Re: MPEG-2 TS Metadata Cue

From: <Clift>, Graham <Graham.Clift@am.sony.com<mailto:Graham.Clift@am.sony.com>>
Date: Monday, April 28, 2014 at 4:31 PM
To: Bob Lund <b.lund@cablelabs.com<mailto:b.lund@cablelabs.com>>, "public-inbandtracks@w3.org<mailto:public-inbandtracks@w3.org>" <public-inbandtracks@w3.org<mailto:public-inbandtracks@w3.org>>
Cc: Mark Vickers <mark_vickers@cable.comcast.com<mailto:mark_vickers@cable.comcast.com>>, Giuseppe Pascale <giuseppep@opera.com<mailto:giuseppep@opera.com>>, Glenn Adams <glenn@skynav.com<mailto:glenn@skynav.com>>
Subject: RE: MPEG-2 TS Metadata Cue

Some questions:


1.       What is the difference between the MpegTsDescriptor[] descriptors in PM section:

interface MpegTsPmt : MpegTsSection { //Transport Stream program map section (see Table 2-28)
    ..
    attribute MpegTsDescriptor[] descriptors;

and the same in Description Table Section


interface MpegTsDescriptionSection : MpegTsSection { // Transport Stream Description Table (see Table 2-30-1)

   attribute MpegTsDescriptor[] descriptors;

}



Descriptors that apply to the entire program, e.g. content_advisory_descriptor, can either come in PMT (MpegTsPMT) or in a separate elementary stream carrying the table of format MpegTsDescriptionSection.


2.       Is the difference between MpegTsElementaryStream and MpegTsElementaryStreamData[] a typo?



interface MpegTsPmt : MpegTsSection { //Transport Stream program map section (see Table 2-28)

    ..

    attribute MpegTsElementaryStreamData[] streams;

}



interface MpegTsElementaryStream {

   ..

}


Yes – thanks for catching it.


3.       Since Elementary Stream Data usually means payload I think this term is confusing.

Maybe MpegTsElementaryStreamMetaData.


4.       The tables 2-28 and 2-30-1 don’t seem to exist

They do in 13818.1 Second edition 2000-12-01. What are you looking at?


5.       What is purpose of pcrPID?

In 13818-1 it says " The Program Map

Table, in Table 2-28, specifies, among other information, which PIDs, and therefore which elementary streams are

associated to form each program. This table also indicates the PID of the Transport Stream packets which carry the PCR

for each program”


6.       Since these are cues should there be timing information?

They all derive from TextTrackCue.



Regards

Graham


From: Bob Lund [mailto:B.Lund@CableLabs.com]
Sent: Monday, April 28, 2014 3:00 PM
To: public-inbandtracks@w3.org<mailto:public-inbandtracks@w3.org>
Cc: Mark Vickers @ Comcast; Giuseppe Pascale; Glenn Adams
Subject: MPEG-2 TS Metadata Cue

Hi All,

Given the direction of the discussion around DataCue, I put together a proposal for an MPEG-2 TS specific metadata cue interface<https://www.w3.org/community/inbandtracks/wiki/Main_Page#MPEG-2_TS_Metadata_Cue>. I’m no WebIDL expert (or even novice) so comments/suggestions are welcome.

The approach is fairly straightforward. There are three types of metadata script can use: program map table, transport stream descriptors and private sections. All of these are tables that have a common set of attributes, including tableId, and table specific attributes. tableId is used to determine the type of table. So, the Cue exposes the tableId and the rest of the table data. The tableId is used to determine the format of the rest of the table data.

Take a look and let me know what you think.

Thanks,
Bob