TV Control API Specification

Abstract

This specification defines an API for sourcing audio and video media, such as TV and radio from broadcast, IPTV, or other sources, with associated channel and program metadata, and allows presentation of the media using the <video> and <audio> HTML elements. The API is agnostic of any underlying audio or video sourcing technologies.

Status of This Document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at https://www.w3.org/TR/.

This document is work in progress and is subject to change. The API is being developed based on requirements from the TV Control Working Group, and previously the TV Control Community Group.

An important issue for the Working Group to address is which functions are appropriate to be accessed from general web applications, and the mechanisms that may be needed to address any security and user privacy concerns.

Changes to this document may be tracked at the specification's GitHub repository.

This document was published by the TV Control Working Group as a First Public Working Draft. This document is intended to become a W3C Recommendation. If you wish to make comments regarding this document, please send them to public-tvcontrol@w3.org (subscribe, archives). All comments are welcome.

Publication as a First Public Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.

This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

This document is governed by the 1 September 2015 W3C Process Document.

1. Introduction

This section is non-normative.

This specification defines the TV Control API, which aims to enable web applications to present audio and video media from broadcast TV and radio, IPTV, or other sources, using the <audio> and <video> HTML elements. The API provides access to programme and service information and allows media recordings to be scheduled and replayed.

TV functionality is accessed through the TVManager object which, via the TVTuner and TVSource objects, allows applications to select and present a TV or radio channel. Presentation is achieved by obtaining a TVMediaStream object from the TVTuner and assigning this to the srcObject attribute of an HTMLMediaElement. The TVMediaStream interface extends MediaStream to allow buffering of the received media, to enable pause/resume and timeshifted playback.

Editor's Note

The purpose and distinction between the TVTuner and TVSource objects requires clarification. See this issue for details.

TVManager also allows recordings to be scheduled and replayed, and application control of the parental lock, to prevent unwanted viewing of particular channels or programs.

TVSource gives access to lists of available channels and programs, and allows applications to set the current channel to be presented. TVChannel contains TV and radio channel attributes, and program schedule information, as a collection of TVProgram objects.

2. Terminology

The EventHandler interface represents a callback used for event handlers as defined in [HTML5].

The Event and EventTarget interfaces are defined in [DOM].

The concepts queue a task and fire an event are defined in [HTML5].

The terms event handler and event handler event types are defined in [HTML5].

The Promise interface, the concepts of a resolver, a resolver's fulfill algorithm and a resolver's reject algorithm are defined in [ECMAScript].

The MediaStream interface is defined in [MediaCapture-Streams].

The MediaRecorder interface is defined in [MediaStream-Recording].

The video element, and HTMLMediaElement, TimeRanges interfaces are defined in [HTML5].

The TextTrack, TextTrackCue, and TrackEvent interfaces are defined in [HTML5]

3. `Navigator` Interface

partial interface Navigator {
    [SameObject]
    readonly        attribute TVManager tv;
};

3.1 Attributes

tv of type TVManager, readonly: MUST return the object that exposes the interface to the TV service.

4. `TVManager` Interface

The TVManager interface represents a bunch of properties and a set of operations that can be used to manage the TV device.

interface TVManager : EventTarget {
    Promise<sequence<TVTuner>>     getTuners ();
    Promise<TVRecording>           addRecording (TVAddRecordingOptions option);
    Promise<void>                  removeRecording (DOMString id);
    Promise<sequence<TVRecording>> getRecordings (optional TVGetRecordingsOptions options);
    Promise<void>                  setParentalControlPin (DOMString oldPin, DOMString newPin);
    Promise<void>                  setParentalControl (DOMString pin, boolean isLocked);
    Promise<sequence<TVCICard>>    getCICards ();
    readonly        attribute unsigned long long totalRecordingSize;
    readonly        attribute unsigned long long availableRecordingSize;
    readonly        attribute boolean            isParentalControlled;
                    attribute EventHandler       ontunerchanged;
                    attribute EventHandler       onrecordingchanged;
                    attribute EventHandler       onparentalcontrolchanged;
                    attribute EventHandler       oncicardchanged;
};

4.1 Attributes

totalRecordingSize of type unsigned long long, readonly: MUST return the total recording size of the TV device.
availableRecordingSize of type unsigned long long, readonly: MUST return the current available recording size of the TV device.
isParentalControlled of type boolean, readonly: MUST return the current state of the TV parental control, which is applied system-wide to the TV device. Once the parental control is unset, all the locked TV channels/programs will become accessible.
ontunerchanged of type EventHandler: Handles the tunerchanged event of type TVTunerChangedEvent, fired when the TV device detects a TV tuner is added/removed.
onrecordingchanged of type EventHandler: Handles the recordingchanged event of type TVRecordingChangedEvent, fired when the recording time frame or the state of the TV recording has been changed.
onparentalcontrolchanged of type EventHandler: Handles the parentalcontrolchanged event, fired when the parental control status is changed.
oncicardchanged of type EventHandler: Handles the cicardchanged event, fired when the CI (Common Interface) card status is changed.

4.2 Methods

getTuners

This method makes a request to retrieve all the TV tuners that are available in the TV device. It returns a new Promise that will be used to notify the caller about the result of the operation, which is an array of TVTuner elements.

No parameters.

Return type: Promise<sequence<TVTuner>>

addRecording

This method adds a recording request for a given channel with explicitly specified start time and end time, or instead an associated TVProgram object. It returns a new Promise that will be used to notify the caller about the result of the operation, which is a newly-created TVRecording object.
Please note the user agent should have a recording scheduler which handles time conflicts between recording requests. If this method tries to add a new request with a time frame overlapped with some existent ones, and given sufficient resource (i.e. tuner), a new TV recording should be created and the scheduler should ensure multiple TV recordings run at the same time. However, if the resource is not sufficient to meet the new request, the Promise should be rejected. Applications may handle this situation with their own strategy, such as explicitly removing the conflicts and re-adding the one to conserve.

Parameter	Type	Nullable	Optional	Description
option	`TVAddRecordingOptions`	✘	✘	Specifies the options for adding recording.

Return type: Promise<TVRecording>

removeRecording

This method makes a request to remove a given recording. It returns a new Promise that will be used to notify the caller about the result of the operation.

Parameter	Type	Nullable	Optional	Description
id	`DOMString`	✘	✘	Specifies the ID of the recording to be removed.

Return type: Promise<void>

getRecordings

This method makes a request to retrieve the available TV recordings according to the given criteria. It returns a new Promise that will be used to notify the caller about the result of the operation.

Parameter	Type	Nullable	Optional	Description
options	`TVGetRecordingsOptions`	✘	✔	Specifies the options for getting recordings.

Return type: Promise<sequence<TVRecording>>

setParentalControlPin

This method makes a request to set the TV parental control PIN used for enabling or disabling parental control. It returns a new Promise that will be used to notify the caller about the result of the operation. Note that the Promise may be rejected with an InvalidAccessError if the old PIN does not match the current one.

Parameter	Type	Nullable	Optional	Description
oldPin	`DOMString`	✘	✘	Specifies the old PIN used for parental control.
newPin	`DOMString`	✘	✘	Specifies the new PIN used for parental control.

