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Labels, IDs and uniqueness (Re: New version of editors draft released (20121212))

From: Harald Alvestrand <harald@alvestrand.no>
Date: Mon, 17 Dec 2012 13:22:40 +0100
Message-ID: <50CF0E90.1090203@alvestrand.no>
To: public-webrtc@w3.org
Changing subject line again....

I think the difference in the two is not so much how it is generated, 
but what its uniqueness guarantee is.

I think the "id" is guaranteed to be unique across all tracks in some 
context (in a PC? In an UA? in a MediaStream? For tracks, that depends 
on what we decide happens to the "id" when a track is created from 
another track - I'd prefer a new "id", which lets them be UA-wide unique).

The "label" is intended to be human readable, and is not guaranteed to 
be unique in any context.

My take.

On 12/17/2012 10:27 AM, Adam Bergkvist wrote:
> On 2012-12-14 14:27, Dan Burnett wrote:
>> On Dec 14, 2012, at 4:41 AM, Adam Bergkvist wrote:
>>> On 2012-12-13 14:59, Dan Burnett wrote:
>>>> I agree that we decided to add "id". I don't agree with
>>>> removing "label".  My understanding from the f2f meeting was that
>>>> we would end up with both MediaStream and MediaStreamTrack
>>>> objects having both "id" (machine-generated) and "label"
>>>> (human-generated) attributes.
>>> I remember us talking about the confusing regarding label meaning
>>> something on MediaStream and something else on MediaStramTrack, but
>>> I don't really recall the exact resolution.
>>> This edit was really a rename of what you refer to as the
>>> "machine-generated" identifier from "label" to "id" to align with
>>> MediaStreamTrack. We've never had a "human-generated" identifier on
>>> MediaStream so it hasn't been removed. :)
>>> I'm not really convinced we need a human settable identifier on
>>> MediaStream unless it's transported over a p2p connection (and we
>>> have a use-case for that). If you want to assign a custom label to
>>> a MediaStream on the local side you can simply add as many new
>>> properties to it as you like (myStream.label = "Web Cam & headset
>>> mic"; ).
>> As long as MediaStream and MediaStreamTrack have the same (one or
>> two) attributes, I'm happy.  I don't see any more need for a
>> human-generated label on a MediaStreamTrack than on a MediaStream, by
>> your argument above, and yet I believe we are keeping label on
>> MediaStreamTrack.  They should be consistent.
> As Martin pointed out in an other mail, it may be the wording 
> "human-generated" that is part of the confusion here. Both label and 
> id are generated by the UA (on track), but one is nicer to read for a 
> humans (label: "USB Camera 1" comared to id: 124a1ea42ae4...)
> I don't have anything against a label on MediaStream-level, I just 
> don't know what it should say. A track represents one device, so in 
> that case the label can describe the device. A stream, on the other 
> hand, may represent everything from zero to n devices. What should the 
> label be there? Should it change if more tracks are added to the stream?
> In my reasoning above, I'm still talking about a label of the kind 
> that track has: UA generated, but human readable. Is that what you 
> mean as well or do you mean really human generated (i.e. not readonly)?
> Regarding consistency with one or two properties, I don't think we 
> need to have the same attributes describing streams and tracks since 
> they represent totally different things. A label attribute on both 
> levels may even be more confusing since they can't mean the same thing.
> /Adam
Received on Monday, 17 December 2012 12:23:12 UTC

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