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-   -   Brightess / Gamma Setting? (https://www.digitalfaq.com/forum/video-capture/198-brightess-gamma-setting.html)

Jerome 05-05-2005 01:07 PM

I wanted to see if you had any recommendations for setting the Brightness or Gamma while recording with an All-In-Wonder (I have a 9800AIW Pro). After making a couple DVDs with the default settings, it was obvious that the picture was way too dark.

I've gone through a pretty tedious method of first calibrating my TV with the Sound & Vision version of Home Theater Tune-Up by Ovation (had done this anyway) and then recording the same test patterns with the AIW, burning a DVD, and then playing it on the TV again. (I knew the computer monitor wouldn't match the TV.) Each time, I only changed the Brightness setting, until I got an acceptable match. I ended up directly modifying the registry settings for accuracy, and using a decimal value of 154, instead of the default 128. Color, Contrast, and Tint seemed to check out fine.

I've since read some of your other posts which suggest changing the Gamma setting instead. I've done a little reading on the subject, and though I don't pretend to understand completely, I wonder if that was the route I should have taken? Did changing Brightness, and therefore really changing the black level (?) give an improper luminosity scale? Would changing only the Gamma better match the response curve of the AIW to the NTSC standard (hope that makes sense), and do you have a preferred setting? Or is this basically unknown at this time?

Thanks!
Jerome

admin 05-05-2005 02:37 PM

You never really want to mess with the brightness. That adjust the luminance, and you lose your proper dark values. Especially when the IRE from the DVD player is added to the picture.

You want to adjust the gamma curve of the image, which essentially redefines the medium tonal quality.

Most of the time, my gamma settings is about 50% from the left, maybe 40% from the left depending on the channel or VHS tape:

http://www.digitalfaq.com/forum/uplo...n/atigamma.gif

http://www.digitalfaq.com/forum/uplo.../atigamma2.gif

Be sure not to drop the darks too much, and remember that the computer and tv are different. Also, cheap DVD players are known to have incorrect IRE, which can make images too dark or have too much contrast. Set to non-USA standards.

By default, this setting should be near the middle, where I usually set it. But, as we all know, ATI doesn't do many things right, in terms of "default" software settings.

These are essentially "proc amp" controls, and the default settings is a (-) negative value (darker than source). Whether "true normal" is 40% or 50% from the left is for us to just guess. Do what looks good.


Jerome 05-06-2005 05:03 PM

Thanks - that's what I was beginning to think, about the possible faults in adjusting Brightness.

I'm now going to go through my whole "calibration" procedure again, this time for Gamma. I'll let you know what I come up with.

Now you've gone and brought up another possible problem for me http://www.digitalfaq.com/forum/smileys/smiley2.gif, but I don't think that's the case. My little Daewoo DVDS150 DVD player was fairly cheap, but it's worked quite well for me. I really don't know if it has a non-standard IRE output (do you?). It seems okay to me - the white level isn't washed out or lacking detail. (Boy, learning stuff all the time with this hobby!)




admin 05-06-2005 08:09 PM

It really just depends. I find that most players made in China, and that also have no "black level" or "picture" modes, are IRE 0, which is wrong for the USA.

USA is IRE 7.5.

Then again, standards are all over the place. Even tv stations, cable, satellite, etc ... are often incorrect.

Just do what looks good, use what looks good. It should NOT be overly dark, nor overly "contrasty".


Jerome 05-06-2005 09:22 PM

I seem to have hit a snag, trying to record at various gamma settings.

Right now, changing gamma varies the viewed picture quite nicely. But, immediately upon starting to record, the gamma value seems to reset to its default of zero. I see it in ATI TV window and later when I view the recorded video. When I stop the recording, the desired gamma value is restored to whatever I'd set it, and therefor the picture brightness.

I was previously able to make changes that "stuck" in the registry here:
HKEY_CURRENT_USER\Software\ATI Technologies\MultiMedia\Features\TV\Video\(Analog TV Tuner;Composite;S-Video) "Bright"=000000xx

And I thought:
HKEY_CURRENT_USER\Software\ATI Technologies\MultiMedia\ResMngr\ "Gamma"=000000xx

would do the trick for gamma, but it only seems to change the "viewed" picture, not the recorded material. Forgive me if I'm missing something - it's late and I'm exhausted, and I hope this makes sense - is there a solution to this?

Thanks,
Jerome

admin 05-06-2005 10:53 PM

I've never had to alter the registry for ATI MMC.
What MMC are you using?



Jerome 05-07-2005 04:29 AM

Okay, I'm using MMC 9.03.

The only reason I'm changing values in the registry is so that I can get exact reproducable settings. Back when I was trying to calibrate using the Brightness slider, I just found it to be too coarse.

The real problem I have now, whether I change the Gamma setting in the registry or using the slider, is that it doesn't record at that Gamma. I can have a nice bright picture displayed, but as soon as the recording starts, it always bumps down to the default minimum Gamma setting. (Near as I can tell - can't actually access and see the setting while recording.) As soon as I stop recording, boom - gamma goes right back to whatever it was previously set at.

