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

Review of scenarios doc (Jan 19 version)

From: Harald Alvestrand <harald@alvestrand.no>
Date: Fri, 20 Jan 2012 14:54:52 +0100
Message-ID: <4F19722C.9060504@alvestrand.no>
To: public-media-capture@w3.org
I have gone through the scenarios doc (version of Jan 19, sorry for not 
updating), and have some comments. This is transcribing from my 
marked-up copy, so forgive me for commenting in serial order rather than 
in order of importance.

Overall, I'm happy with the document as it stands!

- Section 1, scope: I think that you should not claim that networking 
scenarios are out of scope for this task force, rather they should be 
included by reference; what comes out of the task force must satisfy 
both the scenarios described here and the scenarios described in the 
WebRTC scenarios doc.

- Section 2.1: Permisssions - you are assuming, both here and in the 
other scenarios, that ask-before-use is the only possible permission 
mechanism. This is not aligned with draft-ietf-rtcweb-security-01 
section A.3.2, where a means of granting permanent access to a 
particular service is a MUST. This is to avoid training the user to 
"always click through", which is a perennial problem with security dialogs.

- Section 2.2 Election podcast - you don't specify whether the recording 
is happening locally or at a server. These alternatives might be 
mentioned under "Variations" - the Hangouts On Air service is very close 
to the proposed service, and does recording at server.

- Section 2.3 Find the ball - if you really want low resolution, 640x480 
might not be a good example.

- Section 2.4 Video diary - one thing I was thinking while reading this 
was Picture-in-Picture approaches - which would feed directly into 
manipulation functions on the stream while it is being recorded. Perhaps 
mention under Variations?

- Section 2.4 Conference call product debate - this seems like a 
videoconference scenario with a recorder. You might want to point to the 
RTCWEB videoconference scenarios (with or without server) for discussion 
about non-recording concepts.

- Section 4 Concepts:
Stream: I suggest you don't define "Stream". That word is used entirely 
too much, with too many meanings. Just don't use it. The text can be 
moved under MediaStream.

Virtualized device: I think this section mixes up the concept of 
shareable devices and devices which have manipulatable state. We can 
have shareable cameras and non-shareable microphones. I suggest finding 
two terms here.

- Section 5.5: Applying pre-processing doesn't require the UA to do it 
if the UA provides a means of presenting a media stream in a known 
format on a known interface, and consume the media stream again after 
transformation that can be done outside the UA. Implementations that do 
this have been demonstrated (face recognizers in JS, for instance).

- Section 5.6.3 Examples. If the canvas functions defined here work 
today, that should be made clear. It's not easy to see now whether these 
are real examples or suggestions for future extensions.

- Section 5.7.1 Privacy. The *developer* is probably not the term you're 
looking for here about who information is exposed to; the developer is 
not involved when an application runs. You might be thinking about the 

That's all my commentary so far!

Received on Friday, 20 January 2012 13:55:30 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 16:26:08 UTC