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

Re: DTMF again

From: Harald Alvestrand <harald@alvestrand.no>
Date: Mon, 12 Dec 2011 06:48:19 -0800
Message-ID: <4EE61433.4080702@alvestrand.no>
To: public-webrtc@w3.org
On 12/09/2011 11:07 AM, Stefan Hakansson LK 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 
>> <mailto: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!
>
This (application uses insertDTMF on the stream heading towards the 
speakers) seems right to me. Whether or not tones are played back 
locally should be the application's decision, not the API's.

                Harald
Received on Monday, 12 December 2011 14:48:49 UTC

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