W3C home > Mailing lists > Public > public-html-media@w3.org > April 2014

Re: [MSE] F2F discussion items

From: David Singer <singer@apple.com>
Date: Tue, 29 Apr 2014 09:57:57 -0700
Cc: Paul Cotton <Paul.Cotton@microsoft.com>, "public-html-media@w3.org" <public-html-media@w3.org>
Message-id: <600338B5-FFAB-44FB-989B-1E33AE012323@apple.com>
To: Pierre-Anthony Lemieux <pal@sandflow.com>

On Apr 29, 2014, at 9:48 , Pierre-Anthony Lemieux <pal@sandflow.com> wrote:

> Hi David,
> 
>> But on the mpeg list there was exactly the opposite suggestion,
>> that there be only one box.
> 
> Which MPEG list?

The MP4 file format discussion list.

> 
>> That’s inappropriate, I think.  And strange.
> 
> Uh. Ok. Why?

"name is a null-terminated string in UTF-8 characters which gives a human-readable name for the track type (for debugging and inspection purposes). “

It explains the type of track.  Typical common practice is to put in a string from the spec.:

‘vide’   Video track
‘soun’   Audio track
‘hint’      Hint track
‘meta’      Timed Metadata track
‘auxv’      Auxiliary Video track
‘text’      Timed text track
‘subt’      Subtitle track

Something for ‘debugging and inspection’ is quite unsuitable for being both syntax-constrained and constrained to a fixed vocabulary.

> 
> Best,
> 
> -- Pierre
> 
> On Tue, Apr 29, 2014 at 9:42 AM, David Singer <singer@apple.com> wrote:
>> 
>> On Apr 28, 2014, at 20:27 , Pierre-Anthony Lemieux <pal@sandflow.com> wrote:
>> 
>>> Hi David,
>>> 
>>> Some data points/questions below.
>>> 
>>>> Quantity:          Zero or more
>>> 
>>> Does this mean that more than one "kind" box can be associated with a
>>> single track? A given timed text track can serve multiple purposes,
>>> e.g. both SDH and subtitle, and hence be associated with multiple
>>> kinds.
>> 
>> OK.  But on the mpeg list there was exactly the opposite suggestion, that there be only one box.
>> 
>>> 
>>>> contains the track ‘kind’ as defined <<by the W3C spec //
>>>> section X of this spec. // whatever .>>.
>>> 
>>> Also, the 'kind' defined in HTML might not be sufficient alone to
>>> cover common kinds of timed text out there, e.g. 'commentary',
>>> 'large'/'Text for the Visually Impaired', 'easyreader', 'karaoke',
>>> etc…
>> 
>> There has to be some agreement what the kinds mean;  we can’t have random communities inventing kinds and then finding they use the same word with different meanings.  I think that the w3c needs to document them, and if you are not in the w3c’s spec/radar, you are on your own.
>> 
>>> 
>>>> Container:        User data box (‘udta’)
>>> 
>>> At least one specification (Ultraviolet) use the 'name' field of the
>>> 'hdlr' box to carry a comma-separated list of kinds for the timed text
>>> track.
>> 
>> That’s inappropriate, I think.  And strange.
>> 
>>> 
>>> Thanks,
>>> 
>>> -- Pierre
>>> 
>>> On Wed, Apr 9, 2014 at 7:15 AM, David Singer <singer@apple.com> wrote:
>>>> 
>>>> On Apr 9, 2014, at 15:25 , Paul Cotton <Paul.Cotton@microsoft.com> wrote:
>>>> 
>>>>> [MSE] Summary of "Resolving Bug 24370" thread and proposed next steps, Aaron
>>>>> http://lists.w3.org/Archives/Public/public-html-media/2014Apr/0043.html
>>>>> 
>>>> 
>>>> 
>>>> I am checking with the MP4 experts at MPEG, but my inclination is that the box definition belongs in the W3C spec. anyway and would be registered at the MP4RA.  Something like
>>>> 
>>>> 1.1.1.1       Definition
>>>> 
>>>> Box Type:        ‘kind’
>>>> Container:        User data box (‘udta’)
>>>> Mandatory:      No
>>>> Quantity:          Zero or more
>>>> 
>>>> The kind box contains the track ‘kind’ as defined <<by the W3C spec // section X of this spec. // whatever .>>.
>>>> 
>>>> 1.1.1.2       Syntax
>>>> 
>>>> aligned(8) class TrackKindBox
>>>>  extends FullBox(‘kind’, version = 0, 0) {
>>>>  string   thekind;
>>>> }
>>>> 
>>>> 1.1.1.3       Semantics
>>>> 
>>>> thekind is a null-terminated string in UTF-8 characters, giving a track kind as defined by <<section X of Y>>.
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>>>> David Singer
>>>> Manager, Software Standards, Apple Inc.
>>>> 
>>>> 
>>> 
>> 
>> David Singer
>> Manager, Software Standards, Apple Inc.
>> 

David Singer
Manager, Software Standards, Apple Inc.
Received on Tuesday, 29 April 2014 17:20:17 UTC

This archive was generated by hypermail 2.3.1 : Tuesday, 6 January 2015 20:33:03 UTC