Return type: Promise<void>

setParentalControl

This method makes a request to set the TV parental control status. It returns a new Promise that will be used to notify the caller about the result of the operation. Note that the Promise may be rejected with an InvalidAccessError if the PIN does not match the current one.

Parameter	Type	Nullable	Optional	Description
pin	`DOMString`	✘	✘	Specifies the PIN used for parental control.
isLocked	`boolean`	✘	✘	Specifies the parental control status.

Return type: Promise<void>

getCICards

This method makes a request to retrieve a list of CI (Common Interface) cards available in the TV device (e.g. set-top box). It returns a new Promise that will be used to notify the caller about the result of the operation, which is an array of TVCICard elements.

No parameters.

Return type: Promise<sequence<TVCICard>>

4.3 Procedures

The getTuners method when invoked MUST run the following steps:

Let promise be a new Promise object and resolver be its associated resolver.
Return promise to the caller.
Make a request to the TV device to retrieve all the TV tuners that are available in the TV device.
If an error occurs invoke resolver's reject algorithm with error as the value argument.
When the request has been successfully completed:
1. Let tuners be the array of the retrieved TVTuner elements.
2. Invoke resolver's fulfill algorithm with tuners as the value argument.

The addRecording method when invoked MUST run the following steps:

Let promise be a new Promise object and resolver be its associated resolver.
Return promise to the caller.
Make a recording request to the TV recording scheduler according to the options parameter.
If an error occurs invoke resolver's reject algorithm with error as the value argument.
When the request has been successfully completed:
1. Let recording be the newly-created TVRecording object.
2. Invoke resolver's fulfill algorithm with recording as the value argument.

The removeRecording method when invoked MUST run the following steps:

Let promise be a new Promise object and resolver be its associated resolver.
Return promise to the caller.
Make a request to the TV device to remove the given record.
If an error occurs invoke resolver's reject algorithm with error as the value argument.
When the request has been successfully completed:
1. Invoke resolver's fulfill algorithm without assigning a value to the value argument.

The getRecordings method when invoked MUST run the following steps:

Let promise be a new Promise object and resolver be its associated resolver.
Return promise to the caller.
Make a request to the recording scheduler to retrieve the available TV recordings according to the options parameter.
If an error occurs invoke resolver's reject algorithm with error as the value argument.
When the request has been successfully completed:
1. Let recordings be the array of the retrieved TVRecording elements.
2. Invoke resolver's fulfill algorithm with recordings as the value argument.

The setParentalControlPin method when invoked MUST run the following steps:

Let promise be a new Promise object and resolver be its associated resolver.
Return promise to the caller.
Make a request to set the new PIN for parental control according to the newPin parameter.
If an error occurs invoke resolver's reject algorithm with error as the value argument.
When the request has been successfully completed:
1. Invoke resolver's fulfill algorithm without assigning a value to the value argument.

The setParentalControl method when invoked MUST run the following steps:

Let promise be a new Promise object and resolver be its associated resolver.
Return promise to the caller.
Make a request to set the new status for parental control according to the isLocked parameter.
If an error occurs invoke resolver's reject algorithm with error as the value argument.
When the request has been successfully completed:
1. Invoke resolver's fulfill algorithm without assigning a value to the value argument.

The getCICards method when invoked MUST run the following steps:

Let promise be a new Promise object and resolver be its associated resolver.
Return promise to the caller.
Make a request to the TV device to retrieve all the CI (Common Interface) cards that are available in the TV device.
If an error occurs invoke resolver's reject algorithm with error as the value argument.
When the request has been successfully completed:
1. Let cicards be the array of the retrieved TVCICard elements.
2. Invoke resolver's fulfill algorithm with cicards as the value argument.

4.4 Event handlers

The following are the event handlers (and their corresponding event types) that MUST be supported as attributes by the TVManager object.

Event handler	Event name	Event type	Short description
`ontunerchanged`	`tunerchanged`	`TVTunerChangedEvent`	Handles the information of the TV tuner that is added/removed by the TV device.
`onrecordingchanged`	`recordingchanged`	`TVRecordingChangedEvent`	Handles the information of the updates for TV recordings.
`onparentalcontrolchanged`	`parentalcontrolchanged`	`Event`	Handles the information of the status changes for parental control.
`oncicardchanged`	`cicardchanged`	`TVCICardChangedEvent`	Handles the information of the status changes of the TV CI (Common Interface) card in the TV device.

5. `TVTuner` Interface

The TVTuner interface represents a bunch of properties and a set of operations related to the TV tuner.

interface TVTuner : EventTarget {
    sequence<TVSourceType>      getSupportedSourceTypes ();
    Promise<sequence<TVSource>> getSources ();
    Promise<void>               setCurrentSource (TVSourceType sourceType);
    readonly        attribute DOMString      id;
    readonly        attribute TVSource?      currentSource;
    [SameObject]
    readonly        attribute TVMediaStream? stream;
    readonly        attribute double         signalStrength;
    readonly        attribute boolean        isRecordable;
                    attribute EventHandler   oncurrentsourcechanged;
};

5.1 Attributes

id of type DOMString, readonly: MUST return the ID of the TV tuner.
currentSource of type TVSource, readonly , nullable: MUST return the currently configured TV source.
MUST return null if the TV source is not configured.
stream of type TVMediaStream, readonly , nullable: MUST return a TVMediaStream object extended from MediaStream and currently streamed by the TV tuner, which can be played by the video element by assigning the TVMediaStream (MediaStream) to the HTMLMediaElement's srcObject attribute and can be recorded by the MediaRecorder.
MUST return null if the TV tuner is not streaming any data, which happens when the streaming signal is broken or due to any reason that makes the TV tuner fail to do so.
Note that the stream instance should be the same even after the current TV source or its selected TV channel has been changed.
signalStrength of type double, readonly: MUST return the signal strength measured in dBm of the TV tuner. E.g. -31.5.
isRecordable of type boolean, readonly: MUST indicate whether recording on the stream through this TV tuner is supported by the user agent.
oncurrentsourcechanged of type EventHandler: Handles the currentsourcechanged event of type TVCurrentSourceChangedEvent, fired when the method setCurrentSource is invoked to configure the current TV source.

5.2 Methods

getSupportedSourceTypes

This method makes a request to retrieve all the types of the supported TV sources for the TV tuner. It returns the types of the supported TV sources.

No parameters.

Return type: sequence<TVSourceType>

getSources

This method makes a request to retrieve all the TV sources that are available in the TV tuner. It returns a new Promise that will be used to notify the caller about the result of the operation, which is an array of TVSource elements that belong to the TV tuner.

No parameters.

Return type: Promise<sequence<TVSource>>

setCurrentSource

This method makes a request to configure the current TV source of the TV tuner by the sourceType parameter. It returns a new Promise that will be used to notify the caller about the result of the operation.

Parameter	Type	Nullable	Optional	Description
sourceType	`TVSourceType`	✘	✘	Specifies the TV source type for configuring the current TV source.

