Events in timed metadata tracks

1. An information processing apparatus comprising:

processing circuitry configured to

prior to receiving a subscription request from an application to an event scheme,

receive a media presentation description (MPD) for a content stream, the MPD including one or more embedded event stream elements embedded in a timed metadata track, each of the one or more embedded event stream elements identifying a respective event scheme, and

notify the application, based on the one or more embedded event stream elements in the received MPD, of one or more respective event schemes identified by the one or more embedded event stream elements in the MPD,

receive, from the application, the subscription request to the event scheme, the event scheme being one of the one or more respective event schemes identified by the one or more embedded event stream elements in the MPD, and

dispatch to the application, based on the received subscription request, event messages associated with the event scheme in the timed metadata track.

2. The information processing apparatus according to claim 1 , wherein the processing circuitry is configured to dispatch the event messages associated with the event scheme to the application based on a dispatch mode indicated by the subscription request.

3. The information processing apparatus according to claim 1 , wherein an embedded event stream element of the one or more embedded event stream elements of the MPD that identifies the event scheme includes a Uniform Resource Identifier (URI) of the event scheme.

4. The information processing apparatus according to claim 3 , wherein

the embedded event stream element of the MPD indicates a value for the embedded event stream element, and

the URI and the value identify the event scheme.

5. The information processing apparatus according to claim 1 , wherein

only a subset of a plurality of available event schemes is identified by the one or more embedded event stream elements of the MPD.

6. The information processing apparatus according to claim 1 , wherein the one or more embedded event stream elements of the MPD are included in common attributes and elements of the MPD.

7. The information processing apparatus according to claim 1 , wherein the one or more embedded event stream elements includes a plurality of embedded event stream elements, each of the embedded event stream elements identifying a different event scheme of a plurality of available event schemes.

8. The information processing apparatus according to claim 7 , wherein the timed metadata track is different from an inband event stream that is specified by an inband event stream element.

9. A method for processing a timed metadata track of a content stream, the method comprising:

prior to receiving a subscription request from an application to an event scheme,

receiving, by interface circuitry, a media presentation description (MPD) for the content stream, the MPD including one or more embedded event stream elements embedded in a timed metadata track, each of the one or more embedded event stream elements identifying a respective event scheme,

notifying the application, based on the one or more embedded event stream elements in the received MPD, of one or more respective event schemes identified by the one or more embedded event stream elements in the MPD,

receiving, from the application, the subscription request to the event scheme, the event scheme being one of the one or more respective event schemes identified by the one or more embedded event stream elements in the MPD, and

dispatching to the application, based on the received subscription request, event messages associated with the event scheme in the timed metadata track.

10. The method according to claim 9 , wherein the dispatching comprises:

dispatching the event messages associated with the event scheme to the application based on a dispatch mode indicated by the subscription request.

11. The method according to claim 9 , wherein an embedded event stream element of the one or more embedded event stream elements of the MPD that identifies the event scheme includes a Uniform Resource Identifier (URI) of the event scheme.

12. The method according to claim 11 , wherein

the embedded event stream element of the MPD indicates a value for the embedded event stream element, and

the URI and the value identify the event scheme.

13. The method according to claim 9 , wherein

only a subset of a plurality of available event schemes is identified by the one or more embedded event stream elements of the MPD.

14. The method according to claim 9 , wherein the one or more embedded event stream elements of the MPD are included in common attributes and elements of the MPD.

15. A method for providing a timed metadata track of a content stream, the method comprising:

generating the timed metadata track for the content stream, the timed metadata track including embedded event messages, each of the embedded event messages associated with a corresponding event scheme of a plurality of event schemes;

generating a media presentation description (MPD) including one or more embedded event stream elements, each of the one or more embedded event stream elements identifying a respective event scheme of the plurality of event schemes; and

providing the MPD to an information processing apparatus such that, after the MPD is received in the information processing apparatus, an application executed in the information processing apparatus generates a subscription request to an event scheme, the subscribed event scheme being identified by one of the one or more embedded event stream elements of the provided MPD.

16. The method according to claim 15 , wherein the generating the MPD comprises:

generating a plurality of MPDs, the MPDs identifying different event schemes of the plurality of event schemes.