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  1. I have a DVD-Video from a magic set. It's a low production item. I extracted the VOB files, changed the container to MPEG2, and dropped into MediaInfo. It identifies the scan type as progressive. However, jaggies/steps/aliasingis visible in the video.

    In Hybrid, I went to Filtering--Vapoursynth--Line--AntiAliasing and selected Santiag. That seems to have fixed the jaggies/steps/aliasing issue.

    Is that the only solution for a DVD with jaggies/steps/aliasing due to these artifacts being hard-coded into the progressive file?

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    [Attachment 84973 - Click to enlarge]
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  2. Member
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    Cut a small sample from the mpg and post it here for analysis
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  3. That's interlaced video. I should be inverse telecined or deinterlaced, not antialiased.
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  4. try overriding the input scan type and if that does not help share a sample,..
    users currently on my ignore list: deadrats, Stears555, marcorocchini
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  5. UPDATE WITH NEW INFO

    1. I put the MPEG2 file into Hybrid and pressed the Analyze button (ie, the magnifying glass icon at Filtering--Deinterlace/Telecine). Hybrid identified the Input Scan Type as Bottom Field First.

    2. I cut a 33-second section of the MPEG2 file without processing using Mpg2Cut2. According to MediaInfo, this new MPEG2 file has a Scan Order of Bottom Field First. So that means that MediaInfo did not correctly identity the Scan Order of the original full MPEG2 file.

    3. I played the 33-second section of the MPEG2 file in VLC (and turned off Deinterlacing in VLC). One can clearly see the jaggies.

    4. In Hybrid, I added the 33-second section of the MPEG2 file. I applied Vapoursynth QTGMC BFF BOB. In the Vapoursynth preview (see attached) the Original does not show the jaggies. This was unexpected as one can see the jaggies when the video is played in the VLC player.

    5. I then exported the 33-second section of the MPEG2 file as an x264/MP4 file.

    6. I played the MP4 file in VLC (and turned off Deinterlacing in VLC) and there are no more jaggies.

    Conclusion
    a. MediaInfo didn't give me the correct Scan Order information. So always get a second opinion. In this case, use the Hybrid tool to check Scan Order.
    b. I don't understand why the Hybrid preview doesn't show the original video with jaggies, even though I confirmed they jaggies are present in VLC.
    c. The jaggies were not hard-coded into the MPEG2 file as I originally thought. Instead, they appeared because the video was interlaced. Once I entered the correct Input Scan Type in Hybrid, QTGMC deinterlaced properly.
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  6. The "MPEG2_from_DVD ..." is interlaced, bottom field first.

    Interlaced flags mean nothing. The only way to know for sure whether a video is interlaced or telecined, and also to know whether it is bottom or top field first (for interlaced video) is to separate it into fields using either "separatefields()" or a bob filter with the appropriate settings. I always use separatefields() because you can't screw it up, and I always screw things up.

    So the video is exactly what one would expect. Nothing is "hard coded," and all you have to do is treat it as interlaced, bottom field first. You can leave it like that and proceed with whatever it is you want to do or, if you plan to do things which involve re-sizing or certain temporal operations, you should probably deinterlace it first. Do NOT perform inverse telecine because this is just simple video.
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  7. As commented by johnmeyer.
    A basic script for deinterlacing using QTGMC:
    Code:
    ffms2("MPEG2_from_DVD_input_scan_progressive_jaggies.MPG")
    AssumeBFF()
    QTGMC()
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  8. Captures & Restoration lollo's Avatar
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    Interlaced flags mean nothing. The only way to know for sure whether a video is interlaced or telecined, and also to know whether it is bottom or top field first (for interlaced video) is to separate it into fields using either "separatefields()" or a bob filter with the appropriate settings. I always use separatefields() because you can't screw it up, and I always screw things up.
    Yes, people should stop to use MediaInfo report or similar to understand the video architecture. It is just a flags reader (and the flags can be wrong), not a video analyzer!

    AviSynth with SeparateFields() is the way to go, for both assessing field order (TFF or BFF) and the source of the video (interlaced, telecine, etc.).
    The details here: https://web.archive.org/web/20140703141744/http://neuron2.net/faq.html (we posted it many times!)
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    I cut a 33-second section of the MPEG2 file without processing using Mpg2Cut2. According to MediaInfo, this new MPEG2 file has a Scan Order of Bottom Field First. So that means that MediaInfo did not correctly identity the Scan Order of the original full MPEG2 file.
    Something fishy going on here. It doesn't seem logical that a full MPEG would report Prog but a simple snip would then report BFF.

    This was unexpected as one can see the jaggies when the video is played in the VLC player.
    VLC player's deinterlacing is flaky IMO. If the VLC deinterlacer is forced ON, the jaggies would probably be gone.
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  10. Lollo, thanks for the link to that FAQ. I'm sure it's been around forever, but I could have saved a lot of time over the years by simply providing that link.

    As for Alwyn's commend about VLC's deinterlacing, I have had the same experience with its "auto" setting. You have to force it to "on" and then you need to choose a deinterlacer that will work. Even though the more advanced options probably produce a better result, the "dumber" deinterlacers (like blend or bob) are probably better for testing whether the jaggies are caused by interlacing or by some hard-coded spatial problem.
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  11. Just to clarify one minor point. I specifically turned off and then on the de-interlace function on VLC in order to visually confirm whether the jaggies disappeared with the function turned on.
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    I use VDub to analyse interlacing. You can use an AVISynth script as Lollo's link describes, however I find using VDub easier.

    First, you can use the left and right arrow keys to analyse each frame for interlacing (harder to do that it VLC because there is no "back one frame" key, only forward - E)).

    Second, if you set up the Deinterlace filter to Double Frame Rate, you can easily see each field in full screen to assess the file status eg TFF, BFF, PSF, Progressive.
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    Originally Posted by johnmeyer View Post
    Lollo, thanks for the link to that FAQ. I'm sure it's been around forever, but I could have saved a lot of time over the years by simply providing that link.

    As for Alwyn's commend about VLC's deinterlacing, I have had the same experience with its "auto" setting. You have to force it to "on" and then you need to choose a deinterlacer that will work. Even though the more advanced options probably produce a better result, the "dumber" deinterlacers (like blend or bob) are probably better for testing whether the jaggies are caused by interlacing or by some hard-coded spatial problem.
    For this reason I gave up on VLC a long time ago in favor of MPC-BE or MPC-HC. There deinterlace simply works, and it has frame advance and rewind.
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