Quantcast Basic VHS capture quality? - digitalFAQ Forum
  #1  
04-11-2019, 04:04 PM
sevarre sevarre is offline
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Hello! Thanks to this website, I finally have a functioning capture system. I've been a longtime lurker and can't even put it to words how valuable these forums have been (without even posting!). So thank you all for getting me this far.

I have a question about basic quality issues that are encountered when capturing VHS. In particular, I am getting these diagonal rainbow type lines on some VHS tapes when I play them. I've attached an image of a capture where this is most prominent (1980p capture 1.png) and another using the same capture setup where it is not as noticeable (1980p capture 2.png). Both are recordings of TV that my parents made years ago, probably on a terrible quality VCR on some terrible quality setting.

This is my workflow:
(Video Signal) Panasonic AG-1980P -> S-Video -> AIW 9800 Pro -> Computer (WinXP)
(Audio Signal) Panasonic AG-1980P -> RCA to 3.5mm -> Turtle Beach Santa Cruz -> Computer (WinXP)
I am capturing to compressed lossless Huffyuv using Virtualdub. Of course, I am conspicuously missing an external TBC (maybe one day!).

For reference, I've also attached an image of a capture where I am capturing from a handheld tape camera (tape camera capture.png) to the same computer setup.

One thing to note is my AG-1980P is of suspect quality and I know there are a lot of junk ones floating around out there. It looks like it has seen a lot of use, so I am thinking it could be a weak link in my workflow. A friend of mine bought it a couple years ago and I'm not sure where he got it or how much he paid for it.

In general, from what I can tell there are a few fundamental "classes" of issues:
Not Fixable: Stuff like the quality of the recording being incredibly poor, medium damaged beyond repair, etc...
Fixable Before Capture: Improving capture gear, repairing damaged medium, adding an external TBC, etc...
Fixable During Capture: Not sure if anything is in this category. Would include things you could do during capture. Maybe things like only having Virtualdub open
Fixable After Capture: Processing in Avisynth or Premiere Pro, etc...

I am not good at figuring out where specific quality issues fit in these fundamental categories. For this diagonal rainbow issue, I am thinking it is either the 1980P, the fact that it was recorded at some low quality setting, or the age of the tape. Thought I would post this and see if anyone could point me in the correct direction and maybe give general advice on how to tell where an issue might belong in this fundamental category schema.


Attached Images
File Type: png 1980p capture 1.png (477.8 KB, 29 downloads)
File Type: png 1980p capture 2.png (599.3 KB, 25 downloads)
File Type: png tape camera capture.png (607.2 KB, 23 downloads)
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  #2  
04-11-2019, 05:49 PM
latreche34 latreche34 is offline
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A VCR with DNR will get rid of those rainbow effects, Unless they are TV reception artifacts in that case there is nothing that you can do about it.
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  #3  
04-12-2019, 04:51 PM
sanlyn sanlyn is offline
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Still images don't give enough information, so one can only guess. The subject is video, not still cameras -- noise looks and behaves differently in motion. How to create your edited selection;
- Open an unmodified original .avi capture in VirtualDub.
- Use the scroll and edit icons in the bottom left corner of VDub's window to cut your selection. About 8 to 10 seconds of losslesly compressed video with some form of motion (people moving, gesturing, moderate camera motion) will fit within the upload size limit.
- To preserve the original compression and colorspace, click "Video..." -> "direct stream copy" before saving your sample.
- Save your .avi sample, then consult this thread about uploading: How to Properly Upload Images and Attach Files to This Site

Offhand from the images posted there appear to be invalid video levels in the captures (clipped brights, crushed blacks), but as I say it's difficult to judge from still images that have had colorspace conversions. If the noise you mention doesn't appear from your other player, then I'd say it's likely that your 1980p needs work. If the nightmare color moire in the first image exists in all frames, it can't be fixed. If it's possible to reduce the lesser noise in your second 1980p image, it certainly couldn't be done with Premiere Pro. PP isn't a repair app, it's an editor. You'd need Avisynth.

