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NTSC IRE levels and DV camcorder Pass-Through capture.
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edDV
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Post Posted: Jan 15, 2007 12:51 Posts Comp View users profile Send private message Reply with quote
I decided to answer this pvt message here so all can participate.

jrank001 wrote:
Hi edDV:

I wrote to FulciLives asking for some advice. He referred me to you....

I have a Sony DCR-PC110. I also have an Elite Video BVP4 Plus. Should I buy a Canopus ADVC-100 or run the BVPS Plus into my camera via s-video then fire wire to PC? Looking for the best way to get the correct IRE level.

I have about 15 DV tapes I need to load and organize b-days, x-mass, turkey day, and so on to separate and put all onto one DVD for each event. IRE is very important. Looking for your input. A Canopus is about the only thing I don’t have.

My set up:

VCR ---TBC---DETAILER---BVP4---SONY DCR-PC110 (pass though device) PC

I wanted your opinion on what is the best to use to capture to computer for the correct IRE level. Canopus or my DCR-PC110? Am I correcting that already with my BVP4 Plus?

Jay


First, your camcoder DV tapes have correct black if recorded from the camera section of the camcorder. DV camcorders will record black at digital level 16. When this is transferred to the PC over IEEE-1394, black remains at digital level 16 and gets authored to the DVD at digital level 16 and all is well. When an NTSC DVD player plays the DVD, it is supposed to scale digital level 16 to analog level 7.5 IRE for correct NTSC black.

If you play the tape from the camcorder to analog outputs, black will be incorrect at 0.0 IRE. If you capture camcorder playback to an analog NTSC capture device, the bottom 7.5% of the black range will be chopped off, or recorded below black level 16. The result will be "crushed blacks" with loss of detail in black and a dark picture. So you should always use IEEE-1394 to transfer your DV video from the camcorder to the PC.

As for analog "pass through" capture through the camcorder analog inputs, NTSC black level (7.5 IRE) will be incorrectly captured to digital level 32. The result is a grayish black like this example (left side). This slide shows the Vegas levels filter correcting the black level (right side). Other levels filters can also be used to lower Y (luminance) values by 7.5% lowering black from digital level 32 to 16. Vegas has the waveform monitor to help you see what is happening to luminance levels.



Your path:
VCR ---TBC---DETAILER---BVP4---SONY DCR-PC110 (pass though device) PC
allows for adjusting black level from 7.5 IRE to 0.0 IRE before camcorder capture using the BVP4. Adjusting black at the camcorder input to 0 IRE results in black capture to level 16. The only problem is you can't see what you are doing unless you do test captures to view the results of your adjustments. The Vegas waveform monitor is good for this but I wish it operated real time on the capture input so analog adjustments could be directly monitored. Sadly it doesn't so you must capture before the monitors can be used.



The left is uncorrected black level, the right is corrected. So these adjustments can be made before capture in the analog domain or after capture with digital levels filters. The problem with the analog method is seeing what you are doing unless you use trial and error captures. Pros will use analog waveform monitors to adjust black and white levels and use calibrrated TV monitors.



The Canopus ADVC 100 or 110 can also be used for capture in place of the DV camcorder. The ADVC includes a 0.0/7.5 IRE black switch. In the 7.5 IRE mode, NTSC black is captured correctly to digital level 16. No further adjustments are required. If the switch is set to 0 IRE, the ADVC will do the same as a camcorder by mapping analog 7.5 IRE to digital 32 resulting in washed out blacks.





See this JVC tutorial:
http://pro.jvc.com/pro/attributes/prodv/clips/blacksetup/JVC_DEMO.swf

Ask again if any of this is unclear.

Last edited by edDV on Jan 15, 2007 13:47, edited 3 times in total
JohnnyMalaria
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Post Posted: Jan 15, 2007 13:00 Posts Comp View users profile Send private message Reply with quote
I think you should emphasize that the "incorrectness" applies to NTSC as implemented in North America. For NTSC implementations in RoW, the (predominantly Japanese/Far East) equipment is doing the "right thing".
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edDV
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Post Posted: Jan 15, 2007 13:14 Posts Comp View users profile Send private message Reply with quote
Well NTSC started here and 7.5 IRE black was done for a reason back in the 40's-50's.

