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  1. Member
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    topic.
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  2. Mod Neophyte redwudz's Avatar
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    Find a single frame with some horizontal movement like a arm waving and look for the interface lines. I use VirtualDub Mod for this.

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  3. Guest34343
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    That's not a definitive method. You may have progressive PAL that has a one-field phase shift, or you may have 3:2 pulled down material. Both will show combing using your test, but the content is progressive and the progressive frames can be recovered.

    One definitive way is to separate the fields using (say) Avisynth and then step through them one-by-one in a motion sequence. If you see successive pairs of fields that are from the same picture (same instant of time), that is progressive. If there is a new picture for each field, that is interlaced. If you see a repeating pattern of 3 fields from one picture followed by 2 fields from another picture, then you have 3:2 pulled down material.

    There are other pathological cases, such as blended fields, but my point remains -- you have to examine the individual fields. If you apply a deinterlacer based on results of the naive test given by redwudz, you will be needlessly sacrificing quality if you have field-shifted PAL or 3:2 pulldown.
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  4. VirtaulDubMod (unlike VirtualDubMPEG2) doesn't perform the 3:2 pulldown when viewing MPEG files marked for 3:2 pulldown. That is, VirtualDubMod will indicate the video is 23.976 frames per second and will not show any interlaced frames. VirutualDubMPEG2, on the other hand, will indicate that the file is 29.97 frames per second and you will see the typical 3/2 pattern of progressive frames and interlaced frames.

    I assume VirtaulDubMod would do the same for progressive PAL with a field phase shift. And if the frames are actually encoded with the phase shift then you'll have to treat the video as interlaced unless you know how to undo the phase shift -- the same way you have to treat movies recorded off broadcast SDTV as interlaced unless you inverse telecine them.

    In short, VirtualDubMod is a very good tool for detecting interlace video.
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  5. Guest34343
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    Originally Posted by junkmalle
    I assume VirtaulDubMod would do the same for progressive PAL with a field phase shift.
    No, that's incorrect.

    In short, VirtualDubMod is a very good tool for detecting interlace video.
    You contradict yourself. You were wrong about the phase shift handling, and you said it doesn't honor repeat flags, which makes it impossible to identify 3:2 pulldown. Both of these points argue against VDubMod for this purpose.

    Do as I suggested: separate fields and then step through them.

    BTW, to correct the PAL phase shift, use any good field matcher, such as Telecide() or TFM().
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  6. Member
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    I just found this program, DVD2AVI.
    It indicates if the source is interlaced or progressive.
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  7. Member dipstick's Avatar
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    DVD2AVI gets it's information from the Mpeg header. You can also use Bitrate Viewer and Restream to get the same info.

    neuron2's method of splitting the fields is much more accurate. Using that method proves that the DV-AVI from my Camcorder shot in "Frame Mode" is indeed Progressive 30 fps. In reallity, it is really stored as interlaced on tape(just like 24p), but both fields are captured in the same time instance and can be encoded as 30p.
    I stand up next a mountain and chop it down with the ledge of my hand........ I'm a Voodoo child.... Jimi Hendrix,
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