Return type: Promise<void>

5.3 Procedures

The getSources method when invoked MUST run the following steps:

Let promise be a new Promise object and resolver be its associated resolver.
Return promise to the caller.
Make a request to the TV tuner to retrieve all the TV sources that are available in the TV tuner.
If an error occurs invoke resolver's reject algorithm with error as the value argument.
When the request has been successfully completed:
1. Let sources be the array of the retrieved TVSource elements.
2. Invoke resolver's fulfill algorithm with sources as the value argument.

The setCurrentSource method when invoked MUST run the following steps:

Let promise be a new Promise object and resolver be its associated resolver.
Return promise to the caller.
Make a request to the TV tuner to configure the current TV source according to the sourceType parameter.
If an error occurs invoke resolver's reject algorithm with error as the value argument.
When the request has been successfully completed:
1. Invoke resolver's fulfill algorithm without assigning a value to the value argument.

5.4 Event handlers

The following are the event handlers (and their corresponding event types) that MUST be supported as attributes by the TVTuner object.

Event handler	Event name	Event type	Short description
`oncurrentsourcechanged`	`currentsourcechanged`	`TVCurrentSourceChangedEvent`	Handles the information of the current TV source that is configured by the method `setCurrentSource`.

6. `TVSource` Interface

The TVSource interface represents a bunch of properties and a set of operations related to the TV source.

interface TVSource : EventTarget {
    Promise<sequence<TVChannel>> getChannels ();
    Promise<void>                setCurrentChannel (DOMString channelNumber);
    Promise<void>                startScanning (optional TVStartScanningOptions options);
    Promise<void>                stopScanning ();
    readonly        attribute TVTuner      tuner;
    readonly        attribute TVSourceType type;
    readonly        attribute boolean      isScanning;
    readonly        attribute TVChannel?   currentChannel;
                    attribute EventHandler oncurrentchannelchanged;
                    attribute EventHandler oneitbroadcasted;
                    attribute EventHandler onemergencyalerted;
                    attribute EventHandler onscanningstatechanged;
};

6.1 Attributes

tuner of type TVTuner, readonly: MUST return the TV tuner which the TV source belongs to.
type of type TVSourceType, readonly: MUST return the type of the TV source.
isScanning of type boolean, readonly: MUST indicate whether the TV source is scanning the TV channels or not.
currentChannel of type TVChannel, readonly , nullable: MUST return the TV channel that is currently streamed by the TV tuner which owns the TV source. MUST return null if the TV tuner is not streaming any data.
oncurrentchannelchanged of type EventHandler: Handles the currentchannelchanged event of type TVCurrentChannelChangedEvent, fired when the method setCurrentChannel is invoked to tune the currently streamed TV channel.
oneitbroadcasted of type EventHandler: Handles the eitbroadcasted event of type TVEITBroadcastedEvent, fired when the Event Information Table (EIT) is broadcasted by the TV source.
onemergencyalerted of type EventHandler: Handles the emergencyalerted event of type TVEmergencyAlertedEvent, fired when an emergency, such as earthquake or tsunami, occurs and is broadcasted by the TV source.
onscanningstatechanged of type EventHandler: Handles the scanningstatechanged event of type TVScanningStateChangedEvent, fired when the state of scanning the TV channels is changed by the TV source. E.g., it can be fired when the method startScanning or the method stopScanning starts or stops scanning the TV channels, or when a channel is found during the channel scan.

6.2 Methods

getChannels

This method makes a request to retrieve all the TV channels that are available in the TV source. It returns a new Promise that will be used to notify the caller about the result of the operation, which is an array of TVChannel elements that belong to the TV source. And if parental control is enabled, the array of TVChannel elements should exclude the locked channels. Note that the Promise may be rejected with an InvalidStateError if this method gets called during channel scanning.

No parameters.

Return type: Promise<sequence<TVChannel>>

setCurrentChannel

This method makes a request to tune the currently streamed TV channel by the channelNumber parameter. It returns a new Promise that will be used to notify the caller about the result of the operation. Note that the Promise may be rejected with an InvalidStateError if this method is called during channel scanning, or be rejected with an InvalidAccessError if parental control is enabled and the channel is locked.

Parameter	Type	Nullable	Optional	Description
channelNumber	`DOMString`	✘	✘	Specifies the TV channel number for tuning the currently streamed TV channel.

Return type: Promise<void>

startScanning

This method makes a request to start scanning all the TV channels that are available in the TV source by the options parameter. It returns a new Promise that will be used to notify the caller about the result of the operation. Note that this method has to be called first at some setup stages, so that the method getChannels can retrieve the channels that have successfully been scanned by the TV source. Besides, due to some constraints of tuner modules, scanning and streaming are not encouraged to run at the same time.

Parameter	Type	Nullable	Optional	Description
options	`TVStartScanningOptions`	✘	✔	Specifies the options for scanning the TV channels. The `isRescanned` option in the `options` parameter specifies whether or not the process of scanning the TV channels has to clear the currently scanned TV channels before scanning; if it is not passed, this method will rescan all the TV channels as if it is passed as `true`.

Return type: Promise<void>

stopScanning

This method makes a request to stop scanning the TV channels for the TV source. It returns a new Promise that will be used to notify the caller about the result of the operation.

No parameters.

Return type: Promise<void>

6.3 Procedures

The getChannels method when invoked MUST run the following steps:

Let promise be a new Promise object and resolver be its associated resolver.
Return promise to the caller.
Make a request to the TV source to retrieve all the TV channels that are available in the TV source.
If an error occurs invoke resolver's reject algorithm with error as the value argument.
When the request has been successfully completed:
1. Let channels be the array of the retrieved TVChannel elements.
2. Invoke resolver's fulfill algorithm with channels as the value argument.

The setCurrentChannel method when invoked MUST run the following steps:

Let promise be a new Promise object and resolver be its associated resolver.
Return promise to the caller.
Make a request to the TV source to tune the currently streamed TV channel according to the channelNumber parameter.
If an error occurs invoke resolver's reject algorithm with error as the value argument.
When the request has been successfully completed:
1. Invoke resolver's fulfill algorithm without assigning a value to the value argument.

The startScanning method when invoked MUST run the following steps:

Let promise be a new Promise object and resolver be its associated resolver.
Return promise to the caller.
Make a request to the TV source to start scanning all the TV channels that are available in the TV source according to the scanning options specified in the options parameter. If the isRescanned option in the options parameter is not passed or it is passed as true, the user agent MUST clear the currently scanned TV channels before scanning; if it is passed as false, the user agent will simply scan additional TV channels which haven't been scanned yet.
If an error occurs invoke resolver's reject algorithm with error as the value argument.
When the request has been successfully completed:
1. Invoke resolver's fulfill algorithm without assigning a value to the value argument.

The stopScanning method when invoked MUST run the following steps:

Let promise be a new Promise object and resolver be its associated resolver.
Return promise to the caller.
Make a request to the TV source to stop scanning the TV channels.
If an error occurs invoke resolver's reject algorithm with error as the value argument.
When the request has been successfully completed:
1. Invoke resolver's fulfill algorithm without assigning a value to the value argument.

6.4 Event handlers

The following are the event handlers (and their corresponding event types) that MUST be supported as attributes by the TVSource object.