I'm just wondering now if there's another registry setting that would fix this, or even some obscure MMC setting (or bug) that I'm missing.


P.S. This is off-topic, but is the "watch topic" function still working? I'm not getting email notifications of posts. - Jerome

admin 05-07-2005 09:04 PM

I had a feeling you may say ATI MMC 9.03, as it has garnered several proc amp control complaints in past months. I'm going to have to suggest you downgrade to ATI MMC 8.7 or 9.02 for best results.

.
.
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As far as the "watch topic" function, yes, it works. But you have to have your e-mail address updating correctly and the feature enabled. I enable the feature by default when I setup membership. Click on the "PROFILE" button at the bottom of any of your posts, and it brings up a pop-up window. Click the "EDIT" button at the bottom of that window. You can then alter your settings, update e-mail, change password, etc.

I don't use this myself, but this may be of interest to you:
http://www.digitalfaq.com/forum/emai...ubscriptions.a sp

I just did a test, clicked the "WATCH THIS TOPIC" at the bottom of this page, and it added itself into that list, found in the above link. So yes, it works.





Jerome 05-08-2005 04:09 PM

I must say that this Gamma glitch has become incredibly frustrating.

Today I went to work, where I have a AIW 9700, just to see how it compared. Wouldn't you know, it has MMC 9.03 installed, and the Gamma setting works as it should - no problem with it changing during recording.

So, I just spent many hours uninstalling and reinstalling different driver versions on my AIW 9800, to no avail whatsoever. Even after completely removing everything and just installing the original CD drivers and MMC 8.5, it still doesn't work properly.

I'll keep trying, but just had the need to vent a little. http://www.digitalfaq.com/forum/smileys/smiley2.gif

Jerome 05-28-2005 04:58 PM

In case anyone has been holding their breath, I thought I'd give an update.http://www.digitalfaq.com/forum/smileys/smiley2.gif

Still absolutely no luck fixing this Gamma reset problem. Starting with completely clean installs, I've been up and down through the various driver versions. I've swapped my AIW9800 with the AIW9700 I can borrow, done a clean install, and had the same result.

I've had nothing but the stock answers from ATI - "must be an installation error" or "try the new drivers". I just wrote them again that maybe there's an obscure incompatibility with my motherboard (ASUS A7N8X), and would they please consider this? http://www.digitalfaq.com/forum/smileys/smiley2.gif

Anyway, one thing that made me wonder about is the coarseness of the Gamma setting itself. I've obviously been playing aroung with it a lot, and there only seems to be seven different levels. If you move the slider form one extreme to the other, the picture brightness only changes six times. Adding one, for the beginning brightness level, gives only seven real settings. Has anyone else noticed this??

Hadn't gotten around to it in a meaningful way before, but I wanted to thank you sincerely LS, because you've truly (I hope!) raised my consciousness in the video world.http://www.digitalfaq.com/forum/smileys/smiley1.gif

admin 05-28-2005 05:27 PM

I've noticed the incremental settings. If memory serves right, some years back, on a MMC 7.x version, there were tick marks for them. But that disappeared and never came back. I can only guess it was an oversight.

I have no idea why you get the gamme setting errors. You may well be on to something the motherboard issues, though I'm not sure WHY that would be the case. Then again, I've seen weirder.

Jerome 09-17-2005 10:53 AM

Hello again. I'm pleasantly surprised that my account is still active!http://www.digitalfaq.com/forum/smileys/smiley1.gif

I've spent the last few months struggling with my Gamma Problem, as I've not-too-fondly started calling it. Briefly, no matter what setting I used, gamma would reset to the default minimum as soon as recording was started, and then immediately revert to my original setting when recording stopped. Not a happy situation. I must have put a hundred hours into hardware swaps and Windows and ATI software re-installations. This has been an ordeal spanning testing on four different motherboards and my original AIW9800, an AIW9700, and an RMA'd AIW9800 on the hardware side, and multiple clean installs of Windows XP, the hardware drivers, and dozens of permutations of the ATI software. Many times I almost gave up.

I've finally fixed it, with zero credit to the ATI customer care guys. Their last advice was to "reinstall Windows", as if they hadn't read any one of my last dozen or so posts to them.http://www.digitalfaq.com/forum/smileys/smiley7.gifI still don't know the exact cause of the problem, but I now know how to avoid it. I've written ATI (again) about this - maybe now they'll come up with an explanation or fix, but I'm not holding my breath. The simple (in hindsight) technique I used was to allow only the video and WDM drivers included in Win XP Service Pack 2 to be installed, and then install only MDAC/DAO 9.1 and MMC 9.03. Upgrading the drivers by installing the Control Panel package breaks it again. Even using the original ATI installation CD gives a broken gamma control! This leaves me with reduced functionality, but I don't care - I can finally record decent video.

With the experience I had, I'm really amazed that seemingly I am the only person in the entire world who has had this problem! I can reproduce it at the drop of a hat, but absolutely no one else seems to be able to do so. Unbelievable. Maybe some people just don't notice it happening.

Anyway, I thought I'd pass on this little bit of good news.

