Composite vs. s-video output mod, image quality comparision
 

Hi people!

Ofesad here from Argentina.

Today I tested my S-Video output mod to a non-svideo non-svhs vcr. :)

The deck in question is a SONY SLV-L86HF (also known as or L86AR), 6 head stereo with "sapphire tape cleaner", It plays PAL / NTSC vhs's and it has a switch so it can output NTSC or PAL-N signal.

So, here's the "FrankenSony":
http://www.digitalfaq.com/forum/atta...1&d=1553066032


However this post is not about how I mod it, it's more about comparing the image quality of the Svideo mod vs the composite output.

I'd like your inputs regarding the picture so I can see to improve the mod to obtain a better picture quality.
What you see, what you don't see, what you think it could be improved, ... :2cents:


Here's a picture comparision.
http://www.digitalfaq.com/forum/atta...1&d=1553065133

and here a comparision of the video files:

http://www.digitalfaq.com/forum/atta...1&d=1553065523

The Svideo file has 15~18% higher bitrate.


And here are the videos.
Captured with Pinnacle Moviebox on VirtualDub and compression with Huffyuv. RAW material, no filters.
COMPOSITE VIDEO (296 Mb)

SVIDEO VIDEO (340 Mb)


Thank you for reading and your inputs!

Ps: Please don't be mean with the comments! :laugh:

Interesting, hope you can give us some info to where you tapped the Y and C from on this deck. I know many newer deck do all the processing including Y/C mixing inside an IC where it can't be tapped, but there seem to be exceptions.

I've been looking at doing an S-Video mod on my JVC HR-J658 as it seemed it was possible. The PCBs are shared between the lower and higher-end models of those so it seemed the Y and C outputs to the SVHS board were present, and with some probing at leasat the Y channel was there. Haven't gotten around to tinkering any further with it.

The s-video higher bit rate is consistent with the increased detail and noise content (not filtered out as a result of the bandwidth limitation of the composite video processing in the VCR and capture device). There is almost never a reason to capture via composite video connections. It give you more with which to work in the restoration process.

An interesting project for folks with similar VCRs.

Ditto.

@ ofesad:
We ask that you don't post off-site. When your off-site videos disappear, your comparison won't make sense. Most of this thread would be useless.

It's strongly recommended that RGB should not be used for VHS capture. VHS isn't RGB, nor is RGB an entirely accurate representation of your VHS original. VHS is YPbPr, or the equivalent of YUY2.

I've taken the liberty of attaching a slightly edited lossless YUY2 of the posted videos so that your notes won't be entirely useless if your offline posts go away.

Thanks for the comparison.

He asked me about the file size before the post, and I said something that larger needs to be on our file server instead. So he was doing well. I'll be downloading/uploading those in a day or so.

But ~300mb down to ~90mb is quite a feat. I want to look more at what happened there, when I get the time. Was it all editing, or did RGB have something to do with the shrinkage? I know Lagarith can be 25% smaller, but we're talking 1/3rd reduction here. Interesting.

I'm seeing a lot of diagonal lines in the capture, as if the y channel contains the color signal or at least something is not filtered out of it.

No problem! Aint that hard, but some soldering skills are needed.

Actually this mod begun just with the idea of using this VHS, that for me personally has give me always much joy and the picture always seemed pristine, even in composite.

Most SONY's SLV models should be capable of this mod, at least the 6 Head models, would have to check more manuals to be sure, but I would guess that there isn't much difference.

Sadly I don't have JVC. Here in Argentina JVC decks are kindda rare. Most are Panasonic, Sony, Philips or many other brands.
I couldn't find the HR-J658 service manual on the internet. If you have it I could take a peek and give you the tips of what to do.

Thank you dpalomaki! Really appreciated your input.

It all begun as an experiment, but now I am thinking to add more features like Noise Reduction, filtering or some Sharpness control.

