What kind of deinterlacing are you using for TV out?

[mlbdude]

For those that output to a standard definition TV I am curious what kind of deinterlacing you are using and what experiences you have had.

I go back and forth between DXVA (hardware) with either the Sonic or Intervideo decoders and Elecard\DScaler\VideoWeave myself. Can't seem to make up my mind. My goal is to find the smoothest fast motion playback as I possibly can.

What kind of deinterlacing has worked best for you?

[nielm]

(see also http://100fps.com, although this site is mainly geared towards displaying on a non-interlaced display, ie a computer monitor )
Note: I am in PAL 25fps land, replace 25 and 50 with 30 and 60 for NTSC...

As a TV is an interlaced display, there should be no need for complex deinterlacing...

In theory, with a interlaced source video and an interlaced display (TV), simply displaying both fields interleaved in the frame and displaying the result at 25fpd ('Weave' deinterlace) should mean that each line in the source field (half-frame) should be mapped to a the corresponding line on the display, so there would be no need to deinterlace...

In practice, this does not happen, for various reasons including resizing due to the number of VGA display lines not being the same as source video size and underscan/overscan - so that the video lines do not map 1-1 to the TV lines, and poor TV-out chips that just do not generate a good interlaced output.

I don't see why this should be the case, after all DVD players can display interlaced video on a TC, Digital camcorders can also, so why not PC's

Apparantly the PVR-350 and Xcards do handle this correctly, which is why video looks so good with these cards...


So, backup plan should be therefore that doubling the lines in each field and displaying these doubled fields at twice the normal frame rate ('Bob deinterlacing'). The TV-out chip should then generate a 50 field per second interlaced output from this, and it should mean that each line in each source field will eventually be mapped to a single line on the display (some experimentation with odd-field-first and even-field-first may be necessary)...

In practice, this needs a graphics card with a TV-out chip that correctly handles double-frame-rate 50fps input video.. Some dont, and end up blending the 2 50fps images into 1 25fps image, giving a blended effect...


So, in theory 'Bob' type deinterlacing should give better results than 'weave' type... More advanced delinterlacing should not give any better results, and may even give worse results when viewing non-interlaced input (eg movies broadcast in PAL land are not interlaced)

My current settings (Cyberlink PowerDVD) are 'Bob'... Gives slightly better results than 'Weave', but I still get combing effects with smooth camera pans...

[mlbdude]

Thanks nielm, yeah I was aware of the "should not have to" but end up having to thing already. I have tried no deinterlacing with several TV's and a couple of different output boards (nVidia and ATI) and it seems that most of the scan lines are removed but not all. Also, fast motion is not handled well at all.

This is interesting about Bob deinterlacing though - I will mess around with that and see if I like it. Thanks for the informative response.

Supposedly the Matrox cards offer a DVDMax feature that actually outputs everything correctly so that it displays perfect like the 350 and XCard. Have not seen it myself.

P.S. anyone that wants to know the details of interlacing check out the site neilm posted. That is a great resource on the subject.