Media systems and methods including mixed event message tracks

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

obtaining an event message track including a plurality of event message boxes, the event message track configured to be processed by a Dynamic Adaptive Streaming over HTTP (DASH) client for displaying media content;

obtaining an indicator, included in the event message track, that indicates each one of multiple types of the plurality of event message boxes in the event message track; and

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

2. The method of claim 1 , wherein the indicator indicates that each of the plurality of event message boxes is a same event message box 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 plurality of event message boxes has a negative presentation 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 every metadata sample of the event message track has a constant size.

9. The method of claim 8 , wherein the track header further includes a syntax element that indicates a size of each metadata sample of the event message track in a case where the flag indicates that every metadata sample of the event message track has the constant size.

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:

event message track obtaining code configured the cause the at least one processor to obtain an event message track, the event message track configured to be processed by a Dynamic Adaptive Streaming over HTTP (DASH) client for displaying media content, the event message track obtaining code comprising:

event message box obtaining code configured to cause the at least one processor to obtain a plurality of event message boxes of the event message track; and

indicator obtaining code configured to cause the at least one processor to obtain an indicator, included in the event message track, that indicates each one of multiple types of the 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 the DASH client or display media content based on the event message track.

12. The system of claim 11 , wherein the indicator indicates that each of the plurality of event message boxes is a same event message box 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 plurality of event message boxes has a negative presentation 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 every metadata sample of the event message track has a constant size.

19. The system of claim 18 , wherein the track header further includes a syntax element that indicates a size of each metadata sample of the event message track in a case where the flag indicates that every metadata sample of the event message track has the constant size.

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 event message track including a plurality of event message boxes, the event message track configured to be processed by a Dynamic Adaptive Streaming over HTTP (DASH) client for displaying media content;

obtain an indicator, included in the event message track, that indicates each one of multiple types of the plurality of event message boxes in the event message track; and

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