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  #41  
07-16-2022, 10:23 PM
latreche34 latreche34 is offline
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Quote:
Originally Posted by McCarthy View Post
- Magnetic particles gradually lose their charge through remanence decay, which results in color shifts towards weaker hues and a loss of overall detail.
That's technically false, Chroma and luma are encoded within an RF carrier, For the chroma to fade you would have to have it decoded, its level brought down and encoded back into the RF signal, It is almost the same argument for digital where people claim expensive USB cables give cleaner and louder sound. Data within a signal carrier cannot be altered alone, whether frequency modulation for RF, PWM, or digital. the entire scheme is affected. The signs of signal damage (or degradation) for analog video tapes are: RF noise (white or black streaks), tracking problems (bad sync pulse on the edge of the tape), H and V sync signals problems (flagging, line wiggle, frame roll, half frame bar ...etc), HiFi buzzing.
Physical damage accounts for the majority of tape problems compared to signal damage. such as tape shrinkage or stretch, magnetic layer physical degradation, physical damage due to hardware failure, mould and similar problems.
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  #42  
07-16-2022, 10:53 PM
Hushpower Hushpower is online now
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Why then do some of my reds end up 3 pixels right and sometimes 3 pixels down?
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  #43  
07-16-2022, 11:03 PM
McCarthy McCarthy is offline
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Quote:
Originally Posted by latreche34 View Post
That's technically false, Chroma and luma are encoded within an RF carrier, For the chroma to fade you would have to have it decoded, its level brought down and encoded back into the RF signal, It is almost the same argument for digital where people claim expensive USB cables give cleaner and louder sound. Data within a signal carrier cannot be altered alone, whether frequency modulation for RF, PWM, or digital. the entire scheme is affected. The signs of signal damage (or degradation) for analog video tapes are: RF noise (white or black streaks), tracking problems (bad sync pulse on the edge of the tape), H and V sync signals problems (flagging, line wiggle, frame roll, half frame bar ...etc), HiFi buzzing.
Physical damage accounts for the majority of tape problems compared to signal damage. such as tape shrinkage or stretch, magnetic layer physical degradation, physical damage due to hardware failure, mould and similar problems.
False. All magnetic media, including magnetic tapes, experience data decay as (particle) bits lose their magnetic orientation, it doesn't matter in what form the data is encoded, the particles in the tape do not care. This has been known for a long time and affects analog and digital data. First semester computer sciences, at least when I was in for for the Masters.

Gov backed finding: https://www.govinfo.gov/content/pkg/...606c1d6910.pdf

Last edited by lordsmurf; 07-17-2022 at 01:05 AM. Reason: Text removed, text striked. Personal attacks, political ranting, and blatant misinformation NOT allowed. -LS
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  #44  
07-17-2022, 12:00 AM
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Quote:
Originally Posted by latreche34 View Post
That's technically false, Chroma and luma are encoded within an RF carrier, For the chroma to fade you would have to have it decoded, its level brought down and encoded back into the RF signal, It is almost the same argument for digital where people claim expensive USB cables give cleaner and louder sound. Data within a signal carrier cannot be altered alone, whether frequency modulation for RF, PWM, or digital. the entire scheme is affected. The signs of signal damage (or degradation) for analog video tapes are: RF noise (white or black streaks), tracking problems (bad sync pulse on the edge of the tape), H and V sync signals problems (flagging, line wiggle, frame roll, half frame bar ...etc), HiFi buzzing.
Physical damage accounts for the majority of tape problems compared to signal damage. such as tape shrinkage or stretch, magnetic layer physical degradation, physical damage due to hardware failure, mould and similar problems.
Correct. "tape fade" = unscientific jabberwocky nonsense

Quote:
Originally Posted by Hushpower View Post
Why then do some of my reds end up 3 pixels right and sometimes 3 pixels down?
- On how many vastly different VCRs have you tied to play it?
- On how many vastly different TBCs and capture cards?
- And are you 100% certain that's not how the tape was a recording time? Almost all people have false memories of how it looked, mostly because the small CRTs hid flaws, and you now see it pixel perfect.)

