Re: Capturing streams from DOM nodes: open issues

So we would want a "skip dead air" property that could be set on the 
MediaRecorder to cause it to stop recording when the stream stops 
providing media.   Right now, the spec says that MediaRecorder records 
whatever the stream provides.  So if the stream provides nothing at all, 
I don't think anything would get recorded (but the spec should say so 
explicitly.)  If the stream provides black frames  or silence that would 
get recorded.   Would we treat black frames or silence as dead air? 
(When recording audio, some of the silence is necessary for 
intelligibility.)  I think the spec needs some careful clarification here.

- Jim
On 5/15/2014 10:15 AM, Martin Thomson wrote:
> On 15 May 2014 06:49, Jim Barnett <1jhbarnett@gmail.com> wrote:
>> 1) are you thinking of an API other than pause/resume for "don't record that
>> stuff"?
> Yes, because of propagation delays inherent in the application.
>
> 1. Stream pauses.
> 2. Browser generates and dispatches event.
> 3. Application receives event, processes it.
> 4. Application issues pause() to recorder.
> 5. Recorder acts.
>
> The time between 1 and 5 is such that you can't be sure you haven't
> recorded at least some dead air.  You could block recording in
> anticipation of such an instruction, but that will probably cause
> other problems.
>
> And it's far worse in the other direction, where you miss the first
> frames of the newly resumed stream.
>
>> 2) under which of the circumstances that you list below would the
>> MediaStream "end"?
> None of them.  That being the point.  These are cases where the stream
> enters a temporary state of suspension.

-- 
Jim Barnett
Genesys

Received on Thursday, 15 May 2014 15:05:49 UTC