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RE: approaches to recording

From: Young, Milan <Milan.Young@nuance.com>
Date: Mon, 29 Oct 2012 08:25:20 +0000
To: "Cullen Jennings (fluffy)" <fluffy@cisco.com>, "public-media-capture@w3.org" <public-media-capture@w3.org>
Message-ID: <B236B24082A4094A85003E8FFB8DDC3C1A4B8393@SOM-EXCH04.nuance.com>
Cullen, I would appreciate your elaboration on this suggestion.  In particular, I understand once data reaches the TURN server it might retransmit with any protocol, but I don't understand how the data reaches the server in a reliable manner.

Are you saying the TURN server can somehow demand retransmission of lost RTP packets originating from the browser client?  Can the server force the client to submit RTP-like data chunks over TCP?

Thank you


> -----Original Message-----
> From: Cullen Jennings (fluffy) [mailto:fluffy@cisco.com]
> Sent: Saturday, October 27, 2012 11:50 PM
> To: public-media-capture@w3.org
> Subject: Re: approaches to recording
> 
> 
> If the only way to reach your voice recognition engine is via a TURN TCP relay,
> then PeerConnection ends up being reliable ... I have seen this hack deployed
> with SIP devices. I'm not saying I like it, but it does work.
> 
> 
> On Oct 11, 2012, at 10:02 , Stefan Hakansson LK
> <stefan.lk.hakansson@ericsson.com> wrote:
> 
> > Just a thought:
> >
> > - Would not the simplest solution (at least from an API perspective)
> > be to add a reliable mode to MediaStreams when added to
> > PeerConnection? Then MTI codecs etc. would already be discussed.
> > Datachannels in PeerConnection can already be set up in realiable and
> > unreliable mode, so it would fit quite nicely. (I don't know how much
> > extra work it would be on the protocol/ietf side though.)
> >
> > Stefan
> >
> >
> > On 10/11/2012 08:15 AM, Young, Milan wrote:
> >> Yes, the speech industry prefers reliable transports, but an even
> >> more essential request is encoded audio.  It wasn't clear to me
> >> whether the "configurations" mentioned below would support the
> >> ability to specify a codec.  If that ability is planned, what are the
> >> thoughts in aligning our MTI recommendations with WebRTC?
> >>
> >> -Milan
> >>
> >> *From:*Jim Barnett [mailto:Jim.Barnett@genesyslab.com]
> >> *Sent:* Wednesday, October 10, 2012 3:50 PM
> >> *To:* Travis Leithead; SULLIVAN, BRYAN L
> >> *Cc:* public-media-capture@w3.org
> >> *Subject:* RE: approaches to recording
> >>
> >> I just want to observe that lossless streaming is what we (= the
> >> contact center and speech industry) want for  talking to a speech
> >> recognition system.  It would be ideal if PeerConnection supported
> >> it.  Failing that, it would be nice if the Recorder supported it,
> >> but in a pinch we figure that we can use the track-level API to
> >> deliver buffers of speech data and let the JS code set up the TCP/IP
> connection.
> >>
> >> -Jim
> >>
> >> *From:*Travis Leithead [mailto:travis.leithead@microsoft.com]
> >> <mailto:[mailto:travis.leithead@microsoft.com]>
> >> *Sent:* Wednesday, October 10, 2012 5:36 PM
> >> *To:* SULLIVAN, BRYAN L; Jim Barnett
> >> *Cc:* public-media-capture@w3.org
> >> <mailto:public-media-capture@w3.org>
> >> *Subject:* RE: approaches to recording
> >>
> >> That's what RTCPeerConnection is for, right? Or are you wanting
> >> loss-less streaming?
> >>
> >> *From:*SULLIVAN, BRYAN L [mailto:bs3131@att.com]
> >> *Sent:* Wednesday, October 10, 2012 1:08 PM
> >> *To:* Jim Barnett
> >> *Cc:* public-media-capture@w3.org
> >> <mailto:public-media-capture@w3.org>
> >> *Subject:* RE: approaches to recording
> >>
> >> Jim,
> >>
> >> Other than local recording, the most interesting part of this to me
> >> is the ability to stream the content (pre-mixed, or as a multiplexed
> >> set of track streams) to an external resource (URI) for recording or
> >> processing. Realtime streaming is needed for external realtime /
> >> minimal delay processing of the captured content. Thus the proposal 2
> >> seems more suited and flexible.
> >>
> >> Thanks,
> >>
> >> Bryan Sullivan
> >>
