W3C home > Mailing lists > Public > public-tt@w3.org > January 2013

Re: TTML and aspect ratio

From: David Ronca <dronca@netflix.com>
Date: Wed, 30 Jan 2013 18:53:00 +0000
To: "public-tt@w3.org" <public-tt@w3.org>
Message-ID: <F7DC5134CE82754A878475EEBA450B3B30DB54@EXMB105.corp.netflix.com>
> If the extent is specified, then it cannot be ignored by a compliant
> client. A compliant client is obligated to respect that extent
> specification.

Agreed, which means that extent is not useful for indicating the aspect ratio of the root container if the frame size will vary.

> It is sounding to me like you want to avoid specifying root container
> extent at all, 

Definitely want to avoid specifying the root container extent.

>but have a way to automatically determine it in the client
> based on an a specified aspect ratio and possibly a safe area
>specification, is that correct?

If the client knows the aspect ratio of the root container, it can scale presentation for any frame size or display size.

> If so, would other length specifications always use non-pixel metrics or
> percentages? e.g., to specify non-root region origin and extent, use cells
> or percentages, but not pixels?

Percentage could work if the specified behavior for an extent that was not full screen is to center the root container in the display area.
Received on Wednesday, 30 January 2013 18:53:28 UTC

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