Event handler	Event name	Event type	Short description
`oncurrentchannelchanged`	`currentchannelchanged`	`TVCurrentChannelChangedEvent`	Handles the information of the currently streamed TV channel that is tuned by the method `setCurrentChannel`.
`oneitbroadcasted`	`eitbroadcasted`	`TVEITBroadcastedEvent`	Handles the information of the available TV programs in the EIT that is broadcasted by the TV source.
`onemergencyalerted`	`emergencyalerted`	`TVEmergencyAlertedEvent`	Handles the information of the emergency alert when an emergency, such as earthquake or tsunami, occurs and is broadcasted by the TV source.
`onscanningstatechanged`	`scanningstatechanged`	`TVScanningStateChangedEvent`	Handles the information of the state of scanning the TV channels, which is changed by the TV source.

7. `TVChannel` Interface

The TVChannel interface represents a bunch of properties and a set of operations related to the TV channel.

interface TVChannel : EventTarget {
    Promise<sequence<TVProgram>> getPrograms (optional TVGetProgramsOptions options);
    Promise<TVProgram>           getCurrentProgram ();
    Promise<void>                setParentalLock (DOMString pin, boolean isLocked);
    readonly        attribute DOMString     networkId;
    readonly        attribute DOMString     transportStreamId;
    readonly        attribute DOMString     serviceId;
    readonly        attribute TVSource      source;
    readonly        attribute TVChannelType type;
    readonly        attribute DOMString     name;
    readonly        attribute DOMString     number;
    readonly        attribute boolean       isEmergency;
    readonly        attribute boolean       isFree;
    readonly        attribute DOMString?    casSystemId;
    readonly        attribute boolean       isParentalLocked;
                    attribute EventHandler  onparentallockchanged;
};

7.1 Attributes

networkId of type DOMString, readonly: MUST return the identification of a broadcast transmission network. On satellite and IP broadband, typically one networkId corresponds to an operator. On cable and terrestrial, where different radio frequencies might be used in different regions, operators typically use one networkId per such region.
transportStreamId of type DOMString, readonly: MUST return the identification of a time-domain multiplex of several programmes carried in Transport Stream (TS) packets. One or more multiplexes can be transmitted on any given radio frequency in a DVB network.
serviceId of type DOMString, readonly: MUST return the identification of a TV, radio or data programme within a TS multiplex. The number of programmes is limited by the capacity of the underlying physical channel.
source of type TVSource, readonly: MUST return the TV source which the TV channel belongs to.
type of type TVChannelType, readonly: MUST return the type of the TV channel.
name of type DOMString, readonly: MUST return the name of the TV channel. E.g., "CNN", "NHK", etc.
number of type DOMString, readonly: MUST return the Logical Channel Number (LCN) of the TV channel. E.g., "12-1", "12-2", etc.
isEmergency of type boolean, readonly: MUST indicate whether the TV channel is for the emergency purpose.
isFree of type boolean, readonly: MUST indicate whether the TV channel is free to watch.
casSystemId of type DOMString, readonly , nullable: MUST return the system ID if it requires to use a specific CAS (Conditional Access System) to decrypt the stream from the encrypted TV channel.
isParentalLocked of type boolean, readonly: MUST indicate whether the TV channel is locked for parental control.
onparentallockchanged of type EventHandler: Handles the parentallockchanged event, fired when the parental lock status of the TV channel is changed.

7.2 Methods

getPrograms

This method makes a request to retrieve all the TV programs that are available in the TV channel by the options parameter. It returns a new Promise that will be used to notify the caller about the result of the operation, which is an array of TVProgram elements that belong to the TV channel.

Parameter	Type	Nullable	Optional	Description
options	`TVGetProgramsOptions`	✘	✔	Specifies the options for retrieving the TV programs. If this parameter is not passed, this method will return all the available TV programs.

Return type: Promise<sequence<TVProgram>>

getCurrentProgram

This method makes a request to retrieve the current TV program available in the TV channel. It returns a new Promise that will be used to notify the caller about the result of the operation, which is a TVProgram element that belongs to the TV channel.

No parameters.

Return type: Promise<TVProgram>

setParentalLock

This method makes a request to set the parental lock status for the TV channel. It returns a new Promise that will be used to notify the caller about the result of the operation.

Parameter	Type	Nullable	Optional	Description
pin	`DOMString`	✘	✘	Specifies the PIN used for parental control.
isLocked	`boolean`	✘	✘	Specifies the parental lock status for the TV channel.

Return type: Promise<void>

7.3 Procedures

The getPrograms method when invoked MUST run the following steps:

Let promise be a new Promise object and resolver be its associated resolver.
Return promise to the caller.
Make a request to the TV channel to retrieve all the TV programs that are available in the TV channel according to the retrieving options specified in the options parameter.
If an error occurs invoke resolver's reject algorithm with error as the value argument.
When the request has been successfully completed:
1. Let programs be the array of the retrieved TVProgram elements.
2. Invoke resolver's fulfill algorithm with programs as the value argument.

The getCurrentProgram method when invoked MUST run the following steps:

Let promise be a new Promise object and resolver be its associated resolver.
Return promise to the caller.
Make a request to the TV channel to retrieve the current TV program available in the TV channel.
If an error occurs invoke resolver's reject algorithm with error as the value argument.
When the request has been successfully completed:
1. Let program be the retrieved TVProgram element.
2. Invoke resolver's fulfill algorithm with program as the value argument.

The setParentalLock method when invoked MUST run the following steps:

Let promise be a new Promise object and resolver be its associated resolver.
Return promise to the caller.
Make a request to set the new parental lock status for this channel according to the isLocked parameter.
If the pin parameter does not match the current PIN or an error occurs invoke resolver's reject algorithm with error as the value argument.
When the request has been successfully completed:
1. Invoke resolver's fulfill algorithm without assigning a value to the value argument.

7.4 Event handlers

The following are the event handlers (and their corresponding event types) that MUST be supported as attributes by the TVChannel object.

Event handler	Event name	Event type	Short description
`onparentallockchanged`	`parentallockchanged`	`Event`	Handles the information of the parental control status change for the TV channel.

8. `TVProgram` Interface

The TVProgram interface represents a bunch of properties and a set of operations related to the TV program.

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 unsigned long long startTime;
    readonly        attribute unsigned long long duration;
    readonly        attribute DOMString?         shortDescription;
    readonly        attribute DOMString?         longDescription;
    readonly        attribute DOMString?         rating;
    readonly        attribute boolean            isFree;
    readonly        attribute DOMString?         seriesId;
};

8.1 Attributes

eventId of type DOMString, readonly: MUST return the event ID of the TV program. It has to be unique only within a TV channel.
channel of type TVChannel, readonly: MUST return the TV channel which the TV program belongs to.
title of type DOMString, readonly: MUST return the title of the TV program.
startTime of type unsigned long long, readonly: MUST return the start time (in milliseconds) of the TV program.
duration of type unsigned long long, readonly: MUST return the duration (in milliseconds) of the TV program.
shortDescription of type DOMString, readonly , nullable: MUST return the short description of the TV program.
longDescription of type DOMString, readonly , nullable: MUST return the long description of the TV program.
rating of type DOMString, readonly , nullable: MUST return the rating of the TV program.
isFree of type boolean, readonly: MUST indicate whether the TV program is free to watch.
seriesId of type DOMString, readonly , nullable: MUST return the ID of the series (if applicable) which the TV program belongs to.

