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Re: DTMF

From: Randell Jesup <randell-ietf@jesup.org>
Date: Tue, 07 Aug 2012 15:27:44 -0400
Message-ID: <50216C30.5060306@jesup.org>
To: public-webrtc@w3.org
On 8/7/2012 11:32 AM, Adam Bergkvist wrote:
> On 2012-07-19 13:42, Stefan Hakansson LK wrote:
>> I think I proposed at one time that DTMF should be echoed into the audio
>> stream. I did that for two purposes:
>> 1. It seems very strange to me to have an operation on an audio stream
>> track that has no meaning outside the RTP transmission of a
>> PeerConnection. What should happen if you have a MediaStream locally
>> only, and do "insertDTMF"?
>> 2. It would make local feedback simpler. At least on my phone, when I
>> use DTMF (which may be sent over the network using DTMF events - I don't
>> know really and don't care), tones are played locally as a feedback. I
>> assume that many app developers would like the behavior, and if
>> "insertDTMF", for a MediaStreamTrack that is connected to an audio
>> element, did play out as tones you would have that feedback for free.
>> (There are other ways to do it for sure, it is more nice-to-have).
>>
>> That were my reasoning. But if "insertDTMF" should only mean "transmit
>> DTMF events", perhaps is should be an operation on PeerConnection
>> instead. Could we do something like Harald proposed for stats: have
>> something you can do on what is in localStreams?
>
> I think this is worth looking into. DTMF doesn't make sense in a local 
> only case so it would be nice to avoid having the DTMF API in the 
> MediaStream API and instead attach it to PeerConnection (e.g. 
> peerConn.sendDTFM(targetAudioTrack, dtmfData ...);).

What about point 2?  I.e. if I select "send a 5" in my UI, most users 
expect to hear feedback.  It's not mandatory, but if we don't then 
developers will do it themselves via (unsynced, maybe un-echo-cancelled) 
audio elements.

-- 
Randell Jesup
randell-ietf@jesup.org
Received on Tuesday, 7 August 2012 19:30:03 GMT

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