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RE: Fwd: Media Capture and Streams Last Call review

From: Hofmann, Bill <bill.hofmann@dolby.com>
Date: Thu, 16 Apr 2015 00:31:34 +0000
To: Chris Wilson <cwilso@google.com>, Joseph Berkovitz <joe@noteflight.com>
CC: Audio Working Group <public-audio@w3.org>
Message-ID: <64062547EA367442A557186FFBAD8FD7122B3D57@DLB-XCHPW02.dolby.net>
So, speaking for myself, my feedback is that the MediaDeviceInfo result (http://www.w3.org/TR/2015/WD-mediacapture-streams-20150414/#idl-def-MediaDeviceInfo) lacks information that is typically available in the underlying OS implementations that we think would be very helpful for implementations:


·         Channel count and configuration (Mono, Stereo, 5.1, 7.1, etc…)

·         Physical Output (Headphone, Speaker, HDMI, …)

·         Latency (this matters a lot for gaming)

·         Output capabilities (bitstream passthrough vs PCM – relevant in digital media adapter cases (Chromecast, etc))

It is perhaps sufficient from a user interface point of view to have a string to display, but for a program to be able to either adapt to the user selection or to guide the user selection, these are pretty important characteristics, at least in some use cases.  Many if not most of the host OSes that user agents run on expose these sorts of output device characteristics.

Knowing relevant info on the input side is also relevant.

-Bill

From: Chris Wilson [mailto:cwilso@google.com]
Sent: Wednesday, April 15, 2015 7:40 AM
To: Joseph Berkovitz
Cc: Audio Working Group
Subject: Re: Fwd: Media Capture and Streams Last Call review


Oops, ignore my crossposting from this morning!  Joe's much more eloquent introduction was what should have been (and was) said.
On Apr 14, 2015 11:30 PM, "Joe Berkovitz" <joe@noteflight.com<mailto:joe@noteflight.com>> wrote:
Hi Group,

This solicitation for feedback is a perfect moment to address once again the problems with audio device identification and access that we had discussed at the last F2F. I have not yet had a chance to look at this latest draft (I'm at a trade show this week), but if you are involved in this issue, could you please examine it as some of the content may have changed. Please post to the group this week if you have any additional observations on this subject after reading the draft, and we can discuss on tomorrow's conference call.

...Joe

---------- Forwarded message ----------
From: Stefan Håkansson LK <stefan.lk.hakansson@ericsson.com<mailto:stefan.lk.hakansson@ericsson.com>>
Date: Wed, Apr 15, 2015 at 7:31 AM
Subject: Media Capture and Streams Last Call review
To: "rubys@intertwingly.net<mailto:rubys@intertwingly.net>" <rubys@intertwingly.net<mailto:rubys@intertwingly.net>>, "Paul.Cotton@microsoft.com<mailto:Paul.Cotton@microsoft.com>" <Paul.Cotton@microsoft.com<mailto:Paul.Cotton@microsoft.com>>, "mjs@apple.com<mailto:mjs@apple.com>" <mjs@apple.com<mailto:mjs@apple.com>>, "chaals@yandex-team.ru<mailto:chaals@yandex-team.ru>" <chaals@yandex-team.ru<mailto:chaals@yandex-team.ru>>, "art.barstow@gmail.com<mailto:art.barstow@gmail.com>" <art.barstow@gmail.com<mailto:art.barstow@gmail.com>>, "joe@noteflight.com<mailto:joe@noteflight.com>" <joe@noteflight.com<mailto:joe@noteflight.com>>, "matthew.paradis@bbc.co.uk<mailto:matthew.paradis@bbc.co.uk>" <matthew.paradis@bbc.co.uk<mailto:matthew.paradis@bbc.co.uk>>, "hillbrad@fb.com<mailto:hillbrad@fb.com>" <hillbrad@fb.com<mailto:hillbrad@fb.com>>, "dveditz@mozilla.com<mailto:dveditz@mozilla.com>" <dveditz@mozilla.com<mailto:dveditz@mozilla.com>>, "w3c@adambarth.com<mailto:w3c@adambarth.com>" <w3c@adambarth.com<mailto:w3c@adambarth.com>>, "Virginie.GALINDO@gemalto.com<mailto:Virginie.GALINDO@gemalto.com>" <Virginie.GALINDO@gemalto.com<mailto:Virginie.GALINDO@gemalto.com>>, "yosuke@funahashi.cc<mailto:yosuke@funahashi.cc>" <yosuke@funahashi.cc<mailto:yosuke@funahashi.cc>>, "giuseppep@opera.com<mailto:giuseppep@opera.com>" <giuseppep@opera.com<mailto:giuseppep@opera.com>>, "mark_vickers@cable.comcast.com<mailto:mark_vickers@cable.comcast.com>" <mark_vickers@cable.comcast.com<mailto:mark_vickers@cable.comcast.com>>, "runnegar@isoc.org<mailto:runnegar@isoc.org>" <runnegar@isoc.org<mailto:runnegar@isoc.org>>, "tjwhalen@google.com<mailto:tjwhalen@google.com>" <tjwhalen@google.com<mailto:tjwhalen@google.com>>, "daniel.appelquist@telefonica.com<mailto:daniel.appelquist@telefonica.com>" <daniel.appelquist@telefonica.com<mailto:daniel.appelquist@telefonica.com>>, "peter.linss@hp.com<mailto:peter.linss@hp.com>" <peter.linss@hp.com<mailto:peter.linss@hp.com>>, "janina@rednote.net<mailto:janina@rednote.net>" <janina@rednote.net<mailto:janina@rednote.net>>
Cc: "Chairs@w3.org<mailto:Chairs@w3.org> Chairs" <Chairs@w3.org<mailto:Chairs@w3.org>>