8.2 Methods

getAudioLanguages: MUST return the audio languages of the TV program in 3-digit language codes specified by [ISO639-2].
No parameters.

Return type: sequence<DOMString>
getSubtitleLanguages: MUST return the subtitle languages of the TV program in 3-digit language codes specified by [ISO639-2].
No parameters.

Return type: sequence<DOMString>
getGenres: MUST return the genres of the TV program. Please note that the classification might vary between different broadcasting standards.
No parameters.

Return type: sequence<DOMString>

9. `TVTriggerCue` Interface

The TVTriggerCue interface represents a bunch of properties and a set of operations related to the TV trigger, which may be used to carry some information via in-band or out-of-band mechanism based on the current playing content. It's inherited from the TextTrackCue interface, which requires startTime and endTime, and can be accessed by the video element by adding the TextTrackCue to the TextTrack associated with the HTMLMediaElement. Besides, the TextTrack can rely on its oncuechange event to realize a TV trigger becomes active or dismissed.

interface TVTriggerCue : TextTrackCue {
    readonly        attribute TVTriggerType  type;
    readonly        attribute DOMString?     title;
    readonly        attribute DOMString?     url;
    readonly        attribute TVChannel?     channel;
    readonly        attribute TVMediaStream? stream;
    readonly        attribute object?        additionalData;
};

9.1 Attributes

type of type TVTriggerType, readonly: MUST return the type of the TV trigger.
title of type DOMString, readonly , nullable: MUST return the human readable title for the TV trigger.
url of type DOMString, readonly , nullable: MUST return the URL for the TV trigger.
channel of type TVChannel, readonly , nullable: MUST return the channel associated with the TV trigger.
stream of type TVMediaStream, readonly , nullable: MUST return the TVMediaStream object that could be played for the TV trigger.
additionalData of type object, readonly , nullable: MUST return the content source information or other supplemental information for the TV trigger. Please note that the detailed data might vary between different broadcasting standards or only known by private agreements.

10. `TVRecording` Interface

The TVRecording interface represents a bunch of properties and a set of operations related to the TV recording. The recording should automatically start recording at the specified start time. And it may stop either at the specified end time, by an explicit stop() call, or be interrupted by the user agent due to a channel switch against the required underlying resource (i.e. the same tuner which the recording channel belongs to since watching takes priority over recording), or an error.

interface TVRecording {
    Promise<TVMediaStream> getStream ();
    Promise<void>          stop ();
    readonly        attribute DOMString          id;
    readonly        attribute TVChannel          channel;
    readonly        attribute TVProgram?         program;
    readonly        attribute unsigned long long startTime;
    readonly        attribute unsigned long long endTime;
    readonly        attribute TVRecordingState   state;
    readonly        attribute unsigned long long size;
    readonly        attribute unsigned long long duration;
                    attribute DOMString          description;
                    attribute EventHandler       onrecordingchanged;
};

10.1 Attributes

id of type DOMString, readonly: MUST return the ID of the TV recording.
channel of type TVChannel, readonly: MUST return the associated TV channel of the TV recording.
program of type TVProgram, readonly , nullable: MUST return the associated TV program of the TV recording if applicable. Please note the recording should keep track of the relevant updates in Event Information Table (EIT) while program is specified, and then update correspondent attributes and fire a TVRecordingChangedEvent accordingly. Furthermore, if the updated time frame conflicts with some existent ones, and there's no sufficient resource (i.e. tuner) to meet this, then the recording should change its state to stopped.
startTime of type unsigned long long, readonly: MUST return the start time (in milliseconds) of the TV recording.
endTime of type unsigned long long, readonly: MUST return the end time (in milliseconds) of the TV recording.
state of type TVRecordingState, readonly: MUST return the current state of the TV recording.
size of type unsigned long long, readonly: MUST return the actual size of the TV recording. Please note the value should be zero if the TV recording hasn't actually recorded anything.
duration of type unsigned long long, readonly: MUST return the actual duration (in milliseconds) of the TV recording. Please note the value should be zero if the TV recording hasn't actually recorded anything.
description of type DOMString: MUST return the description of the TV recording.
onrecordingchanged of type EventHandler: Handles the recordingchanged event of type TVRecordingChangedEvent, fired when the recording time frame or the state of the TV recording has been changed.

10.2 Methods

getStream: This method makes a request to retrieve the recorded content as a TVMediaStream object, which is extended from MediaStream and can be played by the video element by assigning the TVMediaStream to the HTMLMediaElement's srcObject attribute. MUST return null if the TV recording hasn't actually recorded anything. Note that the Promise may be rejected with an InvalidAccessError if parental control is enabled and the recorded channel is locked.
No parameters.

Return type: Promise<TVMediaStream>
stop: This method makes a request to stop the TV recording.
No parameters.

Return type: Promise<void>

10.3 Procedures

The getStream method when invoked MUST run the following steps:

Let promise be a new Promise object and resolver be its associated resolver.
Return promise to the caller.
Make a request to the TV source to retrieve the recorded content that is available in the TV recording.
If an error occurs invoke resolver's reject algorithm with error as the value argument.
When the request has been successfully completed:
1. Let stream be the retrieved TVMediaStream object.
2. Invoke resolver's fulfill algorithm with stream as the value argument.

The stop method when invoked MUST run the following steps:

Let promise be a new Promise object and resolver be its associated resolver.
Return promise to the caller.
Make a request to the TV recording to stop it.
If an error occurs invoke resolver's reject algorithm with error as the value argument.
When the request has been successfully completed:
1. Invoke resolver's fulfill algorithm without assigning a value to value argument.

10.4 Event handlers

The following are the event handlers (and their corresponding event types) that MUST be supported as attributes by the TVRecording object.

Event handler	Event name	Event type	Short description
`onrecordingchanged`	`recordingchanged`	`TVRecordingChangedEvent`	Handles the information of the updates for TV recordings.

11. `TVMediaStream` Interface

The TVMediaStream interface is an extended MediaStream with a buffering mechanism to support basic seekability. It can be played by the video element by assigning the TVMediaStream to the HTMLMediaElement's srcObject attribute.

interface TVMediaStream : MediaStream {
    sequence<TextTrack> getTextTracks ();
    void                addTextTrack (TextTrack textTrack);
    void                removeTextTrack (TextTrack textTrack);
};

11.1 Methods

getTextTracks

MUST return the text tracks in this stream.

No parameters.

Return type: sequence<TextTrack>

addTextTrack

Parameter	Type	Nullable	Optional	Description
textTrack	`TextTrack`	✘	✘	The TextTrack object to be added.

Return type: void

removeTextTrack

Parameter	Type	Nullable	Optional	Description
textTrack	`TextTrack`	✘	✘	The TextTrack object to be removed.