> >>    *From:*Jim Barnett [mailto:Jim.Barnett@genesyslab.com]
> >>    *Sent:* Wednesday, October 10, 2012 8:28 AM
> >>    *To:* public-media-capture@w3.org <mailto:public-media-
> capture@w3.org>
> >>    *Subject:* approaches to recording
> >>
> >>    The upshot of yesterday's discussion is that there is interest in
> >>    two different approaches to recording, so I'd like  to start a
> >>    discussion of them.  If we can reach consensus on one of them, we
> >>    can start to write things up in more detail.
> >>
> >>    /_Proposal 1._/   Place a recording API, similar to the one in the
> >>    current proposal, on both MediaStream and MediaStreamTrack.  The
> >>    Track-level API would work as in the current proposal and would be
> >>    for media processing and applications that require detailed
> >>    control.  The MediaStream API would record all tracks in the stream
> >>    into a single  file and would be the API for at least simple
> >>    recording use cases.  It would be up to the UA/container format to
> >>    determine the error cases.  For example, if the application adds a
> >>    track to a MediaStream while recording is going on, the action might
> >>    or might not succeed, depending on whether the container format
> >>    could handle the extra track.
> >>
> >>    The advantages of this approach are:  1) it's simple  to define 2)
> >>    it makes the simple cases (single video stream) easy  3)  the
> >>    application has to be prepared to deal with errors (e.g. lack of
> >>    disk space) during recording anyways.  The disadvantage of this
> >>    approach is that it makes behavior in complicated cases
> >>    unpredictable.  Some UAs might be able to handle the addition and
> >>    removal of tracks during recording while others did not.
> >>
> >>    /_Proposal 2. _/Create a separate Recorder object that would serve
> >>    as a destination/sink for  MediaStream.  (I gather that there's
> >>    already been a proposal along these lines - I'd appreciate it if
> >>    someone would send me a copy.) The configuration of this object
> >>    would determine what the MediaStream was allowed to do.  For
> >>    example, the application would create a Recorder object designed to
> >>    handle a certain number of audio and video tracks.  If the platform
> >>    could not support that number, the error would be raised when the
> >>    Recorder was created/configured, not once recording was underway.
> >>    If creation of the Recorder succeeds but the MediaStream attempts to
> >>    exceed the configured number of audio or video tracks, either an
> >>    error would be raised or the extra Tracks would be ignored.
> >>
> >>    It would be easy to add other features to the Recorder.  For
> >>    example, most recordings are stored as files.  The Recorder object
> >>    could be configured with a  URL and automatically right the
> >>    recording to that URL once it was finished.  (I suppose that it
> >>    could also be configured to stream the recording to the URL as it
> >>    was created.)  There could  also be a configuration item specifying
> >>    whether multiple audio tracks were to be merged or recorded
> >>    separately.    Most of these options should  probably be provided as
> >>    a Dictionary at construction time since we would not want them
> >>    changed while recording was going on.
> >>
> >>    There would need to be a distinct interface, probably similar to the
> >>    existing proposal, to handle media capture and media processing at
> >>    the Track level.
> >>
> >>    One objection to this approach has come from Travis, who notes that
> >>    it allows overlapping/simultaneous recording of a stream, for which
> >>    he sees no good use cases.  (On the other hand, it does address
> >>    another of Microsoft's concerns, in that the UA will know before
> >>    recording starts how many tracks there will be.)
> >>
> >>    Any other thoughts and comments?
> >>
> >>    -Jim
> >>
> >
> >
> 
Received on Monday, 29 October 2012 08:25:48 GMT

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