DirecTV has several different HD boxes. All of them contain the same menu system unless you have the newer DirecTivo (THR22). Unfortunately, I am unfamiliar with the Tivo interface. So we'll just cover the DirecTV IRDs (Integrated Receiver/Decoder).
In the menu system of your DirecTV IRD you'll want to navigate to the Settings sub menu. On the left side you want to scroll down to HDTV. Three new selections will appear. They are Video, TV Ratio and TV Resolutions.
[PIE]All of the following screen grabs display DirecTV's new HD GUI (Graphical User Interface). If you do not have it yet, you should be getting it soon.[/PIE] Video Video
- you'll have three new selections - Native, Screen Format, and Bar Color. Native is the resolution and you want this selection to be 'On'. Meaning that your DirecTV IRD is outputting the video at it's native resolution - there is no conversion of the video. Screen Format
- your options are Original Format, Pillar Box, Stretch, or Crop. This is for how SD material will be displayed on your set.
Pillar Box will display the bars on the left and right side of the screen.
Stretch will stretch the image so that it fits the screen width.
Crop will cut off the top and bottom of the image in order for it to fit the full width of the display.
Original format will display the material in it's original format. Bar Color
- this allows you to change the pillar bars' color. TV Ratio
This allows you to change your aspect ratio for your display. This should be set to Widescreen 16:9. TV Resolutions
This is where you would select the resolutions your display supports. Select all resolutions that your display supports.
Your DirecTV IRD is now set up with the proper settings for your display.