[Bug 755115] dashdemux: relate wall clock time to timestamps for live streams

[GStreamer (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=755115

--- Comment #4 from A Ashley <bugzilla at ashley-family.net> ---
I've discussed this stream with a DASH expert that I know. In his opinion the
manifest is not valid.

The SegmentTimeline is intended to cover the entire timeShiftBufferDepth. The
first entry in the SegmentTimeline has a t attribute the defines the first time
value in the buffer. So far, so good.

However, the problem with the stream is that it has a presentationTimeOffset
value, which when subtracted from "now", gives a value that does not exist in
the timeline. 

As defined in the spec:
"The SegmentTimeline element shall contain a list of S elements each of which
describes a sequence of contiguous segments of identical MPD duration. The S
element contains a mandatory @d attribute specifying the MPD duration, an
optional @r repeat count attribute specifying the number of contiguous Segments
with identical MPD duration minus one and an optional @t time attribute. The
value of the @t attribute minus the value of the @presentationTimeOffset
specifies the MPD start time of the first Segment in the series."

There appears to be insufficient values in the SegmentTimeline. The
timeShiftBufferDepth is set to one minute, but there is only 57.6 seconds of
segments in the timeline.

Also the presentationTimeOffset changes on every refresh, which means the DASH
client should be re-basing its timeline every time the manifest is reloaded.

-- 
You are receiving this mail because:
You are the QA Contact for the bug.
You are the assignee for the bug.