Re: Sourcing language information for media tracks

I see, can you link to the repo from the spec itself?

On Sat, Mar 12, 2016 at 4:19 AM, Silvia Pfeiffer <silviapfeiffer1@gmail.com>
wrote:

> https://github.com/w3c/HTMLSourcingInbandTracks
>
> It's been there forever and maintained there also.
>
> Best Regards,
> Silvia.
> On 11 Mar 2016 10:29 PM, "Yosuke Funahashi" <yosuke@w3.org> wrote:
>
>> I can set up a Github repo for this spec under the W3C account If you
>> prefer.
>>
>> Yosuke
>>
>> On 3/11/16 5:53 PM, Philip Jägenstedt wrote:
>>
>>> Silvia, any chance of maintaining this spec on GitHub so that you can
>>> accept
>>> PRs? Not that I'm volunteering, of course, but this seems like the kind
>>> of thing
>>> where it'd be appropriate :)
>>>
>>> On Fri, Mar 11, 2016 at 8:26 AM, Sergey Volk <servolk@chromium.org
>>> <mailto:servolk@chromium.org>> wrote:
>>>
>>>     Hi,
>>>     I've been working on adding media track support in Chromium and was
>>>     trying to use  the spec at
>>>     https://dev.w3.org/html5/html-sourcing-inband-tracks/ for reading
>>>     various media track properties.
>>>     I've ran into a few issues (see the discussion at
>>>     https://codereview.chromium.org/1735003004/ for details):
>>>
>>>     1. The current draft says that for MPEG-4 ISOBMFF files the language
>>>     for audio/video tracks should be: "Content of the language field in
>>>     the MediaHeaderBox."
>>>     But according to various sources (e.g.
>>>
>>> https://developer.apple.com/library/mac/documentation/QuickTime/QTFF/QTFFChap2/qtff2.html
>>> ,
>>>     https://www.scribd.com/doc/10911307/26/mdhd-box, etc) the language
>>>     field in MDHD box is a zero-padded 16-bit value that encodes a
>>>     3-letter ISO 639-2/T language code:
>>>     3-character code specifying language(see ISO 639-2/T); each character
>>>     isinterpreted as 0x60 + (5 bit) code to yield an ASCII character.
>>>     Yet according to the HTML5 spec (see
>>>
>>> https://html.spec.whatwg.org/multipage/embedded-content.html#dom-audiotrack-language
>>> )
>>>     A/V track language attributes must return BCP-47 language tag
>>> strings,
>>>     not the 3-character ISO 639-2/T codes.
>>>     So the inband-tracks-sourcing spec should probably mention that the
>>>     language read from MDHD.language field needs to be translated into
>>>     BCP-47.
>>>
>>>     2. Again, according to multiple sources on the internet (for example
>>>     see
>>>
>>> https://developer.apple.com/library/mac/documentation/QuickTime/QTFF/QTFFChap2/qtff2.html
>>> ).
>>>     There is a new way to specify language info for media tracks in MP4
>>>     files, see the 'Extended Language Tag Atom' section in the link
>>> above.
>>>     The ELNG box is optional, but when present it will have a BCP-47
>>>     language info. So when the ELNG box is present in the .mp4 file, it
>>>     should probably be preferred over the language field of MDHD box.
>>>
>>>
>>>
>> --
>> Yosuke Funahashi
>> Web and TV IG co-chair, Entertainment vertical champion,
>> HTML Media Extensions WG team contact at W3C
>> Project Associate Professor at Keio University
>>
>