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

I've added a new, generalized named metadata item mechanism, ttm:item [1]
which I believe addresses your use case, and also can have many additional
uses, such as representing other EBU and SMPTE metadata items.

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

On Tue, Nov 25, 2014 at 10:11 AM, Glenn Adams <glenn@skynav.com> wrote:

> Thanks for your review and input.
>
> On Tue, Nov 25, 2014 at 2:43 AM, John Birch <John.Birch@screensystems.tv>
> wrote:
>
>>  Hi Glenn,
>>
>>
>>
>> I’ve been looking at your proposal for embedded content (and I like it J
>> 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…
>>
>
> In the above example, charset is a parameter of the MIME type expression
> of the *type* attribute. No relationship with the 'encoding' attribute.
>
>
>> 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?
>>
>
> Correct, 'encoding' is permitted only on the data element when the content
> of the data element uses simple data embedding, i.e., consists only of
> #PCDATA that encodes the data bytes. If a data element uses chunked data
> embedding, i.e., uses chunk element children, then all of the encoded data
> bytes are in child chunk elements, so the encoding attribute applies only
> to the chunk children and not the data parent.
>
> In the above example, the encoding attribute's default value 'base64'
> applies on the chunk children, and is not relevant on the data parent.
>
>
>
>>  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”.
>>
>
> I'm not sure there is a useful use case for formalizing such a
> name/identifier. It wouldn't have any relevant processing semantics in
> TTML2, so it is definitely in the metadata category, which means using a
> ttm:* attribute or a metadata element, e.g., one could use the following
> convention with ttm:desc.
>
> <data type='application/octet-stream'>
>   <metadata>
>     <ttm:desc>original_file_name=foo.bar</ttm:desc>
>   </metadata>
>   <chunk>
>   ... encoded base64 data ...
>   </chunk>
> </data>
>
> I wouldn't mind adding a new ttm:* element that generalizes the task of
> defining metadata parameters, e.g.,
>
> <ttm:parameter name='fileName'>foo.bar</ttm:parameter>
>
> which would allow rewriting the above example to
>
> <data type='application/octet-stream'>
>   <metadata>
>     <ttm:parameter name='original_file_name'>foo.bar</ttm:parameter>
>   </metadata>
>   <chunk>
>   ... encoded base64 data ...
>   </chunk>
> </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).
>>
>
> We could consider it. But it definitely would not be appropriate on chunk,
> which sole purpose is to enable streaming of data fragment children of a
> data element. I guess you are thinking chunk might be used to contain
> multiple original files (separately named) that are concatenated to form a
> single data resource. This is counter to my intention that a chunk contain
> a fragment of a data resource, or, if one wished, an entire data resource
> (if a data element has a single chunk child like in the above example).
>
>
>>
>>
>> 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.
>>
>>
>>
>>
>>
>>
>> *John Birch | Strategic Partnerships Manager | Screen *Main Line : +44
>> 1473 831700 | Ext : 2208 | Direct Dial : +44 1473 834532
>> Mobile : +44 7919 558380 | Fax : +44 1473 830078
>> John.Birch@screensystems.tv | www.screensystems.tv |
>> https://twitter.com/screensystems
>>
>>
>> *Visit us at BVE, Excel London 24-26 February 2015 Stand No. N19*
>>
>> *P** Before printing, think about the environment*
>>
>> *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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>
>