Japan, Korea and Taiwan adopted NTSC in the 60's. By then TV sets and transmitters were more stable so they could start color with 0-100 IRE. The same was done in the 60's for PAL. In PAL lands they decided to obsolete all monochrome sets and start fresh with 625/50 PAL on separate channels.

In the US/Canada/Americas it was decided to maintain compatibility with the large installed base of monochrome and early color TV sets in the field. A change to 0-100 IRE would have required adjustment to all TV sets in the field. I wish they would have bit the bullet then but they didn't.

The issue is finally corrected with the conversion to digital (everything is 16-235 digital) but the legacy analog issues will remain for decades.

jrank001
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Post Posted: Jan 15, 2007 14:57 Posts Comp View users profile Send private message Reply with quote
So to save a lot of hassle for me it would probably be best to purchase an ADVC-110, (What is the difference from the 100 to the 110?) use in place of my Sony DCR-PC110, set switch to 7.5 IRE black, and capture to PC and I’m good to go. Is that correct?

Thanks
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edDV
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Post Posted: Jan 15, 2007 18:00 Posts Comp View users profile Send private message Reply with quote
jrank001 wrote:
So to save a lot of hassle for me it would probably be best to purchase an ADVC-110, (What is the difference from the 100 to the 110?) use in place of my Sony DCR-PC110, set switch to 7.5 IRE black, and capture to PC and I’m good to go. Is that correct?

Thanks


That will do it if you can spare the $230. Fixes that one problem.

bhbuckeye
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Joined: 20 Jan 2004
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Post Posted: Jan 15, 2007 19:46 Posts Comp View users profile Send private message Reply with quote
I have been curious about this for some time... Hope for some help...

I capture two ways from analog:

1) from old vhs-c thru (composite cable + stereo L/R audio) to Canapus ADVc 100...IRE set at 0--to computer thru firewire...video seems ok, is this correct?

2) I have a Sony digital trv-320 which I occasionally put an old analog 8mm tape in and output thru firewire to PC...after reading stuff above I seem to think blacks may be a bit grey...or could be my imagination? Is it doing it right automatically or do I need to set something?

I have been editing/finishing my videos with Ulead VS 7,8,9, and 10. they have various levels of filtering capability which I prefer not to mess with unless given some idiotproof advice...

Thanks in advance.

jrank001
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Joined: 02 Mar 2005
Location: MI, USA
Post Posted: Jan 15, 2007 22:16 Posts Comp View users profile Send private message Reply with quote
edDV. You said that it fixes that one problem. Could you elaborate? Is there something else? Is there a difference between the 100 and 110 units? Which would you get?

Thanks
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FulciLives
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Post Posted: Jan 15, 2007 23:36 Posts Comp View users profile Send private message Reply with quote
jrank001 wrote:
edDV. You said that it fixes that one problem. Could you elaborate? Is there something else? Is there a difference between the 100 and 110 units? Which would you get?

Thanks

I think what he is saying is this ...

Buying the Canopus ADVC-110 to fix the IRE BLACK LEVEL issue is going to fix that ONE problem AT a rather high price tag.

Since you already have DV IN via the camcorder (analog-to-digital passthrough) he is suggesting that it can be fixed afterwards by adjusting the VIDEO LEVELS correctly.

So why spend all that money for a Canopus ADVC-110 when it can be fixed easily afterwards.

At least this is how I am reading his comment(s).

- John "FulciLives" Coleman

P.S.
It can also be fixed prior to capture with the BVP4.
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FulciLives
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Post Posted: Jan 16, 2007 00:06 Posts Comp View users profile Send private message Reply with quote
edDV wrote:
As for analog "pass through" capture through the camcorder analog inputs, NTSC black level (7.5 IRE) will be incorrectly captured to digital level 32. The result is a grayish black like this example (left side). This slide shows the Vegas levels filter correcting the black level (right side). Other levels filters can also be used to lower Y (luminance) values by 7.5% lowering black from digital level 32 to 16. Vegas has the waveform monitor to help you see what is happening to luminance levels.


I just want to make sure I understand this correctly. Please bear with me and confirm or deny what I am saying. Thank you!

If I understand you correctly and I capture a NTSC source (7.5 IRE BLACK) using a device set to 0.0 IRE BLACK (such as the input of a digital camcorder using analog-to-digital pass through) then in order to "fix" the IRE "mis-match" I just have to change the SONY LEVELS in VEGAS as per your image above?

