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1080i output via DVI?
PostPosted: Sat Sep 09, 2006 9:33 pm Reply with quote
nr
 
Joined: 16 Aug 2005
Posts: 18
Location: Malden, MA




I recently bought a TV that accepts both 1080i and 1080p signals from the HDMI input. I've been using mplayer with XvMC and an Nvidia GeForce 6600 (fanless) with Nvidia driver version 7676 and Scott Larson's wonderful bob-deinterlacing patch (all praise!). I run my X server in 1920x1080 mode with the output on the DVI connector, which is connected to the HDMI input of the TV.

I'm capturing lots of 1080i programming with my HD-3000, and the pictures look nice. But when I tune my TV to the same stations directly through the antenna, the pictures look gorgeous. I'd like to try to get the same quality through the HD-3000.

My best guess is that the deinterlacing that the TV does with the over-the-air signal is better than the bob deinterlacing that my computer is doing. (Better deinterlacing is not an option with my Sempron 3300+.) So my question is this: does anybody know how to persuade Xorg 7.0 with the Nvidia driver to output a 1080i signal instead of a 1080p signal, so that I can try letting the TV do the deinterlacing? And further, if that is successful, is there a way to tell the patched mplayer not to deinterlace, or should I just revert to an unpatched mplayer?

If it helps, here's an excerpt from my xorg.conf. The comments come from running the very latest Nvidia driver in verbose mode; I used them to get the mode lines. (I can't use the latest driver because of the '100% cpu usage' bug.)
Code:
Section "Monitor"
   Identifier   "Sony"
   Mode   "1920x1080"
      DotClock 148.50
      HTimings 1920 2008 2052 2200
      VTimings 1080 1084 1089 1125
      Flags "+Hsync" "+Vsync"
   EndMode
   Mode    "1280x720"
      DotClock 74.25
      HTimings 1280 1392 1432 1648
      VTimings 720 725 730 750
      Flags "+Hsync" "+Vsync"
   EndMode
#(--) NVIDIA(0):   1920 x 1080 @ 60 Hz
#(--) NVIDIA(0):     Pixel Clock      : 148.50 MHz
#(--) NVIDIA(0):     HRes, HSyncStart : 1920, 2008
#(--) NVIDIA(0):     HSyncEnd, HTotal : 2052, 2200
#(--) NVIDIA(0):     VRes, VSyncStart : 1080, 1084
#(--) NVIDIA(0):     VSyncEnd, VTotal : 1089, 1125
#(--) NVIDIA(0):     H/V Polarity     : +/+
#(--) NVIDIA(0):   1280 x 720  @ 60 Hz
#(--) NVIDIA(0):     Pixel Clock      : 74.25 MHz
#(--) NVIDIA(0):     HRes, HSyncStart : 1280, 1390
#(--) NVIDIA(0):     HSyncEnd, HTotal : 1430, 1650
#(--) NVIDIA(0):     VRes, VSyncStart : 720, 725
#(--) NVIDIA(0):     VSyncEnd, VTotal : 730, 750
#(--) NVIDIA(0):     H/V Polarity     : +/+
EndSection
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PostPosted: Sun Sep 10, 2006 11:53 am Reply with quote
PeterKnaggs
 
Joined: 21 Mar 2005
Posts: 54




Probably you've already done this, but have you checked that
the deinterlacing is being done OK, you can use the test sample:
http://www.w6rz.net/vertrez1080.zip
I put together a page on XvMC with the nVidia 5200, to try to give all the
details of the configuration that seems to work well here, but I don't
know what you mean "nice" compared to "gorgeous".
http://www.penlug.org/twiki/bin/view/Main/LinuxHardwareInfoNvidia5200
Other than the few puzzling quirks listed at the bottom of the page,
it's turning out to be a very stable configuration, and nothing seems to be
wrong with the video as far as I can tell. I did try the same configuration
on the faster Dell XPS machine, and I seem to be running into some
interrupt problem because the playback is somewhat stuttery. But other
than that, Dapper Drake is turning out to be one heck of a convenient
distro to use for video stuff Smile

Some other things you didn't mention: what distro/kernel are you using?
What monitor/TV is this?
And could you post your /etc/X11/xorg.conf somehow?
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PostPosted: Sun Sep 10, 2006 2:53 pm Reply with quote
nr
 
Joined: 16 Aug 2005
Posts: 18
Location: Malden, MA




The deinterlacing is great. I'm very familiar with seeing 1080i content without deinterlacing: the infamous 'mouse teeth' are very prominent. With the bob-deinterlace patch, no mouse teeth, pretty smooth picture.

Quote:
I don't know what you mean "nice" compared to "gorgeous".

I'm not sure how to quantify this, but the difference is noticeable. Visually the computer image is slightly less smooth or more noisy than the broadcast image. It may have nothing to do with deinterlacing even. MPEG artifacts (squares) seem to be about the same either direct over air or via computer.

I'm using Debian testing with stock kernel linux-image-2.6.17-2-k7. The display is a Sony KDS50A2000. My xorg.conf is posted at
http://www.eecs.harvard.edu/nr/drop/xorg.conf.

Your 5200 page is nice; I used to have a 5200 but then found an opportunity to upgrade to a fanless GeForce 6600 --- better for games Smile
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PostPosted: Sun Sep 10, 2006 8:56 pm Reply with quote
PeterKnaggs
 
Joined: 21 Mar 2005
Posts: 54




nr wrote:

I'm not sure how to quantify this, but the difference is noticeable. Visually the computer image is slightly less smooth or more noisy than the broadcast image. It may have nothing to do with deinterlacing even. MPEG artifacts (squares) seem to be about the same either direct over air or via computer.


To remove the possibility of mpeg artifacts or bad packets out of the mix,
it might be worth downloading one of the longer reference samples from
W6RZ e.g. this one takes about 50% CPU on my 3.4 GHz box with XvMC in
mplayer:
http://www.w6rz.net/newmobcal1920.ts
That one looks very smooth to me, but then again I've no experience with
what it should look like on a non-computer display. On my slower 2GHz
machine it does stutter, although the stutter isn't too noticable when
watching regular TV captures from the HD3000.
Try and see if you can read the text just below the photo in the calendar,
while it's moving. Here, it's fairly readable, although small.

I was wondering about your modeline for the Sony, what happens
if you add "interlace" to the Flags? Does that make things worse?
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PostPosted: Mon Sep 11, 2006 10:30 am Reply with quote
nr
 
Joined: 16 Aug 2005
Posts: 18
Location: Malden, MA




I'm about to leave town for two weeks but will download your sample and do some more experiments when I get back. (I'm also starting to wonder if maybe the MPEG decoder on the TV is doing slightly better than mplayer + XvMC + Nvidia 7676.)
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PostPosted: Mon Sep 11, 2006 6:59 pm Reply with quote
Scott Larson
 
Joined: 15 Oct 2003
Posts: 713
Location: Portland, OR




You should be able to do some A/B comparisons to figure out exactly why one looks better.

I found that things looked better on my cable box but once I made some contrast and saturation adjustments, they're identical (except for the cable box's overscan that cannot be removed).
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1080i output via DVI?
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