Re: DTMF - the "Object Oriented" approach

On 2012-11-16 07:49, Harald Alvestrand wrote:
> On 11/16/2012 07:33 AM, Adam Bergkvist wrote:
>> On 2012-11-14 15:46, 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, 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]
>> The prefix (RTCDTMF) it's pretty nasty, but I guess consistency has
>> precedence in this case.
> :-)
> The way that I think this will be used, it will never appear in JS code,
> so the only people it will be a pain for are the ones who do the
> implementation. I considered RTCMediaStreamTrackWithDTMFExtensions
> briefly, but decided to suggest this one.

If anyone suggests a separate constructor, we'll point them to this 
thread. :)

>> Is the intention that the decorated track needs to be added back into
>> the MediaStream where the original track came from?
> No, it's my intention that the created object is only a handle that can
> be used for sending DTMF. The MediaStreamTrack that it was created from
> is already part of the MediaStream it belongs in.

That's my preference as well. In that case, could we skip the 
inheritance from a MediaSteamTrack (and the MediaStreamTrack-part of the 
name) to avoid confusion? For example, someone using it as a track 
argument to the MediaStream constructor. We could simply call it 
RTCDTMFSender? The corresponding track could be a read-only property on 
the dtmf sender object if you wanted to relate back to the track.


Received on Friday, 16 November 2012 07:08:33 UTC