RE: Proposal from HbbTV

Sylvia,

>In particular, I would like to know if we really need to distinguish three different types of MPEG-2 TS formats?? 

Well if a UA interprets a DVB TS according to the rules for an ASTC TS it's going to give wrong results.
>From a quick look at the differences between the two sets of text, the ATSC rules would not recognise any DVB subtitle (+caption) tracks and would not recognise some DVB video and audio tracks.

<snip>

>Also: what's the purpose in not exposing any of the cue content for MPEG-2 TS ?

HbbTV has no requirement for this and it seems like a lot of work. DVB has many, many different ways of carrying data in an MPEG-2 transport stream and there's no outright winner or lowest common denominator.

Jon
________________________________________
From: Silvia Pfeiffer [silviapfeiffer1@gmail.com]
Sent: 22 September 2014 11:52
To: alexander.adolf@condition-alpha.com
Cc: public-inbandtracks@w3.org; Jon Piesing; Nigel Megitt
Subject: Re: Proposal from HbbTV

For those looking for a quick summary of the changes, the best way to
look at Alexander's changes is by diff. I've also extracted
Alexander's change notes so you can give feedback right here on this
thread.

In particular, I would like to know if we really need to distinguish
three different types of MPEG-2 TS formats?? And if so, does anyone
have the missing information on ISDB? Also, I would suggest creating a
completely separate section for these different formats since they are
so fundamentally different from each other.

Also: what's the purpose in not exposing any of the cue content for MPEG-2 TS ?

1) Diff for the MPEG-DASH section:
============================
http://services.w3.org/htmldiff?doc1=https%3A%2F%2Frawgit.com%2Fsilviapfeiffer%2FHTMLSourcingInbandTracks%2Fmaster%2Findex.html&doc2=https%3A%2F%2Frawgit.com%2Fc-alpha%2FHTMLSourcingInbandTracks%2Fhbbtv-dash%2Findex.html

Change notes and rationale:

* We are proposing to source DASH EventStreams as text tracks. These
are e.g. used for ad insertion, and for dealing with timelines in
second screen applications.
* The updates to the table for sourcing the attributes of text tracks
other than event streams try to provide further detail and align with
MPEG-DASH and DVB's profile of it.
* The updates to the table for sourcing the attributes of audio and
video tracks try to provide further detail and align with MPEG-DASH
and DVB's profile of it.
* At the end of the section, we propose a new table for sourcing the
attributes of text tracks representing DASH EventStreams.


2) Diff for MPEG-4 ISO-BMFF section:
==============================
http://services.w3.org/htmldiff?doc1=https%3A%2F%2Frawgit.com%2Fsilviapfeiffer%2FHTMLSourcingInbandTracks%2Fmaster%2Findex.html&doc2=https%3A%2F%2Frawgit.com%2Fc-alpha%2FHTMLSourcingInbandTracks%2Fhbbtv-isobmff%2Findex.html

Change notes and rationale:
We are proposing adding support for W3C TTML 2nd edition, and for
EBU-TT-D as captions and subtitles. The note below the table tries to
give some guidance on the various profiles and extensions that both
SMPTE-TT and EBU-TT-D apply to TTML. The value of the 'namespace'
field in the 'XMLSubtitleSampleEntry' is still under discussion.
unfortunately, the ISOBMFF spec remains sufficiently vague ("...shall
be set to indicate the namespace...") to warrant further discussion.
Concatenating the namespaces in angle brackets to make the string
discernable to URI parser is one option. Another option would be to
use short names as hinted in the ISOBMFF spec (e.g. "TTML+SMPTETT").
But then there is no registry yet to provide the mappings and help
avoid name clashes.


3. Changes for MPEG-2 TS section:
============================
1. http://services.w3.org/htmldiff?doc1=https%3A%2F%2Frawgit.com%2Fsilviapfeiffer%2FHTMLSourcingInbandTracks%2Fmaster%2Findex.html&doc2=https%3A%2F%2Frawgit.com%2Fc-alpha%2FHTMLSourcingInbandTracks%2Fhbbtv-mpeg2ts-1%2Findex.html

2. http://services.w3.org/htmldiff?doc1=https%3A%2F%2Frawgit.com%2Fsilviapfeiffer%2FHTMLSourcingInbandTracks%2Fmaster%2Findex.html&doc2=https%3A%2F%2Frawgit.com%2Fc-alpha%2FHTMLSourcingInbandTracks%2Fhbbtv-mpeg2ts-2%2Findex.html

3. http://services.w3.org/htmldiff?doc1=https%3A%2F%2Frawgit.com%2Fsilviapfeiffer%2FHTMLSourcingInbandTracks%2Fmaster%2Findex.html&doc2=https%3A%2F%2Frawgit.com%2Fc-alpha%2FHTMLSourcingInbandTracks%2Fhbbtv-mpeg2ts-3%2Findex.html

