
... 3.1 Execution of XHR

[[

1. CB initiates a session with the CB client (session id, user id)

2. The CB client requests a web application that uses MSE for video delivery

3. CB executes the web application: CB parses the html and css data, web app sets the HTMLMediaElement

4. The web application requests the manifest (mpd, etc.) file and the CB parses it

5. The web application creates mediaSource objects and associates it with HTMLMediaElement

6. mediaSource creates sourceBuffer objects that in turn append media segments into the SourceBuffer array with the appenBuffer method

7. The web application defines the media segment URLs (with byte range params, video chunks id, etc.)

8. The web application sends the XMLHTTP Requests towards the media host to request these media segment

9. As the media segments are downloaded by the client, these XMLHTTP Requests are forwarded to the CB client by the CB.

]]

alex: cloud browser doesn't know what request is being executed

[[

Gap1: in MSE the Web browser currently does not have any metadata information about the type of XHRs and therefore does not have any mechanisms to select the required ones.

]]

colin: can understand the need but not sure how to implement it

kaz: one possibility is bringing the requirements to the WoT WG later

alex: problem with buffering, media segment, etc.
... would people to review this use case

colin: will go through this uc again

Accessibility

chris: still struggling with what is expected for accessibility for cloud browser

colin: maybe there are 2 different levels: OS level and DOM level

chris: any suggestions?

colin: for desktop PC browsers, there is alternative text
... how can we do that with cloud browser?
... there is an "Introduction" page: https://www.w3.org/2011/webtv/wiki/Main_Page/Cloud_Browser_TF/Introduction_cloud_browser

chris: each kind of operation
... how to maximize the availability

kaz: currently the topics are rather list of keywords
... maybe you could elaborate concrete use case description, Chris
... also we could see the Media Accessibility User Requirements as the starting point: https://www.w3.org/TR/media-accessibility-reqs/

TPAC 2017

colin: are you going to attend TPAC 2017?

alex: still checking

kaz: Media & Entertainment IG will have its f2f meeting on Monday, Nov. 6th
... and we're expected to have a section on cloud browser there

colin: agenda decided?

kaz: the IG Chairs are generating the initial agenda
... and will have a whole IG call shortly

Next call

alex: next call in 2 weeks

[adjourned]

Summary of Action Items

Summary of Resolutions

[End of minutes]

Minutes formatted by David Booth's scribe.perl version 1.152 (CVS log)
$Date: 2017/06/28 15:37:01 $