[mythtv] rolling up my sleeves: a few questions about commflagging

Brian J. Murrell brian at interlinx.bc.ca
Mon Jan 27 14:50:16 UTC 2014

On Mon, 2014-01-27 at 13:01 +0000, John Pilkington wrote: 
> Yes, it's fetching it from the DB, but AIUI that was changed quite 
> recently with the intention of solving the long-standing problem of 
> variable frame-rates.
> http://www.gossamer-threads.com/lists/mythtv/users/557752#557752

Ahhh.  I see.  The time between keyframes is available which means that
a frame rate, at least from one keyframe to another is calculatable.  In
practice, at least from a couple of recordings I have looked at here,
keyframes are approx. every 15.  Perhaps that is plenty enough to get an
accurate enough calculation of commercial lengths with changing

I will have to look into where mythutil --getmarkup is getting that data
from and see if it's available during commflagging, which is typically
happening live, during recording (to take advantage of page caching to
avoid re-reading the frames from disk).  Certainly it could be a
post-recording-complete process if necessary but that doubles the disk
I/O and adds latency to the commercial flagging data.

Thanks John!


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