So what do all those de-interlace settings do?

[AJ Bertelson]

Found this over at htpcnews.
http://www.100fps.com/

[stanger89]

Here's a short overview of applicable to video playback the 100fps site is more geared to video capture/editing/encoding and perhaps more importantly PAL (50fps).

Basics
NTSC video is made up of two fields (even/odd lines) that are played at 59.94fps on an NTSC TV. For progressive/HDTV displays this needs to be deinterlaced, there are several ways. There are also generally two kinds of source material 29.97fps, called Video, and ~23.97fps, called Film.

Simple deinterlacing:
Bob:
Take one field (240 lines) and make it fill the whole screen (480 lines) this often leaves jagged edges.
ie this
1111111111
to this
1111111111
1111111111

Weave:
Take the two fields and combine them into one frame
ie this
1111111111
and
2222222222
to this
1111111111
2222222222
This sounds great but for video material field 2 happened 1/60th second after field 1 so they don't match up right with fast motion. This problem can be made less objectionable by vertical filtering.

3:2 pulldown:
Basically a special case of Weave. For Film material the original frames come from one picture, and are then "telecined" and stored as 59.94fps interlaced video (most DVDs). 3:2 pulldown takes weaves fields from the same frame together and displays them in a 3-2 pattern to 59.94fps from 23.97. This works great as long as fields from two different pictures aren't combined.

Woops, almost forgot Motion Adaptive Deinterlacing.
This is kind of the holy grail for PC playback, (most filters use the methods I listed above). What this does is look at what is happening on the screen and decides whether to Bob or Weave parts or all of the screen based on motion (or lack of). This is what Faroudja's DCDi does.
http://www.dcdi-video.com/technology/index.html
This is also why Dscaler is so well regarded.

Hopefully that helps.

Thanks to the folks at Secrets for their excellent article on progressive DVD playback (which I based my post on):
http://www.hometheaterhifi.com/volum...e-10-2000.html

There are two things I'm looking foreward to the should help further improve PQ from Sage. The first is nVidia's upcoming Forceware Multimedia which provides a post processor that is supposed to more inteligently detect film/video material.

The second is the OSD for the Xcard. The reason the Xcard would help improve PQ is that by using PDI to connect the Xcard to a compatible capture card you can use Dscaler's advanced features. It's important to note that there is a significant difference between Dscaler the app and the filter SageTV uses. The app can automatically detect film/video and automatically switch deinterlacing modes accordingly. It's always better to use film mode if possible since none of the picture has to be interpolated or "guessed." The dscaler filter Sage uses does not have the intelligence, it only uses a single video mode of your choice. From my experience running Dscaler (the app) a large portion of what we see on TV is film based, Dscaler would report on the order of 75% film while watching TV.

Another option for using the Xcard would be connecting it to a Holo3D via PDI. This would provide full HW decoding (would make some very happy) and, more importantly, deinterlacing ala Faroudja's DCDi.

Just to be clear, you should be able to use the Xcard/PDI with Sage right now, but it would not be an elegant solution until Sage supports its UI/OSD on the Xcard.

One more note, it should also be possible to mod a 350 to connect to a PDI card, I would try this myself if I could play DVDs via the 350.