W3C home > Mailing lists > Public > public-media-capture@w3.org > October 2012

Re: Settings API Proposal v3 feedback summary

From: Stefan Hakansson LK <stefan.lk.hakansson@ericsson.com>
Date: Thu, 4 Oct 2012 14:58:46 +0200
Message-ID: <506D8806.6010701@ericsson.com>
To: "public-media-capture@w3.org" <public-media-capture@w3.org>
On 10/03/2012 03:10 AM, Travis Leithead wrote:
> V4 is now ready. I've posted it on Mercurial for easier reading:
> http://dvcs.w3.org/hg/dap/raw-file/tip/media-stream-capture/proposals/SettingsAPI_proposal_v4.html
> Thanks! Looking forward to your continued feedback.


many thanks for putting this together. I think that overall I like this 
a lot.

Just to make sure I got the main things right, my understanding is:

* the getUserMedia does not deliver a LocalMediaStream any more, instead 
it is more of a "gate", which once opened leads to the UA building up 
"DeviceListAccess" lists

* these lists are "live", devices can come and go, the user more 
approves the use of video or/and audio and not specific devices

* to use a device, the app would have to use the MediaStream constructor 
to build a MediaStream (which can then be consumed by a video element, a 
PeerConnection, ...) from the devices in the DeviceListAccess list

My conclusion thus far: I think it is fine that the app has to construct 
a MediaStream from device tracks (rather than getting a LocalMediaStream 
that is ready to use). It is a bit more cumbersome, but not that much. 
I'm a bit more hesitant to that new devices just populate the 
"DeviceListAccess" and can be used. I have a couple of issues with this:

1. Even if the user is OK with video from a cam facing one way it is not 
certain that she/he would be OK with sharing another view (and I think 
the discussion in WhatWG ages ago said that the user should have to 
manually select the devices that the app could use just like for the 
File API to avoid accidental leak of privacy)

2. For devices where the underlying system cannot resolve camera 
direction (front, back) the old model allowed the app to e.g. have a 
button "select a front facing cam" which when clicked issue 
"getUserMedia". This will be more difficult in your proposal if I 
understand correctly (I guess that the app could display the video of 
every cam in a small video element and ask the user to click on the 
right one though - so this may be a minor issue, except for:)

3. When will the devices in the "DeviceListAccess" be reserved (stopping 
other web or native apps from using them)? When they are added to the 
list or when they are used? There was a clear model for this with 
getUserMedia. (And even if they are not reserved until used, there is 
the risk that the app uses all of them to enable the user to select the 
right one, and then never releases them). And when would htey be released?


Apart from those issues, that perhaps we can find a way around, I like 
the proposal a lot. Some minor comments:

Section 1.1: As already stated, I'm not sure that the user giving OK to 
video is the same as allowing any camera to be used. I guess this is a 
privacy and usability question that needs to be discussed more.

Section 2.1.1: Should not "frameRate" also be (readonly) attribute for 

Regarding the Setting/retrieval application, my understanding is that a 
request would lead to that the constraints for the device in question 
are changed. Correct? Does this also mean that the 
constrainterror/success events could be fired as a result?


