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  1. If you're skeptical of the software's ability to exceed the quality of a conventional capture setup, here are a few examples comparing the same tape played on a VCR vs. decoded with vhs-decode. The VCR captures are straight from my capture box unprocessed, the raw MPG file, without modifications. The vhs-decode results are straight from the NTSC generation script, the raw MKV file, without modifications. This example is Disney World Orlando Magic Kingdom, 1995. Here are the video files as well:

    https://www.mediafire.com/file/415tzi5p5r35nl4/VCR+decode.mkv/file
    https://www.mediafire.com/file/ky0dne5wjmc2573/vhs-decode.mkv/file

    Scene 1

    VCR:



    vhs-decode:



    Observations:

    Picture is sharper on vhs-decode, bringing out detail in leaves, foliage, and rocks in the background. The vhs-decode sharpness level (-sl) filter was not used. VCR source is overdriven, causing the sky to wash out detail in the foliage. Brightness is better on VCR source, but this is due to processing by the VCR. vhs-decode appears to have more overall contrast. Very slight crosshatch pattern on vhs-decode result in the blue stripes on the canopy, but the VCR source has horizontal stripes. The horizontal stripes are verified to be on the tape itself, as vhs-decode exhibits them in other scenes. Likely noise generated by the camera at time of recording.

    Scene 2

    VCR:



    vhs-decode:



    Observations:

    More color bleed in the red shirts on the VCR source. This mostly due to pixelation on the peoples' shoulders caused by a low chroma subsampling resoution. Can be avoided with better capture equipment, but some smearing is also caused by the composite video coming from the VCR as well. Faint horizontal lines in the sky are present in both sources, but on the VCR source this triggers the chroma slightly resulting in alternating pink and green bars. On the white shirts, the overdriven brightness hides details such as wrinkles. This may be due to poor de-emphasis from the VCR.

    Scene 3

    VCR:



    vhs-decode:



    Observations:

    This scene demonstrates several advantages for vhs-decode. The castle building on the left has almost no detail due to noise reduction done by the VCR. Detail in the walls and shingles on the castle roof are restored using vhs-decode. The excessive brightness discussed earlier makes the thin outlines in the white canopy to the right mostly invisible. vhs-decode shows this detail. The points of light representing the lamps on the merry-go-round are sharper and smaller on the vhs-decode source. The bricks under the planters in front of the merry-go-round lose all detail with the VCR source. With vhs-decode, the lines in the bricks and texture are present. Again, color bleed on the back of the woman's red dress is minimized with vhs-decode. For the dropout correction, there are red and yellow lines on the VCR source. vhs-decode does not have this issue. Dropout correction by the VCR is not robust enough to prevent sync pulse corruption and the image skips around as a result. The software decoded video does not lose sync.
    Last edited by Titan_91; 28th Aug 2021 at 18:40.
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  2. Member
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    Originally Posted by Titan_91 View Post
    Thanks. Correct, I tried just copying the folder but I got errors for avisynth.dll. So I started over, installed a clean 64-bit Wine prefix, installed AviSynth+, installed AvsPmod, and merged your plugins folders with mine (adding the files I didn't have, but not overwriting the files I already had). I can use the below script to import a file and load QTGMC:

    Code:
    FFVideoSource("beastwars.mkv")
    QTGMC( Preset="fast" )
    But I get:

    Code:
    I don't know what 'AvsPlusVersionNumber' means.
    (C:/Program Files (x86)/AviSynth+/plugins+/QTGMC.avsi, line 231)
    (New File, line 2)
    Which is where I was stuck at before. Evidently that's a very common issue. This guy had to use the 32-bit plus version from GitHub to get his filters working.

    http://www.digitalfaq.com/forum/video-restore/11042-qtgmc-avisynth-installed.html
    It's actually possible to run QTGMC natively on linux with Vapoursynth. QTGMC is included in the havsfunc plugin so you'll need to install that first. A basic script would look something like this:

    Code:
    from vapoursynth import core
    import havsfunc as haf
    
    clip = core.lsmas.LWLibavSource(source='source.mkv')
    clip = haf.QTGMC(clip, Preset='Fast', TFF=True)
    clip.set_output()
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  3. Capturing Memories dellsam34's Avatar
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    It depends on what method of conventional capture workflow you use and the quality of the VCR, I would say that with the current limitations of the VHS-decode I can fairly say that I can produce better results with the hardware I have, But since I don't have any setup for VHS-decode to compare it to side by side I cannot backup this bold claim unless someone willing to send me the same tape.
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  4. Formerly 'vaporeon800' Brad's Avatar
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    I'm getting inconsistent & confusing noise floors with cxadc captures. Please see the update at the bottom of my previous post.
    (Formerly vaporeon800)
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  5. Formerly 'vaporeon800' Brad's Avatar
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    Last night on Discord, I posted these preliminary screenshot comparisons of hardware low-pass filters.

    Mini-Circuits BLP-10.7+ (cutoff frequency = 14 MHz)
    Mini-Circuits BLP-5+ (cutoff frequency = 6 MHz)

    BLP-10.7+ vs BLP-5+
    https://imgsli.com/NjkxMjE
    https://imgsli.com/NjkxMjE/2/3
    https://imgsli.com/NjkxMjE/4/5
    https://imgsli.com/NjkxMjE/6/7

    Note for other international buyers: the cheapest shipping option their site showed was $87. Using the contact form at the bottom of the item page, shipping estimate was $35. I placed the order via email, and the invoice said $26 once it was actually shipped.
    (Formerly vaporeon800)
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  6. The 10.7+ filter recovers a little more detail. I believe that's the same one I'm using actually and is the one I settled on.
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  7. Formerly 'vaporeon800' Brad's Avatar
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    Here are clips from a capture of one of my worst tapes. This is from a summer animation program I took part in as a kid. As I recall, the machine could somehow be set to record 1, 2, 3, etc. individual frames at a time to VHS. This constant start/stop would be a chaotic signal even if this was the 1st-gen recording. I believe what we were given is 3rd-gen.

    I didn't think YouTube would handle this comparison quite so poorly.

    Image Attached Files
    (Formerly vaporeon800)
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  8. Good example! I also have some time shifted recordings from an old security VCR. These do not sync properly when playing back to a CRT TV. Might be a tracking issue. I'll try and find the tape.
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  9. Capturing Memories dellsam34's Avatar
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    The DCR-TRV340 is the most stable capture and vhs-decode being the worst, But chroma wise the DCR is the worst due to DV compression maybe?
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  10. It could be DV compression in part, though the ADV may have a more advanced chroma decoder than the DCR too, though I don't know to what degree that comes into play with Y/C as opposed to composite. Chroma seems more stable/less flickery in vhs-decode though even when it's unstable vertically, maybe the fact that it's tbced before upconversion makes a difference the video quite wiggly, idk.

    Also, forgot to mention earlier, but I have a first decode of a PAL Betamax capture. This is with standard VHS settings so it won't really look right yet and chroma won't work since it's a bit different on beta. I haven't done any further work on it yet as I haven't found the technical details (frequencies, color encoding, emphasis etc) for PAL Betamax yet. (The dropout is on the tape, doc was not turned on in vhs-decode.)

    Click image for larger version

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  11. Sorry for a random question during all of this: Has anyone tapped RF on an AG1980? I'd like to start messing around with this on one of my Panasonic decks. Apologies if this has already been discussed, would love a link if so.

    Amazed at all this work and want to say thanks to everyone for their effort!
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  12. Formerly 'vaporeon800' Brad's Avatar
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    Why not start with a less-complex VCR? I think to access the test point you have to flip up the circuit board. Also, if either of my AG-1980 units was working at full-quality, I personally wouldn't want to risk messing them up somehow.
    (Formerly vaporeon800)
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