IRE settings

[gshelley61]

0 IRE = 16 on the digital scale (true video black)

0-16 is reserved for below black signals

[hrlslcbr]

Ok. So the first image is not correct...
BTW, BJ_M thanks for the pluge charts

[gshelley61]

Here is a link to .pdf owners manual for a multi-format test pattern generator... it does a very good job of explaining what all the various test patterns are for and what the signal levels are supposed to be (depending on whether your display is HDTV, DTV, NTSC, etc.) There's even a primer at the end describing the display calibration process. Note that all 9 DTV output formats are at 0 IRE black level. Modern "digital ready" televisions are perfectly capable of handling 0 IRE, leaving very little reason to cling to the 7.5 IRE dark grey NTSC black level standard imposed decades ago to avoid transmission and display problems in the older equipment.

http://www.bkprecision.com/manual/1253_manua.pdf

List price is $625 on these, if you're interested in getting one...

[vhelp]

There still remains the other loose hole in this mess. DVD players.

The way I see it currently, the faults with the video recorded from
these dvd recorders, lie with either/and/or the:

* DVD Player (factory default IRE, and other color attributes not yet discussed)
* DVD Recorders (factory default IRE, etc)

The only most accurate test I've seen so far, (w/ respect to IRE and dvd
recorders) is the pic that NightWing demonstrated (I re-posted near bottom
of page 1 of this topic) how it shows a perfect transition from Original
to dvd recorder - both were the same color tone, which represented
a good reproduction process.

You can view the images again here, for an understanding:

--> Pioneer DVR-220 video recording test.. (Page 1's images)

But as I was saying, I do think that the DVD player has a play in this
problem area with IRE and color tone reproduction, and I'm sure it was
noted or suggested elsewhere's, though I'm bringing back here as a reminder,
to help keep us within perspective of the two major cause of video color tone
being reproduced accurately in the final MPEG-2 creation.

I'll use my own iLO dvd recorder for this scenario
and post my unit's capability in handling IRE color tones (in another thread)
.
The reason why I asked (earlier) what movie was used in that image posted on
page 1, was because I wanted to try the same demonstration, but with my Apex
AD-1500 player, to see if I were to come up with the same color level as the
image on page 1. (I think that a Sharp 600 dvd player was used in that test)
.
I was thinking that if my version did not match, then that would mean that
you have two items to contend with (dvd player vs. dvd recorder) both throwing
a screw loose in the process. But, if my version were to match the image on
page 1, then that would mean that you only have the one item to worry about,
..that being the dvd recorder.., which would make things much easier to finalize
a decision on which to get.. (so far, the DVR-220 is the unit to get, if you
want total reproduction in your video transfers, as the test image on page 1
proves)
.
And, I will be able to provide the same type of test images as those on
page 1 here. So, that will definately help me out in these tests, and the
many more I'll be doing in other scenarios.. thanks to my new tool.

Bare in mind, that there were only a few dvd recorders used in these tests
here. There are a lot more brands/models/makes etc., that may prove just
as good as the DVR-220 but just have to be discovered The DVR-220 could
have just ben a coensidense, if anything.

IMO, it's important to lay down the truth, as far as video detail/accuracy
goes. One good reason, is for those who *DO* want the maximum returns on
their investments. Others (like newbie's) might not care to know. That's
fine. I know I want the maximum returns in my investments. But that's me.
And these tests help bring all the pieces together in their right places.

-vhelp 3171
EDITED - 03.03.05.pm - by vhelp

[lordsmurf]

Ok. So the first image is not correct...
BTW, BJ_M thanks for the pluge charts

Well. .... it IS correct. But the "digital" can change too for the IRE. A lot of it depends on the properties of the video. edDV gave a clean explanation for it somewhere, either in this post or the one where it was original posted.

[lordsmurf]

Here's something fun...

I was recording a show this weekend, and the IRE of the cable broadcast changed THREE TIMES within the hour long block of programming. About every 2nd commercial break, it would return with a new value. These were VERY VISIBLE changes too, not slight ones you'd need a meter for.

[gshelley61]

Yeah, the black levels from broadcast and cable programming and commercials are all over the place...

