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  1. HI all,

    Apologies if this should be in newbies instead, I couldn't decide.

    I wondered what were the differences between using Virtualdub's inbuilt "Deinterlace filter" and QTGMC with Avisynth please?

    My source is PAL VHS and i'm only after reasonable output for my parents not videophile quality.

    What i've currently done is capture the vhs using Virtualdub to a lossless AVI.

    General
    Complete name : D:\9thJan2018.avi
    Format : AVI
    Format/Info : Audio Video Interleave
    Format profile : OpenDML
    File size : 35.3 GiB
    Duration : 49mn 5s
    Overall bit rate : 103 Mbps

    Video
    ID : 0
    Format : YUV
    Codec ID : UYVY
    Codec ID/Info : Uncompressed 16bpp. YUV 4:2:2 (Y sample at every pixel, U and V sampled at every second pixel horizontally on each line). A macropixel contains 2 pixels in 1 u_int32.
    Duration : 49mn 5s
    Bit rate : 102 Mbps
    Width : 720 pixels
    Height : 480 pixels
    Display aspect ratio : 3:2
    Frame rate : 29.970 fps
    Standard : NTSC
    Color space : YUV
    Chroma subsampling : 4:2:2
    Compression mode : Lossless
    Bits/(Pixel*Frame) : 9.849
    Stream size : 35.0 GiB (99%)

    Audio
    ID : 1
    Format : PCM
    Format settings, Endianness : Little
    Format settings, Sign : Signed
    Codec ID : 1
    Duration : 26mn 23s
    Bit rate mode : Constant
    Bit rate : 1 536 Kbps
    Channel(s) : 2 channels
    Sampling rate : 48.0 KHz
    Bit depth : 16 bits
    Stream size : 290 MiB (1%)
    Alignment : Aligned on interleaves
    Interleave, duration : 43 ms (1.28 video frame)
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  2. Member Bernix's Avatar
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    QTGMC as I understand is high end quality deinterlacer. Virtualdub is using default blending method as deinterlacer. So VD filter is very fast at cost of quality. You lost lots of information from source. On other hand QTGMC is superb quality at cost of speed. But since your source is VHS and you are not videophile , VD filter should be sufficient
    BTW your source seems more likely NTSC than PAL 720x480 and fps at 29,970 seems like NTSC.

    Bernix
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  3. Thanks for the reply

    I have no idea why it says it's 29.970fps, it is definitely PAL unless something very strange has gone on, i've never bought any videos outside of the UK

    It is those compact VHS though if that makes a difference?!

    I must admit i'm trying a virtualdub inbuilt filter now and it's going to take 1.5hours! Longer than I thought it'd be! Plus it will rise from 60GB to 80GB!!
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  4. Member Bernix's Avatar
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    I bet it is done during capturing. Recheck your capture settings in virtualdub. Also Pal has 576 rows not 480.
    EDIT:
    I must admit i'm trying a virtualdub inbuilt filter now and it's going to take 1.5hours! Longer than I thought it'd be!
    So QTGMC seems useless for you because of speed.

    Bernix
    Last edited by Bernix; 9th Jan 2018 at 13:59. Reason: EDIT
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  5. Use yadif - probably unbeatable when speed and quality must match. AFAIR there should be yadif filter for virtualdub.
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  6. Yadif has been included in VirtualDub's internal Deinterlace filter for several years now.

    Click image for larger version

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    It's usually the best option in VirtualDub. AviSynth's QTGMC is better, but much slower.
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  7. Originally Posted by jagabo View Post
    Yadif has been included in VirtualDub's internal Deinterlace filter for several years now.

    Image
    [Attachment 44357 - Click to enlarge]


    It's usually the best option in VirtualDub. AviSynth's QTGMC is better, but much slower.
    thanks! I actually already used that one without realising
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  8. Member Bernix's Avatar
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    As I talked about loss of information I meant a blend. If you don't need quality, once watch then delete, it can speed up a process. But I feel now everybody will cast stones at me.
    Once watch delete isn't worth do deinterlacing of VHS probably

    Bernix
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  9. Video Restorer lordsmurf's Avatar
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    I wish QTGMC would be imported to VirtualDub.
    I'm curious why it has not.
    I've have thought for sure VirtualDub Filter Mod would have included it.
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  10. QTGMC is not a deinterlace filter, it's a deinterlacing script, big difference. at the ultrafast and superfast presets it uses Yadif for deinterlacing. Personally, I always thought QTGMC was over-rated, it automates some of the analysis and processing but in all honesty if one were motivated enough there's no reason why they couldn't accomplish the same thing by manually choosing a filter chain.
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  11. Video Restorer lordsmurf's Avatar
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    True, QTGMC is a script, but I'd still think it would be possible to make that a background process/task. Sort of how calling QTGMC is essentially hidden in Avisynth with a single line.

    Yadif + good anti-aliasing would be next best solution. But no AA in VirtualDub either. Again, we have the script santiag in Avisynth, based on NNEDI3.

    VirtualDub just doesn't have anything good. Yadif is behind the times on quality.

    I'd never use QTGMC beyond faster, preferring slow in most cases.

    Avisynth+ x64 and VirtualDub FM x64 is a nice combo for speed on QTGMC. 2x-3x realtime isn't bad (ie 1 hour of footage take 20-30 minutes to deinterlace). I started to do that not long ago, huge speed boost.
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  12. A while ago I actually tried to understand what QTGMC is: my impression was "too many dependencies / non-trivial to port". Maybe I was wrong or looked at wrong thing?
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  13. Yes, it's a script that relies on a number of AviSynth plugins (which in turn may have additional dependencies). I don't know how difficult it would be to port but the VapourSynth guys did it so it's not impossible. (Maybe the VapourSynth version would even be a better starting point as they probably rewrote or cleaned a lot of stuff during porting.)
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