[mythtv-users] MythTv component out HOWTO

Steve Skarda steveskarda at gmail.com
Mon Apr 10 17:23:04 UTC 2006

A couple of folks asked in another thread how to do component out so rather
than muddy up that already long thread, I thought I'd start a new one.

These are the tricks for me in order to get component out to work with a
Nvidia card on a MythTv box.  This information has been posted on this list
before, but I'll try to summarize in one place.  Disclaimer, I am new to
Linux and MythTv but I will share what I know, albeit limited knowledge from
reading posts and experimenting on my system.

There are only two Nvidia cards that support component out.  6200 and
6600.   But not all manufacturers enabled the S-Video to Component dongle so
you need one that does.

The Nvidia Linux drivers have standard TVFormat and Mode that supports
component.   No modelines required!  To get it going, I have this in my
Xorg.conf.  The key line is TVStandard.   Don't try component.  It doesn't
work.  See the Nvidia README file for details on why this works.

Section "Screen"
    Identifier     "Default Screen"
    Device         "NVIDIA Corporation NV43 [GeForce 6600]"
    Monitor        "Visual Sensa"
    DefaultDepth    24
    Option         "TVStandard" "HD1080i"
    SubSection     "Display"
        Depth       24
        Modes      "1920x1080"

Section "Monitor"
    Identifier     "Visual Sensa"
    HorizSync       15.0 - 620.0
    VertRefresh     15.0 - 600.0
    Option         "RenderAccel" "True"
    Option         "DPMS"
    Option "ConnectedMonitor" "TV"

But that's not all.   If you try to do video at 1080i, X will lock up.
This is a bug on all Nvidia versions up through and including, 8756.  To
workaround that, launch nvidia settings.  Make sure that 'Sync to VBlank'
under Video Texture Adaptor is NOT checked.  Also,  in your Xorg.conf, you
need to have the line, Option "RenderAccel" "True" as you can see in my Xorg
above.  Finally, the nvidia-settings need to be loaded everytime X starts.
I have a line in my startup group that runs the command:
nvidia-settings -l
I think there is a cleaner way to do this with a line in your xorg but I
don't know how to do that.

That's it.   Component out from Mythtv without a transcoder.  Althougth, I'd
still recommend not dumping your transcoder if you have one for these

Know problems:
-There is bad overscan.  The people that know a lot about video say that is
due to the TV.  That may be true but there is no way to adjust it since the
TVStandard "HD1080i" overrides all modelines from what I can tell and there
is no overscan setting in nvidia-settings when 1080i is selected.   A
workaround to this problem is to set the gui size in the MythTV general
settings.  I had to cut more than 100 pixals out of my picture for both
height and width which makes me believe it is a nvdia problem (or my
problem) more so than the TV.  Then check play video at the size of gui.
Others have complained about artifacts in the screen but I don't see
anything so this works for me.
-I have interlacing artifacts.  They are minor, only a line or two at the
top of the screen during scenes with significant motion but it is annoying
none the less.
-The bug in Nvidia is not likely to get fixed.  There aren't currently many
people that have this setup so Nvidia doesn't have the bug high on their
development list.  I got that from their Nvidia Linux forum.
-I have read on nvnews that the quality coming from the component out is
bad.  I have nothing to compare to so I don't know if that is true.  (I am
planning on purchasing a front projector with DVI so I am not going to
bother buying a transcoder to find out).  The poster stated that switching
to the transcoder made a huge improvement and they could see text for the
first time.  I will say that I can't read text on my desktop on my
television so there may be some truth to that.  Here is a link to the post
if you are considering buying a 6200 for this capability.

The folks that asked for this HOWTO seemed to suggest that it should be in
the WIKI.  To me, it seems that only smart people post on the official WIKI,
but if people find this information helpful, I can collate whatever replies
I get in the form of corrections or clarifications on this thread and post
something to the HOWTO areas of the Wiki.  Let me know if you think that
would be useful.

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