[mythtv-users] New HD setup, couple questions.

Billy Macdonald billymacdonald at gmail.com
Tue Jan 23 16:23:48 UTC 2007

On 1/23/07, Calvin Harrigan <charriglists at bellsouth.net> wrote:
> So I broke down and bought an HDHR.  Neat little device.  Easily
> configured, works like a charm.  My mythtv box is a slightly older setup.
> Athlon XP 1800+
> 512MB PC2700
> 400 Gig Seagate
> Hauppauge PVR-250
> ASRock 741GX based motherboard.
> Built in Audio (no digital out :-(   )
> Built in 100 MB nic
> Gentoo using the latest 0.20 stable release in portage. 2156?
> Sony 50" LCD projection set connected via DVI->HDMI adapter
> This set has worked well for me since myth 0.7 or so.
> I've been able to get this modest hardware working with HD pretty
> decently.  Using XVMC and custom modelines for my tv.  I've managed to
> create and use the following modes.
> 1920x1080i
> Looks awesome, no de-interlacing necessary by mythtv.
> Max 65% CPU
> Was able to watch a 1080i recording, record a 1080i & a SD program all
> at the same time without a much as a hiccup.
> 1280x720p
> The native mode of the TV, also the mode the gui runs in.
> Uses it for mythvideo (mplayer) and most myth functionality.
> About 70% CPU (forgot exactly)
> 720x480p
> Works but source video needs to be deinteraced.  (one of the later
> questions).  Works well for emulators.
> 10-15% CPU
> 720x480i
> Works but there are deinterlacing artifacts, seems to be hardware (tv or
> video card)
> 10-15% CPU
> Instead of trying to deinterlace,  I use the feature in myth to switch
> modes and use the deinterlacer in the tv to do the work.  I also have
> dishnetwork which I capture using the PVR250.  I switch to 480 mode to
> be able to use the wide zoom feature of the TV.  You know that mode that
> progressively stretches the image as it goes towards the edge of the TV.
>   That works great.  It results in a sharper image than scaling and
> deinterlacing.
> My questions are two fold.  Because I have the 1080i modeline in the
> xorg.conf file, mythtfrontend starts up at that mode and scales fonts,
> themes etc to that resolution, though it almost immediately switches to
> 1280x720p because of the mode switching options I set to run the GUI in
> 1280x720p.  The fonts/graphics are really small.  (Yes I have made the
> fonts bigger in the setup screens)  Is there a way to convince mythtv to
> scale to a preset mode (1280x720p in this case) other than the mode it's
> started in?
> The second question has to do with deinterlacing.  Because I couldn't
> get a good 480i mode working on my setup I have to use the 480p, thus I
> have to deinterlace the the signal I get from the pvr 250.  Problem is
> that deinterlacing seems to be a all or nothing option at this point.
> Needless to say I don't want to deinterlace the 1080i stream, just the
> 480i.  Is there a way to deinterlace based on resolution, I assume it
> would have to be a hack since I couldn't find anything in the
> documentations, menu options, or the list.  I would like to add it to
> the resolution switching options if it decided which way it should be
> handled.
> I'd like to thank the developers for an awesome project and the user
> community for all the interest and support in this project.

You've accomplished a lot of what I wanted to accomplish when I
started setting up my HD.   I too wanted to setup a 1080i modeline so
I didn't have to deineterlace, but wasn't successful with my TV and
have given that up.  I was able to find a faster PC for the frontend.

But I do have 1280x720 as the GUI size and 1600x1200 for 1080i shows.
I have a 1080p TV, but couldn't get 1920x1080 video to work without a
lot of artifacts, but that is a different story.

Anyway, to solve the sizes problems I had to put in the GUI size &
offsets on the screen before the one where you select the different
resolutions for different video formats.  So put your x & y to be 1280
& 720 for the GUI size and that should fix that.  I actually tweaked
it so that I could overscan the 720p signal but still have the gui
fit.  Without the overscan I would often get a lot of noise on the top
edge of my pvr250 recordings.

For the different deinterlace settings, I never found a solution but
gave up when I couldn't get the modeline to work.  I think playback
groups might be what you want to look at, though I'm not sure.

Good luck!

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