Quantcast Potential issues with VHS capture - digitalFAQ Forum
  #1  
10-07-2018, 04:32 AM
editor editor is offline
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Hi all,

I am involved in a project requiring the capture, restoration and editing of some PAL VHS tapes.

I have 4 VHS tapes that run about 2 hours each, and which I have had a colleague of mine recently convert into ProResLT .mov (native PAL resolution, interlaced).

From what I understand, the pathway was a JVC high end VHS deck, using S-video connection into a Datavideo frame sync and then S-Video into a Matrox card and then using some software called InstaCapture on a PC to record the 720 x 576 capture.

From these raw captures, I intend to render out h264 mp4 files (interlacing intact) and send them to the good folks here at digitalfaq to process (minimise chroma noise, lines and other VHS artefacts..)

(I need to send files via web, as I live outside of the US, hence needing to make the files smaller for web transfer).

I have reason to believe that this test render I have done is not quite right, and was hoping to get a second opinion from a forum member here.

Please see file attached.

Thanks in advance for your time.


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File Type: mp4 test.mp4 (4.50 MB, 13 downloads)
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  #2  
10-07-2018, 05:56 AM
Eric-Jan Eric-Jan is offline
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The VCR used for this capture added some "ghosting" the bright white rim you see on the contour on the right of the players,
but, overall the picture is a bit on the dark side, (gamma correction?)i guess some of it can be corrected @digitalfaq, or you could try it yourself with Davinci Resolve which is mainly a color correcting/grading video editor, which i find a joy to work with, the easy way is to pipet the white and black levels in a frame, you can fine adjust these leves aslo if needed.
The ghosting effect lies not in my field to adjust, you should ask others for that, i would try to capture this on a different vcr i have, or make an other setup with another vcr and use another vcr/dvr as passthrough, my JVC vcr has more unwanted effects than my Pannasonic or Sony vcr, could it be captured again with a different setup ? that will save some time, in post.

btw i use also ProRes422 LT and have no problems with that, others might not agree to that, but judge that for yourself.
(better keep it in ProRes before sending it to DigitalFaq, ProRes is a edit codec, the final result can then be rendered in MP4 codec)

Last edited by Eric-Jan; 10-07-2018 at 06:09 AM.
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10-07-2018, 06:08 AM
hodgey hodgey is offline
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Doing processing on after lossy encoding is really not ideal, but if you have don't have any other option, there are at least some settings that should be different. I don't know what encoder you use, so I'm just going to use general terms. Maybe a better alternative is to ask for help with some avisynth scripts which you can then run on the video yourself.

The test click is encoded as progressive from what I can see, which you don't want. The encoder will be more efficient if it knows the material is interlaced. Additionally the colour data is by default stored at half of both the vertical and horizontal resolution of the brightness7luminance data, so if the encoder thinks the data is progressive, it's going to serously mess up the colour data when resizing.

You would probably also want to encode with 4:2:2 chroma subsampling (e.g only halving the colour data in the horizontal direction) to avoid further data loss.

The bitrate ought to be way higher, and ideally, use CRF( constant rate factor) mode rather than a set bitrate, this mode will try to keep a set quality level so noisy scenes will get sufficient bitrate.

You may also want to consider h.265 here, as it's a bit more efficient than h.264 if you can live with longer encoding time.

Quote:
The VCR used for this capture added some "ghosting" the bright white rim you see on the contour on the right of the players,
You sure that is "ghosting", it looks more like oversharpening haloes/artifacts to me, which the Panasonic decks are worse at than JVCs, at least in my experience.
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10-07-2018, 06:36 AM
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Quote:
Originally Posted by hodgey View Post

The test click is encoded as progressive from what I can see, which you don't want. The encoder will be more efficient if it knows the material is interlaced.
I used Pavtube HD Converter to transcode from Prores .mov to h264 mp4. I definitely did not have 'deinterlacing' selected. Why has it made the file progressive?

I have heard this software is not the best..seems this is yet another reason to steer clear of it.
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10-07-2018, 06:45 AM
Eric-Jan Eric-Jan is offline
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Quote:
Originally Posted by hodgey View Post
You sure that is "ghosting", it looks more like oversharpening haloes/artifacts to me, which the Panasonic decks are worse at than JVCs, at least in my experience.
sorry for that, i'll keep it at VHS artifact then, strange because my Panasonic doesn't have this effect, and my S-VHS JVC does, maybe my JVC should be serviced.....
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10-07-2018, 07:04 AM
hodgey hodgey is offline
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Quote:
Originally Posted by editor View Post
I used Pavtube HD Converter to transcode from Prores .mov to h264 mp4. I definitely did not have 'deinterlacing' selected. Why has it made the file progressive?

I have heard this software is not the best..seems this is yet another reason to steer clear of it.
The software may not know that the original material is interlaced. Prores does seem to support interlaced encoding, but I don't know if the software will take that into consideration, and I don't know whether the original file is marked as interlaced either. I have no idea whether this software supports encoding interlaced h.264, it's not the most common use case these days.

EDIT:
Quote:
sorry for that, i'll keep it at VHS artifact then,
Actually, you might be right that it's more of a ghosting artifact. It's a bit hard to tell based on a compressed image. It could be caused by a number of things, including the compression and VCR, or it could be embedded on the tape, it's hard to say, we'll see what others here think I guess.

