Filip Roséen authored Nov 04, 2016 and Thomas Guillem committed Nov 04, 2016

matroska_segment_c::EnsureDuration is used to calculate the duration
for a stream which does not include the value as metadata. Given that
the function potentially will have to run through the entire file in
order to get the last timecode, these changes make sure that we abort
if an element does not have a finite size.

If an element, on the way, does not have a finite size we cannot
simply jump over it, but have to parse it's entire contents (which
might be an expensive operation). And most often when an element does
not have a finite size, the media is being streamed.

We however have an exception to infinite clusters that are referenced
by a Cue, in which case we will try to parse it (to allow content
saved from a live stream where the Cues refers to every cluster to
have a duration).

Signed-off-by: Steve Lhomme <robux4@videolabs.io>
Signed-off-by: Thomas Guillem <thomas@gllm.fr>