Quote:
Originally Posted by McCarthy View Post
False. All magnetic media, including magnetic tapes, experience data decay as (particle) bits lose their magnetic orientation, it doesn't matter in what form the data is encoded, the particles in the tape do not care. This has been known for a long time and affects analog and digital data. First semester computer sciences, at least when I was in for for the Masters.
Nope, wrong. The image luma/chroma(color) data is not affected by demagnetizing. You've mixed up fact and non-fact, and arrived at (or copied) the false notion that "tapes fade". They do not. Tapes go bad in other (and obvious) ways, the image doesn't desaturate or whatever, values do not alter. Read a book about VHS theory.

Start here: https://amzn.to/3IJRhwQ

Of course, since this person simply ranted, rather than answer questions from the previous post (ie, Why did he think the random figure of "20-30% lost quality?"), and then submitted a bogus email address (why his account is now invalid), I have zero faith he'll do this. Hopefully others will be smarter.

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  #45  
07-17-2022, 12:05 AM
latreche34 latreche34 is offline
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Quote:
Originally Posted by Hushpower View Post
Why then do some of my reds end up 3 pixels right and sometimes 3 pixels down?
A Chroma burst delay, Chroma and luma timing is separate from the actual Y-C RF envelope, Just like frame and line timing, chroma timing is affected as well. But just a good guess, I don't know the circumstances of your problem, more investigation is needed.

Quote:
Originally Posted by McCarthy View Post
False. All magnetic media, including magnetic tapes, experience data decay as (particle) bits lose their magnetic orientation, it doesn't matter in what form the data is encoded, the particles in the tape do not care. This has been known for a long time and affects analog and digital data. First semester computer sciences, at least when I was in for for the Masters.

Gov backed finding: https://www.govinfo.gov/content/pkg/...606c1d6910.pdf
Data loss not decay, What do you see when data is lost? Tape drop outs, noisy bars, timing instability (timing errors). Not color fade, luma fade, that's just absurd.
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  #46  
07-17-2022, 12:22 AM
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Quote:
Originally Posted by latreche34 View Post
A Chroma burst delay, Chroma and luma timing is separate from the actual Y-C RF envelope, Just like frame and line timing, chroma timing is affected as well. But just a good guess, I don't know the circumstances of your problem, more investigation is needed.
Gear also heavily affects chroma offset, color bleeding, etc. Internal hardware filtering can also help recover the original data, though it'll never be pixel perfect. The limits of analog.

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  #47  
07-17-2022, 07:30 AM
RobustReviews RobustReviews is offline
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This, I think, proves you are not a scientist.

Talk about 'apples to oranges', this even predates the chemistry used for domestic videotape, they're not at all comparable. This is a study of digital data tape coated with prehistoric oxide chemistry, designed to be driven into full saturation. It says precisely nothing about videotape.

This shows a considerable lack of knowledge of the subject. You can't use this, sorry.
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  #48  
07-18-2022, 08:53 AM
Eric-Jan Eric-Jan is offline
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Yeah, don't store VHS tapes near loudspeakers or devices with magnetic fields like transformers, storing your tapes also in room temperature and a no(t) to damp air, and your tapes will go for a long time, maybe once in while spool back and forward the tapes against pushthrough sound of the linear audio tracks ? don't know if this is a issue for VHS tapes, i think the RetroTink series is not tuned for VHS, and way too expensive to just try this, a DVD/HDD recorder from the thrift shop (as passthrough) is cheaper and will have more affect.
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  #49  
07-20-2022, 06:16 AM
hodgey hodgey is offline
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Re the talk about "tape fade", many newer VCRs have features that will auto-adjust sharpness and noise reduction stuff based on some tape condition parameter. (e.g BEST/Video calibration in JVCs, CVC on panasonic decks, OPC/APC on Sony's and so on.) Additionaly there is some non-linear deemphasis/detail enhancement (especially on LP/EP/SLP speeds) that will be affected by how noisy the input is which will also have some impact.

