[mythtv-users] Strange time counter issue with recent NBC OTA recordings

Jim Stichnoth stichnot at gmail.com
Fri Nov 15 00:09:32 UTC 2013


On Thu, Nov 14, 2013 at 3:43 PM, Tom Dexter <digitalaudiorock at gmail.com>wrote:

> On Thu, Nov 14, 2013 at 3:47 AM, John Pilkington <J.Pilk at tesco.net> wrote:
> > On 14/11/13 03:42, Tom Dexter wrote:
> >>
> >> I record New York City OTA stations and am running MythTV 0.25.3.
> >>
> >> For the last couple of weeks, all my NBC (channel 4.1) recordings have
> >> had strange things happening with the progress time counters.  The
> >> shows record and play just fine...nothing missing or anything else
> >> like that.  What's odd is that, while a one hour show will in fact
> >> show as having a length of 1:00:00 or thereabouts, the progress while
> >> it's playing will go from 0 to 50 minutes.  Also, if I jump to 50
> >> minutes or anything past that, it ends up at the end of the show.
> >>
> >> NBC has had a long history of mixing frame rates and other odd stuff.
> >> If I remember correctly, in earlier versions of MythTV things like
> >> this that used to cause MythTV to report incorrect show lengths.  I
> >> figured this may be something similar.
> >>
> >> Anyone else noticing anything like this?
> >>
> >> Thanks
> >> Tom
> >
> >
> > This sounds like seektable trouble.  Does mythcommflag --rebuild improve
> > matters?
> >
> > ISTR that commits that probably aren't in 0.25.3 store time marks as
> well as
> > frame numbers in or around the seektables to handle variable frame rates.
> > Doesn't explain why it's suddenly happening for you, though.
> >
> > John P
> >
>
> It seemed a little unlikely to me that this would be a seektable
> issue, given that it's happening specifically (and only) on NBC
> recordings starting a couple of weeks ago.  Also, just like previous
> frame rate issues I recall in the past with NBC is does *not* occur
> with things like reality shows, but rather only with things like
> dramas were they tend to do this sort of stuff.
>
> However as a test I decided to try a seektable rebuild on one of the
> shows with this issue.  Whatever is going on with the frame rates or
> whatever there is apparently enough to trip up that reuild.  The
> progress went up to a bit over 80% (exactly 50 minutes / 60 minutes),
> and failed with this:
>
> mythcommflag --rebuild --chanid 1041 --starttime 20131111220100
> 2013-11-14 17:59:00.590753 C  mythcommflag version: fixes/0.25
> [vmythtv-0.25.3] www.mythtv.org
> 2013-11-14 17:59:00.590830 C  Qt version: compile: 4.8.4, runtime: 4.8.4
> MythTV Commercial Flagger, building seek table for:
>     The Blacklist - General Ludd
> Rebuild started at Thu Nov 14 17:59:00 2013
> Rebuild completed at Thu Nov 14 18:01:09 2013
> 2013-11-14 18:01:09.077420 E  decoding error
>             eno: Input/output error (5)
>
> Strange one...like I said...progress counter aside, these shows
> actually play perfectly.
>
> For years, MythTV has been playing whack-a-mole with dealing with accurate
position/duration display and seeking, for recordings with variable frame
rates and discontinuous timecodes.  In 0.27, that problem has been fixed
"once and for all" (at least I hope).  It's quite likely that your
suspicion is right and your NBC affiliate is doing something new like
splicing 720p ads into the 1080i show.  I assume you're only seeing this
for new recordings.

BTW, you always see this "error" in the mythcommflag log.  This particular
one just means it reached EOF.

Jim
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