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TTML Profiles for Internet Media Subtitles and Captions (IMSC)
https://w3c.github.io/imsc/
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Incompatible SMPTE ST 2052-1:2013 extension namespace name #512

Open palemieux opened 4 years ago

palemieux commented 4 years ago

SMPTE ST 2052-1:2013 (SMPTE-TT) modified the extension namespace name originally defined in SMPTE ST 2052-1:2010, from http://www.smpte-ra.org/schemas/2052-1/2010/smpte-tt to http://www.smpte-ra.org/schemas/2052-1/2013/smpte-tt. [ed.: It is not clear why this change was made.]

IMSC 1.0.1 and IMSC 1.1 use http://www.smpte-ra.org/schemas/2052-1/2010/smpte-tt exclusively for the smpte:backgroundImage attribute.

IMSC 1.0.1 references undated SMPTE ST 2052-1.

IMSC 1.1 references SMPTE ST 2052-1:2013.

palemieux commented 4 years ago

I suggest changing the reference back to SMPTE ST 2052-1:2010, esp. since smpte:backgroundImage is deprecated in IMSC 1.1.

palemieux commented 4 years ago

Summary:

The normative reference:

SMPTE ST 2052-1:2013 "Timed Text Format (SMPTE-TT)". SMPTE. URL: https://doi.org/10.5594/SMPTE.ST2052-1.2013

is modified to read:

SMPTE ST 2052-1:2010 "Timed Text Format (SMPTE-TT)". SMPTE. URL: https://doi.org/10.5594/SMPTE.ST2052-1.2010

nigelmegitt commented 4 years ago

I think that makes sense too. Would be interested to know if @mikedo has a view on this.

css-meeting-bot commented 4 years ago

The Timed Text Working Group just discussed Incompatible SMPTE ST 2052-1:2013 extension namespace name imsc#512, and agreed to the following:

The full IRC log of that discussion <nigel> Topic: Incompatible SMPTE ST 2052-1:2013 extension namespace name imsc#512
<nigel> github: https://github.com/w3c/imsc/issues/512
<nigel> Nigel: I did try to ping Mike Dolan about this but he did not respond (on this issue).
<nigel> .. I think this is super tricky to know what to do without input from SMPTE.
<nigel> Pierre: The long term decision is tricky. IMSC has used the 2010 version from the beginning. In the short term the
<nigel> .. right thing to do for internal consistency in IMSC is to update the reference to 2010.
<nigel> .. For dealing with this in the longer term we need input from SMPTE.
<nigel> Glenn: TTV did implement it as specified so we would have to go back and retrofit this change.
<nigel> Pierre: I looked at TTV. For IMSC I think it still uses 2010. It does have a profile for SMPTE-TT 2013 but my reading of
<nigel> .. the code...
<nigel> Glenn: Okay I did not go back to verify if the IMSC part uses the SMPTE-TT 2013 part for that namespace.
<nigel> .. You may be right.
<nigel> Pierre: I didn't spend hours but my take is TTV supports 2010 and 2013 but IMSC uses 2010.
<nigel> Glenn: I support the suggested change.
<nigel> .. I don't remember if this group ever consciously made the decision to use the 2013 namespace. Do you?
<nigel> Pierre: We never discussed it. When we started IMSC SMPTE-TT was at 2010 so we used it.
<nigel> .. When we moved to IMSC 1.1 we tried to date all references but in our excitement we didn't check if 2013 was
<nigel> .. backward compatible with 2010, and it looks like it is not.
<nigel> .. We need SMPTE to tell us if that was intended or an error within SMPTE.
<nigel> Glenn: I suspect it was something that wasn't checked.
<nigel> Pierre: That's why I suggest we revert the reference to the dated 2010 version.
<nigel> Glenn: I agree.
<nigel> RESOLUTION: Publish this erratum as at https://github.com/w3c/imsc/issues/512#issuecomment-562895873
<nigel> Nigel: Just double checking there are no objections before closing this agenda topic?
<nigel> group: [no objections]