Re: [rtcweb] Separating stream manipulation from the SDP loudness (Re: Proposed Plan for Usage of SDP and RTP)

Peter Thatcher <pthatcher@google.com> Sun, 10 March 2013 05:02 UTC

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Date: Sat, 9 Mar 2013 21:02:11 -0800
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From: Peter Thatcher <pthatcher@google.com>
To: Harald Alvestrand <harald@alvestrand.no>
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Subject: Re: [rtcweb] Separating stream manipulation from the SDP loudness (Re: Proposed Plan for Usage of SDP and RTP)
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There's a difference between the resolution that you open the camera at and
the resolution you send over the network at.  Does the current constraints
API let you capture at one resolution and send at another?  Also, does it
let you change the send resolution on the fly?

These are important controls that, as far as I know, are not currently
supplied to the application.  They could potentially be supplied by SDP,
new methods, or as you suggest, perhaps even as some kind of constraint.
But I don't think they are currently provided.
On Mar 9, 2013 7:54 PM, "Harald Alvestrand" <harald@alvestrand.no> wrote:

> As usual, I'm trying to use subject line change in order to achieve some
> separation of concerns...
>
> On 03/07/2013 10:22 PM, Silvia Pfeiffer wrote:
>
>> Agreed, but it's also not sufficient. SDP is not "programmer friendly"
>> enough because it has too many details that are protocol-details only and
>> it's too hard to see the semantic bits in SDP and ignore the rest.
>>
>> For example: the programmer wants to say - I want to get this video
>> resolution, this audio bitrate & channels, I want to use this camera and
>> this microphone for this call. Having to manipulate SDP directly for this
>> is a programmer's nightmare.
>>
>
> I think we've been over exactly those pieces, and our current proposed
> solution is called the Media Stream API and the constraints mechanism - and
> they have exactly nothing to do with SDP, or even with PeerConnection.
>
> I don't think we've got it to be "unproblematic" yet, but also, I don't
> think SDP, JSON or even the offer-answer model is either the problem or the
> solution on this set of functionalities.
>
> Or did I misunderstand something basic?
>
>                Harald
>
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