Re: [rtcweb] The DTMF API [Was: Traffic should be encrypted. (Re: Let's define the purpose of WebRTC)]

[Justin Uberti <[e-mail]>]

On Tue, Nov 15, 2011 at 9:43 PM, Hadriel Kaplan <[e-mail]>wrote:

>
> On Nov 15, 2011, at 11:01 AM, Randell Jesup wrote:
>
> > The problem is you need a bunch more timing info that when it starts.
> DTMF is not just "this was played", though many use it that way.  DTMF has
> length as well, and that length may even be indeterminate.  Many SIP ATAs
> and the like only support sending DTMF as X ms on, Y ms off, but you'll
> note that those are often configurable, and the protocol is much more
> expressive than that.
> >
> > That said: we absolutely can decide that we only support only sending
> "now", and that the duration is fixed (or configurable).  For the uses
> we're talking about, that's probably sufficient.  Some odd PSTN-interop
> things have been known to use DTMF duration ("hold 4 to fast-forward" or
> "press and hold 5 to pan the security camera"), but they're rare IMHO, and
> PSTN interop isn't the prime usecase (and many/most other voip devices
> don't support press-and-hold anyways).  I'd be fine with this.
>
>
> You'd be surprised how many things use/need DTMF duration. :(
>
> It caused a lot of issues for certain Mobile/Cellular networks a long time
> ago where the cell phones couldn't generate a duration for DTMF - I can't
> remember if it was a limitation of the phones or the cellular technology,
> but it caused lots of user complaints.
> It also caused issues in H.323 because H.245 UII supported both indicating
> with/without duration and those sending without had problems talking to
> those needing it.
>
> Regardless, as an FYI - I had put the following DTMF API requirements in
> draft-kaplan-rtcweb-sip-interworking-requirements-01:
>
>      ----------------------------------------------------------------
>      A2-13           WebRTC MUST provide a means for the
>                      Browser to generate [RFC4733] DMTF RTP
>                      Events for at least the events 0-15, in
>                      an audio-type RTP packet stream.
>      ----------------------------------------------------------------
>      A2-14           WebRTC MAY provide a means for the
>                      Browser to receive [RFC4733] DMTF RTP
>                      Events for the events 0-15.
>      ----------------------------------------------------------------
>      A2-15           WebRTC MUST provide a means for the
>                      Javascript application to invoke [RFC4733]
>                      DTMF events to be generated, and their
>                      duration, with a default duration of 50ms.
>                      In other words, the Javascript should be
>                      able to tell the Browser to generate event
>                      "0" for 50ms based on a button click, for
>                      example.
>      ----------------------------------------------------------------
>      A2-16           WebRTC MUST provide a means for the
>                      Javascript application to enable or
>                      disable [RFC4733] use, per session.
>      ----------------------------------------------------------------
>
>
OK, how about

[Local]MediaStreamTrack.sendDTMF(in DOMString tones, in optional long
duration)

ex:
sendDTMF("1")  // plays tone 1 for 50 ms
sendDTMF("2", 200)  // plays tone 2 for 200 ms
sendDTMF("123")  // plays tones 1, 2, 3 in succession, each for 50 ms
sendDTMF("456", 200)  // plays tones 4, 5, 6 in succession, each for 200 ms