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

Comments on the revised recording proposal

From: Robert O'Callahan <robert@ocallahan.org>
Date: Mon, 10 Dec 2012 23:20:12 +1300
Message-ID: <CAOp6jLbt_0KZiVH7-1WcGvZZK-h6=hLVSND0bT-c+-R5_Wq7-Q@mail.gmail.com>
To: Jim Barnett <Jim.Barnett@genesyslab.com>
Cc: "public-media-capture@w3.org" <public-media-capture@w3.org>
The type "Boolean" should be written as "boolean".

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.

"When this method is called, if recording is true, the UA must raise a
dataavailable event containing its current Blob of data and then start
collecting a new Blob." Is this event fired synchronously during the
requestData(), or asynchronously? I suggest the latter. The spec should use
the HTML terminology "queuing a task" (and specify the task source).

"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.

As others mentioned, the event objects need to be specified in more detail.

Instead of introducing an "auto" format, just make the fields of the
Formats dictionary optional.

What are the semantics of calling setRecordingOptions and passing a list of
formats for 'container', 'audio' or 'video'? This needs to be explained. It
might make more sense to avoid using "Formats" for both getting and setting
format options. In fact, why aren't we just using a single MIME type to
specify the format to record into, since a MIME type can specify both the
container and codec types? Could we just have a "DOMString? attribute type"
(for consistency with Blob), plus a method "boolean canRecordType(type)"?
(I suggested this before, but I guess it was rejected --- which is fine
except I can't find the reason :-).)

Rob
-- 
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Received on Monday, 10 December 2012 10:20:46 UTC

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