Also, since SVHS are becoming harder and harder to find (and even if you find one, could be for parts or overly used), this would be a good solution for bring life back to common VCR's and getting a better picture. Probably not as good as SVHS decks, but still an intemediate.

The mod would fit many others VCRs too. Would have to check more manuals but, you can bet for Philips, Panasonic and JVC's VCR would be capable of being modded too.

Thank you for noticing. I would double check next time!

It's weird, I just checked VirtualDub and huffyuv and it's all set to YUY2. :hmm:

It was around 4am here when I posted the video, so maybe was a little sleepy and changed the config. Sorry for the screw up. :depressed:

Thank you for taking the time to improve the material!

Thank you for noticing! Today I will be doing some testing, changing values and see if it improves! :congrats:

Do you happen to have any idea whether such a mod would be possible on a Sony SVO-965P duplicator? I bought it so that I could have some way to play PAL tapes, but if it would be possible to modify it for better quality I'd be interested.

It would be a nice mod for Betamax decks since so few have S-Video output. I know someone out there has done it, but never published a how-to or any details. Most older decks should have the chroma and luma separated within the deck after de-modulation and amplification, the trick is finding where that point is to tap it.

In general, service manuals for most common VCRs, including commercial/professional/industrial models can be found on line, often for a nominal price $10 or so. They will usually contain circuit diagrams and if one knows what one is doing, the diagrams can be read to determine whether or not the Y and C signals can be readily picked off for amplification and redistribution.

However, care needs to be taken to ensure proper impedance, frequency response, and headroom in the signal path. This is necessary to preserve standard levels and phases for color decoding.

I am so sorry to have leave this post dead, but I was working on other things and the mod had to wait. Today I have news and will answer the pending posts. :o

I looked for the SVO-965P service manual, but I couldn't find it, at least for free. Like dpalomaki said, there are some sites that sell the manual for 10usd or least.

If you happen to have the manual, PM it to me so I will give it a look and will confirm if possible. :congrats:

Also, if you need to play PAL tapes, I can ship some decks from here. There are decks that work on 110~240v and play pal-m,pal-n and ntsc. Some can also output in ntsc.

Sadly here in Argentina the Betamax was never a thing. There are some Sony betamax decks for sale but I don't even have a tape to test.
Actually my Sony was quite a late model. I have seen a little of everything: old decks with no chroma separation (most 4 heads) and the later 6 head stereo, wich some had chroma separation and others dont. Mostly depends on the main IC used.

Yeah, but also there are some manual that don't tell you if they have chroma separation. Just "video signal", so you have to check all the IC going back an fordward... :mad4:
I love Panasonic, but it does some really shitty manuals.
Sony, so far, has the most detailed info.

-- merged --

News news! I finally took the time to update the mod. Changed some values and think I have solved most of the issues I was having.

Still theres a long way to go and more tests to do.

Also I am developing a TBC circuit to add to the mod, but that's for another post. :D

So, here are some new captures samples where you can see the difference better. :wink2:

Would love some opinions on color and luminance.

At first I had some issues with luma, but then I solved it.
Altought I still think that it looks kinda dark compared to composite, but the color separation is truly noticiable.

COMPOSITE CAPTURE

SVIDEO CAPTURE

(Lordsmurf, please upload'em to the FTP) :D

Remember: this is captured directly from the Sony deck with a Pinnacle 610 usb capture card, compressed with Huffyuv. No filters or effects o enhancements.

Any update to the TBC circuit that you have been developing? Also, I tried to view the files shared on your Google drive, but they are gone

I almost forgot about this thread. Do you have some info about what you did? I have a SLV-SE800 which is a PAL model from around the same time. The higher-up models including that one from this time had a "reality regenerator" feature, that was a separate image processing chip. What's interesting is that the video is input as separate Y and C to it so I maybe it would be possible to tap separate Y and C there. I presume you would want some buffer amps in either case to avoid impedance and level mismatches. Additionally, I think this, and maybe your mod as well would bypass the OSD chip so you would avoid the blue-screen on signal loss which is my main gripe with these Sonys. They're otherwise pretty well built, more comparable to JVCs and Panasonics at the time terms of build quality than more budget stuff like LG and Samsung.

