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Re: New API surface - inbound outbound streams/tracks

From: Harald Alvestrand <harald@alvestrand.no>
Date: Tue, 13 Nov 2012 05:48:32 +0100
Message-ID: <50A1D120.8040305@alvestrand.no>
To: public-webrtc@w3.org
On 11/12/2012 03:42 PM, Jim Barnett wrote:
>
> If DTMF is sent via PeerConnection, rather than on a specific track, 
> can there ever be ambiguity about which Track the DTMF is actually 
> sent on,
>
Yes. Any time there is more than one outgoing audio track.
>
> and could this ambiguity ever cause problems on the receiving end?  I 
> can’t personally think of a case where there would be a problem, but 
> it’s worth a few moments’ consideration.
>
I can't personally think of an use case where you need more than one 
audio connection to a legacy PSTN gateway, but my imagination is sharply 
limited about gateways.

> -Jim
>
> *From:*Tommy Widenflycht (ᛏᚮᛘᛘᚤ) [mailto:tommyw@google.com]
> *Sent:* Monday, November 12, 2012 8:08 AM
> *To:* Adam Bergkvist
> *Cc:* public-webrtc@w3.org; Travis Leithead
> *Subject:* Re: New API surface - inbound outbound streams/tracks
>
> You are proposing to introduce an extremely complicated inheritance 
> structure instead of adding 3 or 4 methods on RTCPeerConnection. How 
> is that better? And even more important how is this to be explained to 
> our users?
>
>     pc.addStream(stream);
>
>     var outboundStream = pc.localStreams.getStreamById(stream.id
>     <http://stream.id/>);
>
>     var outboundAudio = outboundStream.audioTracks[0]; // pending syntax
>
>     if (outboundAudio.canSendDTMF)
>
>       outboundAudio.insertTones("123", ...);
>
>
> Having the same MediaStream magically change type feels just weird. To 
> be compared to
>
>     pc.addStream(stream);
>
>     if (pc.canSendDTMF(...))
>
>     pc.sendDTMF(...);
>
>
> I agree that the second example won't win any prices for "Best 
> designed API of the year" but it is infinitely simpler and to the point.
>
> On Fri, Nov 9, 2012 at 1:14 PM, Adam Bergkvist 
> <adam.bergkvist@ericsson.com <mailto:adam.bergkvist@ericsson.com>> wrote:
>
> Hi
>
> A while back I sent out a proposal [1] on API additions to represent 
> streams that are sent and received via a PeerConnection. The main goal 
> was to have a natural API surface for the new functionality we're 
> defining (e.g. Stats and DTMF). I didn't get any feedback on the list, 
> but I did get some offline.
>
> I've updated the proposal to match v4 of Travis' settings proposal [2] 
> and would like to run it via the list again.
>
> Summary of the main design goals:
> - Have a way to represent a stream instance (witch tracks) that are 
> sent (or received) over a specific PeerConnection. Specifically, if 
> the same stream is sent via several PeerConnection objects, the sent 
> stream is represented by different "outbound streams" to provide fine 
> grained control over the different transmissions.
>
> - Avoid cluttering PeerConnection with a lot of new API that really 
> belongs on stream (and track) level but isn't applicable for the local 
> only case. The representations of sent and received streams and tracks 
> (inbound and outbound) provides the more precise API surface that we 
> need for several of the APIs we're specifying right now as well as 
> future APIs of the same kind.
>
> Here are the object structure (new objects are marked with *new*). 
> Find examples below.
>
> AbstractMediaStream *new*
> |
> +- MediaStream
> |   * WritableMediaStreamTrackList (audioTracks)
> |   * WritableMediaStreamTrackList (videoTracks)
> |
> +- PeerConnectionMediaStream *new*
>     // represents inbound and outbound streams (we could use