Return type: void

The nature of no buffering of the MediaStream places certain restrictions on the behavior and attribute values of the associated HTMLMediaElement and on the operations that can be performed on it. Yet since TVMediaStream is with a buffered mechanism to support basic seekability, it may be less restrictive to some extent, as shown below:

Attribute Name	Attribute Type	Valid Values When Using a TVMediaStream	Additional considerations
`currentSrc`	`DOMString`	The empty string	When `srcObject` is specified the User Agent MUST set this to the empty string. (Same as `MediaStream`.)
`preload`	`DOMString`	none	A `TVMediaStream` cannot be preloaded. (Same as `MediaStream`.)
`buffered`	`TimeRanges`	Same as `HTMLMediaElement`.	Unlock the restriction applied by `MediaStream`.
`networkState`	`unsigned short`	NETWORK_IDLE	The media element does not fetch the `TVMediaStream` so there is no network traffic. (Same as `MediaStream`.)
`readyState`	`unsigned short`	HAVE_NOTHING, HAVE_ENOUGH_DATA	A `TVMediaStream` may be created before there is any data available, for example when a stream is received from a remote peer. The value of the `readyState` of the media element MUST be HAVE_NOTHING before the first media arrives and HAVE_ENOUGH_DATA once the first media has arrived. (Same as `MediaStream`.)
`currentTime`	`double`	Same as `HTMLMediaElement`.	Unlock the restriction applied by `MediaStream`.
`duration`	`unrestricted double`	Same as `HTMLMediaElement`.	Unlock the restriction applied by `MediaStream`.
`seeking`	`boolean`	Same as `HTMLMediaElement`.	Unlock the restriction applied by `MediaStream`.
`defaultPlaybackRate`	`double`	Same as `HTMLMediaElement`.	Unlock the restriction applied by `MediaStream`.
`playbackRate`	`double`	Same as `HTMLMediaElement`.	Unlock the restriction applied by `MediaStream`.
`played`	`TimeRanges`	Same as `HTMLMediaElement`.	Unlock the restriction applied by `MediaStream`.
`seekable`	`TimeRanges`	Same as `HTMLMediaElement`.	Unlock the restriction applied by `MediaStream`.
`loop`	`boolean`	Same as `HTMLMediaElement`.	Unlock the restriction applied by `MediaStream`.

11.3 Time-shifting

Applications may utilize TVRecording and TVMediaStream to fulfill time-shifting scenarios. When time-shifting is enabled, it may add a TV recording for the current playing channel without specifying start time, which makes the recording starts from now on, or instead by specifying the live TV program. (The user agent should be able to play and record the same channel at the same time.) Then when it comes to switch to the time-shifted content, the TVMediaStream generated from the TV recording can be assigned to the video element used for playing the current MediaStream. So the application may play with the video element to set proper playback rates, seek to specific time, play/pause the buffered stream, and listen to some correspondent events. And when time-shifting is switched off (i.e. the recorded content has been fast forwarded to the current end), the application should assign the original MediaStream back to the video element. Please note applications may need to regularly clean up old TV recordings used for time-shifting.

12. `TVCICard` Interface

The TVCICard interface represents a bunch of properties related to CI (Common Interface) card which is used to decrypt encrypted TV channel.

interface TVCICard {
    readonly        attribute TVCICardState state;
    readonly        attribute DOMString     casSystemId;
    readonly        attribute boolean       isInUse;
};

12.1 Attributes

state of type TVCICardState, readonly: MUST return the state of the CI card.
casSystemId of type DOMString, readonly: MUST return the CAS (Conditional Access System) system ID for the pertaining CI card.
isInUse of type boolean, readonly: MUST indicate whether the CI card is in use. Note that if multiple cards happen to represent the same casSystemId, at most one of them can have this attribute set.

13. `TVStartScanningOptions` Dictionary

The TVStartScanningOptions dictionary contains the information for scanning the TV channels.

dictionary TVStartScanningOptions {
             boolean isRescanned;
};

13.1 Dictionary `TVStartScanningOptions` Members

isRescanned of type boolean: Specifies whether or not the process of scanning the TV channels has to clear the currently scanned TV channels before scanning.

14. `TVGetProgramsOptions` Dictionary

The TVGetProgramsOptions dictionary contains the information for retrieving the TV programs.

dictionary TVGetProgramsOptions {
             unsigned long long startTime;
             unsigned long long endTime;
             DOMString          genre;
};

14.1 Dictionary `TVGetProgramsOptions` Members

startTime of type unsigned long long: Specifies the start time of a time period which bounds the time slots of TV programs to be retrieved.
endTime of type unsigned long long: Specifies the end time of a time period which bounds the time slots of TV programs to be retrieved.
genre of type DOMString: Specifies the genre of TV programs to be retrieved.

15. `TVAddRecordingOptions` Dictionary

The TVAddRecordingOptions dictionary contains the information for adding a TV recording.

dictionary TVAddRecordingOptions {
    required DOMString           description;
    required TVChannel           channel;
             TVProgram?          program;
             unsigned long long? startTime;
             unsigned long long? endTime;
};

15.1 Dictionary `TVAddRecordingOptions` Members

description of type DOMString, required: Specifies the description of the TV recording.
channel of type TVChannel, required: Specifies the channel to be recorded.
program of type TVProgram, nullable: Specifies the program to be recorded. Please note this could be omitted if the recording time frame can be determined by startTime and endTime.
startTime of type unsigned long long, nullable: Specifies the start time of a recording time frame. When not specified, it implies the recording should start from now on. Please note this could also be ommited and auto determined if program is specified.
endTime of type unsigned long long, nullable: Specifies the end time of a recording time frame. When not specified, it implies the recording should continue until a stop() call of TVRecording or the user agent forces it to stop due to resource control. Please note this could also be ommited and auto determined if program is specified.

16. `TVGetRecordingsOptions` Dictionary

The TVGetRecordingsOptions dictionary contains the information for retrieving the TV recordings.

dictionary TVGetRecordingsOptions {
             TVRecordingState? state;
             DOMString?        id;
};

16.1 Dictionary `TVGetRecordingsOptions` Members

state of type TVRecordingState, nullable: Specifies the state of the TV recordings to be retrieved.
id of type DOMString, nullable: Specifies the ID of the TV recording to be retrieved.

17. `TVTunerChangedEvent` Interface

The TVTunerChangedEvent interface represents the event related to the TV tuner that is added/removed by the TV device.

interface TVTunerChangedEvent : Event {
    readonly        attribute TVTunerChangedEventOperation operation;
    readonly        attribute DOMString                    id;
};

17.1 Attributes

operation of type TVTunerChangedEventOperation, readonly: MUST return the type of operation that changes the TV tuner.
id of type DOMString, readonly: MUST return the ID of the TV tuner that is added/removed.

18. `TVCurrentSourceChangedEvent` Interface

The TVCurrentSourceChangedEvent interface represents the event related to the current TV source that is configured by the method setCurrentSource.

interface TVCurrentSourceChangedEvent : Event {
    readonly        attribute TVSource? source;
};

18.1 Attributes

source of type TVSource, readonly , nullable: MUST return the TV source that is currently configured by the TV tuner. MUST return null if the TV source is not configured.

