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irajs / CMAF

Common Media Application Format Specification
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What is the behavior if an emsg box is missed in a live stream? #7

Closed YasserSyed closed 8 years ago

YasserSyed commented 8 years ago

What happens if an emsg box is missed in a live stream? Does a MPD play a role in informing the player?

cconcolato commented 8 years ago

My understanding is that nothing happens. You'll refresh the MPD at the time indicated in the MPD you didn't miss.

dwsinger commented 8 years ago

Unclear what change to the spec. is needed here; emsg handling is outside CMAF, CMAF merely needs to admit that they might exist.

dwsinger commented 8 years ago

filed on w15947 (San Diego output)

ghost commented 8 years ago

Resolved with regard to CMAF.
Regarding DASH and MPD, an 'emsg' box can be repeated on multiple Segments for robustness, so that a player joining a live presentation can receive a repeated message if it missed the first instance. This is the same behavior as SCTE-35 messages. Event messages are also represented in the MPD EventStream, so a player joining a live presentation or randomly accessing a PVR buffer can read the Event Messages on the timeline even when it doesn't read them on a Segment.