W3C home > Mailing lists > Public > public-html@w3.org > November 2008

Re: setting HTMLMediaElement volume and playbackRate attributes

From: Dave Singer <singer@apple.com>
Date: Thu, 27 Nov 2008 13:33:37 -0800
Message-Id: <p06240842c554c243be92@[17.202.35.52]>
To: Philip Jägenstedt <philipj@opera.com>, Eric Carlson <eric.carlson@apple.com>
Cc: HTML WG <public-html@w3.org>

I think if I am implementing a jog/shuttle 
controller, which allows the rate to slide 
between +1 and -1, I don't want to worry if I 
happen to sample it at zero and set the rate to 
that.  True, I am in the odd state of playing at 
a rate of zero, but that's not so perceptibly 
different from a rate of 0.00000001, and is not 
philosophically different from an unmuted volume 
of zero.

It's odd, but not harmful, so I don't see a reason to have the wrinkle.



At 13:49  +0100 24/11/08, Philip Jägenstedt wrote:
>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


-- 
David Singer
Multimedia Standards, Apple Inc.
Received on Thursday, 27 November 2008 21:34:26 UTC

This archive was generated by hypermail 2.3.1 : Monday, 29 September 2014 09:38:59 UTC