RE: TV Control API Specification - Clarification

Hello Haseenamol

Great to hear that you are implementing the TVControl API from September 2016. Here are my thoughts on your two queries..

[Query1]
This interface defines a method in the application space that would be triggered when there is a change in the set of tuners available. As your implementation has only a fixed set of tuners, this event interface would not be needed. The application can get the set of tuners from the TVManager.getTuners() method.

[Query2]
The Audio and Subtitle language formats were added at the program level to provide the greatest degree of flexibility. We often see programs on the same channel having different (additional) languages and this, as well as "all programs have the same languages" is supported when the Audio and Subtitle languages are provided at the program level.
Since TVProgram objects will be obtained through the TVChannel.getPrograms() or TVChannel.getCurrentProgram() methods, it should be easy to populate from the PMT/TVCT.
Also note that a TVProgram is returned through the TVManager.getRecordings() method and as this is not channel specific, the Audio and Subtitle language information would be lost if it was only at the TVChannel level.

Paul

From: HASEENAMOL [mailto:haseenamol@tataelxsi.co.in]
Sent: Monday, April 17, 2017 7:06 AM
To: public-tvcontrol@w3.org
Subject: TV Control API Specification - Clarification

Hi,

We are progressing with the implementation of TVControl API based on September 2016 draft version (https://www.w3.org/TR/2016/WD-tvcontrol-api-20160915/#tvprogram-interface). We found that TVControl group is still working on the spec and  there is lot of changes in the interfaces in the latest version against September 2016 version.

I have some clarification in the following interfaces (these interfaces are same in September and latest work-in progress versions),
[Query1]
21. TVTunerChangeEvent<https://w3c.github.io/tvcontrol-api/#dom-tvtunerchangeevent> Interface
The TVTunerChangeEvent<https://w3c.github.io/tvcontrol-api/#dom-tvtunerchangeevent> interface represents the event related to the TV/Radio tuner that is added/removed by the device.
interface TVTunerChangeEvent<https://w3c.github.io/tvcontrol-api/#dom-tvtunerchangeevent> : Event<https://dom.spec.whatwg.org/#event> {
    readonly attribute TVTunerChangeEventOperation<https://w3c.github.io/tvcontrol-api/#dom-tvtunerchangeeventoperation> operation<https://w3c.github.io/tvcontrol-api/#dom-tvtunerchangeevent-operation>;
    readonly attribute DOMString<https://www.w3.org/TR/WebIDL-1/#idl-DOMString>                   id<https://w3c.github.io/tvcontrol-api/#dom-tvtunerchangeevent-id>;
};
In most of the cases the tuner devices are fixed, not plug-n-play, so in such cases does the interface implementation is mandatory ? Can be make it as optional ?

[Query2] 12. TVProgram Interface

The TVProgram interface represents a set of properties and operations related to a TV/Radio program (e.g. a DVB or ATSC Event). An instance of a TVProgram corresponds to one showing of that program: if the same program is shown at two different times or on different channels then each showing is represented by a different TVProgram instance.

interface TVProgram {
    sequence<DOMString> getAudioLanguages();
    sequence<DOMString> getSubtitleLanguages();
    sequence<DOMString> getGenres();
    readonly attribute DOMString    eventId;
    readonly attribute TVChannel    channel;
    readonly attribute DOMString    title;
    readonly attribute DOMTimeStamp startTime;
    readonly attribute DOMTimeStamp duration;
    readonly attribute DOMString?   shortDescription;
    readonly attribute DOMString?   longDescription;
    readonly attribute DOMString?   parentalRating;
    readonly attribute boolean      isEncrypted;
    readonly attribute DOMString?   seriesId;
};

             Audio/Subtitle languages info will be based on the channel and has to be read from the PMT/TVCT, in such case do we have to keep getAudioLanguages/getSubtitleLanguages in TVProgram class? Can we move it into TVChannel ?

Best Regards
Haseenamol

Senior Specialist - Broadcast | Embedded Product Design
TATA ELXSI
Neyyar Techno park Campus Trivandrum 695 581 India
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