A Brief Look at De-Interlacing Modes

The process of taking interlaced content and displaying it in a non-interlaced form is often referred to as de-interlacing (for obvious reasons). There are two basic methods of de-interlacing, commonly known as "bob" and "weave."

Bob de-interlacing is more technically referred to as linear interpolation and it simply fills in the missing lines of resolution by interpolating between the resolution lines that are available. This interpolation form of de-interlacing is particularly useful if there are a lot of solid colors on the screen and if the decoder screws up and decides to combine two fields from different frames.

Weave de-interlacing, as the name implies, simply combines alternating lines of resolution from two separate interlaced fields. Using either method individually is generally not the best way of doing things, but thanks to the decent amount of power in today's PCs more sophisticated algorithms can be implemented to dynamically switch between bob and weave on a per pixel basis within a frame (usually referred to as adaptive per pixel de-interlacing).

NVIDIA's PureVideo supposedly takes adaptive per pixel de-interlacing one step further with what they call Spatial-Temporal de-interlacing. The idea here is that normal per pixel adaptive de-interlacing uses data from fields within a single frame to essentially fill in the blanks. NVIDIA's Spatial-Temporal de-interlacing can use data from fields in other frames to improve de-interlacing quality. We'll have to see if this ends up improving quality or not in our tests later in the article.

Frame Rate Conversion and You NVIDIA's PureVideo Driver and Encoder


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  • phusg - Tuesday, March 1, 2005 - link

    Has anyone found a 6600GT card manufacturer that bundles nvDVD including the DVD decoder yet? Reply
  • akozak - Tuesday, January 4, 2005 - link

    Hey Anand,

    Don't mean to poo-poo on your hardwork - but almost all of your images are using different frames.

    a) Galaxy Quest - differences in star placements, planet alignment

    b) Apollo 13 - head is shifted b/w images

    c) Friends - characters shift - legs are different locations etc

    In fact the only ones that look like they are the same frame show no differences.

    Have you looked at the difference in frames? If you took one frame before or one frame after on one card, would it match up to the other card's image you already have?

  • b3roldan - Friday, December 31, 2004 - link

    hi, I'm using a vanilla 6800 from inno3d w/ Forceware 66.93.

    I was just wonderin if you guys were also experiencing problems I've had with these games or if t'was just me.

    Metal Gear Solid 2: Substance
    - Everything's black and white. Wondering if it has anything to do with nvidia's 0x32 Z stencil (shadowing technology).

    - Walls are multi-colored, sometimes transparent

    I've just upgraded from a 9800PRO 128mb, which worked pretty well with these games.

    Just wonderin if there are others with the same prob... thx :)
  • Gatak - Thursday, December 23, 2004 - link

    What nvidia or ATi ought to do is to prove a simplier interface and especially much better documentation on how to access the hardware directly.

    The GPU's are incredibly fast for lots of things. For example it would indeed be possible to do video encoding, photo manipulation effects (Apple core.image/video!) or even sound compression.
  • jago25 - Thursday, December 23, 2004 - link

    Shame I'll never be able to use it..seeing as I don't use Windows.

    You can use a GPU to do anything. Might be a good idea to make it easier to do so rather than having to develop more codecs as that's a never ending job.
  • hellokeith - Wednesday, December 22, 2004 - link

    The article really needs to be corrected per the 6800 PCI Express vs 6800 AGP. People are talking about this on numerous HTPC/AVS forums and being mislead. Only the PCI Express 6800 has the new silicon. Reply
  • karlreading - Wednesday, December 22, 2004 - link

    ive jumped through the other pages from a comment on page one, so if this has already been answered, lynch me now:
    anand said he knows of no manufacturer that bundles nv DVD.
    im pretty sure its on my bfg disc that came with me 6800GT OC ;)
    thats me sorted then.
  • mikepers - Wednesday, December 22, 2004 - link

    This should help:


    There's a link for the correct driver and the decoder and at the bottom a link which shows which cards support what. Sort of sucks that my AGP 6800 Ultra has less features then a 6600 card but it is what it is...
  • CrystalBay - Tuesday, December 21, 2004 - link

    Remember Buy.com ? Where are you Harvey!!!! Reply
  • tfranzese - Tuesday, December 21, 2004 - link

    mcveigh, he provided the link to where you could find that for the ATi side of things. I'm curious about the S3 things, though it wouldn't surprise me if true. Reply

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