Also, be vary of bad power supply caps in these, all 3 related Sonys I've used had dodgy power supply caps.

I see that luma pattern, Kind of like dot crawl but fills the entire screen, Looks like some more filtering needed. Though it's an interesting project.

Sorry for the video files I erased'em time ago, I needed the space :depressed::unsure:

I reached many people regarding TBC cirquits schematics and for the most, the reply was that, due that it's a old technology, chips aren't manufactured anymore.

However, disregarding the general advice of this forum of get a Datavideo TBC, since here in Argentina are impossible to find (I have been looking for one in over 4yrs), I got a Datavideo Se-500 Video mixer. Wich, has a built-in full-frame TBC synchronizer plus proc-amp.
I have to say I am VERY impressed with the results. Picture it's super stable, no dropp'd frames, no issue whatsoever.
ALSO, this version has a hidden Switch unde the control panel that let's you choose the output format (PAL/NTSC), wich it's awesome for me since I got tapes in both formats.

In comparision, using my HS1000 / AG4700 connected directly to the Ati capture card I would get dropp'd and inserted frames from time to time (around 100 frames / hr).
With the SE500 I got 0 in both with 3hr tapes.

Well, you know power supplies are always source of problem and most in these equipments.

I kinda leave the project cause I got more SVHS decks, now I have 10 HS1000/AG4700 + AGW1 + 2 FS88 + 1 FS90. Today I saw a FS200 mint for sale for 75usd.... dunno if I should get it.

Still, the Frankensony it's on my desk taken apart and with cables coming in and out of it :laugh:
I am pretty sure I would need some a buffer for the Y/C signal, however, finding parts here are next to impossible. So I am getting old decks from time to time to scrap for parts that I can use to build it or use his parts on the sony.

Also, past december a electric storm took the like of my Sony 55" lcd, so kinda been busy with that, the insurance and looking for a new tv (still not have one) + many clients asking for video and photo restoration during these times.

Yeah, exactly. I was looking to use the processor of some SVHS camcorder or another deck.
Could be worth to check Mouser or DigitalKey for some ic's that could do the work, maybe theres something in stock still.

Ofesad

Major update

For Betamax:
https://www.digitalfaq.com/forum/att...1&d=1698349952

It would be possible to get Svideo output from certains Betamax HiFi Players.

For VHS:

Several Sony HiFi decks support the Svideo mod.

Some European Sony Hifi decks dont need the mod, due that they can output Svideo signal directly using a SCART to RCA+Svideo adapter. :congrats:
https://www.digitalfaq.com/forum/att...1&d=1698350847


I have ordered some IC's to do more testing, will update when I got'em.

Greetings from Argentina.

Ofesad.

Interesting. But test, verify. Diagrams can lie, wouldn't be the first time.

As far as I know none of the European VHS only decks can output separate YC over SCART, Only S-VHS machines and certain DVD combo units that have component for the VHS side.

Correct, most common VHS decks wont output Svideo.

Like I mentioned, some european SONY's HiFi models are capable of output Svideo with the Scart to RCA+Svideo Adapter. I have tested a couple and I will start a listing soon.

If you have access to some Sony HiFi decks, please try it too.

Ofesad

Have you done a dot crawl extensive test ?
Is it certain that this mod can't be achieved on a pal deck ? I'd be willing to spend some time on this if i was certain as i've acquired quite a few decks recently especially an excellent Toshiba "pro drum" type that delivers.
Edit: found the service manual, if you can give me some hints i'd appreciate but from my non expert eye it seems everything happens inside the IC301 (left side is video processing / right is audio, see Toshiba.jpg)