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RE: scope of media stream recording and capture specification(s)

From: Jim Barnett <Jim.Barnett@genesyslab.com>
Date: Wed, 6 Feb 2013 19:06:37 +0000
To: Glenn Adams <glenn@skynav.com>, "public-media-capture@w3.org" <public-media-capture@w3.org>
CC: W3C Web and TV <public-web-and-tv@w3.org>
Message-ID: <57A15FAF9E58F841B2B1651FFE16D28101E9D1@GENSJZMBX03.msg.int.genesyslab.com>
I agree that we need to clarify the relationship between our specs.  You are right that the GetUserMedia document describes how to create a local MediaStream.  However the WebRTC specification (http://dev.w3.org/2011/webrtc/editor/webrtc.html) allows you to create a remote MediaStream (one that’s getting its data from a remote peer.)  MediaRecorder should work with either type of media stream, so it’s not limited to local streams.

We do intend to coordinate with the Downloading and Recording TF.  There will need to be discussion of how many of their use cases are within our scope (and how to ensure that what we do is compatible with their solutions to the things that are outside our scope.)

-          Jim

From: Glenn Adams [mailto:glenn@skynav.com]
Sent: Wednesday, February 06, 2013 11:49 AM
To: public-media-capture@w3.org
Cc: W3C Web and TV
Subject: scope of media stream recording and capture specification(s)

As presently specified, the MediaStream Recording specification [1] is characterized as a generic recording API without limitation of scope. However, the abstract states:

This document defines a recording API for use with MediaStreams as defined in Media Capture and Streams [GETUSERMEDIA<http://www.w3.org/TR/2013/WD-mediastream-recording-20130205/#bib-GETUSERMEDIA>].

In contrast, the reference [GETUSERMEDIA] refers to [2], which states in its introduction:
Access to multimedia streams (video, audio, or both) from local devices (video cameras, microphones, Web cams) can have a number of uses, such as real-time communication, recording, and surveillance.

This document defines the APIs used to get access to local devices that can generate multimedia stream data. This document also defines the stream API by which JavaScript is able to manipulate the stream data or otherwise process it.

In this latter case, the scope is limited to "local devices" such as cameras, phones, etc. In addition, the MediaStream Recording specification [1] defines interface members such as: image{Height,Width}, onphoto, takePhoto, which are clearly oriented to specific kinds of local devices.

As such, I would like to see the title and description of MediaStream Recording [1] changed to reflect its application to local devices. For example,

  *   change title to "MediaStream Recording of Local Input Devices"
  *   change short name from mediastream-recording to mediastream-local-device-recording
  *   change abstract and introduction to make clear this scope is limited to local devices
Similar changes are suggested for the title and short name of Media Capture and Streams to make it clear to readers that other uses are not in scope, such as capture and recording of non-local media stream.

As an alternative, the scope of these two specifications could be explicitly widened to include capture and recording of non-local media streams, in which case, the work would need to be coordinated with the Web & TV IG's Recording and Downloading Media Task Force [3].


[1] http://www.w3.org/TR/2013/WD-mediastream-recording-20130205/

[2] http://www.w3.org/TR/2012/WD-mediacapture-streams-20120628/

[3] http://www.w3.org/2011/webtv/wiki/Download

Received on Wednesday, 6 February 2013 19:07:05 UTC

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