Last edited by hodgey; 10-07-2018 at 07:18 AM.
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  #7  
10-07-2018, 11:01 AM
sanlyn sanlyn is offline
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Agreed with all comments. There are signs of oversharpening, including edge halos, as well as mosquito noise, lack of fine detail and texture, and high-compression detail loss. Overall y-levels exceed 16-235, with some dense blacks and thick shadow with no detail. Chroma is oversaturated when YUV goes to RGB. There is ghosting on the red letters in the background and chroma ghosting on figures during motion when any deinterlacer is used (I used QTGMC and yadif), so encoding interlaced video as progressive didn't help at all. Lossy h264 for restoration and repair isn't really suitable, and the low bitrate makes it even less so.

Overall the low detail, oversharpening, edge noise, and other problems make this look almost like a dim second generation tape dub. Or else the original VHS was in poor shape from the beginning.
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  #8  
10-07-2018, 05:33 PM
Eric-Jan Eric-Jan is offline
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In short.... a new capture might be a good advice, it's not really "handy" to let this done by some one else, since certain things are unknown, and when these tapes are already 2nd generation copies...
a "capture" by (mini)DV device might be even a better a idea
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  #9  
10-07-2018, 10:04 PM
editor editor is offline
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Thanks for all the feedback so far.

Please check this capture I just did myself - admittedly not a fair comparison to the mp4 above, as it's the original raw ProRes capture file, but I'd like some feedback anyway if any of you guys have a moment to check.

Thanks


Attached Files
File Type: mov test2_.mov (30.00 MB, 6 downloads)
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  #10  
10-07-2018, 10:54 PM
sanlyn sanlyn is offline
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Thanks for the sample. But it's not much better, just the same poor quality minus some compression artifacts (but compression noise on motion is still visible. So much for ProRes). Less ghosting but still some edge noise, and really starved of fine detail. Don't you notice the distortion across the top border? It's because the top several pixels of every odd-numbered (bottom) field are warped toward the right. It can't be corrected.

In every respect it's unacceptable. Hope you're not paying real money for it.

BTW it looks dim because it's overcast light, but overall it just seems like visually lame output from the player with no dynamic range and poor color density. Perhaps the original recording was made on a really cheap recorder.
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  #11  
10-07-2018, 11:55 PM
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Quote:
Originally Posted by sanlyn View Post
Thanks for the sample. But it's not much better, just the same poor quality minus some compression artifacts (but compression noise on motion is still visible. So much for ProRes). Less ghosting but still some edge noise, and really starved of fine detail. Don't you notice the distortion across the top border? It's because the top several pixels of every odd-numbered (bottom) field are warped toward the right. It can't be corrected.

In every respect it's unacceptable. Hope you're not paying real money for it.
I thought it was better in terms of not being so dark. It's a really rotten tape, just looking at it, it's full of pleats and creases. Also it's some no-name brand and the tape dates back to 1985 - plus yes, it's a VHS - VHS dub according to the owner, so everything is against us.

The capture you just saw was played on an FS200 into a Panasonic ES-15 (which was recommended to me) using S-Video.

Without the ES-15 or the Datavideo TBC, the playback is so unstable as to be unusable (irrespective of whether we try playing it with a VCR that is equipped with TBC or not) so we need to use something in between. I doubt these devices are causing the issues you specify above, as some very short test captures we did without them (ES-15 or Datavideo TBC) yield more or less identical results.

Here is a sample captured as an .avi. Please let me know if you see or can measure a difference between it and the Prores file.

Thanks again.


Attached Files
File Type: avi test3_.avi (48.41 MB, 10 downloads)
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  #12  
10-08-2018, 05:28 AM
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kpmedia kpmedia is offline
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The source must also be considered, before it was recorded to tape. Don't assume it had no flaws.

- The last AVI recording seems fine, aside from the obvious tearing, and typical VHS noise that need restoration.
- The MOV is desaturated and has more blur. The ProRes must be too compressed. You can change it to have less compression.
- The MP4 has no tearing, but h264 softening is enabled, and contrast seems high.

The AVI without tearing would be most ideal here.

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  #13  
10-08-2018, 07:07 AM
sanlyn sanlyn is offline
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Quote:
Originally Posted by kpmedia View Post
The source must also be considered, before it was recorded to tape. Don't assume it had no flaws.
I think we've seen enough to lay a good portion of blame on the source. The quality of the broadcast may have been acceptable or not, but there's no way it's a first generation tape -- not even a DVD/VHS combo or budget VCR would look that bad.

Last edited by sanlyn; 10-08-2018 at 07:20 AM.
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  #14  
10-08-2018, 11:37 AM
Eric-Jan Eric-Jan is offline
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Quote:
Originally Posted by sanlyn View Post
I think we've seen enough to lay a good portion of blame on the source. The quality of the broadcast may have been acceptable or not, but there's no way it's a first generation tape -- not even a DVD/VHS combo or budget VCR would look that bad.
Yes, I 100% agree with that !
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  #15  
10-09-2018, 04:48 AM
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Thank you to all who participated and offered their opinions.

I will proceed with .avi captures for the remaining tapes.

Thanks again.
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