[BJ_M]

Here's something fun...

I was recording a show this weekend, and the IRE of the cable broadcast changed THREE TIMES within the hour long block of programming. About every 2nd commercial break, it would return with a new value. These were VERY VISIBLE changes too, not slight ones you'd need a meter for.

i have one station like this - BRAVO CANADA , they are all over the place -- for some time they were always -10 , then jumped between -10 and 0 and 16 ..

now they seem to jump between 0 and 16 depending on the hour -- almost like one operator comes on shift and changes it one way - and the next changes it back ..

[sdsumike619]

[vhelp]

Wait, ..if I understand you ...

you have this expansive dv cam (approx $1600 bucks) that
you use to shoot your video footage with, but you use your
canon ZR-20 dv cam to transfer (capture) it to your HD..
so far, so good ??

But, your issue is with the PC monitor is not matching your TV ??

First, the picture on your pc is 0-255 color range, vs. your TV's
16-235 color range. To get a closer match, your PC monitor (your
graphics card) has to be in overlay mode in order to match more
closer to the TV source. Won't always match perfectly, due to
other machanics and things, (beyond my head) but that is part of
it.
.
Your DV cam (all dv cams I believe) are IRE 0 while most TV programs
you watch are also at IRE 0 as well. It gets confusing because DVD
is at IRE 7.5, but what screws things up is that the DVD player (not
all) follow the same formula when processing video (color space)
.
You have, IRE; Color Range; Color Conversion Formula's, etc. And,
not every brand and device follow everything perfectly. That is why
many experience oddities in the outputs these devices produce.

Anyways. If you want to match your TV, to be perfectly honest with
you. You won't be able to. Unless you have an older ATI Rage Fury
pro (ATIRFP) graphics card.. you might get closer. I have one. It
uses the older Rage Theater chip. The newer generation Graphics Cards
do not incorporate a closet match to TV output as the ATIRFP card.
But, my card get closest to TV (depending on how I set it up) But,
you won't find one, because they are virtually extinct. I spent over
4 months finding one. Anyways.

How are you processing your videos (from start to finish) that you
need to have TV and PC matching so prisicely ??

-vhelp 3263

[sdsumike619]

[gshelley61]

I happen to work in the TV advertising business, and have seen lots of professional level videography shooting and editing for commercials. Great care and lots of time is taken during the shoot as far as lighting and white balance are concerned. In a studio setting, a rather large amount of lighting is used. It appears from the frame sample that you are not using nearly enough lighting.

As far as your project monitor goes, most video editors are using high quality LCD computer screens these days, though some will still double check their work on a CRT. They never look exactly the same. Different software media players vary in how video will look on the computer screen, complicating things even more.

Probably the best thing to do is try to tweak your computer monitor with a standardized test DVD like Avia or Video Essentials. At least that way your media player and display will be OK as far as black level, luma, color...

[sdsumike619]

well see that's what I don't get, on the computer screen that frame looks dull like ther eisn't enough light, yet on the TV screen going through the preview feature in Vegas, it's bright and the brightness isn't even set high on the TV...I think there was plenty of light.. I don't know, it just looks so damn bright on the TV, u have to turn the brightness dowwwwwwn =(

[spa]

Ok. So the first image is not correct...
BTW, BJ_M thanks for the pluge charts

Well. .... it IS correct. But the "digital" can change too for the IRE. A lot of it depends on the properties of the video. edDV gave a clean explanation for it somewhere, either in this post or the one where it was original posted.

It is not correct. (I pointed that out a couple of months ago.) Black is always digital 16; there are not two standards for the digital value that is considered black.

Some players allow you to indicate what input voltage will be recorded as black (as 16 digital): 7.5 IRE or 0 IRE. There is not a fixed relationship between digital and analog values, unlike what is shown in the first graphic.

[sync]

If a MiniDV outputs 0 IRE, does that mean it looks too dark when output to NTSC tv?

[edDV]

If a MiniDV outputs 0 IRE, does that mean it looks too dark when output to NTSC tv?