>     // separate types if more flexibility is required)
>     * MediaStreamTrackList (audioTracks)
>     * MediaStreamTrackList (videoTracks)
>
> MediaStreamTrack
> |
> +- VideoStreamTrack
> |  |
> |  +- VideoDeviceTrack
> |  |   * PictureDevice
> |  |
> |  +- InboundVideoTrack *new*
> |  |   // inbound video stats
> |  |
> |  +- OutboundVideoTrack *new*
> |      // control outgoing bandwidth, priority, ...
> |      // outbound video stats
> |      // enable/disable outgoing (?)
> |
> +- AudioStreamTrack
>    |
>    +- AudioDeviceTrack
>    |
>    +- InboundAudioStreamTrack *new*
>    |   // receive DTMF (?)
>    |   // inbound audio stats
>    |
>    +- OutboundAudioStreamTrack *new*
>        // send DTMF
>        // control outgoing bandwidth, priority, ...
>        // outbound audio stats
>        // enable/disable outgoing (?)
>
> === Examples ===
>
> // 1. ***** Send DTMF *****
>
> pc.addStream(stream);
> // ...
>
> var outboundStream = pc.localStreams.getStreamById(stream.id 
> <http://stream.id>);
> var outboundAudio = outboundStream.audioTracks[0]; // pending syntax
>
> if (outboundAudio.canSendDTMF)
>     outboundAudio.insertTones("123", ...);
>
>
> // 2. ***** Control outgoing media with constraints *****
>
> // the way of setting constraints in this example is based on Travis'
> // proposal (v4) combined with some points from Randell's bug 18561 [3]
>
> var speakerStream; // speaker audio and video
> var slidesStream; // video of slides
>
> pc.addStream(speakerStream);
> pc.addStream(slidesStream);
> // ...
>
> var outboundSpeakerStream = pc.localStreams
>         .getStreamById(speakerStream.id);
> var speakerAudio = outboundSpeakerStream.audioTracks[0];
> var speakerVideo = outboundSpeakerStream.videoTracks[0];
>
> speakerAudio.priority.request("very-high");
> speakerAudio.bitrate.request({ "min": 30, "max": 120,
>                                "thresholdToNotify": 10 });
> speakerAudio.bitrate.onchange = speakerAudioBitrateChanged;
> speakerAudio.onconstraintserror = failureToComply;
>
> speakerVideo.priority.request("medium");
> speakerVideo.bitrate.request({ "min": 500, "max": 1000,
>                                "thresholdToNotify": 100 });
> speakerAudio.bitrate.onchange = speakerVideoBitrateChanged;
> speakerVideo.onconstraintserror = failureToComply;
>
> var outboundSlidesStream = pc.localStreams
>         .getStreamById(slidesStream.id);
> var slidesVideo = outboundSlidesStream.videoTracks[0];
>
> slidesVideo.priority.request("high");
> slidesVideo.bitrate.request({ "min": 600, "max": 800,
>                               "thresholdToNotify": 50 });
> slidesVideo.bitrate.onchange = slidesVideoBitrateChanged;
> slidesVideo.onconstraintserror = failureToComply;
>
>
> // 3. ***** Enable/disable on outbound tracks *****
>
> // send same stream to two different peers
> pcA.addStream(stream);
> pcB.addStream(stream);
> // ...
>
> // retrieve the *different* outbound streams
> var streamToA = pcA.localStreams.getStreamById(stream.id 
> <http://stream.id>);
> var streamToB = pcB.localStreams.getStreamById(stream.id 
> <http://stream.id>);
>
> // disable video to A and disable audio to B
> streamToA.videoTracks[0].enabled = false;
> streamToA.audioTracks[0].enabled = false;
>
> ======
>
> Please comment and don't hesitate to ask if things are unclear.
>
> /Adam
>
> ----
> [1] http://lists.w3.org/Archives/Public/public-webrtc/2012Sep/0025.html
> [2] 
> http://dvcs.w3.org/hg/dap/raw-file/tip/media-stream-capture/proposals/SettingsAPI_proposal_v4.html
> [3] https://www.w3.org/Bugs/Public/show_bug.cgi?id=15861
>
Received on Tuesday, 13 November 2012 04:49:04 GMT

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