Re: IMSC1 and profile designator

On Thu, Oct 8, 2015 at 2:08 AM, Nigel Megitt <> wrote:

> In ยง 6.1 it is stated that the #profile feature MAY be used. I take this
> to mean that it is permitted to specify a ttp:profile attribute on the
> tt:tt element but not required. There's no suggestion of including the
> ttp:profile attribute within a document in a different location to what is
> defined in TTML1SE.

Unfortunately, the way that IMSC is specified, i.e., in terms of whether a
feature may be used or not, doesn't translate very well to guidance about
actual authoring. In this case, the #profile feature covers quite a bit of
functionality beyond @ttp:profile, and doesn't by itself address the
presence or absence of this attribute.

I do see the following notes under 7.1 and 8.1:

"As specified in 6.10 Features
the presence of the ttp:profile attribute is not required by this profile.
The profile designator specified above is intended to be generally used to
signal conformance of a Document Instance
the profile. The details of such signaling depends on the application, and
can, for instance, use metadata structures out-of-band of the Document

For TTV support of IMSC1, we plan to emit a warning by default if no
@ttp:profile is specified. I would like to see IMSC1 updated to specify
that this profile SHOULD be specified. Whether it is specified or not is
independent of whether a processor supports the #profile feature as defined.

> Since the same principle of extension as in TTML1SE applies, it is also
> legal (but out of scope of the specification) to include the
> ebuttm:conformsToStandard element but strict processors can ignore it.
> Kind regards,
> Nigel
> On 08/10/2015 08:56, "Cyril Concolato"
> <> wrote:
> >Hi,
> >
> >Reading IMSC1, it is unclear where the defined profile designators
> >should be used? In particular it says "the presence of the ttp:profile
> >attribute is not required by this profile." Why not? Where should it be
> >used? Is there an equivalent to ebutt:conformsToStandard to use them?
> >
> >Regards,
> >Cyril
> >
> >--
> >Cyril Concolato
> >Multimedia Group / Telecom ParisTech
> >
> >@cconcolato
> >
> >

Received on Thursday, 8 October 2015 14:25:14 UTC