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looking for a guide that has some better info on IVTC

Discussion in 'DivX / XviD' started by mux, Feb 10, 2005.

  1. mux

    mux Member

    Sep 12, 2003
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    I'm looking for a good guide to using dvd2avi. One that give better explanation for NTSC, FILM and when to use options like inverse telecine later in the process.

    From what I've read if your source is FILM, set dvd2avi to force film and you're ok there.

    If your source is NTSC or FILM at less than 90% then the video option should be none, but then you must run it through inverse telecine later.

    Why? I know IVTC will take it from 29fps back to 23fps.

    Why is this needed?

    If the source is NTSC and 29fps and I just leave it at 29fps when I encode it to xvid or divx, then IVTC is not needed. Right?

    What is the point to reduce it from 29fps to 23fps? If the source is 29fps on the DVD why reduce it to 23fps in an encoding? What is the advantage? It seems like you are asking for audio/video sync problems by doing this. I seem to be missing the advantage here.

    I've tried some NTSC video. Encoded it at the 29fps like it is on the DVD and I've done the exact same video and run it through inverse telecine to reduce it to 23fps. I don't see the difference during playback between the two files. One is 29fps and the other is 23fps and they both look good and play good.

    That's what I would like explained better. Is this needed for some reason I don't see? Or is this just personal preference?

    Why not just force film on an NTSC video and reduce it to 23fps that way? Or is the IVTC process better at the frame reduction?

    Any help with these questions, or a guide with a lot of good explanations would be great.

  2. Kingd

    Kingd Guest

    It's rather simple Mux, less frames means less video to encode which means better quality. Also interlacing can be a problem which Inverse Telecining can take care of by removing those interlaced frames (jagged edge). On Tv you don't notice, but when you watch on a monitor, it's easy to see the horizontal lines that appear in the picture and can become annoying. Sometimes most frames are interlaced so telecining does not fix that and you must deinterlace instead. This can get complicated but here's a good explanation:

    As for your question, according to this guide, your right in that force filming is the way to go but Force Film is not 100% effective unless it truly shows at 100% FILM by dvd2avi. It becomes less and less accurate as the percentage drops and therefore using IVTC becomes a better option because that analyzes every frame whereas Force Film is simple and usually fails when a film shows 95% or lower. Again, the real problem then becomes whether or not you need to IVTC or deinterlace and that can be tricky.

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