Re: Proposed Language for #111 - Revision 5

The proposal is a good way forward. I see two issues that have been 
raised in the last TTWG call by Mike Dolan and Piere Lemieux that still 
needs to be addressed.

a) The processor that supports both IMSC profiles is still called 
"Multiple-Profile IMSC Processor". I think it may be better called 
"Combined IMSC Text and Image Profile Processor" or something similar.

b) The section "normal processing" still mentions abortion of the 
processing  as first option and may be reworded as follows:

"If a Document instance is considered compatible with a Combined IMSC 
Text and Image Profile Processor Processor, but is determined to be 
incompatible, then this processor may restart processing with the Image 
Profile as the default profile."

Best regards,

Andreas

Am 08.01.2016 um 04:17 schrieb Glenn Adams:
> The following is revision 5 of my proposed text. I have added language 
> to address the comments received today from Mike and Nigel. Revisions 
> (from what we reviewed in today's meeting) are highlighted.
>
> Add to Section 3:
> IMSC Processor. A /Processor/ that supports one or both IMSC Profiles.
> Single-Profile IMSC Processor. An IMSC Processor that supports one and 
> only one of the profiles defined in Section 5, namely, the Text 
> Profile or the Image Profile. Multiple-Profile IMSC Processor. An IMSC 
> Processor that supports both of and only the profiles defined in 
> Section 5, namely, both the Text Profile and the Image Profile.
> Compatible Profile. A non-IMSC profile with which IMSC is expressly 
> designed to be compatible for the purpose of enhancing content 
> interoperability. A Document Instance declared or determined to be 
> associated with a Compatible Profile does not violate IMSC defined 
> content constraints with respect to one of the profiles defined in 
> Section 5.
> Note: The profiles defined by [EBU-TT-D], [ST2052-1], and 
> [ttml10-sdp-us] are examples of Compatible Profiles.
> Create a new Section 5.4, entitled /Profile Specification and Processing/:
> [profile specification]
> The ttp:profileattribute SHOULD be present on the ttelement and equal 
> to the designator of the IMSC1 profile to which the document conforms; 
> unless the document also conforms to [EBU-TT-D], in which case the 
> ttp:profileattribute SHOULD NOT be present on the ttelement, and 
> instead the designator of the IMSC1 profile to which the document 
> conforms and the URI "urn:eebu:tt:distribution:2014-01"SHOULD each be 
> carried in an ebuttm:conformsToStandardelement as specified in [EBU-TT-D].
> [profile defaulting]
> A Single-Profile IMSC Processor SHALL process a Document Instance in 
> accordance to the single profile which it supports. If a profile is 
> determined by [profile specification]and its value is not equal to the 
> profile designator associated with that single supported profileand is 
> not a Compatible Profile with respect to that single supported 
> profile, then the Document Instance MAY be considered incompatible 
> with that Processor and subject to abort processing. If no profile is 
> determined by [profile specification], then the Document Instance 
> SHOULD be tentatively considered to be compatible with that Processor 
> and subject to normal processing.
> A Multiple-Profile IMSC Processor SHALL process a Document Instance in 
> accordance to one of its supported profiles. If a profile is 
> determined by [profile specification]and its value is not equal to the 
> profile designator associated with any of the supported profilesand is 
> not a Compatible Profile with respect to any of the supported 
> profiles, then the Document Instance MAY be considered incompatible 
> with that Processor and subject to abort processing. If no profile is 
> determined by [profile specification], and if no external profile 
> metadata is provided by the Document Interchange Context, then the 
> Document Instance SHOULD be tentatively considered to be compatible 
> with the Text Profile and subject to normal processing as such.
> In order to avoid the invocation of this [profile 
> defaulting]procedure, content authors and interchange agents SHOULD 
> specify the profile that applies to a Document Instance, by means of 
> either the [profile specification]procedure or external profile 
> metadata, or both. If both internal and external profile metadata is 
> provided and if there is a disagreement between the two designated 
> profiles, then the external profile metadata takes priority.
> Note: A Document Interchange Context can obtain external profile 
> metadata by multiple means, including but not limited to: profile 
> parameter data provided by a content container or envelope, using a 
> pre-processor that attempts to guess the applicable profile, etc.
> Note: If a Document Instance is considered compatible with a 
> Processor, but is determined to be incompatible, then normal 
> processing may be aborted. As an alternative, a Processor is permitted 
> to restart processing with the Image Profile as the default profile in 
> case an incompatibility is detected and the [profile 
> defaulting]procedure was previously used to select the Text Profile.
> Note: The determination and processing of the profile of an arbitrary 
> TTML Document Instance that is not compatible with either Profile 
> defined herein is outside the scope of this specification.
> Modify Section 6.10 #profile entry to replace the first paragraph
> "The ttp:profileattribute ..."
> with the following:
> "The constraints and recommendations specified by [profile 
> specification](see §5.4 above) apply."