Consumer MiniDV (and Digital8 ) camcorders all seem to output analog composite, S-Video and Y with zero IRE blacks and 100 IRE whites. When you play them into a TV set adjusted for 7.5 IRE blacks, the camcorder will look dark unless the TV brightness is adjusted.

I use a Philips HDTV monitor that has a good preset for 7.5-100 IRE called "movie". This works well for my Pioneer DVD player, cable box and VCRs. The TV also has a user programmable "personal" setting that I adjust for 0-100 IRE using the Vegas DV format color bar. This TV setting works perfectly with my DV camcorders, Canopus ADVC-100 (in DV format monitor mode) and the Chinese DVD players.

When you transfer the DV camcorder material to the computer, digital levels are 16 black (0 IRE on the scope) and 235 white (100 IRE). These are the correct levels for DV, DVD MPeg2 and other CCIR-601 reference inputs. When I capture TV or VHS material with my Canopus ADVC-100 (7.5 IRE input mode) it also scales to 16-235 digital levels.

I encode DVD's at these digital levels. When I play the DVD back on the Pioneer DV-363 NTSC DVD player, I get correct 7.5-100 IRE analog levels. When I play back on the Chinese players I get 0-100 IRE on the Nextbase 9000 and 0-93 IRE on the Cyberhome 300.

If I pull a VOB file from a burned DVD to the Vegas DV format timeline, I get 16 black and 235 white levels as expected. Commercial DVDs produce the same result. Everything matches on the Vegas timeline.

I think I'm finally close to a calibrated environment

Note: With the above levels everything looks good on the TV monitor but computer monitors show a bit dark when viewing the raw video (e.g. in Vegas, Premiere, ULead, VirtualDub, etc.). The media players display brighter video (e.g. Power DVD, Nero Showtime, VideoLan and Windows Media Player). The ATI MMC File player plays darker.

[spa]

When you transfer the DV camcorder material to the computer, digital levels are 16 black ... and 235 white .... These are the correct levels for DV, DVD MPeg2 and other CCIR-601 reference inputs.

LordSmurf, are you going to fix the first graphic? As edDV points out, digital black is 16, white is 235. The first graphic suggests that it might be otherwise. (The implications carry to the other slides, but it would be nice to have the first one fixed.)

Steve

[edDV]

Here are some reference docs

http://encyclopedia.lockergnome.com/s/b/CCIR_601

This one explains how YCbCr (16-235 luminance) is converted to RGB 0-255 and back using the formulas found in hardware chips.
http://www.intersil.com/data/an/an9717.pdf

A new kick ass test chart for DV and HDTV
http://www.belle-nuit.com/testchart.html

I modified the chart to show only levels info.


Here I try to relate waveform sections to the test image.

[sync]

If a MiniDV outputs 0 IRE, does that mean it looks too dark when output to NTSC tv?

Consumer MiniDV (and Digital8 ) camcorders all seem to output analog composite, S-Video and Y with zero IRE blacks and 100 IRE whites. When you play them into a TV set adjusted for 7.5 IRE blacks, the camcorder will look dark unless the TV brightness is adjusted.

So what is the thinking behind designing NTSC camcorders to output 0 IRE? I doubt that they did this thinking that consumers would some day be creating their own DVDs.

[edDV]

If a MiniDV outputs 0 IRE, does that mean it looks too dark when output to NTSC tv?

Consumer MiniDV (and Digital8 ) camcorders all seem to output analog composite, S-Video and Y with zero IRE blacks and 100 IRE whites. When you play them into a TV set adjusted for 7.5 IRE blacks, the camcorder will look dark unless the TV brightness is adjusted.

So what is the thinking behind designing NTSC camcorders to output 0 IRE? I doubt that they did this thinking that consumers would some day be creating their own DVDs.

That is a very good question. Consumer DV camcorder manufactureres have made things very difficult with these non-standard analog NTSC outputs. Same goes for the Chinese DVD players that output zero IRE NTSC blacks.

Professional DV equipment (DVCAM, DVCPro, etc.) have menu options to enable analog levels at either 7.5-100 IRE (for the Americas) or 0-100 IRE (for Japan). This is a requirement because the analog TV station environmet is 7.5-100 IRE. A consumer home theater environment has the same issues. Consumer DV equipment should be outputting 7.5-100 IRE analog levels as well. At least the mid to upper level DVD players like my Pioneer DV-363 are outputting correct 7.5-100 IRE levels.

