W3C home > Mailing lists > Public > public-webrtc@w3.org > December 2011

Re: DTMF again

From: Justin Uberti <juberti@google.com>
Date: Fri, 9 Dec 2011 14:17:13 -0500
Message-ID: <CAOJ7v-0omr6y217=wvQs+rBQyZF4GaLiNvtYUkQ6G2OWfW=DVQ@mail.gmail.com>
To: Stefan Hakansson LK <stefan.lk.hakansson@ericsson.com>
Cc: "public-webrtc@w3.org" <public-webrtc@w3.org>
On Fri, Dec 9, 2011 at 2:07 PM, Stefan Hakansson LK <
stefan.lk.hakansson@ericsson.com> wrote:

>  On 12/09/2011 07:59 PM, Justin Uberti wrote:
>
>
>
> On Thu, Dec 1, 2011 at 8:20 AM, Stefan HÃ¥kansson LK <
> stefan.lk.hakansson@ericsson.com> wrote:
>
>> So, a concrete proposal:
>>
>> we define the operation "insertDTMF" that is available on
>> AudioMediaStreamTrack's (or should that be named AudioStreamTrack?):
>>
>> insertDTMF("1")  // plays tone 1 for 50 ms
>> insertDTMF("2", 200)  // plays tone 2 for 200 ms
>> insertDTMF("123")  // plays tones 1, 2, 3 in succession, each for 50 ms
>> insertDTMF("456", 200)  // plays tones 4, 5, 6 in succession, each for
>> 200 ms
>>
>> (I prefer "insert" over "send" as nothing is sent unless the MediaStream
>> that the AudioStreamTrack belongs to is added to a PeerConnection)
>>
>
>  I think the name "sendDTMF" is slightly more intuitive, but I can see
> your point too. If others prefer sendDTMF I'm fine with that.
>
>>
>> "insertDTMF" leads to the insertion of the actual tones in the audio, so
>> if the MediaStream in question is attached to an audio element, those tones
>> would be played out. This has the advantage that it is much simpler to
>> locally give audio feedback to the user that dtmf is sent - when I use DTMF
>> on my phone I hear the tones.
>>
>
>  Not sure what you mean here. Do you mean if the local media stream was
> hooked up to an <audio/>, the tones would be played out? If so, wouldn't
> that mean that your own voice is being fed back to the audio output (which
> I'm sure we don't want)?
>
> I meant like this:
>
> Imagine you do "insertDTMF()" on an audio track of an outgoing stream (to
> send DTMF to the other end), if you now want an audio feedback to the
> person sending the DTMF, you could simultaneously do "insertDTMF" on the
> audio track of the incoming MediaStream (assuming a bidirectional session).
> That would lead to that you hear the tones locally as you push the dial pad
> to generate them.
>
> So, you would not hear yourself!
>

OK, I get it. If a "null" AudioTrack could be created, this could also be
used to play out tones as a user dials from the keypad.

>
>  I agree we want to allow the tones to optionally be played out locally,
> but I think we need a different mechanism to control this (possibly a flag
> on the stream or API call).
>
>>
>> "insertDTMF" also, if the MediaStream in question is attached to an open
>> PeerConnection, leads to RTP packets according to RFC4733 being inserted in
>> the RTP stream corresponding to this AudioStreamTrack.
>>
>> (if reception of DTMF is also supported by the browser, I guess that in
>> addition to inserting the tones in the AudioStreamTrack, events informing
>> the application should be dispatched)
>>
>>
>>
>
>
Received on Friday, 9 December 2011 19:18:10 UTC

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