VHS capping- where to convert to S-video

[qlizard]

I am in the process of converting old VHS tapes to DVD. I have an SVHS machine but am wondering where I should convert the signal to S-video. I guess the question is where the best comb filter exists. Here is my setup:

JVC SR-V10 SVHS (usually I set to “auto” and TBC/DNR to “on”)
Prime Image C-sync TBC (used for TBC and color correction)
Panasonic ES10S (pass-through for correction of “flagging” at top)
Sony TRV-33 Camcorder (pass through to DV)
Firewire to PC

I could convert the signal at the VCR, the TBC, the ES10S, or even the camcorder. I am guessing I should use S-video from the beginning, at the VCR.

But if so, I have another question. On some really bad tapes I have trouble with audio using the SR-V10 (the volume is very, very low). For these, I use a Toshiba M-735 (6-head but not SVHS). Here the signal outputs in composite. What then? I will be testing obviously, but if anybody has any guidance it would be appreciated.

[davideck]

VHS is a component (S-Video) format; Luminance and Chrominance are recorded separately on tape. It is therefore best to stay in the S-Video domain whenever possible...

[edDV]

I could convert the signal at the VCR, the TBC, the ES10S, or even the camcorder. I am guessing I should use S-video from the beginning, at the VCR.

The VHS and S-VHS tapes have Y and C recorded separately. Therefore they should be kept as separate Y and C to the A/D. Exceptions would be obscure.

But if so, I have another question. On some really bad tapes I have trouble with audio using the SR-V10 (the volume is very, very low). For these, I use a Toshiba M-735 (6-head but not SVHS). Here the signal outputs in composite. What then? I will be testing obviously, but if anybody has any guidance it would be appreciated.

In that case Y and C get mixed at the output of the VHS deck to composite. You would use your best Y/C splitter next but keep in mind that VHS (not S-VHS) bandwidth limits Y below 3MHz and C near 3.58+/- 0.5 MHz (4.42MHz for PAL) so a comb filter isn't necessarilly required at that point. I would split it before the next box that processes components.

[lordsmurf]

Here is my setup:

JVC SR-V10 SVHS (usually I set to “auto” and TBC/DNR to “on”)
Prime Image C-sync TBC (used for TBC and color correction)
Panasonic ES10S (pass-through for correction of “flagging” at top)
Sony TRV-33 Camcorder (pass through to DV)
Firewire to PC

Nice.

I would stick with s-video at all times, when available.

Remember that sometimes crossover can cause a B&W picture. Something to note in case your picture goes B&W when you use both s-video and composite in the same chain.

Also take note that sometimes s-video can cause chroma/luma artifacts on very damaged signals, so you have to try composite at those times. Not something you see often. Last time I saw that was a year or two ago.

[davideck]

You would use your best Y/C splitter next but keep in mind that VHS (not S-VHS) bandwidth limits Y below 3MHz and C near 3.58+/- 0.5 MHz (4.42MHz for PAL) so a comb filter isn't necessarilly required at that point.

In fact, a chroma bandpass filter might look better here than a comb filter.
The bandpass filter will not harm the luminance, but a lower end comb filter will typically introduce vertical transition artifacts (chroma jaggies) at even low bandwidths.

Tests should be done...

Remember that sometimes crossover can cause a B&W picture. Something to note in case your picture goes B&W when you use both s-video and composite in the same chain.

That just sounds like a bad S-Video cable.

Also take note that sometimes s-video can cause chroma/luma artifacts on very damaged signals, so you have to try composite at those times. Not something you see often. Last time I saw that was a year or two ago.

You're suggesting that things somehow improve by simply mixing these "very damaged signals" together.
This sounds more like equipment failure or an improper setup.

[qlizard]

What is a bandpass filter and where do i get one?

In fact, a chroma bandpass filter might look better here than a comb filter.
The bandpass filter will not harm the luminance, but a lower end comb filter will typically introduce vertical transition artifacts (chroma jaggies) at even low bandwidths.

[edDV]

What is a bandpass filter and where do i get one?

In fact, a chroma bandpass filter might look better here than a comb filter.
The bandpass filter will not harm the luminance, but a lower end comb filter will typically introduce vertical transition artifacts (chroma jaggies) at even low bandwidths.

Here you go, a great comb filter and bandpass filter 101.
http://members.aol.com/ajaynejr/vidcomb.htm

Normal NTSC and PAL overlap Y and C frequencies above 3MHz NTSC and upper 3+ MHz PAL.