19. `TVEITBroadcastedEvent` Interface

The TVEITBroadcastedEvent interface represents the event related to the available TV programs in the EIT that is broadcasted by the TV source.

interface TVEITBroadcastedEvent : Event {
    readonly        attribute object programs;
};

19.1 Attributes

programs of type object, readonly: MUST return the available TV programs in the EIT that is broadcasted by the TV source. Please note that it needs to be casted into a list of TVProgram instances. The cached value for this array needs to go into an internal slot for the object, and it should be cached there until the next time that the underlying array changes when the cached value will be updated.

20. `TVEmergencyAlertedEvent` Interface

The TVEmergencyAlertedEvent interface represents the event related to the emergency alert that is broadcasted by the TV source.

interface TVEmergencyAlertedEvent : Event {
    readonly        attribute DOMString? type;
    readonly        attribute DOMString? severityLevel;
    readonly        attribute DOMString? description;
    readonly        attribute TVChannel? channel;
    readonly        attribute DOMString? url;
    sequence<DOMString> getRegions ();
};

20.1 Attributes

type of type DOMString, readonly , nullable: MUST return the the nature of the emergency, i.e. “Earthquake”, "Tsunami", “Child Abduction”. Please note that the classification might vary between different broadcasting standards.
severityLevel of type DOMString, readonly , nullable: MUST return the severity level of the emergency alert. Please note that the classification of severity level might vary between different broadcasting standards. MUST return null when the emergency announcement is over.
description of type DOMString, readonly , nullable: MUST return the human readable description of the emergency alert.
channel of type TVChannel, readonly , nullable: MUST return the emergency channel which might be switched to for more information about the emergency.
url of type DOMString, readonly , nullable: MUST return the URL where more information might be available.

20.2 Methods

getRegions: MUST return the associated regions of the emergency alert. Please note that it might vary between different broadcasting standards. It could return an empty sequence if the emergency system doesn't reveal detailed geographical scope of the alert to the endpoint.
No parameters.

Return type: sequence<DOMString>

21. `TVScanningStateChangedEvent` Interface

The TVScanningStateChangedEvent interface represents the event related to the state of channel scanning, which is changed by the TV source.

interface TVScanningStateChangedEvent : Event {
    readonly        attribute TVScanningState state;
    readonly        attribute TVChannel?      channel;
};

21.1 Attributes

state of type TVScanningState, readonly: MUST return the state of channel scanning, which is changed by the TV source.
channel of type TVChannel, readonly , nullable: MUST return the TV channel that is scanned by the TV source. MUST return null if the state is not "scanned".

22. `TVCurrentChannelChangedEvent` Interface

The TVCurrentChannelChangedEvent interface represents the event related to the currently streamed TV channel that is tuned by the method setCurrentChannel.

interface TVCurrentChannelChangedEvent : Event {
    readonly        attribute TVChannel? channel;
};

22.1 Attributes

channel of type TVChannel, readonly , nullable: MUST return the TV channel that is currently streamed by the TV tuner. MUST return null if the TV tuner is not streaming any data.

23. `TVRecordingChangedEvent` Interface

The TVRecordingChangedEvent interface represents the event related to the update of a TV recording.

interface TVRecordingChangedEvent : Event {
    readonly        attribute DOMString  id;
    readonly        attribute boolean    isTimeChange;
    readonly        attribute boolean    isStateChange;
    readonly        attribute DOMString? errorName;
};

23.1 Attributes

id of type DOMString, readonly: MUST return the ID of the updated TV recording.
isTimeChange of type boolean, readonly: MUST indicate whether the recording time frame of the TV recording has changed.
isStateChange of type boolean, readonly: MUST indicate whether the state of the TV recording has changed.
errorName of type DOMString, readonly , nullable: MUST return the name of the DOMException, i.e. "AbortError", if this change involves with an error.

24. `TVCICardChangedEvent` Interface

The TVCICardChangedEvent interface represents the event related to the changes in the state of the CI (Common Interface) card.

interface TVCICardChangedEvent : Event {
    readonly        attribute TVCICardState state;
    readonly        attribute DOMString     casSystemId;
};

24.1 Attributes

state of type TVCICardState, readonly: MUST return the updated state of the card.
casSystemId of type DOMString, readonly: MUST return the CAS (Conditional Access System) system ID of the card.

25. Enumerations

The attribute type in the TVSource can have the following values:

enum TVSourceType {
    "dvb-t",
    "dvb-t2",
    "dvb-c",
    "dvb-c2",
    "dvb-s",
    "dvb-s2",
    "dvb-h",
    "dvb-sh",
    "atsc",
    "atsc-m/h",
    "isdb-t",
    "isdb-tb",
    "isdb-s",
    "isdb-c",
    "1seg",
    "dtmb",
    "cmmb",
    "t-dmb",
    "s-dmb"
};

Enumeration description
`dvb-t`	The TV source works for DVB-T (terrestrial).
`dvb-t2`	The TV source works for DVB-T2 (terrestrial).
`dvb-c`	The TV source works for DVB-C (cable).
`dvb-c2`	The TV source works for DVB-C2 (cable).
`dvb-s`	The TV source works for DVB-S (satellite).
`dvb-s2`	The TV source works for DVB-S2 (satellite).
`dvb-h`	The TV source works for DVB-H (handheld).
`dvb-sh`	The TV source works for DVB-SH (satellite).
`atsc`	The TV source works for ATSC (terrestrial/cable).
`atsc-m/h`	The TV source works for ATSC-M/H (mobile/handheld).
`isdb-t`	The TV source works for ISDB-T (terrestrial).
`isdb-tb`	The TV source works for ISDB-Tb (terrestrial, Brazil).
`isdb-s`	The TV source works for ISDB-S (satellite).
`isdb-c`	The TV source works for ISDB-C (cable).
`1seg`	The TV source works for 1seg (handheld).
`dtmb`	The TV source works for DTMB (terrestrial).
`cmmb`	The TV source works for CMMB (handheld).
`t-dmb`	The TV source works for T-DMB (terrestrial).
`s-dmb`	The TV source works for S-DMB (satellite).

The attribute type in a TVChannel can have the following values:

enum TVChannelType {
    "tv",
    "radio",
    "data"
};

Enumeration description
`tv`	The TV channel is broadcasted as a regular TV type.
`radio`	The TV channel is broadcasted as a radio type.
`data`	The TV channel is broadcasted as a data type.

The attribute operation in the TVTunerChangedEvent can have the following values:

enum TVTunerChangedEventOperation {
    "added",
    "removed"
};

Enumeration description
`added`	A TV tuner is added.
`removed`	A TV tuner is removed.

The attribute state in the TVScanningStateChangedEvent can have the following values:

enum TVScanningState {
    "cleared",
    "scanned",
    "completed",
    "stopped"
};

Enumeration description
`cleared`	The currently scanned TV channels have been cleared. This event may be fired before a channel scan is started.
`scanned`	A TV channel has been found by the TV source during the channel scan. The `channel` attribute in the `TVScanningStateChangedEvent` object references the channel found.
`completed`	The channel scan has completed.
`stopped`	The channel scan has been stopped.

