Events message tracks types and mixed event message tracks

1. A method performed by at least one processor, the method comprising:

obtaining an indicator included in an event message track and indicating each one of multiple types of a plurality of event message boxes in the event message track; and

providing the event message track to a client or displaying media content based on the event message track.

2. The method of claim 1 , wherein the indicator indicates that the event message boxes are of a same type.

3. The method of claim 1 , wherein the indicator indicates that the event message track includes at least two types of event message boxes.

4. The method of claim 1 , wherein the indicator indicates that at least one of the event message boxes has a time offset relative to a sample presentation time.

5. The method of claim 1 , wherein the indicator is a Uniform Resource Name (URN).

6. The method of claim 1 , wherein the indicator is Uniform Resource Indicator (URI) data value.

7. The method of claim 1 , wherein the obtaining the indicator comprises inserting the indicator in a header of the event message track.

8. The method of claim 1 , wherein the event message track further includes a track header that includes a flag indicating whether metadata samples of the event message track have a constant size.

9. The method of claim 8 , wherein the track header further includes a syntax element that indicates a size of each of the metadata samples.

10. The method of claim 1 , wherein the event message track is a timed metadata track.

11. A system comprising:

at least one memory storing computer code; and

at least one processor configured to access the computer code and operate as instructed by the computer code, the computer code including:

indicator obtaining code configured to cause the at least one processor to obtain an indicator included in an event message track and indicating each one of multiple types of a plurality of event message boxes in the event message track; and

providing or displaying code configured to cause the at least one processor to provide the event message track to a client or display media content based on the event message track.

12. The system of claim 11 , wherein the indicator indicates the event message boxes are of a same type.

13. The system of claim 11 , wherein the indicator indicates that the event message track includes at least two types of event message boxes.

14. The system of claim 11 , wherein the indicator indicates that at least one of the event message boxes has a time offset relative to a sample presentation time.

15. The system of claim 11 , wherein the indicator is a Uniform Resource Name (URN).

16. The system of claim 11 , wherein the indicator is Uniform Resource Indicator (URI) data value.

17. The system of claim 11 , wherein the indicator is in a header of the event message track.

18. The system of claim 11 , wherein the event message track further includes a track header that includes a flag indicating whether metadata samples of the event message track have a constant size.

19. The system of claim 18 , wherein the track header further includes a syntax element that indicates a size of each of the metadata samples.

20. A non-transitory computer-readable medium storing computer code that is configured to, when executed by at least one processor, cause the at least one processor to:

obtain an indicator included in an event message track and indicating each one of multiple types of a plurality of event message boxes in the event message track; and

provide the event message track to a client or display media content based on the event message track.