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Re: [SVG 1.2] 7 multimedia

From: Antoine Quint <ml@graougraou.com>
Date: Sat, 15 Nov 2003 16:51:41 +0100
Message-Id: <9AE44C3A-1783-11D8-BD45-000393D124C4@graougraou.com>
Cc: www-svg@w3.org, Patrick Schmitz <cogit@ludicrum.org>
To: "Jim Ley" <jim@jibbering.com>

Hey Jim,

On 15 nov. 03, at 16:03, Jim Ley wrote:

> Volume, does a value of 1.0 equal the maximum volume available to the
> device, or the current volume of the device - e.g. if the device is at 
> half
> volume, will the values 0.5-1.0 all be the same, or be a range within 
> 0-0.5
> ?

First off, as I am sure you would have noticed, the A/V examples are 
wrong with respect to the property name, which is in fact 
"audio-level".

As for your question, I feel the draft is clear enough at the end of 
section 7.3: "If the element has an element volume of 0, then the 
output signal will be inaudible. If the element has an element volume 
of 1, then the output signal will be at the system volume level. 
Neither the audio-level property or the element volume override the 
system volume setting."

So the range is always from 0 to 1, relative to both the parent 
"audio-level" properties (which work similarly to graphic opacity 
properties) and current system volume level.

> Video element:  what happens if you leave off the height/width 
> attributes?

As far I understand, <video> is a "subclass" of <image>, and it should 
just not render. I expect the next draft will be more eloquent on that 
case, and read something like:

"The width/height of the rectangular region into which the referenced 
document is placed.
A negative value is an error (see Error processing). A value of zero 
disables rendering of the element.
Animatable: yes."

> Do we have any access to closed captioning or other accessibility
> information related to the multimedia elements?

The SVGVideoElement interface has a pointer to the SVGVideo interface, 
which inherits from the SVGVisualMedia interface, which itself inherits 
from the SVGMedia interface which has the getMetadata() method. This 
should give you access to any metadata linked to the image. If your 
closed-captioning is available as metadata you will have a chance to 
get to it, otherwise I'm afraid you won't, at least not for now.

> Also can we start them from times other than the start?

As I understand, like with any element, if the "begin" attribute has a 
negative value, the media will be started by the offset specified. This 
remains to be checked as I don't have an implementation on my machine 
that implements this (ASV6 seems not to). I copied Patrick Schmitz, he 
should know (I may very well be talking nonsense here)...

Antoine
-- 
Antoine Quint <aq@fuchsia-design.com>
W3C SVG Working Group Invited Expert
SVG Consulting, Teaching and Outsourcing
Fuchsia Design <http://www.fuchsia-design.com/>
Received on Saturday, 15 November 2003 10:56:04 GMT

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