The way it stands, we need two switchable TV monitor calibrations 7.5-100 and 0-100 IRE for analog inputs.

It is important to understand that in the digital domain, the world has universally standardized on the CCIR-601 digital levels of 16-235 for 8 bit luminance (64-940 for 10 bit). All DV, DVD, DTV (SD and HD) equipment and digital media should use these levels. The color bar above is showing the correct 8 bit digital levels.

Digital connections like IEEE-1394, SDI, DVI-HD, HDMI, etc. use 16-235 (8bit) or 64-940 (10bit) digital levels. When all equipment becomes digital, this analog levels issue will disappear. Until then, the analog interfacing issues above will apply.

[edDV]

FYI here is the 1920x1080 HDTV version of that chart on the Vegas timeline.

The important concept to take away from this is digital levels are the same for DV, DVD(MPeg2), HD-DVD(MPeg2,VC-1,H.264), HDV, DTV, HDTV and in PAL or NTSC territories.

The digital future looks consistant.

[hrlslcbr]

Note: With the above levels everything looks good on the TV monitor but computer monitors show a bit dark when viewing the raw video (e.g. in Vegas, Premiere, ULead, VirtualDub, etc.). The media players display brighter video (e.g. Power DVD, Nero Showtime, VideoLan and Windows Media Player). The ATI MMC File player plays darker.

The brighter video output might be related to the overlay mixer; If I select VMR9 in windows media player, the video looks darker.

BTW, anyone knows of a vectorscope similar to the one in vegas (but free...)?
Thank you.
edDV: how am I supposed to encode that test chart to a DVD if the possible colour range is 16-235 and the chart has colours from 0 to 255?

[gshelley61]

Digital connections like IEEE-1394, SDI, DVI-HD, HDMI, etc. use 16-235 (8bit) or 64-940 (10bit) digital levels. When all equipment becomes digital, this analog levels issue will disappear. Until then, the analog interfacing issues above will apply.

There is a slow transition occuring as we speak to eventually abandon the NTSC North America analog broadcast standard, including the 7.5 IRE black level. Many TV stations are already broadcasting ATSC digital signals, which are 0 IRE. Consumer digital camcorders are all 0 IRE. All modern television displays can handle 0 IRE blacks. In fact, digital fixed pixel displays (LCD, DLP, etc.) expect and work best when fed 0 IRE black level signals.

All analog television broadcasting in the U.S. will eventually be shut own. But edDV is right... until that transition is complete, and while there are still other 7.5 IRE sources out there (like VHS), our video gear really needs the capability to handle and properly display both 0 IRE and 7.5 IRE images.

[edDV]

players display brighter video (e.g. Power DVD, Nero Showtime, VideoLan and Windows Media Player). The ATI MMC File player plays darker.

The brighter video output might be related to the overlay mixer; If I select VMR9 in windows media player, the video looks darker.

That is true. The players use overlay and you can usually adjust overlay display properties in the display adapter "advanced" settings.

BTW, anyone knows of a vectorscope similar to the one in vegas (but free...)?
Thank you.
edDV: how am I supposed to encode that test chart to a DVD if the possible colour range is 16-235 and the chart has colours from 0 to 255?

I haven't found a free waveform monitor / vectorscope app. Tektronix has a free demo download that works only as a plug-in for AVID systems. Other than working only with AVID, the main problem is the price US$ 1,250.00
http://www.tek.com/Measurement/cgi-bin/framed.pl?Document=/Measurement/video_audio/wfm...Set=television

Here are a couple of DV standard color bars (720x480). Just import them into a DV environment as a jpg and they should show 16-235 levels.

