PCR repetition errors introduced - why?

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PCR repetition errors introduced - why?

Post by mqarkcambie » Mon Sep 15, 2014 5:58 am


I have an AppearTV frame taking a DVB ASI stream which is clean on the way in - when I take the ASI, make a multicast from it and look at that multicast there are PCR repetition errors introduced.

What's happening to the PCR in this process that it gets out of spec but without introducing noticeable jitter or CC errors?


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Re: PCR repetition errors introduced - why?

Post by PID_Stop » Mon Sep 15, 2014 9:26 am

'PCR repetition error' is a bit ambiguous: it could mean that the device is repeating identical time stamps; it could also mean that it's associating PCR with the wrong or unnecessary PIDs (which seems more likely to me). Typically, PCR is associated with the video PID: for example, if you are sending content as service 3, you would expect to find PCR on PID 49. Service 4 would find PCR on PID 65, and so on. If your AppearTV box is doing some sort of multiplexing or transport stream processing function, you will want to make sure it isn't throwing in extra PCR data somewhere else, putting it in the wrong place.

Mis-mapping PCR to the wrong PID or to extra PIDs isn't necessarily going to result in jitter or continuity errors...

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Re: PCR repetition errors introduced - why?

Post by Kelly » Tue Sep 16, 2014 12:36 pm

I don't think it applies here, but in thinking about your comment; I suppose a repetition error could be technically some form of Deterministic Jitter, because it was data dependent. That being said, I'm leaning toward Jeff's opinion: There is probably an errant PID set up in your stream, or some mis-mapping or maybe a duplicated PID.
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