[mythtv-users] 8400GS -> GT 430 -> ?? (60Hz, VDPAU High Quality)

[Gary Buhrmaster]

On Mon, Jun 11, 2012 at 7:15 PM, Tom Dexter <digitalaudiorock at gmail.com> wrote:
....
> I'm in the US as well (I get New York OTA broadcast channels).  I
> recently went from an old GeForce 7100GS with no VDPAU at all to a
> small form factor GT 430 card and it handles VDPAU high quality
> without a hitch.  Not only 720p/1080i OTA but 1080p x264 videos and
> others as well.  That makes me wonder if it isn't just something in
> your configuration.

The issue with the 430 is only for interlaced content (where the
GPU is running code), all the VDPAU cards have dedicated
decoding hardware for mpeg1/2, h.264 (various capabilities in the
various cards).  The specs when running the 430 indicate that the
card simply has little to no headroom for 60hz interlaced content,
so that if the particular activity is either interrupted to do something
else (the card does have to deal with other things), or the process
is slightly more complex for some scene or another, there may
be "glitches" in the output.  And, to make matters even more
different, there are reports that various nVidia driver versions have
made a difference (some seem to work faster than others, although
I have not seen any definitive reference, just anecdotal reports).

Unfortunately, not all interlaced content is the same,
and broadcasters encode/compress differently in different
areas.  So even the NBC broadcast in NYC may be
different than the NBC broadcast in Chicago.  So, what
works for one might not work for another.

There are numerous things one can do to "improve" the 430 in
the US.
* Turn off composite (in the xorg.conf)
* Overclock (if your card supports it).
* Do not notice the occasional "glitch" (some people simply
  do not see the "glitches", for others, they can not ignore
  the glitches/artifacts).
* Run a "faster" card.  Where, interestingly, that might mean
  a 2xx card (if you do not need HDMI audio).  The architectural
  changes in the 4xx series required GPU resources than a
  2xx card (I do not remember which 2xx cards are the current
  favorite, I just remember some of them were actually better;
  the list archives should tell you).

I do agree that in this particular case, it sounds like something
else (than the 430 opportunities) may be going on.

Gary