[mythtv-users] problem decoding 720p content

[Michael Weber]

On 12/10/06, Mark Kendall <mark.kendall at gmail.com> wrote:
> On 12/9/06, Michael Weber <mtweber at gmail.com> wrote:
> > On 12/7/06, Michael Weber <mtweber at gmail.com> wrote:
> > > I have two of the exact same computers (Intel Core Duo 1.66GHz, Asus
> > > N4L-VM DH, 1GB, with nvidia PCX5300 128MB graphics), both are running
> > > off the same minimyth distribution, so the os settings are the same.
> > > The playback settings are the same (ffmpeg, kernel deinterlace).  One
> > > machine decodes 720p perfectly and the other cannot without buffer
> > > underruns (every couple seconds).
> > >
> > > At first I though that the network bandwidth was somehow different
> > > (faulty wiring or something), but I just ran an iperf bandwidth test
> > > and both machines came out at 90MBit+.
> > >
> > > Does anyone have any ideas how this could happen?
> > >
> > > BTW, 1080i on both machines works flawlessly.
> > >
> > > mike
> > >
> >
> > I have some more information.  Neither of the computers work on my
> > DLP(1280x720), and both work on my LCD (1360x768).  So it has
> > something to do with the resolution.  And, if I change the resolution
> > of the DLP to 1080i then 720p content works again.
>
> I've seen similar issues when using 720p and bobdeint. I assumed for a
> long time that it was a decoding issue but was in fact down to the
> nvidia driver reporting a refresh rate of just under 50 fps when bob
> needed 50. Are you definitely using kerneldeint?
>

I am using kerneldeint, but AFAIK, the 720p content shouldn't be using
the de-interlace filter since 720p is already progressive scan.

It is interesting that you mentioned something about the refresh rate.
 I don't think that it has anything to do with scaling (actually I
never did).  Under the 1280x720 setting of the DLP, I have changed the
over/underscan from -20 to +20 -- none of them fix it.  This range of
setting should pretty much rule some mysterious scaling problem.

mike