The attribute type in the TVTriggerCue can have the following values:

enum TVTriggerType {
    "channel-change",
    "time",
    "content-boundary",
    "fingerprint",
    "watermark",
    "context",
    "segment",
    "caption"
};

Enumeration description
`channel-change`	Triggers when channel is switched.
`time`	Triggers based on date and time.
`content-boundary`	Triggers based on content boundary.
`fingerprint`	Triggers based on content fingerprints.
`watermark`	Triggers based on content watermarks.
`context`	Triggers based on contextual information in content.
`segment`	Triggers based on program chapters or other segments within the program.
`caption`	Triggers based on subtitle captions.

The attribute state in TVRecording can have the following values:

enum TVRecordingState {
    "scheduled",
    "recording",
    "stopped"
};

Enumeration description
`scheduled`	The state of recording is scheduled.
`recording`	The state of recording is currently on.
`stopped`	The state of recording is stopped from `scheduled` or canceled from `recording`.

The attribute state in TVCICard can have the following values:

enum TVCICardState {
    "inserted",
    "accepted",
    "removed",
    "error"
};

Enumeration description
`inserted`	The CI card is inserted.
`accepted`	The CI card is accepted.
`removed`	The CI card is removed.
`error`	The CI Card has encountered an error.

26. Acknowledgements

The following people have contributed to this draft specification through their participation in the TV Control API Community Group: Kazayuki Ashimura, Marco Chen, Daniel Davis, Francois Daoust, Yoshiharu Dewa, Paul Higgs, Bin Hu, Shelly Lin, Sangwhan Moon, Chris Needham, John Piesing.

27. Conformance

As well as sections marked as non-normative, all authoring guidelines, diagrams, examples, and notes in this specification are non-normative. Everything else in this specification is normative.

The key word MUST is to be interpreted as described in [RFC2119].

All of the text of this specification is normative except sections explicitly marked as non-normative, examples, and notes.

This specification defines conformance criteria that apply to a single product: the user agent that implements the interfaces that it contains.

Implementations that use ECMAScript to implement the APIs defined in this specification MUST implement them in a manner consistent with the ECMAScript Bindings defined in the Web IDL specification [WEBIDL], as this specification uses that specification and terminology.

A. References

A.1 Normative references

[DOM]: Anne van Kesteren; Aryeh Gregor; Ms2ger; Alex Russell; Robin Berjon. W3C. W3C DOM4. 19 November 2015. W3C Recommendation. URL: https://www.w3.org/TR/dom/
[HTML5]: Ian Hickson; Robin Berjon; Steve Faulkner; Travis Leithead; Erika Doyle Navara; Theresa O'Connor; Silvia Pfeiffer. W3C. HTML5. 28 October 2014. W3C Recommendation. URL: https://www.w3.org/TR/html5/
[ISO639-2]: ISO. Codes for the representation of names of languages -- Part 2: Alpha-3 code. 22 October 1998. URL: http://www.iso.org/iso/catalogue_detail?csnumber=4767
[MediaCapture-Streams]: Daniel Burnett; Adam Bergkvist; Cullen Jennings; Anant Narayanan; Bernard Aboba. W3C. Media Capture and Streams. 19 May 2016. W3C Candidate Recommendation. URL: https://www.w3.org/TR/mediacapture-streams/
[RFC2119]: S. Bradner. IETF. Key words for use in RFCs to Indicate Requirement Levels. March 1997. Best Current Practice. URL: https://tools.ietf.org/html/rfc2119
[WEBIDL]: Cameron McCormack; Boris Zbarsky. W3C. WebIDL Level 1. 8 March 2016. W3C Candidate Recommendation. URL: https://www.w3.org/TR/WebIDL-1/

A.2 Informative references

[ECMAScript]: Ecma International. ECMAScript Language Specification. URL: https://tc39.github.io/ecma262/
[MediaStream-Recording]: Miguel Casas-sanchez; James Barnett; Travis Leithead. W3C. MediaStream Recording. 31 August 2016. W3C Working Draft. URL: https://www.w3.org/TR/mediastream-recording/

Abstract

Status of This Document

1. Introduction

2. Terminology

3. Navigator Interface

3.1 Attributes

4. TVManager Interface

4.1 Attributes

4.2 Methods

4.3 Procedures

4.4 Event handlers

5. TVTuner Interface

5.1 Attributes

5.2 Methods

5.3 Procedures

5.4 Event handlers

6. TVSource Interface

6.1 Attributes

6.2 Methods

6.3 Procedures

6.4 Event handlers

7. TVChannel Interface

7.1 Attributes

7.2 Methods

7.3 Procedures

7.4 Event handlers

8. TVProgram Interface

8.1 Attributes

8.2 Methods

9. TVTriggerCue Interface

9.1 Attributes

10. TVRecording Interface

10.1 Attributes

10.2 Methods

10.3 Procedures

10.4 Event handlers

11. TVMediaStream Interface

11.1 Methods

11.2 HTMLMediaElement Attributes When Playing a TVMediaStream

11.3 Time-shifting

12. TVCICard Interface

12.1 Attributes

13. TVStartScanningOptions Dictionary

13.1 Dictionary TVStartScanningOptions Members

14. TVGetProgramsOptions Dictionary

14.1 Dictionary TVGetProgramsOptions Members

15. TVAddRecordingOptions Dictionary

15.1 Dictionary TVAddRecordingOptions Members

16. TVGetRecordingsOptions Dictionary

16.1 Dictionary TVGetRecordingsOptions Members

17. TVTunerChangedEvent Interface

17.1 Attributes

18. TVCurrentSourceChangedEvent Interface

18.1 Attributes

19. TVEITBroadcastedEvent Interface

19.1 Attributes

20. TVEmergencyAlertedEvent Interface

20.1 Attributes

20.2 Methods

21. TVScanningStateChangedEvent Interface

21.1 Attributes

22. TVCurrentChannelChangedEvent Interface

22.1 Attributes

23. TVRecordingChangedEvent Interface

23.1 Attributes

24. TVCICardChangedEvent Interface

24.1 Attributes

25. Enumerations

26. Acknowledgements

27. Conformance

A. References

A.1 Normative references

A.2 Informative references

3. `Navigator` Interface

4. `TVManager` Interface

5. `TVTuner` Interface

6. `TVSource` Interface

7. `TVChannel` Interface

8. `TVProgram` Interface

9. `TVTriggerCue` Interface

10. `TVRecording` Interface

11. `TVMediaStream` Interface

11.2 `HTMLMediaElement` Attributes When Playing a `TVMediaStream`

12. `TVCICard` Interface

13. `TVStartScanningOptions` Dictionary

13.1 Dictionary `TVStartScanningOptions` Members

14. `TVGetProgramsOptions` Dictionary

14.1 Dictionary `TVGetProgramsOptions` Members

15. `TVAddRecordingOptions` Dictionary

15.1 Dictionary `TVAddRecordingOptions` Members

16. `TVGetRecordingsOptions` Dictionary

16.1 Dictionary `TVGetRecordingsOptions` Members

17. `TVTunerChangedEvent` Interface

18. `TVCurrentSourceChangedEvent` Interface

19. `TVEITBroadcastedEvent` Interface

20. `TVEmergencyAlertedEvent` Interface

21. `TVScanningStateChangedEvent` Interface

22. `TVCurrentChannelChangedEvent` Interface

23. `TVRecordingChangedEvent` Interface

24. `TVCICardChangedEvent` Interface