IRE settings

[edDV]

...

I'd like to fix the 7.5 IRE issue but I don't know if I should alter the black levels or the white levels. Contrast alteration definitely darkens the video, but I don't know if I'm giving it overkill. I'd like to fix the bug though as it seems to be a thorn in everybody's side.

I can't speak to the Panasonic DVDR recorder and I haven't tried this in Virtualdub yet but here is what needs to be done to an improberly encoded MPeg2 with black at level 32. This occurs when NTSC (tuner, vcr, laserdisc, etc.) are recorded on a DV camcorder or DVD Recorder that assumes zero setup.

Here is an analog cable channel captured through a DV camcorder. In this case the entire signal is shifted up in brightness 7-10%. You can see white clipping at 108 IRE (digital level 255).



Ideally the problem can be corrected with a negative 7-10% "brightness" shift. In other words, the entire waveform needs to be shifted down the IRE scale by 7.5 IRE nominal. This example needs a bit more shift due to incorrect cable levels as well. I'll correct it with the Vegas levels filter. Here you see the desired result. The picture shows the original on the left and the correction on the right.



Other sources (e.g. VCR, laserdisc) might be scaled 7.5-100 IRE rather than 7.5-107.5 IRE. In those cases, black needs to go down 7.5% but white (contrast) also needs to be increased 7-8%. These luminance adjustments are independent of chroma and hue.

I hope this shows what you need to do.

[vhelp]

Now this is what I was searching for in a filter. What got me started
on the idea (you beat me too it, Vegas Man) was the iLO. I've pointed
some thread on sample pics in other areas (can't remember them at this
time though) and I was thinking on a form of color shift somewhere's,
but I couldn't put my finger on it.

But, now that you have found (or seemed to, needs to be verified) if
you can figure out the formula/equation for this (probably has something
to do within the YUV -> RGB formula) we could apply it into a filter
that we could use.

Building on this idea (edDV 's latest color shift findings) I would
like to simulate it in a tool that I am working on in delphi.

@ edDV

Do you know so far, what is needed to build the formula, so that I
could try my hand at emplementing it in my tool ??

EDITED:
I was thinking that this could be applied to other varation in the IRE
levels of other equipments, and create templates for each item that
shifts the IRE.

Thanks,
-vhelp 3537

[edDV]

The normal "washed out" NTSC capture problem is caused by 7.5 IRE black being mapped to level digital level 32.

I know nothing about the green shift problem on the Panasonic. Do you have any links?

[vhelp]

If the question was directed at me, no.. I don't know of any links.
Less you ment for Cyrax9 's post here, here and here.

-vhelp 3539

[BJ_M]

might be a timing issue --

[edDV]

...

EDITED:
I was thinking that this could be applied to other varation in the IRE
levels of other equipments, and create templates for each item that
shifts the IRE.

Thanks,
-vhelp 3537

All I did was shift the Y levels down 7.5%. That shifted 7.5-107.5 IRE down to 0-100 IRE for Y.

see here too.
https://www.videohelp.com/forum/viewtopic.php?t=277980

[vhelp]

In your last post, you said..

>> All I did was shift the Y levels down 7.5%. That shifted 7.5-107.5 IRE down to
>> 0-100 IRE for Y.

But, what is the notes on the "white" levels..

>> Other sources (e.g. VCR, laserdisc) might be scaled 7.5-100 IRE rather than
>> 7.5-107.5 IRE. In those cases, black needs to go down 7.5% but white (contrast)
>> also needs to be increased 7-8%. These luminance adjustments are independent of
>> chroma and hue.

But, I'm confused about the above % setup for "white" levels. What part of
the "Y" values are being black-leveled, then white-leveled ??
(I don't see how that is possible, when adjusting the "Y" levels for black,
then white)

I ask, because I want to duplicate this (in code) with a known image, and
then compare w/ your Vegas graph, to see if the levels fall exactly in place.

Thanks for your responses.

-vhelp 3600

[edDV]

A waveform monitor is highly useful to sort this out. Depending on sources, the incoming video levels can be 7.5-100 IRE or like the cable box above 7.5-107.5 IRE. If the latter, all that is needed is a -7.5 IRE black level shift.

In the more general case the -7.5 IRE black level shift must be followed with a linear boost of Y gain to place whites up to 100IRE.

The Vegas Levels filter (Input Start setting) acts to stretch blacks down linearly without affecting white position. Input end setting stretches whites without affecting black.

I made this test pattern to show how it works. Left side is reference with 0,25,50,75 and 100IRE blocks. The Right side will have the filter applied.


