Difference between revisions of "NVIDIA Component Out"

Revision as of 18:32, 29 January 2007

(written for MythTV 0.20 and below) The best high definition set up from an nVidia card is via DVI, HDMI, or VGA to the HD television since those are all progressive and digital (except for VGA). VGA is in there because it works with your television in much the same manner as it works with your computer monitor. While component-out directly from a graphics cards provides excellent picture quality over composite or S-Video connection, it does have its share of problems when it is coming from a computer. However, we are all limited by what inputs our televisions have.

If VGA, DVI, HDMI, or Component connections are used to connect from your MythTV box to your television, you have to be aware that you will be displaying interlaced video on an progressive display which will introduce issues (that can be mostly solved) that will be addressed below.

Although some users report that "with finally getting the component out on the Nvidia card to work, I have the best Myth display I have ever had, and that is with using composite, s-video, 3 different VGA transcoders, and finally the component out", in fact utilising a VGA to component transcoder provides higher quality. Using a television that supports DVI is the best method. For anyone that does not have a TV capable of DVI or VGA and wants to avoid the expense of a transcoder as these can cost upwards of $125US, this is one option that does work.

This guide assumes a person has the Nvidia drivers loaded and functioning for VGA. I would recommend starting with the latest nVidia drivers. If you have problems, work your way backwards to the previous driver, and so on, until those problems go away.

The Nvidia Linux drivers have "TVStandard" and "Modes" that supports component out directly from the card. No modelines required! To get it going, look at the following excerpt from Xorg.conf. The key line to getting the component out to work is TVStandard. Note: Component is not a valid "TVStandard" such as SVideo and composite. The Nvidia README is a great resource for those looking to better understand the options. A basic example is shown below, providing the quick-n-easy option for simply uncommenting the two options for the resolution you would like to use while leaving the rest commented out.

   Section "Screen"
       Identifier     "Default Screen"
       Device         "NVIDIA Corporation NV43 [GeForce 6600]"
       Monitor        "Visual Sensa"
       Option     "UseEDID" "FALSE"
       Option     "ConnectedMonitor" "TV"
       Option     "TvOutFormat" "Component"
       #------------480p Group-----------------------------
       #Option     "TVStandard" "HD480p"
       #Option     "metamodes" "CRT: 720x480 +0+0"
       #------------720p Group-----------------------------
       Option     "TVStandard" "HD720p"
       Option     "metamodes" "CRT: 1280x720 +0+0" 
       #------------1080i Group-----------------------------
       #Option     "metamodes" "CRT: 1920x1080 +0+0" 
       #Option     "TVStandard" "HD1080i" 
       Option      "AddARGBGLXVisuals" "True"
   End Section

   Section "Monitor"
       Identifier     "Visual Sensa"
       HorizSync       15.0 - 620.0
       VertRefresh     15.0 - 600.0
       # You probably do not want your screen blanking while you are watching a recording
       # Option         "DPMS"
   EndSection

   SubSection  "Display"
       Depth     24
       Modes    "720x480" "1280x720" "1920x1080"
   EndSubSection

There's a bug in the Nvidia drivers prior to and including 8756:

In nVidia drivers releases prior to and including 8756, if you try to do video at 1080i, X will lock up. This problem does not exist with 9746. To workaround this issue under the other drivers, launch the "nvidia-settings" GUI and make sure that 'Sync to VBlank' under Video Texture Adaptor is NOT checked. The nvidia-settings also needs to be loaded everytime X starts, and this can be done ini a variety of ways depending on the distribution you are using (check with your distribution's documentation). Some have placed it in their startup group to run the command "nvidia-settings -l" and others have placed the following in their .Xsession file instead of having nvidia-settings in your startup group:

/usr/bin/nvidia-settings --assign="XVideoBlitterSyncToVBlank=0" \\ --assign="XVideoTextureSyncToVBlank=0" --assign "SyncToVBlank=0"

That's it. Component out from Mythtv without a transcoder.

As of nVidia driver version 9746, the option "ConnectMonitor" is no longer used. In previous versions of the driver, you would set "Option "ConnectMonitor" "TV" to tell the driver to enable the TV-Out encoder. Unless the card detects a television at start up (the television must be on before turning on the computer), the card won't enable the TV-Out encoder.

Known problems

1). Overscan. There is no way to compensate for the television's overscan since the TVStandard "HD1080i" overrides all modelines. 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. Then check play video at the size of gui. Others have complained about artifacts in the screen.

2). Interlacing. Displaying interlaced video on an HD display will result in artifacts. It is best to enable the checkbox next to "de-interlace video" and select "Bob" as the method. This will result in an upscaled picture that should look pretty good (not excellent). It will, however, require some CPU processing to do the interlaced->progressive transition, but not a lot. If you have a decently powered frontend system, you won't even notice the difference. You will, however, periodically see some artifacts during fast movement, but you have to consider that your source image is interlaced and it is being modified to be displayed on a progressive screen.

A big warning: The quality from component out is actually quite good when compared to composite or S-Video output. Composite and S-Video output is always interlaced video, so your standard definition TV broadcasts will look as they normally do. Up-scaling the video from interlaced to progressive (regardless of the resolution (480p, 720p, 1080i) and you may see a difference in the picture quality with SD television recordings. Displaying DVD's or video from MythVideo (depending on the quality of the source) will look fantastic.

References

Here is a post if you are considering buying a 6200 for component out capability. http://www.nvnews.net/vbulletin/showthread.php?t=67261&highlight=6200+component

The snippet of the Xorg.conf was obtained from Mitchell Gore's posting: http://www.gossamer-threads.com/lists/mythtv/users/245570?search_string=MythTV%20%2B%20HD;#245570

See Also

MythUser list [1] and [2]

How to article on getting component out to work. No problems with overscan with latest nVidia drivers.