RE: [ttml2] embedded content, background image styling, other edits

Hi Glenn,

I’ve been looking at your proposal for embedded content (and I like it ☺ but I noticed the following:

...
<data type="text/plain; charset=us-ascii" length="44">
  <chunk length="19">
    VGhlIHF1aWNrIGJyb3duIGZveA==
  </chunk>
  <chunk length="25">
    IGp1bXBzIG92ZXIgdGhlIGxhenkgZG9nLg==
  </chunk>
</data>
...

I don’t see ‘charset’ as an attribute of data in the later definition… I thought initially this was a typo and that it should be encoding, but then realised that ‘encoding’ is not permitted on the parent data element when using chunks?

On a separate note, I have been discussing on the EBU-TT group reflector how to normalise EBU-TT binaryData with this proposal. As your proposal is broadly in line with the SMPTE usage, it would seem to make sense that EBU-TT migrates towards a compatible strategy. Nigel has proposed a deprecation of some attribute names and a mapping of the binaryData element name in our schema using substitution. However, the binaryData element in EBU-TT includes an attribute that does not appear within your proposed scheme, which is the fileName attribute. This optional attribute may contain “A filename that may be used to identify the original filename of the tunnelled binary data”. There is some discussion as to the usage of this element, it could be viewed as metadata of ‘historic interest’ (e.g. the name of the DOS file that is encapsulated by the binary data) or it could be seen as a directive (i.e. what to name a file should a processor re-create a file from the binary data). My personal leanings are towards the former use…

Regardless of the use of this attribute, I would like to propose that the TTWG consider adding a similar attribute to the data and chunk elements in TTWG. (As an aside the chunk element you propose would be a better resolution to one of the original EBU-TT requirements where multiple floppy disk based DOS files make up an STL document.) Clearly the name ‘fileName’ would be inappropriate in a more generic specification but I tentatively suggest the following (below).

Best regards,
John


<chunk
  encoding<https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#embedded-content-attribute-encoding> = (base16|base32|base32hex|base64|base64url) : base64
  length = xsd:nonNegativeInteger<http://www.w3.org/TR/xmlschema-2/#nonNegativeInteger>
  xml:id<https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#content-attribute-id> = ID
  ident = xs:string
  {any attribute not in default or any TT namespace}>
  Content: #PCDATA
</chunk>


An ident attribute may be specified, and may contain an identifier for the contained data from an external context (e.g. the original filename).

And
<data
  encoding<https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#embedded-content-attribute-encoding> = (base16|base32|base32hex|base64|base64url) : see prose below
  format<https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#embedded-content-attribute-format> = <data-format><https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#embedded-content-value-data-format>
  length = xsd:nonNegativeInteger<http://www.w3.org/TR/xmlschema-2/#nonNegativeInteger>
  src<https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#embedded-content-attribute-src> = <data><https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#embedded-content-value-data>
  type<https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#embedded-content-attribute-type> = xsd:string<http://www.w3.org/TR/xmlschema-2/#string> : see prose below
  xml:id<https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#content-attribute-id> = ID
  ident = xs:string
  xml:lang<https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#content-attribute-lang> = xsd:string<http://www.w3.org/TR/xmlschema-2/#string>
  xml:space<https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#content-attribute-space> = (default|preserve)
  {any attribute not in default or any TT namespace}>
  Content: #PCDATA | (Metadata.class<https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#element-vocab-group-metadata>*, chunk<https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#embedded-content-vocabulary-chunk>+) | (Metadata.class<https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#element-vocab-group-metadata>*, source<https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#embedded-content-vocabulary-source>+)
</data>


If simple data embedding is used, i.e., the content of the data element is one or more text nodes, then an ident attribute may be specified, and may contain an identifier for the contained data from an external context (e.g. the original filename). If chunked or sourced data embedding is used, i.e., the content of the data element contains any child chunk<https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#embedded-content-vocabulary-chunk> or source<https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html#embedded-content-vocabulary-source> element, then an ident attribute must not be specified.


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From: Glenn Adams [mailto:glenn@skynav.com]
Sent: 23 November 2014 22:50
To: TTWG
Subject: [ttml2] embedded content, background image styling, other edits

I've updated the TTML2 ED [1] a few times in the last few days to:

  *   add embedded content element types (new section 9)

     *   audio
     *   chunk
     *   data
     *   font
     *   image
     *   resources
     *   source

  *   add background image styling

     *   tts:backgroundImage
     *   tts:backgroundRepeat
     *   tts:backgroundPosition

  *   sub-divide former parameters section into profiles section and parameters section
For detailed diffs, see change sets [2][3][4][5][6].

[1] https://dvcs.w3.org/hg/ttml/raw-file/tip/ttml2/spec/ttml2.html

[2] https://dvcs.w3.org/hg/ttml/rev/d16d284100b9

[3] https://dvcs.w3.org/hg/ttml/rev/67327764d375

[4] https://dvcs.w3.org/hg/ttml/rev/25035c814da5

[5] https://dvcs.w3.org/hg/ttml/rev/cc2b7aad7e7a

[6] https://dvcs.w3.org/hg/ttml/rev/e3fdbceb09cb



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