[mythtv] Funky 720p playback

[John Lofgren]

I am astonished to report that I actually received some feedback from
WLS (ABC 7 Chicago) regarding this issue.  I submitted this comment to
the engineering department through the WLS website:

>>>
Comments: I use a DVR to record Lost from your
station through Comcast.  For the last
few episodes, the framerates of the
signals have been something non-standard
and this is causing the playback to be
terrible from the DVR.  What gives?
<<<

I just received this response:

>>>
Hi John-
   Thanks for contacting ABC 7 Chicago.  We do appreciate questions and
comments. This issue has been fixed.

Thank you
The Engineering Department
<<<

I have not yet tested whether whatever they "fixed" actually solves
this problem, and I don't know whether the other shows in question
(Grey's anatomy, etc) were also "fixed."

Cheers,
John


On Wed, Mar 5, 2008 at 10:39 AM, Bill Cizek <cizek at rcn.com> wrote:
>
>
>  >
>  > Robert Kulagowski wrote:
>  >> Keith Cremer wrote:
>  >>
>  >>> On Mar 2, 2008, at 1:20 PM, Bill Cizek wrote:
>  >>>
>  >>>
>  >>>>> AFAICT this WLSDT is not broadcasting broken streams, they are
>  >>>>> just  using
>  >>>>> an encoding extension we don't support very well. These streams
>  >>>>> do  in fact
>  >>>>> play on powerful MythTV machines. I believe they are broadcasting
>  >>>>> about 40
>  >>>>> fps on a 60fps stream and marking some of the frames as
>  >>>>> repeatable,  but I
>  >>>>> haven't added the debugging statements to MythTV to confirm this.
>  >>>>> If true,
>  >>>>> MythTV doesn't know what is going on and so the only way it
>  >>>>> adjusts  is with
>  >>>>> the A/V sync code. This works, but is CPU intensive.
>  >>>>>
>  >>>>> -- Daniel
>  >>>>>
>  >>>>>
>  >>>> I've got a 3.2 GHz P4 and it plays,  it's just funky - kind of
>  >>>> like  you
>  >>>> describe above.
>  >>>>
>  >>>> Are you referring to the top_field_first and repeat_first_field flags?
>  >>>>
>  >>>> I checked my problem recordings and these flags are set within them.
>  >>>>
>  >>>> Recordings where they're unset play fine.
>  >>>>
>  >>>> If there's anything I can do to help fix / test this let me know.
>  >>>>
>  >>>> -Bill
>  >>> Mine are playing back on a high end Core 2 with plenty of power to
>  >>> spare.  I'll do some test captures using the HDHomeRun and VLC to
>  >>> see  if the stream is intact, and then look at the playback in Myth.
>  >>>
>  >>
>  >> On a 2.8Ghz P4, it's pretty much unwatchable; the audio and video get
>  >> separated by 3-5 seconds.  (But 720p from Fox is OK and works AFAICT).
>  >>
>  > I'm not sure if I'm experiencing the same issue.  My 720p content is
>  > coming from my STB over firewire, not a HD HomeRun.  1080i
>  > mpeg2content is fine, as is 720p/1080p H264, only 720p mpeg2 content
>  > seems to be the issue.  I'm running a core 2 duo @ 2.9Ghz, so I think
>  > I've got all kinds of cpu power.  I opened ticket #4859 with logs and
>  > a sample.  Mplayer has no problem playing the file.
>  >
>  > Brad
>  >
>
>  I checked your file, Brad and it plays fine on my system (P4 3.2 GHz,
>  NFS frontend with SPDIF output)
>
>  Since you have a dual core cpu you might want to enable multithreaded
>  decoding.  From the looks of your logs you aren't using it.  That might
>  help.
>
>   Also, if this is a new system you might need to tune NFS, mysql and your
>  network.  It's been a while but I remember having to tweak a lot of stuff to
>  get things working well.
>
>  I opened #4867 for this problem.  I also noticed that xine plays these
>  recordings ok (including Lost from last week).
>
>  -Bill
>
>
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