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Re: setting HTMLMediaElement volume and playbackRate attributes

From: Philip Jägenstedt <philipj@opera.com>
Date: Mon, 24 Nov 2008 13:49:19 +0100
To: Eric Carlson <eric.carlson@apple.com>
Cc: HTML WG <public-html@w3.org>
Message-Id: <1227530959.13190.27.camel@localhost>

On Sun, 2008-11-23 at 12:51 -0800, Eric Carlson wrote:
> 
> On Nov 23, 2008, at 12:27 PM, Philip Jägenstedt wrote:
> 
> > playbackRate 0 is equivalent to pausing playback and in my opinion it
> > seems like a bad idea to have several ways to do that.
> >
>    I agree that a "playbackRate == 0" is equivalent to "paused ==  
> true", but isn't "volume == 0" is equivalent to "muted == true"?

While I wouldn't mind removing the muted attribute, I guess the thinking
is that it makes it easier for a JS interface to toggle the volume
between muted/non-muted states (although really this could just as well
be done by saving the volume before muting).

>    Why is it OK for volume but not rate?
> 
>    Why is "playbackRate = 0.0000000000.1" allowed, but "playbackRate =  
> 0.0" throws an error?

If an UI handles |playbackRate| < x by pausing I don't think anybody
would mind as long as x is small. But I suppose you're arguing that
setting playbackRate to 0 should simply be allowed. I don't feel
strongly about the issue, but if playbackRate 0 is allowed it should be
well defined which (if any) events it fired.

Philip

> eric
> 
> 
> >
> > On Sun, 2008-11-23 at 10:20 -0800, Eric Carlson wrote:
> >>
> >>   Why is it OK to set the volume to zero but it is an error to set
> >> the playback rate to zero?
> >>
> >>   The spec says the following about "volume" [1]:
> >>
> >> 	The volume attribute must return the playback volume of any audio
> >> portions of the media element,
> >> 	in the range 0.0 (silent) to 1.0 (loudest).
> >>
> >>   It says the following about "playbackRate" [2]:
> >>
> >> 	The attribute is mutable, but on setting, if the new value is 0.0, a
> >> NOT_SUPPORTED_ERR exception
> >> 	must be raised instead of the value being changed.
> >>
> >>   How is this helpful? Further, why is it OK to set the rate to
> >> 0.00001 but an error to set it to 0 when there is no real difference
> >> between the two from the user's perspective?
> >>
> >> eric
> >>
> >> [1] http://www.whatwg.org/specs/web-apps/current-work/multipage/video.html#dom-media-volume
> >> [2] http://www.whatwg.org/specs/web-apps/current-work/multipage/video.html#dom-media-playbackrate
> >>
> > -- 
> > Philip Jägenstedt
> > Opera Software
> >
> 
> 
-- 
Philip Jägenstedt
Opera Software
Received on Monday, 24 November 2008 12:50:03 GMT

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