[mythtv-users] Improving UK DVBT with Filters

Mike Perkins mikep at randomtraveller.org.uk
Mon Mar 10 18:11:10 UTC 2008


Neil Milne wrote:
> On 22/02/2008, Adam Skinner <kingmoffa at gmail.com> wrote:
>> I've just got myself a nice 1080p 42" LCD telly - and am using mythtv
>>  with it via a vga connection - 1024x768.   I can only get 1080p via HDMI
>>  which wont be coming until I buy a graphics card with hdmi (audio
>>  needed).
> 
> Nice, I only have a 720p set :-( My hardware is an Athlon 3000+ CPU
> with an FX5200 nvidia card so similar to your setup.
> 
> I've spent a bit of time trying to improve the SD picture (UK
> freeview) over what you get with an 'out-of-the-box' setup - here's
> what I've done:
> 
> I drive the TV using VGA (I did try using a DVI output but couldn't
> get the Xorg conf to match what the TV was expecting so never got a
> sync. VGA works fine though...)
> 
> I run at the native panel resolution (close enough) at 1368x768 at
> 60Hz (limitation of my TV)
> 
> On the frontend side I run a deinterlacer 'bob', have the mpeg2
> decoder set to 'libmpeg2' and use opengl vsync. I did find using video
> as timebase worked better, but it messes up the internal DVD player
> and AC3/DTS passthrough (certainly did prior to 0.21 anyway, not sure
> about 0.21+) so have that unchecked for the moment. I think at the
> moment I also have realtime priority enabled, can't remember what
> method though, it's one of the methods mentioned in the mythtv
> documentation anyway.
> 
> This does a pretty good job for me. There is the occasional jerkiness
> on scrolling titles etc which I assume is due to the 50/60Hz mismatch,
> but it looks pretty good otherwise.
> 
> I think there is a bunch of new display related stuff in 0.21 which I
> will have to play with when I do the upgrade, so all the above is
> relevant to 0.20.
> 
> I don't know if your FX5200 has the grunt to drive your TV at native
> res, I guess you could try. I think the most effective way of
> improving my pic was to run at the panel native res.
> 
As you are mostly receiving 50Hz input, I would have thought that you'd be 
wasting your time driving the screen at 60Hz. Why not run at 50 and save 
yourself the 'occasional jerkiness'?

Mike Perkins


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