4. http://services.w3.org/htmldiff?doc1=https%3A%2F%2Frawgit.com%2Fsilviapfeiffer%2FHTMLSourcingInbandTracks%2Fmaster%2Findex.html&doc2=https%3A%2F%2Frawgit.com%2Fc-alpha%2FHTMLSourcingInbandTracks%2Fhbbtv-mpeg2ts-4%2Findex.html

5. http://services.w3.org/htmldiff?doc1=https%3A%2F%2Frawgit.com%2Fsilviapfeiffer%2FHTMLSourcingInbandTracks%2Fmaster%2Findex.html&doc2=https%3A%2F%2Frawgit.com%2Fc-alpha%2FHTMLSourcingInbandTracks%2Fhbbtv-mpeg2ts-5%2Findex.html
(note: this patch destroys the document structure)

6. http://services.w3.org/htmldiff?doc1=https%3A%2F%2Frawgit.com%2Fsilviapfeiffer%2FHTMLSourcingInbandTracks%2Fmaster%2Findex.html&doc2=https%3A%2F%2Frawgit.com%2Fc-alpha%2FHTMLSourcingInbandTracks%2Fhbbtv-mpeg2ts-6%2Findex.html
(note: this patch destroys the document structure)

7. http://services.w3.org/htmldiff?doc1=https%3A%2F%2Frawgit.com%2Fsilviapfeiffer%2FHTMLSourcingInbandTracks%2Fmaster%2Findex.html&doc2=https%3A%2F%2Frawgit.com%2Fc-alpha%2FHTMLSourcingInbandTracks%2Fhbbtv-mpeg2ts-7%2Findex.html
(note: this patch destroys the document structure)

Change notes and rationale summary:
The text you currently have deals with ATSC systems only. We propose
to add support for DVB and ISDB systems, too. In the proposed updates
to the opening of the MPEG2-TS section, we set the scene for TS
originating from different kinds of broadcast systems. The link to
"ATSC Worldwide" is a dead one as I couldn't find any such page. This
may seem logical for a national SDO at first, but then ATSC is used in
South Korea and in most countries in South America; whence creating an
"ATSC Worldwide" page might actually make sense.

Regards,
Silvia.


On Mon, Sep 22, 2014 at 6:24 PM, Silvia Pfeiffer
<silviapfeiffer1@gmail.com> wrote:
> On Wed, Sep 17, 2014 at 8:29 AM,  <alexander.adolf@condition-alpha.com> wrote:
>> Dear Media Resource In-band Tracks Community Group,
>>
>> As suggested by Silvia and Bob, I have refactored the pull request on GitHub into smaller chunks, which hopefully will be easier to handle. The comments on GitHub to each of them contains a link to a visual diff. They can all be merged without conflicts. If you go through them one by one and merge them all, the end result will be identical to what the initial, big pull request contains. Please ignore all the commits in the GitHub history, and focus on the diffs (visual or source, whichever works better for you).
>>
>> ----------------------------------------------------------------------
>> https://github.com/silviapfeiffer/HTMLSourcingInbandTracks/pull/2
>>
>> This contains the changes to the MPEG DASH section.
>> ----------------------------------------------------------------------
>> https://github.com/silviapfeiffer/HTMLSourcingInbandTracks/pull/3
>>
>> This contains the changes to the ISOBMFF section.
>> ----------------------------------------------------------------------
>> https://github.com/silviapfeiffer/HTMLSourcingInbandTracks/pull/4
>> https://github.com/silviapfeiffer/HTMLSourcingInbandTracks/pull/5
>> https://github.com/silviapfeiffer/HTMLSourcingInbandTracks/pull/6
>> https://github.com/silviapfeiffer/HTMLSourcingInbandTracks/pull/7
>> https://github.com/silviapfeiffer/HTMLSourcingInbandTracks/pull/8
>> https://github.com/silviapfeiffer/HTMLSourcingInbandTracks/pull/9
>> https://github.com/silviapfeiffer/HTMLSourcingInbandTracks/pull/10
>>
>> These contain the changes to the MPEG2-TS part, on a section by section basis.
>> ----------------------------------------------------------------------
>>
>> Please see the GitHub comments for each of the pull requests for more details.
>>
>> I have however not included the references in these pull requests to improve the signal to noise ratio. I will of course add the references to https://github.com/tobie/specref as you approve and merge the pull requests.
>>
>> I hope that this refactoring is along the lines of what you had expected.
>>
>>
>> Many thanks and cheers,
>>
>>   --alexander adolf
>
> Hi Alexander,
>
> Thanks for grouping the patches logically. You have, however, somehow
> made them on my fork of the spec rather than on the w3c's main spec in
> GitHub:
> https://github.com/w3c/HTMLSourcingInbandTracks
>
> I will review them on my fork, but it will make sense for you to
> change your upstream to be the one of w3c.
> Also, Bob is our main expert around MPEG, so he will probably be the
> one to merge your patches.
>
> Regards,
> Silvia.

Received on Wednesday, 24 September 2014 12:51:44 UTC