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ivtc in virtualdub

Discussion in 'Video - Software discussion' started by davexnet, Oct 14, 2003.

  1. davexnet

    davexnet Active member

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    Hello - I've a fairly typical AVI, 29.97 fps, progressive, with 1 out of every 5
    frames repeated.
    I want to drop the repeated frame and reduce
    fps to 23.976.
    Seems like a simple thing, but I can't seem to do it using virtualdub *unless* you recompress the AVI and I don't want to do this.
    Surely there's a solution?
     
  2. Minion

    Minion Senior member

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    If your 29.97fps file is actually Progressive then you can not use IVTC, You can only use IVTC on Previously Teliclined Interlaced material...If this File was Converted to 29.97fps from 23.97fps By repeating every 4th Frame then you Can use V-Dub to convert it to 23.97fps without Re-compressing...First Set the "Video" to "Full stream Copy" and then under "Video" go to "Frame Rate" and under "Frame Rate conversion" check the "Convert To FPS" Box then Write "23.976fps" in the Box and Click "OK" now under "file" go to "save as AVI" and save the File...This will convert it to 23.976fps without re-compressing the File but do not try the 3:2 Pulldown Removal or IVTS Settings cuz they will not work when trying to work on Purely Progressive sources....Cheers
     
  3. davexnet

    davexnet Active member

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    Hello -
    I tried your method, it did produce a 23.976
    AVI, but it still contains many duplicate
    frames.
    It seems as if virtualdub dropped frames at
    random. Like this it's more jerky than the
    original.
    Dave
     
  4. Minion

    Minion Senior member

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    You might also try the Decimate Filter were you can choose what frames to drop....Why do you need to convert it to 23.97fps anyways??
     
  5. davexnet

    davexnet Active member

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    two reasons really, it saves space, if I want to save the AVI. If I want to crate an SVCD from it, you get far better results if the
    source is 23.976 with no duplicates.
    I could use ivtc in tmpgenc, but what if I
    want to use CCE or one of he others?
     
  6. Minion

    Minion Senior member

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    IVTC Will not work on Progressive Files and you did say that it was Fully Progressive didn"t you?? The reason it will not work is Because IVTC removes the Telicline from a file that was previously teleclined and if the File is Progressive then the File was Not teliclined in the first Place so there is nothing to remove..IVTC Rebuilds the Progressive Frames from the Teleclined Interlaced Frames but there is nothing to rebuild if all the Frames are Progressive...Like I said before if you use a Decimate Filter you can choose which Frames to drop to make up the target Frame Rate so you can set it to drop every 5th frame or whatever frames you believe are duplicates.....
     
  7. davexnet

    davexnet Active member

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    Oddly enough,the ivtc in Tmpgenc *does* work
    with progressive AVI's that have duplicate
    frames!
    It has a special setting called "24 fps
    non-interlaced source".
    This setting works perfectly, and does exactly
    what I'm trying to do.
    I would just like to find a way to do it
    AVI>AVI that's all.
     
  8. Minion

    Minion Senior member

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    Tmpgenc does output to AVI...Do your Settings then go to "File" to "Output to" "AVI" then choose your Codec setting and save the file....
     
  9. davexnet

    davexnet Active member

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    Thanks I didn't know that...
    but as I mentioned in the first post, I didn't
    want to recompress... I wanted the equivalent of a direct stream copy !

    Dave
     
  10. vurbal

    vurbal Administrator Staff Member

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    If you want to encode an actual telecined AVI with CCE, you can use AviSynth with the Decomb plugin. The script should look something like this (for AviSynth 2.5):

    LoadPlugin("decomb.dll")
    AVISource("film.avi")
    Telecide(order=1)
    Decimate(cycle=5)
    ConvertToYUY2()

    As Minion mentioned, if the video is progressive it is not telecined. If you want to simply remove every 5th frame, I believe you can eliminate the Telecide(order=1) line in the script and simply use Decimate.

    It may be that the AVI was made from a source with significant amounts of actual NTSC material, and was converted to pure progressive NTSC. If that's the case, you'll end up with jerky motion in places by just removing every 5th frame.
     
    Last edited: Oct 20, 2003
  11. davexnet

    davexnet Active member

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    Hello - thanks for the info re: avisynth.
    Does it run my opening it from virtualdub?
    Or is there another way?
    The avi source is 29.97 fps one repeated frame
    in every 5. It's progressive, not interlaced.

    This is quite a common occurrence isn't it?
    It is derived from capturing a true 29.97
    fps telecined source, but it's a low-res capture, just the top field.
    Dave
     
  12. Minion

    Minion Senior member

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    Virtual Dub has a Decimate Filter that you can use on it but you will probably still have to re-encode the file though...The File you have isn"t Teliclined cuz if it were some of the frames would be interlaced..Your file is Probably a DivX file or a XviD file isn"t it??Divx files usually output to Progressive Frames so it was Probably made from a 29.97fps Interlaced source or interlaced teliclined source but then encoded Useing the Divx codec which is why it is Progressive now..Many codecs output Progressive frames even when useing Interlaced sources one example is WMV/ASF....
     
  13. vurbal

    vurbal Administrator Staff Member

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    I'm not sure I understand the question. When you use AviSynth to frameserve, you load the script (whatever.avs) into your Vdub, instead of directly reading the original video file. If you mean, do the AviSynth filters get applied before sending the video to Vdub, the answer is yes. That's how I test my scripts for encoding captured video (actually I use VdubMod).
     
  14. davexnet

    davexnet Active member

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    Sorry about the typo -
    "Does it run my opening it from VirtualDub"
    should have been -
    "Does it run by opening it from VirtualDub"

    I'm a newbie at avisynth, but I have used it
    before, either opening the script from vdub
    or vdubmod. I assume that's the typical method
    of using it -

    regarding the AVI is question, yes, it is a
    divx, my guess is it was captured from a
    29.97 interlaced source but only a single
    field was captured - Thus, no interlaced
    frames in my avi, just a dupl. every 5.
    Also, I have a question about interlacing
    artifacts in a 25fps AVI.
    See this thread:
    http://virtualdub.everwicked.com/index.php?act=ST&f=4&t=4748&s=43af3f389df744d635ae36ec824f8ea9

    Thanks,
    Dave
    thanks,
    Dave

     

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