Quote:
Originally Posted by sevarre View Post
In general, from what I can tell there are a few fundamental "classes" of issues:
Not Fixable: Stuff like the quality of the recording being incredibly poor, medium damaged beyond repair, etc...
Fixable Before Capture: Improving capture gear, repairing damaged medium, adding an external TBC, etc...
Fixable During Capture: Not sure if anything is in this category. Would include things you could do during capture. Maybe things like only having Virtualdub open
Fixable After Capture: Processing in Avisynth or Premiere Pro, etc...
Poor quality, damage beyond repair? We've seen many of those, but we've also seen many that could be repaired to a certain extent or at least made watchable. Links to some sample restoration projects are posted in a later paragraph, below.

Fixable During Capture: Using either an external proc amp or the capture device's proc amp connection in VirtualDub, the filtration most often used is a full-speed brightness and contrast controls to adjust input levels to the required YUV y=16-235 range for safe digital signal levels. How this is done and measured in Virtualdub capture via the histogram, proc amp, and temporary cropping control is shown in the advanced VDub capture guide, post #3 and post #4 .

External proc amps are sometimes used for very elementary color correction, but such units are optimized for analog capture (pro gear for digital sources are not appropriate); these are quite expensive, such as the Sign Video PA-100, and are not as effective as post-process RGB controls but are useful for controlling signal levels. Besides, VHS will change color balance with almost every scene change, which can be highly frustrating at capture time and not easily undone later. The DNR in most VCR's is adequate for captures, although many advanced users realize that far more sophisticated denoisers are available in post-process and will often disable the DNR. There are no decent denoisers that you can use during capture; they're too slow, too CPU-intensive, usually require unwanted colorspace changes, and are really too destructive. Sharpners are forbidden: there is nothing uglier or worse than trying to work with VHS noise and other defects that have been sharpened during capture.

Fixable After Capture: glitches such as those displayed in your #2 1980p image are repaired after capture: fuzzy DCT edge ringing artifacts (look at the gal's legs); an associated effect is in the right-hand figure, where there are obvious edge halos on high contrast edges (a bright edge halo on the left, a thick black edge halo on the right); not to mention signs of typical "floating grunge" from frame to frame with the usual VHS noise, and some false contouring in the right-hand man's face and suit due to mild posterizing effects. Add to that the illegal video levels and mild clipping and you need Avisynth, which has specialized filters that address those problems and more. Unfortunately Premiere can't do anything with those defects.

Premiere Pro shouldn't be on the list of repair tools, but it does have its uses. As mentioned earlier PP is an editor, not a restoration app. Like most NLE's it has serious limitations: it doesn't resize, deinterlace, or inverse telecine very well, is sloppy at some colorspace conversions, and has no talent for denoising. On the other hand it has excellent advanced color correction and masking/blending tools (which most owners don't learn to use even though they paid big bucks to get them), has good special transition and timeline features when working with lossless input files, and can do some decent DVD, BluRay, and web encoding.

Most repair, cleanup, and restoration work is done post-capture using Avisynth and VirtualDub together. The capture and restoration areas of the forum have hundreds of cleanup threads, many with extensive details on the filters and techniques used, and feature everything from mildly ugly artifacts to very ugly aging/damage/processing blunders and stupid filming errors. In reply to a request for restoration samples, a collection of several past projects was listed in an earlier thread in post #11 and post #10.

There are hundreds of other before-after posts. One is an unfiltered mp4 example of a capture of a noisy ancient analog cable tv broadcast of a 1954 movie recorded at slow 6-hour speed on a cheap VCR and cheap VHs tape 28 years ago. The original, telecined unaltered cap is Liv5A_cut_EP_original_cap.mp4 (33mb). The result after cleanup with avisynth and VirtualDub is the inverse telcined/denoised/color corrected Liv5A_ivtc_cut_EP_playback sample.mp4 (33mb). That capture was made with a Panasonic PV-S4670 VCR, a Panasonic DMR-ES10 line tc pass-thru, an AVT-8710 frame-level tbc, a PA-100 proc amp for level control, and either an ATI All in Wonder 7500 AGP Radeon or 9600XT AGP capture card (I don't recall which one) using VirtualDub capture and huffYUV/YUY2.

