Test cases: invalid syntax vs. invalid semantics

Dear all,

continuing the discussion from last telcon regarding the behaviour of a 
UA in case of an invalid media fragment, let me sketch the possible 
situations and proposal outcomes.

1) Invalid Syntax
For example, #t=3,4,4 is invalid syntax. The UA is always able to detect 
syntax errors and thus knows that the media fragment is invalid. Now, 
what is a UA in this case supposed to do? Two proposals are on the table:
- the whole resource is requested by the UA (preferred by Philip and 
Davy, see [1])
- the UA only requests setup information (preferred by Silvia)


2) Invalid Semantics
2a) UA is able to detect that the fragment is invalid
For example, #t=7,3 is semantically invalid and the UA is able to detect 
this. Again, the same two possibilities as described above are available.

2b) UA is not able to detect that the fragment is invalid
For example, #t=15,20 when the resource has a duration of 10s. When the 
UA does not know the duration, it is not able to detect that this 
fragment is invalid. What will the visual result be in this case? Note 
also that it is possible in this case that the UA requests a temporal 
range (i.e., Range: t:npt=15-20) which the server (for the moment) will 
answer with a 416 ...

I think we need to answer these questions in order to efficiently 
progress with the test cases.

Best regards,

Davy

[1] http://www.w3.org/2011/04/06-mediafrag-minutes.html#item03

-- 
Davy Van Deursen

Ghent University - IBBT
Department of Electronics and Information Systems - Multimedia Lab
URL: http://multimedialab.elis.ugent.be/dvdeurse

Received on Friday, 8 April 2011 09:43:11 UTC