So, it's possible these changes may have confused some people leading them to think tape aging causes softer images or whatever.

What you do get rather when the magnetic signal on tape is weaker is more noise relative to the actual video signal, which would mean the raw output from the tape will be noisier, maybe especially chroma since that's stored more directly. That can be impacted by many parameters though, so it's not as simple as always attributable to aging though.

Quote:
Originally Posted by Hushpower View Post
Why then do some of my reds end up 3 pixels right and sometimes 3 pixels down?
I think this is more due to chroma/luma delays in the VCR than the on-tape signal. The on-tape signal can't "move" on it's own. Vertical offset in particular can be caused by the internal comb filter, unless in EDIT mode, VCRs will blend the color signal with a color signal delayed by 1 line (NTSC) or 2 lines (PAL) to reduce cross-talk between vcr tracks. Due to how the color is stored on the tape this acts to cancel out the part of the signal picked up from adjacent video tracks on the tape, but unless compensated it can introduce some color offset. High end vcrs, especially SVHS ones, often had more fancy chroma noise reduction as well (originally as an optional part of VHS HQ specs).

Example from a Panasonic NV-F77, the non-SVHS little brother to the NV-FS200. You can see the chroma is shifted down on the first image (Normal) compared to the second one (EDIT setting). Easier to spot if you open each image in a new tab and switch between them.
f77 normal.png
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When looking at the output on e.g my JVC HR-S8600 and JVC HR-S6900, SVHS the chroma isn't shifted between EDIT and Normal so those seemingly compensate for it, while other non-SVHS decks I checked seemed to have the same chroma shift. My Panasonic NV-HS870 also seemed to have a chroma shift (despite being SVHS and featuring digital NR) on default settings (no EDIT setting on this one.) The much older Panasonic AG5700 SVHS I have seemed to compensate at least to a degree (no picture setting at all on this one.) Idk if this applies to all non-SVHS decks or if ones with more advanced chroma NR act differently etc as I haven't studied in detail. Suspect it's more noticeable on PAL due to needing 2 lines of delay for comb filtering rather than just 1 line on NTSC due to how the color is encoded.

This effect is compounded on dubbed tapes of course which can lead to chroma being very offset.

Broadcast video gear like TBCs and VCRs with digital processing seem to often feature Y/C delay adjustment sliders so presumably this is a thing that needs to be compensated for even there.

Horizontal offset I'm a bit less sure about the cause of, but presumably there may be some slight differences in Y/C delay internally too, either on recording or playback.


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  #50  
07-20-2022, 11:48 AM
Eric-Jan Eric-Jan is offline
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These noise compensations i only see on the output of the SCART of my Panasonic combo, the component output does not have this, and is much better to watch from anyway the compensations also "trail" when there's movement, very weird effect not nice to look at, with normal video levels there's no problem on SCART or composite, one should avoid these connections anyway for transfers.
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  #51  
03-08-2023, 04:32 PM
NJRoadfan NJRoadfan is offline
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That test is with the new RetroTink 5X hardware, which has full frame TBC like functionality ("triple buffer" in the menu options). Problem is the 5X currently lacks a pass-through mode and will deinterlace/upscale any 480i video fed into it. I don't have a 5X (yet), but its a no-go until 480i pass-thru is added/enabled.
I know it's bad form to quote yourself but..... The Retrotink 5x has added 480i pass-through mode in the latest firmware update. Eventually I'll get my hands on one to evaluate.
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  #52  
03-08-2023, 05:25 PM
ENunn ENunn is offline
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Originally Posted by NJRoadfan View Post
I know it's bad form to quote yourself but..... The Retrotink 5x has added 480i pass-through mode in the latest firmware update. Eventually I'll get my hands on one to evaluate.
Tried it for myself, looks like most if not all of of the detail is preserved compared to my usual GV-USB2 setup.

GV-USB2


Tink5x


Brightness and contrast is a bit off but I can correct that in post.

Unfortunately it doesn't really correct dropouts well, even in triple buffer mode. :/


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