In the normal case, a comb filter is required to separate these upper frequencies (for high luminance detail and minimal cross-color).

To save the high cost of a comb filter, VHS chops luminance frequencies low before recording.

In the specific case of composite output from a VHS deck, a bandpass filter may do better than a comb filter since comb filters have tradeoffs. With S-VHS and normal NTSC/PAL, a comb filter will extract the higher resolution luminance (out to 4.2 MHz+) that a bandpass filter will chop at 3 MHz.

[davideck]

What is a bandpass filter and where do i get one?

A Chroma Bandpass Filter separates luminance from chrominance.

I was assuming that at least one of your devices had a bandpass filter at its front end. Do all of your devices have comb filters?

In any event, it would be best to test the composite_to_s-video conversion of each device and compare for yourself.

[lordsmurf]

Remember that sometimes crossover can cause a B&W picture. Something to note in case your picture goes B&W when you use both s-video and composite in the same chain.

That just sounds like a bad S-Video cable.

Also take note that sometimes s-video can cause chroma/luma artifacts on very damaged signals, so you have to try composite at those times. Not something you see often. Last time I saw that was a year or two ago.

You're suggesting that things somehow improve by simply mixing these "very damaged signals" together.
This sounds more like equipment failure or an improper setup.

Nope.

Crossover oftens results in B&W signals.

And the luma errors goes both ways. Sometimes a device will not like composite, sometimes the s-video. It's a signal problem. Equipment fine, setup fine.

Seen it many times first-hand, and heard complaints about these things for years now, even before DVD tech was around. Just one of those things.

[vhelp]

Just a slight OT here ...

>> The comb filter takes composite video and outputs S-video.

(from the link posted prev'ly by edDV, agin below)

--> http://members.aol.com/ajaynejr/vidcomb.htm

Out of curiosity..
.
.
I am also curious how the filter (algorithem'wise) are applied to
the LUMA and CHROMA (cb/cr) components during the combing process

EDIT: oops, didn't realize that the link above pretty much covers most
of the questions I had asked. Sorry

-vhelp 3620

[edDV]

Just a slight OT here ...

>> The comb filter takes composite video and outputs S-video.

(from the link posted prev'ly by edDV, agin below)

--> http://members.aol.com/ajaynejr/vidcomb.htm

Out of curiosity..
.
.
I am also curious how the filter (algorithem'wise) are applied to
the LUMA and CHROMA (cb/cr) components during the combing process

EDIT: oops, didn't realize that the link above pretty much covers most
of the questions I had asked. Sorry

-vhelp 3620

The important concept is it only takes a resistor network to combine Y and C into composite but it takes an expensive complex filter to reseparate them and there will be artifacts.

[NTSCrelic]

lordsmurf wrote:

Crossover oftens results in B&W signals.

lordsmurf, please explain "Crossover". That's a new term for me. Thanks

[lordsmurf]

Crossover. May not be a tech term.

The optimal method of transfer would be something like this:

VCR
|
s-video cable
|
TBC
|
s-video cable
|
proc amp
|
s-video cable
|
DVD recorder

But if you don't have s-video cables on everything, or don't have enough cable, you might try this:

VCR
|
s-video cable
|
TBC
|
composite cable
|
proc amp
|
s-video cable
|
DVD recorder

You started to push the signal along another sort of connection. Many, many, many devices get pissy if you try to feed it an s-video and output composite. Or the other way around. You'll often get no picture, or a B&W picture because of it.

[NTSCrelic]

That's curious. You'd think either setup would work ok. It would be interesting to see what's actually happening to the video in that situation. Nevertheless, sounds like keeping chroma and luma seperate all the way is the way to go.

[qlizard]

Thanks for the insight.
I'm very leery about sacrificing any video quality, so I'm going to look for another SVHS and hope that it doesn't have the same issues with the audio on the few tapes I have trouble with.

Until then, I'll do what I have in the past- capture the video using my SVHS, then capture again using the other machine, put them both on a timeline in premiere, take the audio from the second machine and line it up with the video from the first. I then lock them both down and edit them together. A royal pain in the arse, but then I get the good video with the good audio.

[gshelley61]

If you have to start with a composite source (your Toshiba VCR), I'd maintain the composite signal up until the Panasonic DVD recorder, then use the s-video output from there. Name brand DVD recorders generally have excellent quality motion adaptive digital Y/C separation filters... probably better than any other device in your signal chain.