Thanks for trying to help.

Jerome


admin 09-17-2005 11:56 AM

The sad truth about computers is sometimes flaws are system-based and so only a couple people with a certain configuration of software or hardware have the problem.

But it's good to know you found a fix, and thanks for sharing that here. It may be useful to somebody else down the road.



Jerome 10-12-2005 05:51 PM

Hi LS,

Well, it turns out that I did not find a fix after all. A couple days after writing last I finally did some A/B comparisons of the recordings, and there was no difference - all were dark. I had wrongly assumed that what I was seeing on-screen was what I would get as a final result. It was the case for all other settings, but not for Gamma.

I've had another go-round with ATI support, and their last suggestion was to use their VCR format for recording, instead of MPEG. "According to our product specialist, only when you are using vcr format can you use the gamma and colour settings for recording. From there you can then export the .vcr file to MPEG2." Okay, it sounded bizarre and inconvenient, but at least I had a glimmer of hope, until I tried it.

I am now completely disillusioned with this setup. I like the AIW a lot, but I'm just not going to waste any more time trying to make it work properly. I'm seriously considering another capture card, a Hauppauge PVR-150. First, what is your opinion of this card? Second, do you think I'll be able to install one successfully, even though the AIW will remain in my system until I decide to do a video-only upgrade?

Thanks - Jerome

admin 10-13-2005 04:45 AM

Whoever you spoke to at ATI tech support is a moron. Their VCR format is nothing more than a specified output, an aberration of MPEG-2. Various outputs would not have any effect on the active proc amp controls, as that happens far in advance of the saved file. Bizarre and inconvenient about sums it up.

I really wish your ATI card worked. It should work. I have no idea why it won't work. It may be a hardware conflict of some sort, but I have no idea why. Maybe even a Windows problem (are you using Windows 2000, by chance?).

You do not want a Hauppauge PVR-150 card. Those have audio problems. A Hauppauge PVR-250 would be alright, but that lacks a tuner. If you want a tuner too, then get the Hauppauge PVR-350. Those cards work fine.

You could always just invest in a proc amp for $40-50. Correct the picture in hardware before it ever gets to the computer. That may be cheaper, and would provide the same, if not better, results. A Vidicraft unit, which uses composite cables (not s-video or coax) would do the trick.

And I'm assuming you've record video at the native gamma setting, burn it, and played it on tv? Was it still dark then too?


Jerome 10-13-2005 08:15 AM

http://www.digitalfaq.com/forum/smileys/smiley1.gif Yeah, the VCR thing really sounded like they were grabbing at straws.

I really wish this card worked too. As I said, I like it a lot otherwise, but I'm at the end of the road. I've just been through so many different hardware platforms and clean Windows XP and ATI software installs that it comes down to the only two things in common: their software and AMD processors, and I think it's their software. At this point I'd really like to see a working system - anyone's working system, with captures taken with different gamma settings that show a change in the recordings. I've gotten to where I wonder if this adjustment really works at all, for anybody.http://www.digitalfaq.com/forum/smileys/smiley5.gif

About the Hauppauge cards - I think you've made a small mistake about the PVR-250. According to their product comparison chart, it actually does have a tuner:
http://www.hauppauge.com/pages/compare_pvr.html

I was thinking of the 150 because of: "New low cost design. Same video quality as the WinTV-PVR-250 at a lower cost. Includes IR Blaster to control your set top box". From a little reading, they've saved money by consolidating the separate audio and video chips used in the 250 and 350 into one chip. Is this why you think it has audio problems? Otherwise, the 150 seems to have the same features as the 250. The 350 is overkill for me - I don't need an FM tuner or an MPEG decoder output.

Thanks for the advice on a Vidicraft Proc Amp, but I'm not too excited about that path right now. I'll keep it in mind, though.

http://www.digitalfaq.com/forum/smileys/smiley1.gif And yes, I've done all that you mention last. That's really how I realized I had a problem. I figured I wouldn't get a great picture on a computer monitor and lived with the dark images, but after repeatedly seeing it on my DVDs played on a TV it finally started to dawn on me that something was wrong. Gamma didn't work, so I just satisfied myself with adjusting Brightness, until you straightened me out.

admin 10-13-2005 09:07 AM

The 150 has well documented audio issue and complaints on numerous forums. I've seen and heard the error first hand, you don't want to mess with that. It over or under modulates, giving you hum/hiss in the audio, or over-the-top cracks in the audio. It's terrible.

There is something difference between the 250 and 350. I may be thinking of the output, not the tuner.

I would get the 250 if you buy a Hauppauge.


Jerome 10-13-2005 09:51 AM

Thanks! Sorry I've been running this a little off-topic.

I appreciate the advice about the 250 and especially the 150. You're right - I sure don't want to mess with an audio problem as bad as you describe.

I'll get the 250, unless there's a comparable alternative out there you'd recommend? All I want right now is something with a tuner, S- and Composite inputs, and hardware MPEG encoding.

admin 10-13-2005 10:48 AM

I would not really suggest anything other than the Hauppauge or the ATI AIW cards.


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