Re: Future of SourceType - Call For Consensus?

SourceTypeEnum (and the corresponding sourceType constraint) can specify 
audio or video sources.  MediaSourceEnum (and the corresponding 
MediaSource constraint) specifies only video sources. Otherwise they 
seem to be trying to do the same thing and we certainly don't need both 
of them.

The only question is what we would do if at some point in the future 
some spec wants to be able to specify more complex audio source types.  
I suppose we would let that spec define its own audio enum/constraint 
pair.  That keeps the existing Media Capture spec simple, and wouldn't 
have any dependency on Screen Capture.

However since MediaSourceEnum applies only to video, perhaps it should 
be called VideoSourceEnum.  That makes it clearer that it we want to 
select among different types of audio sources in the future, we will 
define  AudioSourceEnum.



On 8/20/2014 8:07 AM, Harald Alvestrand wrote:
> I've reviewed the thread that came from this, and have also reviewed 
> the spec proposed at
> https://github.com/fluffy/w3c-screen-share
>
> One interesting thing about that proposal is that it does *not* extend 
> SourceTypeEnum - instead it defines a new enum called MediaSourceEnum:
>
> enum MediaSourceEnum {
>     "camera",
>     "browser",
>     "application",
>     "screen"
> };
>
> This seems to underscore the idea that SourceTypeEnum does not have an 
> use case, and we should remove it - if the primary use case suggested 
> for it goes off to do something else rather than using the extension 
> point, that's a hint that we might not need it.
>
> I suggest, based on the discussion and the proposal, that we delete 
> SourceTypeEnum and all references to it from the getusermedia spec, 
> and leave the selection of sources for screen capture to the screen 
> capture spec.
>
> Does that seem reasonable?
>
>
> On 07/04/2014 10:01 AM, Harald Alvestrand wrote:
>> At the moment, we have 3 bugs that touch on SourceType, listed here:
>>
>> https://www.w3.org/Bugs/Public/buglist.cgi?quicksearch=sourcetype&list_id=40270 
>>
>>
>> Reminder: SourceType is this enum:
>>
>> enum SourceTypeEnum {
>>     "none",
>>     "camera",
>>     "microphone"
>> };
>>
>> At the moment, we have no part of the spec that depends on this - the 
>> only thing you can do with it is to read the attribute on a track, 
>> and ask for specific types via a constraint (which is useless for 
>> "none", and only has a single possible value for video and audio 
>> tracks).
>>
>> It's been suggested as a future extension point (such as specifying 
>> "I want a screen capture"), but experience with future extension 
>> points is that it's very easy to get them wrong unless you already 
>> know the extension you want when you design them.
>>
>> We've had very little comment on the bugs so far - so I'm trying for 
>> a call on the list:
>>
>> ***Proposal: SourceType should be removed from getusermedia version 
>> 1.0.***
>>
>> If we don't hear anyone arguing in favour of keeping it for a week 
>> (July 11), we'll take that as permission to remove (there's always 
>> the possibility to reinstate).
>>
>> If we get arguments ..... we'll take it from there.
>>
>>        Harald, chair hat on
>>
>>
>>
>
>

Received on Wednesday, 20 August 2014 15:09:09 UTC