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Re: DTMF - the "Object Oriented" approach

From: Harald Alvestrand <harald@alvestrand.no>
Date: Thu, 15 Nov 2012 22:59:30 +0100
Message-ID: <50A565C2.3080704@alvestrand.no>
To: public-webrtc@w3.org
On 11/15/2012 12:07 PM, Stefan Hakansson LK wrote:
> On 11/14/2012 03:46 PM, Harald Alvestrand wrote:
>> Takeaways from Lyon were that:
>>
>> - Executing DTMF needs reference to an audio track (to know where to
>> send the data) and to a PeerConnection (to know that we've successfully
>> negotiated use of the DTMF codec).
>> - The WG preferred an "object oriented" model: creating a DTMF handler
>> object, rather than the "fortran" approach of having all functions
>> directly on the PeerConnection.
>>
>> Suggested edits, delta from the October 19 version of the spec:
>>
>> - In section 8.4, rename AudioMediaStreamTrack to
>> DTMFSendingMediaStreamTrack.
>> Add the following text:
>>
>> A RTCDTMFSendingMediaStreamTrack is created by calling the
>> createDTMFSender() method on a PeerConnection. This constructs an object
>> that decorates a MediaStreamTrack with the functions required to send 
>> DTMF.
>>
>>
>> - In section 4.3.2, add the function
>>
>> RTCDTMFSendingMediaStreamTrack createDTMFSender(MediaStreamTrack track);
>>
>> - In section 4.3.2.2, add the paragraph
>>
>> createDTMFSender
>>
>> The createDTMFSender() creates an RTCDTMFSendingMediaStreamTrack that
>> references the given MediaStreamTrack. The MediaStreamTrack MUST be an
>> element of a MediaStream that's currently in the PC's localStreams
>> attribute; if not, throw an Illegal Argument Exception. [NOTE - get
>> correct name for exception before inserting]
>>
> This looks good to me. I think we also need to specify:
>
> * What happens if the MediaStream with the track that the 
> RTCDTMFSendingMediaStreamTrack is associated to is removed from the 
> PeerConnection? I assume there would be an error event next time the 
> app tries to send DTMF.
My thought:

I think that if it's removed from the PC, canSendDTMF should change to 
false.
Any time canSendDTMF is false, sendDTMF should throw an exception.

Do we need to find a way to throw an event if it's removed from its PC 
while in the middle of sending tones, or can we just ignore that situation?

>
> Stefan
>
Received on Thursday, 15 November 2012 21:59:59 GMT

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