[FFmpeg-devel] dshow: pts relative to zero or stream time preferred?

Michael Niedermayer michaelni at gmx.at
Wed Mar 26 00:11:31 CET 2014

On Tue, Mar 25, 2014 at 04:58:42PM -0600, Roger Pack wrote:
> Hello.
> I noticed that with today's dshow, it passes through pts timestamps
> "relative to the directshow filtergraph" like:
> 889246977000
> which could mean "first packet" (pts 0) for instance (packets after
> that would be relative to that value).
> I could modify it so that the first packet (that represents pts 0) has
> a pts of 0 (i.e. it's zero based).
> However, then, sometimes, it might pass through negative pts values,
> which might not be good.
> Does anybody have a feel for which type/style of timestamps are preferable here?
> Just wondering.
> Thank you.
> -roger-

timestamps from capture devices must all be relative to the same
point otherwise they could not be synchronized
if they all return the time since year 19XY that works
if they all start from pts=0 but that corresponds to different points
in time it does not work

of course one could change every capture device to start from pts=0
and export the actual time that corresponds to, and then add that back
somewhere before synchrinization but that would be more complex


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Opposition brings concord. Out of discord comes the fairest harmony.
-- Heraclitus
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