W3C home > Mailing lists > Public > public-media-capture@w3.org > December 2012

Re: Comments on the revised recording proposal

From: Robert O'Callahan <robert@ocallahan.org>
Date: Tue, 11 Dec 2012 09:28:31 +1300
Message-ID: <CAOp6jLZNE1Yp7Aikhn08roTmdc97cipA21pdjsn1Sz1y-Ke_BA@mail.gmail.com>
To: Jim Barnett <Jim.Barnett@genesyslab.com>
Cc: "public-media-capture@w3.org" <public-media-capture@w3.org>
On Tue, Dec 11, 2012 at 3:04 AM, Jim Barnett <Jim.Barnett@genesyslab.com>wrote:

>  *From:* rocallahan@gmail.com [mailto:rocallahan@gmail.com] *On Behalf Of
> *Robert O'Callahan
>
>
> I think the language around "once timeslice milliseconds of data have been
> gathered, the UA must raise a dataavailable event containing that Blob of
> recorded data" needs to be relaxed a bit to allow for the fact that UAs
> often can't map recorded data chunks to precise millisecond boundaries.***
> *
>
> ** **
>
> >> How would you suggest rephrasing this?  As I read it, the current
> language doesn’t require that _*exactly*_ timeslice milliseconds of data
> be in the event, only that _*at least*_ timeslice milliseconds of data be
> available.  Do we want to add a phrase saying that the UA may wait until it
> finds a convenient data boundary?  I’m just not sure how to say it.
>

Me neither. Perhaps we should say that the value is just a hint, and the UA
should try to ensure there are about 'timeslice' milliseconds of data
represented by each data packet, but there are no normative requirements.

****
> "A recordingwarning event will be raised if this is called while recording
> is occurring, and the call will have no effect." For a programmer error
> like this Web platform APIs don't usually raise an event. UA-specific
> developer tools can and should alert Web developers, and there is no need
> to address this in specs.
>
> ** **
>
> >> Is it really accepted practice to silently ignore a command?  That’s
> what Travis had in his original proposal, but I thought it was better
> practice to signal the problem.  However if it’s standard API design to
> ignore this kind of error, I’ll change the spec.
>

For programmer errors that are detected synchronously, the two common
patterns are to ignore the call, or throw an exception. I think either
would be fine here.

One other question: what would the right task source for recording tasks
> be?   They might fit under the user interaction source, since the media
> itself is likely part of a user interaction,  but the user himself may have
> nothing to do with the recording.  On the other hand, recording isn’t
> important enough to need its own task source, is it?  So what should it be?
>

I suggest the DOM manipulation task source, since that's what the media
element events use.

Rob
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Received on Monday, 10 December 2012 20:29:08 UTC

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