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Re: [Bug 18485] Change DTMF API to be on PeerConnection

From: Justin Uberti <juberti@google.com>
Date: Wed, 8 Aug 2012 14:26:15 -0700
Message-ID: <CAOJ7v-2REyCdrcsKeqYtSbSZp4KAzR2_Bfh+7n-Ez9sjQeRoEw@mail.gmail.com>
To: Stefan Hakansson LK <stefan.lk.hakansson@ericsson.com>
Cc: public-webrtc@w3.org
Option D seems like a good way to get what we need without spending too
much effort on this legacy use case.


On Wed, Aug 8, 2012 at 5:43 AM, Stefan Hakansson LK <
stefan.lk.hakansson@ericsson.com> wrote:

> On 08/08/2012 12:52 PM, Harald Alvestrand wrote:
>
>> [Continuing discussion on list]
>>
>> I updated the bug in order to solicit views from the WG - would you
>> prefer A, B or C?
>>
>> On 08/08/2012 12:23 PM, bugzilla@jessica.w3.org wrote:
>>
>>> https://www.w3.org/Bugs/**Public/show_bug.cgi?id=18485<https://www.w3.org/Bugs/Public/show_bug.cgi?id=18485>
>>>
>>> Stefan Hakansson LK<stefan.lk.hakansson@**ericsson.com<stefan.lk.hakansson@ericsson.com>>
>>>  changed:
>>>
>>>              What    |Removed                     |Added
>>> ------------------------------**------------------------------**
>>> ----------------
>>>                    CC|
>>>  |stefan.lk.hakansson@ericsso
>>>                      |                            |n.com
>>>
>>> --- Comment #2 from Stefan Hakansson LK<stefan.lk.hakansson@**
>>> ericsson.com <stefan.lk.hakansson@ericsson.com>>  2012-08-08 10:23:07
>>> UTC ---
>>> (In reply to comment #1)
>>>
>>> As for alternatives B and C, I think that the tones should not be
>>> inserted in
>>> the same MediaStream as the outgoing DTMF. The tones are to be used for
>>> local
>>> feedback, and you would not like to play the other outgoing audio
>>> locally.
>>>
>>> I think we should go for alternative A initially.
>>>
>> My thought was that if an app wants ringback of the tones, he does:
>>
>> incomingStream = pc.remoteStreams[0].**audioTracks[0]
>> outgoingStream = pc.remoteStreams[0].**audioTracks[0]
>>
> Guess it should read
> outgoingStream = pc.localStreams[0].**audioTracks[0]
>
>
>> pc.sendDTMF(outgoingStream, "12345")
>> pc.sendDTMF(incomingStream, "12345")
>>
>> the two should then play out at ~ the same time.
>>
>> I don't want to force there to be always ringback present - that's app
>> dependent.
>>
>
> I agree, and this makes sense. Personally I don't have a strong opinion,
> we could go for A (the web author wanting local feedback could easily
> accomplish that with a audio element and some files with tones), B or C. We
> could even consider an alternative D:
>
> pc.canSendDTMF(**MediaStreamTrack)
> pc.sendDTMF(MediaStreamTrack, tones, duration, optional MediaStreamTrack)
>
> where tones are inserted in the audio of the second (optional)
> MediaStreamTrack supplied.
>
>
>
>
>> In case C, even this is possible:
>>
>> speakers = <whatever constructor we have for a synthetic media source>
>> <add speakers to an audio tag>
>> pc.sendDTMF(speakers, "12345")
>>
>> It means that behind the scenes, the "PC" implementation must be able to
>> touch any audio stream in the system, but then again - streams aren't
>> real physical items, they're control-surface abstractions anyway.
>>
>
> Agree.
>
>
>
>>
>>>
>>>  based on discussion on the list, there seems to be 3 alternate
>>>> descriptions of
>>>> what sendDTMF actually does.
>>>>
>>>> I outline them below as text that can be inserted into the description.
>>>>
>>>> A)
>>>> 1) If the track argument to sendDTMF is not an audio track connected to
>>>> this
>>>> PeerConnection on an outgoing SSRC where use of RFC 4733 DTMF has been
>>>> negotiated, throw a<IllegalParameter>  exception.
>>>> 2) Send the tones using RFC 4733 signalling.
>>>>
>>>> B)
>>>> 1) If the track argument to sendDTMF is not an audio track connected to
>>>> this
>>>> PeerConnection, throw an<illegalParameter>  exception.
>>>> 2) If sendDTMF is connected to an outgoing SSRC where use of RFC 4377 is
>>>> negotiated, send the tones using RFC 4377 and return.
>>>> 3) Insert the corresponding tones into the media stream as if they were
>>>> coming
>>>> from the media source.
>>>>
>>>> C)
>>>> 1) If sendDTMF is connected to an outgoing SSRC on this PeerConnection
>>>> where
>>>> use of RFC 4377 is negotiated, send the tones using RFC 4377 and return.
>>>> 2) Insert the corresponding tones into the media stream as if they were
>>>> coming
>>>> from the media source.
>>>>
>>>> The difference between B) and C) is that B) insists on using the right
>>>> PC to
>>>> generate tones.
>>>>
>>>
>>
>>
>
>
Received on Wednesday, 8 August 2012 21:27:04 GMT

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