>> -----Original Message-----
>> From: Travis Leithead
>> Sent: Monday, October 1, 2012 4:37 PM
>> To: public-media-capture@w3.org
>> Subject: Settings API Proposal v3 feedback summary
>> Before preparing the 4th version of the settings API proposal, I thought
>> it would be nice to step back and summarize the feedback received on v3.
>> I've not been as responsive to responding to individual threads, so I'm
>> using this one as an opportunity to aggregate all the feedback into one
>> location.
>> There was lots of positive responses. Thank you!
>> I have a v4 that I'll be releasing shortly, so stay tuned.
>> -Travis
>> 1  Liked the approach/heading in the right direction [Rich-2] [Stefan-1]
>> [Adam-1]
>> 2  Are all the various dictionaries values read/write or read-only?
>> [Stefan-1]
>> 3  Should the constraints/settings be inlined in the spec? (No strong
>> preference) [Stefan-1]
>> 4  Is this proposal and constraints applied to gUM complimentary? [Stefan-
>> 1]
>> 5  Establishes a nice "source-of-track" pointer [Randell-1]
>> 6  Derivative of an earlier proposal (suggested in [Randell-2]?)
>> 7  Doesn't solve multiple consumers competing for changing settings
>> [Randell-1] (clarified by [Stefan-2/3])
>> 8  Forces all tracks that want changes to have a MediaDevice
>> (PeerConnection, Video element src) [Randell-1] [Stefan-2]
>> 9  Proposal for unified device/track concept (duck-typing) [Rich-2]
>> (comments [Travis-2])
>> 10 Liked the prior proposal with immutable track lists over the devices-
>> based LMS [Adam-1] [Adam-3]
>> 11 takePicture(); how is it related to regular media stream recording?
>> [Adam-1]
>> 12 Can the *Info dictionaries be exposed to gUM for early device
>> filtering? [Adam-1]
>> 13 Should align with PeerConnection track ideas/ track-subtypes [Adam-2]
>> 14 Additional settings requested [Giridhar-1]
>> 15 Proposal on how to scope what settings we expose [Rich-1]
>> 16 Idea on how to consolidate/group the settings [Josh-1/2] [Jim-1]
>> [Travis-1]
>> 17 How do we define interoperable settings (how do we test them)?
>> [Frederick-1] [Jim-2]
>> 18 How should UA's optionally surface device-specific settings? [Jim-2]
>> 19 Re-consider one track-per-type in gUM? [Adam-3]
>> 20 Don't hide capabilities behind get/changeSettings APIs [Rich-2]
>> (comments [Travis-2])
>> [Stefan-1] http://lists.w3.org/Archives/Public/public-media-
>> capture/2012Sep/0000.html
>> [Stefan-2] http://lists.w3.org/Archives/Public/public-media-
>> capture/2012Sep/0002.html
>> [Stefan-3] http://lists.w3.org/Archives/Public/public-media-
>> capture/2012Sep/0003.html
>> [Randell-1] http://lists.w3.org/Archives/Public/public-media-
>> capture/2012Sep/0001.html
>> [Randell-2] http://lists.w3.org/Archives/Public/public-media-
>> capture/2012Aug/0044.html
>> [Adam-1] http://lists.w3.org/Archives/Public/public-media-
>> capture/2012Sep/0004.html
>> [Adam-2] http://lists.w3.org/Archives/Public/public-media-
>> capture/2012Sep/0006.html
>> [Adam-3] http://lists.w3.org/Archives/Public/public-media-
>> capture/2012Sep/0005.html
>> [Giridhar-1] http://lists.w3.org/Archives/Public/public-media-
>> capture/2012Sep/0008.html
>> [Rich-1] http://lists.w3.org/Archives/Public/public-media-
>> capture/2012Sep/0013.html
>> [Rich-2] http://lists.w3.org/Archives/Public/public-media-
>> capture/2012Aug/0144.html
>> [Josh-1] http://lists.w3.org/Archives/Public/public-media-
>> capture/2012Sep/0017.html
>> [Josh-2] http://lists.w3.org/Archives/Public/public-media-
>> capture/2012Sep/0020.html
>> [Jim-1] http://lists.w3.org/Archives/Public/public-media-
>> capture/2012Sep/0018.html
>> [Jim-2] http://lists.w3.org/Archives/Public/public-media-
>> capture/2012Sep/0022.html
>> [Travis-1] http://lists.w3.org/Archives/Public/public-media-
>> capture/2012Sep/0019.html
>> [Travis-2] http://lists.w3.org/Archives/Public/public-media-
>> capture/2012Aug/0146.html
>> [Frederick-1] http://lists.w3.org/Archives/Public/public-media-
>> capture/2012Sep/0021.html
>> Additionally, I'm thinking about the following:
>> * How often will settings be changed in bulk vs. one-at-a-time (with user
>> feedback)?
>> * How will developers know to request another device via gUM? (how will
>> they know that more devices are available)?
Received on Thursday, 4 October 2012 12:59:18 UTC

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