W3C home > Mailing lists > Public > www-style@w3.org > December 2010

Re: Defining safe areas for media devices and set top boxes

From: David Singer <singer@apple.com>
Date: Fri, 3 Dec 2010 14:12:50 -0800
Cc: Robert O'Callahan <robert@ocallahan.org>, Joćo Eiras <joao-c-eiras@telecom.pt>, "www-style@w3.org" <www-style@w3.org>
Message-Id: <E0641C6B-3021-4E05-A16B-1BD6BCA00868@apple.com>
To: Chris Lilley <chris@w3.org>
Chris has it.  The area outside the safe area is an area that the content author wants to paint, but he knows that the physical display edge will occur somewhere in it.

I have to say, this was a problem with the gain tubes on CRT displays.  It used to be true that one would adjust the horizontal gain (using a rheostat) so the picture was safely away from the physical edges, but that leaves an ugly black border on the screen.  Then it became fashionable to raise the gain on the horizontal scan amplifier, so the picture extended to (and slightly past) the edge.  Temperature and other variations mean that the precise position at which horizontal flyback occurred was not stable.  There were also quality-of-focus issues towards display edges (as the tube rounded off).

You might notice that the preceding was written describing analog tube amplifiers applied to scanning CRT displays.  

AFAIK, you can use all of a digital display.  Are we expecting web browsers to be written on devices that have this as an issue?  Are there digital displays which (deliberately, I guess) do not display all the margin outside the safe area (maybe on the grounds that it's boring)?


On Dec 3, 2010, at 1:58 , Chris Lilley wrote:

> On Friday, December 3, 2010, 9:55:43 AM, Robert wrote:
> 
> ROC> Either I'm particularly slow tonight or your message is unclear.
> ROC> Why can't you simply set the browser viewport to the "safe area" of the TV screen?
> 
> The safe area on TV is not exactly like a browser viewport, and not exactly like page margins.
> 
> In some ways its more like the bleed area on printed material. There can be stuff outside the safe area (solid colours, images, textures) and depending on how its cropped for final display some or all of that area may be visible. 
> 
> The 'action safe area' is outside the 'title safe area' and can have images and video, and will be visible, but must not contain text.
> 
> See
> http://en.wikipedia.org/wiki/Safe_area
> 
> -- 
> Chris Lilley   Technical Director, Interaction Domain                 
> W3C Graphics Activity Lead, Fonts Activity Lead
> Co-Chair, W3C Hypertext CG
> Member, CSS, WebFonts, SVG Working Groups
> 
> 

David Singer
Multimedia and Software Standards, Apple Inc.
Received on Friday, 3 December 2010 22:13:25 GMT

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