Well I have VEGAS 7.0b Build 151 (even though I admit that I barely know how to use it) and I did that. What I mean is I loaded a source video and brought up the SONY LEVELS and it looked like this at the default:



So again if I understand you correctly I just have to change the INPUT START from the above example to the following example:



And doing that ... and nothing more ... is all that is needed to fix the IRE "mis-match"?

That almost seems "too easy" if you know what I mean ieek.gif

- John "FulciLives" Coleman
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edDV
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Joined: 06 Mar 2004
Location: Northern California, USA
Post Posted: Jan 16, 2007 00:33 Posts Comp View users profile Send private message Reply with quote
bhbuckeye wrote:
I have been curious about this for some time... Hope for some help...

I capture two ways from analog:

1) from old vhs-c thru (composite cable + stereo L/R audio) to Canapus ADVc 100...IRE set at 0--to computer thru firewire...video seems ok, is this correct?


I don't have any VHS-C camcorder samples here to test. All other VHS records what it is given as an input. Normally this would be NTSC with 7.5 IRE setup. The internal VHS tuner will produce 7.5 IRE setup. In the Americas, best to assume all VHS has 7.5 IRE setup (ADVC switch in 7.5 IRE position).

With the switch in the 7.5 IRE position, VHS will look like this after capture.


With the switch set to 0 IRE the black is captured abnormally high like this.



bhbuckeye wrote:

2) I have a Sony digital trv-320 which I occasionally put an old analog 8mm tape in and output thru firewire to PC...after reading stuff above I seem to think blacks may be a bit grey...or could be my imagination? Is it doing it right automatically or do I need to set something?


My experience playing 8mm and Hi8 with a Digital8 camcorder has been very good for levels. Black gets assigned to digital level 16. White varies by recording camcorder. Prosumer models control whites better. Consumer 8mm/Hi8 camcorders tend to use all the range up to digital level 255 and often clip at 255.

Here are some examples. D8 playback camcorder was a DCR-TRV103.

Sony CCD-V5000 Hi8


Sony CCD-V5000 Hi8 (Low light)


Canon consumer Hi8 (~1991)


Sony 8mm


Last edited by edDV on Jan 16, 2007 02:24, edited 1 time in total
edDV
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Location: Northern California, USA
Post Posted: Jan 16, 2007 01:12 Posts Comp View users profile Send private message Reply with quote
jrank001 wrote:
So to save a lot of hassle for me it would probably be best to purchase an ADVC-110, (What is the difference from the 100 to the 110?) use in place of my Sony DCR-PC110, set switch to 7.5 IRE black, and capture to PC and I’m good to go. Is that correct?

Thanks


That would work without need for correction. But if you use the equipment above, you might want to experiment with the proc amp and paint a marker for -7.5% on brightness.

The 100 and 110 are very similar. The new 110 can work off computer power. Power supply is optional. The older 100 had a second set of inputs on the back which I find useful.

http://lib.store.yahoo.net/lib/computervicestore/Canopus.advc-100-ds.pdf
http://www.canopus.com/products/ADVC110/index.php

edDV
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Post Posted: Jan 16, 2007 01:16 Posts Comp View users profile Send private message Reply with quote
jrank001 wrote:
edDV. You said that it fixes that one problem. Could you elaborate? Is there something else? Is there a difference between the 100 and 110 units? Which would you get?

Thanks


It fixes the black level problem. A proc amp can also correct white levels and color shifts. For example, it would be nice to pull down the white sky levels on those consumer camcorders.

edDV
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Location: Northern California, USA
Post Posted: Jan 16, 2007 01:27 Posts Comp View users profile Send private message Reply with quote
FulciLives wrote:


And doing that ... and nothing more ... is all that is needed to fix the IRE "mis-match"?

That almost seems "too easy" if you know what I mean ieek.gif

- John "FulciLives" Coleman


That is it. If you watch the waveform monitor, it causes the black end of the video to stretch down. "Output End" does a similar stretch at the whites. The downside is all frames need to be processed slowing the render a bit.

You will see that the picture is far more sensitive to small level shifts at the black end of the scale.