[qlizard]

If you have to start with a composite source (your Toshiba VCR), I'd maintain the composite signal up until the Panasonic DVD recorder, then use the s-video output from there. Name brand DVD recorders generally have excellent quality motion adaptive digital Y/C separation filters... probably better than any other device in your signal chain.

gshelley, thanks for the suggestion. I think I'll try and check it out. One thing I forgot to mention is that my TBC has BNC composite input and output. I bought some cables that have BNC connectors at one end and normal RCA plugs at the other for connection to my other equipment. Anything I should be concerned with?

[gshelley61]

No, there's no difference at all between RCA and BNC composite signals. BNC's are just heavy duty connectors used in pro gear. There are inexpensive RCA to BNC adapters at Radio Shack.

[davideck]

That's curious. You'd think either setup would work ok. It would be interesting to see what's actually happening to the video in that situation. Nevertheless, sounds like keeping chroma and luma seperate all the way is the way to go.

Absolutely!

An S-Video source should not be mixed into composite and then reseparated back into S-Video on the way to a capture device with S-Video inputs.
If chroma (or luminance, or audio) is lost somewhere along the path, then the problem should be identified and removed.

my TBC has BNC composite input and output. I bought some cables that have BNC connectors at one end and normal RCA plugs at the other for connection to my other equipment. Anything I should be concerned with?

Does your TBC have S-Video connections?

[davideck]

If you have to start with a composite source (your Toshiba VCR), I'd maintain the composite signal up until the Panasonic DVD recorder, then use the s-video output from there. Name brand DVD recorders generally have excellent quality motion adaptive digital Y/C separation filters... probably better than any other device in your signal chain.

That makes sense unless there is a device earlier in the chain that separates composite into components for internal processing. In that case, the S-Video output (if there is one) of that device should be used.

[gshelley61]

Yes, that's true. If your TBC has s-video inputs and outputs, and a Y/C timing adjustment... it may split composite sources for processing as davideck mentioned... in that case, you would probably want to use the s-video output of the TBC (unless you see any separation artifacts like dot crawl).

[qlizard]

Does your TBC have S-Video connections?

Yes, the TBC has S-video connections, as does the dvd recorder, and the camcorder. My question from above is when using the regular VHS machine, which of these components would contain the best filter for conversion from composite to S-video. It sounds like you're saying the earlier the better, while gshelley is suggesting that the dvd recorder would probably contain the best filter.

[qlizard]

The TBC does have a Y/C timing adjustment along with a bunch of other cryptic adjustments (greek symbols). I use it mainly for proc amp color adjusting and for shifting the color "bleed" one direction or another. The other buttons scare me.

[davideck]

It sounds like you're saying the earlier the better, while gshelley is suggesting that the dvd recorder would probably contain the best filter.

I am saying that if a device has separated its composite input into S-Video components for internal processing then it is best to stay with S-Video connections from then on, no matter how good a downstream separator might be.

Since your TBC has S-Video connections and a Y/C timing adjustment, I suspect that it is separating its composite input into S-Video internally.

You should experiment to see which setup provides the best results...
You should also check to see if your TBC allows you to select between a bandpass or comb filter separator for the reasons discussed earlier in this thread...

[qlizard]

This has been very helpful. Thank you.
Luckily there is an online manual available for my TBC. I will read through it and test your suggestions.

[JohnnyBates]

So - If I have a VHS tape and I want to transfer it to DVD with my JVC M100 DVD Recorder and my JVC SVHS deck I should use the S-VIDEO cable.

If I want to transfer a Laserdisc to my JVC M100 DVD Recorder I should use the composite output from the LD because the comb filter in the LD player is nowhere near as good as what's in the M100.

If I get things like external TBCs and Proc Ams I should try and keep the cable run the same format for as long as possible.

Sound about right?

Thx.

E

[davideck]

So - If I have a VHS tape and I want to transfer it to DVD with my JVC M100 DVD Recorder and my JVC SVHS deck I should use the S-VIDEO cable.

Yes.

If I want to transfer a Laserdisc to my JVC M100 DVD Recorder I should use the composite output from the LD because the comb filter in the LD player is nowhere near as good as what's in the M100.

Yes, although an experiment to verify the relative comb filter quality (on an authored DVD) would be worthwhile.

If I get things like external TBCs and Proc Ams I should try and keep the cable run the same format for as long as possible.

The goal is to minimize the conversions from composite to S-Video. Zero is best for S-Video sources. One is best for composite sources.