[mythtv-users] HD deinterlacing

[Tom Dexter]

On 10/2/07, Andrew Gallatin <gallatin at cs.duke.edu> wrote:
> Andrew Gallatin [gallatin at cs.duke.edu] wrote:
> > Ryan Steffes [rbsteffes at gmail.com] wrote:
> > > Did your recording show the correct length?  I've noticed a problem
> > > that I haven't started to track down where recordings (again,
> > > predominantly NBCHD, which is why I asked) have periodic burst of
> > > faster motion.  The length of the show itself shows as being shorter
> > > than it should be, though.  For example, an hour long show may show as
> > > being 53 minutes long and when watching it, there's occasional bursts
> >
> > I'm in the same area as you (recognized you from AVS forums).
> > I see the same thing as you.  I typically see it on NBC and CBS,
> > but almost never on PBS.
> >
> > I'm pretty sure that it is due to either our local stations, or
> > the networks, doing something fancy for "film" (24fps) content.
> > This is why things like live shows (sports, Letterman) doesn't
> > have this problem, as it is filmed at 30fps.  There was a dicussion
> > about this a few months ago on our local (Raleigh, NC) AVS forum
> > HD reception thread.
>
> Found the link:
>
> http://www.avsforum.com/avs-vb/showthread.php?p=10602534#post10602534
>
>
>
> Drew
>

I just checked out that avsforum link.  That's exactly what I've been
seeing recently with New York NBC broadcasts here in NJ (mostly dramas
and comedy), where MythTV keeps seeing it switch from interlaced to
progressive (constantly enabling and disabling de-interlacing):

2007-10-04 13:47:11.831 NVP: interlaced frame seen after 95 progressive frames
2007-10-04 13:47:11.914 Set video sync frame interval to 33366
2007-10-04 13:47:11.914 Enabled deinterlacing
2007-10-04 13:47:12.015 NVP: progressive frame seen after 4 interlaced frames
2007-10-04 13:47:12.082 Set video sync frame interval to 33366
2007-10-04 13:47:12.082 Disabled deinterlacing
2007-10-04 13:47:12.347 NVP: interlaced frame seen after 9 progressive frames
2007-10-04 13:47:12.431 Set video sync frame interval to 33366
2007-10-04 13:47:12.431 Enabled deinterlacing
2007-10-04 13:47:12.682 NVP: progressive frame seen after 9 interlaced frames
2007-10-04 13:47:12.749 Set video sync frame interval to 33366
2007-10-04 13:47:12.749 Disabled deinterlacing

This didn't start happening until this years season with New York NBC,
so they must have changed something.  If I play those mpegs with
mplayer it keeps thinking the frame rate is changing from
24000/1001fps to 30000/1001fps every few seconds (not just at
commercials).

Luckily the only affect I see in myth is the occasional speed up of
video for a second (usually only right after a commercial) and the
length being incorrect by about 7 minutes.

Strange stuff.  I wonder what on earth they're doing.

Tom