Here I applied a -5%shift to black. Note that white stays put and gray levels shift down proportionately.



Here I applied a +5%shift to white. Note that black stays put and gray levels shift up proportionately.



Here I applied a -5%shift to black and +5%shift to white. In this case, 50% gray (50 IRE) stays put and white and black are stretched 5%.

[jamiemark]

For people who don't have the patience to read through all the technical mumbo-jumbo (like me), can someone list the brands of dvd recorders with the proper NTSC IRE setting. For those that don't, like Toshiba for example, how is the problem corrected (using on screen settings)? Simplest terms possible, please

[gshelley61]

For people who don't have the patience to read through all the technical mumbo-jumbo (like me), can someone list the brands of dvd recorders with the proper NTSC IRE setting. For those that don't, like Toshiba for example, how is the problem corrected (using on screen settings)? Simplest terms possible, please

It would be hard to list them all, since not every brand and model number has been purchased and tested by forum members looking for IRE problems...

Here are some of them, though (US/Canada models) -

Toshiba models starting with the 2004 product line have the black level input settings: D-R4, RD-XS34, RD-XS54, D-R5, RD-XS35, RD-XS55. Use the "Standard" input recording black level setting.

Pioneer models that I am aware of that have input black level settings: DVR-210, DVR-310, DVR-510H, DVR-220, DVR-225, DVR-320, DVR-420H, DVR-520H, DVR-531H, DVR-533H, DVR-633H, DVR-640H. Use the 7.5 IRE input recording black level setting.

Panasonic added input black level settings to all their DVD recorders starting with the DMR-E50. I'm not going to list them... just know that any newer US/Canada model Panasonic has it. Use the "Darker" input recording black level setting.

Some Sony units do, some don't. It's a mixed bag because some of their more recent models are actually just re-badged Samsungs. The RDR-HX900 does have input black level settings, I think.

There are others, of course. These are the name brand units I know of off the top of my head.

[jamiemark]

Thanks for the info. So once and for all, is 0.0 or 7.5 the CORRECT IRE setting for North America??

[gshelley61]

Thanks for the info. So once and for all, is 0.0 or 7.5 the CORRECT IRE setting for North America??

Traditional analog US/Canada NTSC has 7.5 IRE black level setup... that includes over-the-air analog broadcast, analog cable, VHS, laserdisc, etc. To properly record these sources to a digital video format like DVD, you must have 7.5 IRE input black level compensation (otherwise, the digital video/DVD will have washed out blacks when played back).

Analog video formats everywhere else in the world (including Japan NTSC) have 0 IRE as their black level standard, and therefore no black level compensation is necessary to transfer those sources to digital.

[trhouse]

The Sony GX315 and JVC DR-M10S have no black level adjustments and are both set up for IRE=0 sources so they produce slightly light images from IRE=7.5 sources like those mentioned above.

[samijubal]

Where do satellites figure into all this? I don't see any black level problems when I record. I gave up on cable a decade and a half ago or so.

[gshelley61]

Where do satellites figure into all this? I don't see any black level problems when I record. I gave up on cable a decade and a half ago or so.

The s-video and composite video outputs of satellite and cable boxes should have 7.5 IRE black level setup in the US and Canada, just like any other analog NTSC device.

[StuR]

I've breifly scanned through this post as 'IRE errors' is a subject thats come up during DVDRW reviews and now I've noticed the sticky.
Can someone please tell me that it's not an issue for PAL systems (in the UK), please so I can have one less thing to think about .

[edDV]

I've breifly scanned through this post as 'IRE errors' is a subject thats come up during DVDRW reviews and now I've noticed the sticky.
Can someone please tell me that it's not an issue for PAL systems (in the UK), please so I can have one less thing to think about .

PAL does not have the 7.5 IRE black issues. PAL uses 0 IRE for black and 100 IRE for white.
It only becomes an issue for PAL when the source is analog NTSC.

ITU-REC601 digital levels (DV, DVD, digital broadcasting, etc.) are 16 for black and 235 for white worldwide.

[StuR]

woo hoo. Thanks.
So... PAL home vhs>DVD will not give IRE errors, and all this talk of IRE errors in dvd recorders like JVC's, Toshiba and Pioneer can be ignored as it's a US (NTSC) problem. Strange that Toshiba allow input brightness adjust, and Pioneer Black/White levels adj. not mentioning Sat/Hue.
Do I take it this is a little bonus feature and not crucial. Firsts rec. was Philips DVDR3305 which over brightned incoming signal (even best Q. RGB scart) so thought this was an issue.
Current rec. - Sony GX300 - balance O.K. but made sure it could be adjusted.

