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Dash-Industry-Forum / Guidelines-TimingModel

DASH-IF implementation guidelines: the DASH timing model
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Is "32 bit timescales are preferable for installed-base of browsers" still valid? #29

Closed sandersaares closed 4 years ago

sandersaares commented 5 years ago

IOP v4.3 section 4.4.3.1 contains the sentence fragment "32 bit timescales are preferable for installed-base of browsers."

My knowledge of browser internals is small but is this still a relevant concern in 2019? If not, I propose we remove this statement. @epiclabsDASH can you comment?

sandersaares commented 5 years ago

F2F comment: OK to remove

sandersaares commented 4 years ago

No longer present in timing model text that references timescales.

TobbeEdgeware commented 4 years ago

I'm not sure it is relevant here but there is the Javascript MAX_SAFE_INTEGER = 2^53 -1 due to all Javascript numbers being represented as double. This leads to overflow in timestamps for example if AST=1970-01-01 is used together with the default Smooth Streaming timescale of 10,000,000 ticks/second.

sandersaares commented 4 years ago

That's true. There's a statement in the timing model text that says timestamps should be kept under the 2^53 limit. There is also an example about the 90 KHz timescale saying it is no problem. I will also add an example for the Smooth Streaming timescale to point out that common source of problems!