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

On Apr 13, 2011, at 12:03 , Philip Jägenstedt wrote:

> From todays teleconf.
> 
> The question comes up in some test cases in <http://www.w3.org/2008/WebVideo/Fragments/TC/ua-test-cases.html>.
> 
> It it my experience that media not starting at time 0 is extremely rare, I've really only seen it in poorly remuxed MPEG-2 transport streams and similar. I would say that *if* a user agent supports media that doesn't start at 0, then we should clamp the request start to the start time when necessary. I don't think that we should make the start/end relative to the media start position, as that would be inconsistent.


Everyone seems to say "we don't want to support media that doesn't start at t=0", but then my next question is:

Assuming I have an item example.ogv starting at t=0. I now request <http://example.com/example.ogv?t=10,20>. Does the resulting video stream start at t=0 (i.e. has everything been recoded, if the underlying format has embedded timestamps) or at t=10, or do we simply leave it implementation-defined?

And, of course, the next question is: what does <http://example.com.ogv?t=10,20#t=5,15> show? seconds 5-10 of the original media file? seconds 10-15 of the original media file? Something else?

Note that these examples may actually occur in real life: it's easy enough to envision an application that simply tacks #t=xxxx onto an existing URL to show just a little bit of it.
--
Jack Jansen, <Jack.Jansen@cwi.nl>, http://www.cwi.nl/~jack
If I can't dance I don't want to be part of your revolution -- Emma Goldman

Received on Wednesday, 13 April 2011 11:59:09 UTC