[linux-dvb] relating PTS to 'real' time
public at whitelabel.org
Tue Aug 23 14:56:39 CEST 2005
John Birch wrote:
> There is no process relating PCR /PTS to real time (assuming by real
> time you mean GMT or UTC etc)
> PCR values wrap at an interval greater than 24 hours.
> There is rarely any relationship between the PCR value and 'wall clock
> The PTS relates to the PCR - that is the PTS is the presentation time
> stamp for the content it is embedded in (video, audio or subtitles).
> When the PCR value in the stream matches the PTS, the content should be
> presented (i.e. the video frame should be visible, audio heard, or
> subtitle displayed).
ok. That makes things a lot clearer.
What I'm trying to do is break the stream into small chunks, and save
them mapped against 'wall clock time' - If the PTS and PCR don't carry a
reliable form of 'wall clock time', should I just make sure the PC's
clock is accurate and use that?
I don't need subsecond accuracy, or even second accuracy. +/- a minute
is probably ok.
> Hope this helps...
> John Birch
> Senior Software Engineer,
> Screen Subtitling Systems
> The Old Rectory, Church Lane
> Claydon, Ipswich, Suffolk
> IP6 OEQ
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