[jjeff]

Wow this thread hasn't changed in over 3 years but I thought I'd ad this recent information for anybody looking at a Panasonic international DVDR. I'm not sure how other international DVDRs act(Pioneer etc.) so I can only say this about Panasonics.
Because internationals are not meant for US use(I'll say US but in reality this effects Canada and I believe Mexico as well) they do not conform to the US +7.5 IRE standard for composite/S-video blacks. Instead they are expecting a 0 IRE from all inputs and also don't add 7.5 IRE to outputs. What this means is if you feed such a recorder a +7.5 IRE input(from basically any US line output(composite/S-video) device) you'll get DVDs that are +7.5 IRE too bright(out of spec). If you play a standard DVD in such a international recorder(from it's S-video or composite outputs) the output will be too dark for US TVs(by 7.5 IRE) because it doesn't add 7.5 to the DVD output(which our TVs are expecting), HDMI or component outputs will be fine.
http://www.avsforum.com/avs-vb/showthread.php?t=1269371 This AVS thread talks more about using such a recorder in the US. It can be done but has it's limitations.
I wouldn't really call this a bug as such(like the HS2) since the recorder is just doing what it was designed to do and the rest of the world does for IRE.

[edDV]

Wow this thread hasn't changed in over 3 years but I thought I'd ad this recent information for anybody looking at a Panasonic international DVDR. I'm not sure how other international DVDRs act(Pioneer etc.) so I can only say this about Panasonics.
Because internationals are not meant for US use(I'll say US but in reality this effects Canada and I believe Mexico as well) they do not conform to the US +7.5 IRE standard for composite/S-video blacks. Instead they are expecting a 0 IRE from all inputs and also don't add 7.5 IRE to outputs. What this means is if you feed such a recorder a +7.5 IRE input(from basically any US line output(composite/S-video) device) you'll get DVDs that are +7.5 IRE too bright(out of spec). If you play a standard DVD in such a international recorder(from it's S-video or composite outputs) the output will be too dark for US TVs(by 7.5 IRE) because it doesn't add 7.5 to the DVD output(which our TVs are expecting), HDMI or component outputs will be fine.
http://www.avsforum.com/avs-vb/showthread.php?t=1269371 This AVS thread talks more about using such a recorder in the US. It can be done but has it's limitations.
I wouldn't really call this a bug as such(like the HS2) since the recorder is just doing what it was designed to do and the rest of the world does for IRE.

7.5-100 IRE NTSC applies to North and South America. Even Brazil's PAL-M and Argentina's PAL-N use setup, or at least they did. I'm not certain whether Taiwan, Korea, Philippines, etc currently use setup for analog NTSC.

If such an "international DVD recorder" has an analog NTSC tuner, it should have a 0 or 7.5 setup menu selection. Otherwise it would record incorrectly in the Americas.

A curious anomaly is if you record a 7.5-100 IRE NTSC signal to a 0 IRE DVD recorder or camcorder, it will make a non-standard 32-255 digital recording, but if you play it back on the same machine it will play out 7.5-100 IRE from the analog outputs. If you play it on an NTSC DVD player, it will play 15-107.5 IRE (washed out) from either the analog or digital outputs.

[jjeff]

Panasonic international DVDRs have no NTSC tuner but will record just fine from a line input if set to NTSC in the setup. I say record just fine, that is if you feed it a 0 IRE signal and not a 7.5 which most US devices send out from their composite/S-video outputs.
On your last point, yes that's true which is why I believe people may not notice the problem at first.
edDV, I was surprised to see how often your name came up in this thread years ago. You certainly seem to have a good hand on the IRE standard and those old posts really helped me understand it better myself

[LCSHG]

Jjeff
You might be interested in the site below
I think the picture of the rocks may point out the issue better than graphs
http://www.glennchan.info/articles/technical/setup/75IREsetup.html

[Scott16]

I have a lot of DVD-Rams with video I recorded on my Panasonic DVD Recorders over the years are there any free video editors that will convert the
video on them from IRE-0 to IRE-7.5?
all the DVD-Rams files are .VRO files (the older DVD Recorders) or .VOB files (the current DVD recorders).

Interestingly when I uploaded one of the videos to Youtube I used their video enhancement feature and it automatically repaired the video (not sure if it actually fixed the file or if it just adjusted the picture on playback but it does look 100 times better than it did before.