A series of demo posts on how to use various Avisynth filters and VirtualDub advanced image filters is in Information Overload #2, Information Overload #3, and Information Overload #4.

There are enough samples and discussions in the capture and restoration forums to keep anyone busy and full of ideas and resources for a very long time.
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  #4  
04-18-2019, 10:42 PM
sevarre sevarre is offline
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latreche34 and sanlyn thank you SO much for your replies. I've attached the video samples of my captures according to your instructions, sanlyn.

capture1.avi from the same tape as capture1 in the original post.
capture2.avi from the same tape as capture2 in the original post.

I found a sealed VHS tape my parents have and tried that out to see what an absolutely unplayed VHS might look like on the 1980-P system. Rainbow noise is still present, so seems like the 1980-P needs work. I did one capture with the 1980-P line TBC on and one with it off, just to test it. Line TBC ON does indeed look better, which I guess is obvious, but thought I would test it.

capture3 (tbc off).avi never before played VHS capture with line TBC off.
capture3 (tbc on).avi never before played VHS capture with line TBC on.

Also attached is a home video capture from a Hi8 Handycam. No apparent rainbow noise present. Further evidence that the 1980-P needs work.

hi8 capture (composite).avi home video Hi8 Handycam capture via composite

sanlyn, thank you so much for your detailed post. I have much to learn. That Jerry Lewis restoration looks GREAT. I think the next appropriate step is to get my 1980-P situation figured out. While I do that I have plenty to read/digest about post-capture work. Also, I appreciate your insight about figuring out where certain issues fall in the "fundamental categories" distinction and for setting me straight on the use cases of Premiere Pro and Avisynth. Linking those threads is incredibly helpful to me.



Last edited by sevarre; 04-18-2019 at 11:36 PM. Reason: added attachment links
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  #5  
04-19-2019, 08:44 AM
dpalomaki dpalomaki is offline
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FWIW: barber pole-like color interference is a symptom of bad capacitors on the Y/C board. If your AG-1980 still original that is a likely issue. A dim display is also a common capacitor problem on the timer board. A lot of discussion of this in the Video Equipment repair forum.
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  #6  
04-19-2019, 12:18 PM
sevarre sevarre is offline
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Quote:
Originally Posted by dpalomaki View Post
FWIW: barber pole-like color interference is a symptom of bad capacitors on the Y/C board.
Interesting. I might take a look over at that part of the forum in a bit. My idea is to purchase a functioning VCR to get these transfers going and then maybe try my hand at reviving this one. I've revived a couple old Pioneer stereo receivers, but those are all through hole component and I'm sure this 1980P is a much nastier beast.
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  #7  
04-21-2019, 11:41 AM
sanlyn sanlyn is offline
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Quote:
Originally Posted by sevarre View Post
latreche34 and sanlyn thank you SO much for your replies. I've attached the video samples of my captures according to your instructions, sanlyn.

Attachment 9986 from the same tape as capture1 in the original post.
Attachment 9987 from the same tape as capture2 in the original post.

I found a sealed VHS tape my parents have and tried that out to see what an absolutely unplayed VHS might look like on the 1980-P system. Rainbow noise is still present, so seems like the 1980-P needs work. I did one capture with the 1980-P line TBC on and one with it off, just to test it. Line TBC ON does indeed look better, which I guess is obvious, but thought I would test it.

Attachment 9988 never before played VHS capture with line TBC off.
Attachment 9989 never before played VHS capture with line TBC on.

Also attached is a home video capture from a Hi8 Handycam. No apparent rainbow noise present. Further evidence that the 1980-P needs work.

