W3C home > Mailing lists > Public > public-audio@w3.org > April to June 2015

Re: Media Capture and Streams Last Call review

From: Stefan Håkansson LK <stefan.lk.hakansson@ericsson.com>
Date: Wed, 22 Apr 2015 05:24:26 +0000
To: Joe Berkovitz <joe@noteflight.com>, Audio Working Group <public-audio@w3.org>
Message-ID: <1447FA0C20ED5147A1AA0EF02890A64B1D1F21E3@ESESSMB209.ericsson.se>
Many thanks for providing valuable feedback!

On 21/04/15 20:59, Joe Berkovitz wrote:
> Hello Stefan,
>
>
> Thank you for your recent solicitation of feedback to on the Media
> Capture and Streams API, which I passed to the Web Audio Working Group.
>
>
> The Web Audio WG so far has identified one key item that we would like
> to see addressed. The MediaDeviceInfo result from enumerateDevices()
> (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 -- it will be very low for
> on-board hardware, perhaps quite high for wireless audio bridging like
> Apple TV)____
>
> __·__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 and default the user selection, the above 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. ____
>
>
> Aside from the difficulty with enumerating devices, there is also
> perhaps a need to make it possible for applications to query the set of
> available devices with respect to the above charateristics.
> MediaTrackConstraints and MediaTrackSettings do not currently  include
> constraint attributes that map to items in the above list. And even if
> they do, arriving at a practical goodness-of-fit metric that can be
> generalized across a spectrum of audio apps may be difficult.
>
>
> The same concerns apply to the set of input devices.__
>
> __ __
>
> Please let us know if this issue makes sense to the group and can be
> addressed within the timeframe of the coming run-up to a Last Call WD.
> We'd be happy to arrange some sort of inter-WG call to try to make
> progress on this together.
>
>
> Thank you!
>
>
> Best regards,
>
>
> Joe Berkovitz
>
> co-chair Web Audio WG
>
>
> *Noteflight LLC*
> Boston, Mass.
> phone: +1 978 314 6271
> www.noteflight.com <http://www.noteflight.com/>
> "Your music, everywhere"
>
> On Wed, Apr 15, 2015 at 1:31 AM, Stefan Håkansson LK
> <stefan.lk.hakansson@ericsson.com
> <mailto:stefan.lk.hakansson@ericsson.com>> wrote:
>
>     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/
>
>     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
> www.noteflight.com <http://www.noteflight.com>
> "Your music, everywhere"
Received on Wednesday, 22 April 2015 05:25:01 UTC

This archive was generated by hypermail 2.3.1 : Wednesday, 22 April 2015 05:25:02 UTC