Vegas SMPTE DV 720x480 Colorbar



BelleNuit 720x480 Test signal (I put level 16 black over the bandwidth-codec test areas)
Get the tif file and instructions at http://www.belle-nuit.com/testchart.html




For the PAL folks. Also get your tifs at http://www.belle-nuit.com/testchart.html

Vegas SMPTE DV 720x576 PAL Colorbar


fixed size in Photoshop

[hrlslcbr]

Not really 'free', is it?
Do you know of a histogram like the one in Vegas (that doesn't change the values if you select or deselect any option), just to know if the video has the proper 16-235 levels.
Cheers.

[gshelley61]

Doesn't VirtualDub have a histogram? Or, there's a filter tool for that? I don't remember...

How about this, then -

http://www.dvstreamer.com/video/index.shtml

[hrlslcbr]

Yes, there's a filter, but I want a histogram to check if my videos are ok to encode to DVD (16-235) and with the VirtualDub one you must know if the videos are 16-235 or 0-255.
I'm downloading that program. I think that's what I'm looking for.

EDIT: nope, it only works with DV video...

[Cyrax9]

Okay, I'm trying to understand this, but my eyes are about to bleed out my skull as they do every time I try to understand the "fix" to the IRE issue.

I have a Panasonic DMR-HS2 and a Panasonic DMR-E500HS, the E500HS is being used in it's "Cherry" settings (see Panasonic Recorder sticky) and I'm now learning that all they've done is shift the luma to make things "greener" in the long run.

So here's my question, let's say I "fix" the luma with a filter in Virtualdub (I don't have any non-crapware programs yet, although if I can find Avid at a decent price and if it'll work on my Machine I'll bite,) although I don't see the "green" issue. Now what? Can I just change the contrast of a video in VirtualDub to fix the IRE Settings. We know Panasonic makes things "too bright" so should I just shift the IRE to -7.5 using, say a contrast filter in Virtualdub and then frameserv to TMPGEnc+ to create a "correct" VOB? I apologize if I sound confusing but I'm trying to fix an IRE issue I understand (too bright!) while not understanding exactly how to fix it. Thank you all for your time.

[gshelley61]

Contrast controls luma (white) levels. Brightness controls black levels. If your recordings look "washed out" when played back on a regular NTSC DVD player, you may be capturing 7.5 IRE sources (VHS, TV, etc.) without compensating the black level properly. It must be mapped (stretched) down to 0 IRE for a correct digital video transfer, whether AVI or MPG.

Your Panasonic 500 should have a analog input video black level adjustment built in (it should be set to "darker" for 7.5 IRE level sources). The older Panasonic unit may not have this black level setup adjustment. Direct digital conversion of MiniDV or Digital8 tapes using the DV firewire input does not require any black level adjustment (they are already at 0 IRE to start with).

[Cyrax9]

Contrast controls luma (white) levels. Brightness controls black levels. If your recordings look "washed out" when played back on a regular NTSC DVD player, you may be capturing 7.5 IRE sources (VHS, TV, etc.) without compensating the black level properly. It must be mapped (stretched) down to 0 IRE for a correct digital video transfer, whether AVI or MPG.

Your Panasonic 500 should have a analog input video black level adjustment built in (it should be set to "darker" for 7.5 IRE level sources). The older Panasonic unit may not have this black level setup adjustment. Direct digital conversion of MiniDV or Digital8 tapes using the DV firewire input does not require any black level adjustment (they are already at 0 IRE to start with).

The sources are usually VHS or TV (Shows that'll never see a DVD release mind you.) but the problem shows up only when I play the disc in another unit, such as a PC DVD-ROM Drive.

While the E500 does have the "darker" setting I'm wary of having the "green color" issue and was wondering if there was a way I could filter the video in VirtualDub (where the Chroma isn't just shifted green.) using Chroma/Luma filtering to avoid having a "Green video" or a washed out image. Since the source is otherwise fine, the only real issue is re-encoding without the obnoxious IRE Bug.

Since the IRE issue seems to be such a big deal, has anybody attempted to code a filter for it for use with programs like Virtualdub or AVISynth that would allow you to frameserve to TMPGEnc+? I'm curious as I'd like to avoid having a Green picture or a washed out image. It's only on other units that it shows up but when it shows, it's clearly noticable.

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.

(OH and shame on me for confusing Chroma and Luma settings, I'm studying TV production and I can't believe I screwed that up!)