Attachment 9990 home video Hi8 Handycam capture via composite

sanlyn, thank you so much for your detailed post. I have much to learn. That Jerry Lewis restoration looks GREAT. I think the next appropriate step is to get my 1980-P situation figured out. While I do that I have plenty to read/digest about post-capture work. Also, I appreciate your insight about figuring out where certain issues fall in the "fundamental categories" distinction and for setting me straight on the use cases of Premiere Pro and Avisynth. Linking those threads is incredibly helpful to me.
Thanks for the new samples.

Captures with motion show occasional white flashing across the top, which looks like false copy protection errors. I've had those results with tapes in very bad condition played on several VCrs. I had to add a frame-level tbc for correction even though scaline-level errors had been corrected by7 a line tbc. In any case it's apparent from other problems that the 1080P need some work. Come t think of it, it's about maintenance headache time form my own 1080P. Tyheb Capture 2 tape also has a dropout problem (white comets) causeds bvy degeneration of the magnetic layer -- it can be fixed in post-processing.

Watch out for your signal levels during capture. The 1080P captures show illegalm signal levels and serious black crush problems as well as something crushing darks at y=16 even after levels correction -- possibly another circuitry problem on the 1080P. The golf shots also had crushed shadows and clipped brights due to illegal video levels that were not adjusted during capture.

Capture 2 illegal video levels, crushed darks at y=16


Capture 2 level and contrast correction but y=16 blocking


Illegal video levels, YU&V histogram and analysis readout


original levels


levels and contrast adjusted, some shadow details and slight bright detail recovered


Attached Images
File Type: jpg A Capture2 Original levels - borders removed.jpg (32.4 KB, 78 downloads)
File Type: jpg B Capture2 Adjusted levels and contrast.jpg (43.3 KB, 77 downloads)
File Type: jpg C illegal levels YUV - borders removed.jpg (55.2 KB, 77 downloads)
File Type: jpg D original levels - borders removed.jpg (91.7 KB, 78 downloads)
File Type: jpg E adjusted levels - borders removed.jpg (97.2 KB, 76 downloads)
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  #8  
04-25-2019, 08:23 PM
sevarre sevarre is offline
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sanlyn thanks for more detailed analysis. After doing these captures I did some more captures and played with vdub’s levels and histogram tools and adjusted brightness until there was no red in the histogram, so maybe that will help a bit.

Anyway, I appreciate your analysis and it will help point me in the right direction once I finally get to the post processing mode. Also, one unrelated question- is it best practice to plug the audio out signal from the VCR directly to the “line in” port on the sound card?
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  #9  
04-25-2019, 10:07 PM
sanlyn sanlyn is offline
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Most USB capture dongles have their own builtin audio processing. You can try going directly to the "in' jack. Some have already tried it, with varying results. it depends on the capture device. Don't forget to change the audio source in VirtualDub capture settings.
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  #10  
05-06-2019, 12:25 PM
sevarre sevarre is offline
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Alright, so I recapped the Y/C board and Timer board on the 1980P (more details if interested on this thread Where to repair AG1980, or do it myself?). !!

The barber pole/diagonal rainbow line issue appears RESOLVED! However, there are still some definite issues. The video appears to exhibit some wavy/flashy kinda behavior, not really sure how to best describe. Kind of like a strobe/flashing running diagonally through the video. I am thinking could be more issues with the circuitry on the Y/C board (I did miss three caps unfortunately).

I plan on giving the heads a thorough cleaning as I've never cleaned them before (bought some Chamois tips) and maybe also doing some other more "mechanical" maintenance that probably hasn't been done in who knows when. For now I will upload a sample of lossless compressed avi to show the before and after of the recap work. I DO think it looks better and am pleased to see that barber pole striping is GONE.

pre recap.avi
post recap.avi *Not sure if I adjusted levels during capture, so colors might be off still*

I will try some other tapes and see what I get and update later. One step closer to getting to the post production/avisynth FUN.


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