PS: I described the Vegas levels filter at the bottom of this thread.
http://forum.videohelp.com/viewtopic.php?t=259098&start=90

Last edited by edDV on Jan 16, 2007 01:36, edited 2 times in total
FulciLives
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Post Posted: Jan 16, 2007 01:33 Posts Comp View users profile Send private message Reply with quote
edDV wrote:
FulciLives wrote:


And doing that ... and nothing more ... is all that is needed to fix the IRE "mis-match"?

That almost seems "too easy" if you know what I mean ieek.gif

- John "FulciLives" Coleman


That is it. If you watch the waveform monitor, it causes the black end of the video to stretch down. "Output End" does a similar stretch at the whites. The downside is all frames need to be processed slowing the render a bit.

You will see that the picture is far more sensitive to small level shifts at the black end of the scale.

Would there be a levels adjustment tool for AviSynth that works the same? I would imagine so ...

I'll have to look into it.

- John "FulciLives" Coleman
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JohnnyMalaria
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Post Posted: Jan 16, 2007 08:32 Posts Comp View users profile Send private message Reply with quote
FYI, for DV material, you can perform real-time Proc Amp adjustments during capture using our Enosoft DV Processor.
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gadgetguy
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Post Posted: Jan 16, 2007 10:35 Posts Comp View users profile Send private message Reply with quote
FulciLives wrote:
... Would there be a levels adjustment tool for AviSynth that works the same? I would imagine so ...

I'll have to look into it.

- John "FulciLives" Coleman


AviSynth has the built in Levels() filter and you can view the effects with Histogram()
I've also read that there are other, more fully featured filters available but I don't know if they would be any better for this specific issue.
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anonjon
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Post Posted: Feb 02, 2007 10:43 Posts Comp View users profile Send private message Reply with quote
Can your DVProcessor adjust the IRE levels after I've captured? How fast can it do that for me?

Also, there isn't a simple filter in Pinnacle Studio that I could use, is there?

JohnnyMalaria
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Post Posted: Feb 02, 2007 11:06 Posts Comp View users profile Send private message Reply with quote
anonjon wrote:
Can your DVProcessor adjust the IRE levels after I've captured? How fast can it do that for me?


Yes, it can.

Speed-wise: I just ran a test on a 16 second clip.

With the program visible, it took 11 seconds to process it on a 1.8GHz Pentium M laptop (single CPU).

With the program minimized, it took 7 seconds.

(Minimizing it means that the preview windows don't need to be updated).

By default, the processing will occur in real-time. You have to set the Disable seeking/navigation option to run as fast as possible.
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anonjon
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Post Posted: Feb 02, 2007 12:06 Posts Comp View users profile Send private message Reply with quote
I'm sorry to have to ask you another question, but now that I've got it installed, what exactly do I do? I can load the DV-AVI file alright, but what then? I got into the video Proc Amp, but which one do I adjust? Will adjusting this particular part change everything else? Will that be good? Thanks for responding!

JohnnyMalaria
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Post Posted: Feb 02, 2007 13:56 Posts Comp View users profile Send private message Reply with quote
Before loading the AVI, goto the main configuration settings and set the "Disable seeking/navigation" - this will prevent the software from running in real-time. Instead, it will run as fast as the computer permits(!)

Enable the Proc Amp

Open the Proc Amp settings and enable the Luma Offset slider. Leave the others disabled.

Adjust the slider to read -48.

Close the Proc Amp settings window if you want to.

Choose either Type-1 or Type-2 AVI for output.

Press the large Run button.

That's it!

Once running, you can minimize the application - that will speed things up somewhat since it doesn't have to draw the input and output video windows etc.

Note: You can save the configuration via the Save... button on the main window. Then, next time you run the program, you can Load... the same settings back (or drag-and-drop the configuration file).
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andie41
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Post Posted: Feb 02, 2007 14:28 Posts Comp View users profile Send private message Reply with quote
Quote:
FulciLives wrote:
... Would there be a levels adjustment tool for AviSynth that works the same? I would imagine so ...

I'll have to look into it.

- John "FulciLives" Coleman


AviSynth has the built in Levels() filter and you can view the effects with Histogram()
I've also read that there are other, more fully featured filters available but I don't know if they would be any better for this specific issue.

The levels filter will work, but I find using levels, as in a graphics editor, can redistribute values throughout the range -16-235, which is not always desirable. I prefer using ColorYUV(off_y=-16), perhaps with a bit of gain added, if needed.

FulciLives
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Post Posted: Feb 02, 2007 15:49 Posts Comp