The WebRTC and Device APIs Working Groups request feedback on the Last
Call Working Draft of Media Capture and Streams, a JavaScript API that
enables access to cameras and microphones from Web browsers as well as
control of the use of the data generated (e.g. rendering what a camera
captures in a html video element):
http://www.w3.org/TR/2015/WD-mediacapture-streams-20150414/<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.w3.org_TR_2015_WD-2Dmediacapture-2Dstreams-2D20150414_&d=AwMFaQ&c=lI8Zb6TzM3d1tX4iEu7bpg&r=qzKCNHFKJMzZBJ52at1DkA-_8TPxvcij-zS_VXs8c5A&m=PiflLuM3beNCS--ttpIt8UwALAoEwAf9VIZE85iJw6c&s=sfsZCzZoSM7S5DC1drdCbdI-pmtuCci4S5cv37zmIic&e=>

The groups have identified the following other W3C Working Groups as
likely sources of feedback:

- HTML Working Group, especially the HTML Media Task Force, as our API
extends the HTMLMediaElement interface and defines a new type of media
input via MediaStream

- WebApps Working Group, especially on the overall usage of Web IDL and
the definition of error handling
Audio Working Group, as the Web Audio API builds upon the MediaStream
interface

- WAI Protocol and Formats Working Group, especially on the impact of
the user consent dialog and the applicability of the indicators of
device usage in assistive tools

- Web and TV Interest Group, as the manipulation of media input can be
relevant to some of their use cases (e.g. glass to glass)

- Web App Security Working Group, especially on our links between
secured origins and persistent permissions, and our current policy with
regard to handling access to this "powerful feature"

- Web Security Interest Group, especially on our security considerations
Privacy Interest Group, as access to camera and microphone has strong
privacy implications

- Technical Architecture Group, for an overall review of the API,
especially the introduction of the concept of a IANA registry-based
constraints system, the use of promises, and our handling of persistent
permissions

We naturally also welcome feedback from any other reviewers.

The end of last call review for this specification is set to May 15
2015; should that deadline prove difficult to meet, please get in touch
so that we can determine a new deadline for your group.

As indicated in the document, comments should be sent to the
public-media-capture@w3.org<mailto:public-media-capture@w3.org> mailing list.

Thanks,

Frederick Hirsch, Device APIs Working Group Chair,
Harald Alvestrand and Stefan Hakansson, WebRTC Working Group Chairs and
Media Capture Task Force Chairs



--
.            .       .    .  . ...Joe

Joe Berkovitz
President

Noteflight LLC
Boston, Mass.
phone: +1 978 314 6271<tel:%2B1%20978%20314%206271>
www.noteflight.com<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.noteflight.com&d=AwMFaQ&c=lI8Zb6TzM3d1tX4iEu7bpg&r=qzKCNHFKJMzZBJ52at1DkA-_8TPxvcij-zS_VXs8c5A&m=PiflLuM3beNCS--ttpIt8UwALAoEwAf9VIZE85iJw6c&s=jbtvviX_pOtKvdia38O5v3FUP4LR2-J9kds0QfSE76Q&e=>
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Received on Thursday, 16 April 2015 00:32:58 UTC

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