Re: Do we need to support media that doesn't start at 0?

Jack,

On 15/04/2011 9:30, Jack Jansen wrote:
> Great, everyone seems to agree!
>
> I especially like the way David phrased it (for NPT start-of-media is deemed to be t=0, regardless of any timestamps embedded in the media), but I can't find anything similar to this in the spec. At least, not around section 4.2, where I would have expected it. I suggest we add it (with suitable emphasis).
Not sure I agree on that :). Taking into account our Media Resource 
Definition [1] and the various discussions we had on for instance which 
pixels do we mean in spatial fragments [2], temporal (and also spatial) 
fragments needs to be applied after decoding the media. Suppose we have 
an MP4 file where the first timestamp is 10s. When we play this file, 
you will see nothing the first 10s. Thus, applying #t=5 to this file 
will result in 5s nothing followed by the first frame (this is how I 
always interpreted the spec ...)

> This also means that the test cases (which, incidentally, aren't listed on the homepage:-), TC0007-UA, TC0007-S and friends, need to be revised.
You're right, after reading what I wrote above and reading TC0007-UA, I 
finally understand the statement "for NPT start-of-media is deemed to be 
t=0, regardless of any timestamps embedded in the media", which means 
that I actually agree with everyone, I think :). I will fix the related 
test cases!

Best regards,

Davy


[1] http://www.w3.org/2008/WebVideo/Fragments/WD-media-fragments-reqs/#side1
[2] http://www.w3.org/2010/11/01-mediafrag-minutes.html


-- 
Davy Van Deursen

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

Received on Wednesday, 20 April 2011 06:56:48 UTC