FAQ: How to correct luminance levels - Page 14

Keiyakusha · 27th September 2009, 16:24

thewebchat
AFAIK input range is something that can be changed only by reencoding and output is the range after decoding, which can be TV or PC depending on circumstances. So all is right here.

EDIT:
For example when using CoreAVC and video is h264 with any range and properly set --fullrange flag (if needed), then it's shouldn't be necessary to change anything regardless of input content. But in other cases if you have fullrange yuv as input - you should correct levels. I believe MPC-HC with EVR-CP renderer allows correcting levels in renderer (not using shader). And Haali's renderer too.

thewebchat · 27th September 2009, 16:47

I don't understand what you are trying to say. EVR/CP will only convert using TV->PC range expansion. I don't even know what the option in MPC-HC to change the "output range" does, as it produces no difference and the output is RGB (converted with TV-PC of course) anyway. It is true that CoreAVC, on detecting the full range flag, will clamp the output levels to 16-235 when passing the decoded stream to the renderer. However, like I said, this removes 14.2% of the detail in the stream. Is there a way to force EVR-CP to use PC->PC for RGB conversion.

Keiyakusha · 27th September 2009, 16:55

Ahh I see what do you mean. Well I not sure what output range in EVR-CP does, but I thought its something like:
0-255 -> convert to PC
16-235 -> do not convert anything

Jackie · 5th October 2009, 18:05

Hi,

just for my understanding: I have an ATI HD 4850 and a Samsung LCD TV that can be set to limited and full range.

I can use both 0-255 and 16-235 setups correctly, the question is which one is the very best. To my understanding, most studio material is produced using YCbCR 4:2:2 with 16-235, ist that right? So isn't that the best setting to chose if your components all support it?

mark0077 · 5th October 2009, 18:12

Will you use your PC for anything else, like webpages, desktop work etc. If so, full range is the way to go for your tv setting, desktop set to output full range. ATI drivers should do 16-235 -> 0-255 for you automatically, if not some ATI users will surely be able to help with that.

If all you use is 16-235 then you can set everything to limited range, but I don't see any advantage, your TV is going to have to do a conversion from 16-235 to 0-255 internally anyways. At the end of the day your LCD will be outputting 0-255, so its a matter of whether you want your TV doing the 16-235 conversion, or your PC. I trust my Pc much more than my own Samsung TV, even for things like de-interlacing. Series 9 does a horrible job compared to software de-interlacers like yadif, and much much worse again than hardware de-interlacers.

Personally I would set your TV to full range, and output 0-255 from PC, just verify your ATI drivers are doing 16-235 conversion for you when watching movies. (I use ffdshow for this rather than my graphics card, both should do a great job)

Jackie · 5th October 2009, 18:29

Quote:

Originally Posted by mark0077

Will you use your PC for anything else, like webpages, desktop work etc. If so, full range is the way to go for your tv setting, desktop set to output full range. ATI drivers should do 16-235 -> 0-255 for you automatically, if not some ATI users will surely be able to help with that.

If all you use is 16-235 then you can set everything to limited range, but I don't see any advantage, your TV is going to have to do a conversion from 16-235 to 0-255 internally anyways. At the end of the day your LCD will be outputting 0-255, so its a matter of whether you want your TV doing the 16-235 conversion, or your PC. I trust my Pc much more than my own Samsung TV, even for things like de-interlacing. Series 9 does a horrible job compared to software de-interlacers like yadif, and much much worse again than hardware de-interlacers.

Personally I would set your TV to full range, and output 0-255 from PC, just verify your ATI drivers are doing 16-235 conversion for you when watching movies. (I use ffdshow for this rather than my graphics card, both should do a great job)

<zhanThanks alot, I understand your arguments, so I have set my ATI to FULL RGB 0-255, but my Samsung TV will display any colors below 16 from the test File BLACK_LEVEL_TEST_CLIP_HD.mp4 (see first page of this thread, I hace downloaded it there) as black. To my understanding, all black levels from 1-16 should also be seperately visible is that right?

This only happens when I set my Samsung TV (A LE40F86) to xvyCC "on", then everything looks right, but when xvyCC is off, these black levels are cut. To my understanding, this is not the purpose of xvyCC, so what's wrong here?

mark0077 · 5th October 2009, 18:32

Well if your watching content thats 16-235 (which is like 99% of material out there), you shouldn't be able to see the detail below 16 or above 235. Your graphics drivers should scale 16-235 to 0-255 removing those details.

If it doesn't you'll need to figure out what setting in your drivers does this, or you can use ffdshow and set it to output RGB32, and it will then instead do this conversion for you. Your graphics card in this case won't do any conversions as its getting RGB32. This is what I use and get excellent conversions. There are various threads about the settings to use here but enabling "dithering" and "high quality yv12 to rgb conversion" enabled in the Output options in ffdshow should almost do the trick.

Jackie · 5th October 2009, 18:53

Thanks alot mark, I think I have figured out how it works now: I have set Full RGB as Pixel Format, and my Samsung TVs HDMI settings to "normal" instead of "low", I think now the results are correct. Can anybody tell me in detail what "HDMI setting" normal/low on Samsung LCD does, since it is not really clear from the manual.

mark0077 · 5th October 2009, 19:02

The normal / low from using my own TV is

Normal - Assume input is 0-255, basically just outputs what its given to screen
Low - Assume input is 16-235, therefore converts internally to 0-255 to give correct contrast

iSeries · 12th October 2009, 13:54

Hi,

I'm having trouble getting Full RGB from my ATI 4550 to my LCD TV. In the ATI settings, it was set to output Full RGB (0-255) by default. However playback of a calibration file shows that nothing below 16 is being displayed (no matter how high I set Brightness), and nothing above 235 is being displayed (no matter how low I set the contrast). Also I had to set the brightness on my TV to a ludicrous level (something like 75) just to get 17-25 to flash. I've tried 'forcing' Full RGB through ffdshow as per the advice here but no luck. The only way I can get my TV to display 0-255 is by setting ffdshow to 16-235 and setting YCbCr 4:4:4 in the ATI control utility.

Is sending YCbCr 4:4:4 and letting my TV do the RGB conversion just as good as sending RGB?

ACrowley · 17th October 2009, 18:39

anybody use Windows 7 ? Looks like W7 outputs correct liminacne Levels by default. I dont have to adjust it manually ,for all codecs/formats. All Streams are displayed as 0-255, from all Decoders with EVR
I use a ATI HD4870.

madshi · 17th October 2009, 19:15

Quote:

Originally Posted by ACrowley

anybody use Windows 7 ? Looks like W7 outputs correct liminacne Levels by default. I dont have to adjust it manually ,for all codecs/formats. All Streams are displayed as 0-255, from all Decoders with EVR
I use a ATI HD4870.

<sigh> 0-255 is neither correct nor incorrect. It's correct for some displays and incorrect for other displays.

ACrowley · 18th October 2009, 09:19

Quote:

Originally Posted by madshi

<sigh> 0-255 is neither correct nor incorrect. It's correct for some displays and incorrect for other displays.

ofcourse..but its usually correct for TFT PC Displays /PC Playback

madshi · 18th October 2009, 09:24

Quote:

Originally Posted by ACrowley

ofcourse..but its usually correct for TFT PC Displays /PC Playback

Yes, and usually incorrect for home cinema projectors, plasma displays etc.

Mercury_22 · 18th October 2009, 17:48

Quote:

Originally Posted by iSeries

Hi,

I'm having trouble getting Full RGB from my ATI 4550 to my LCD TV. In the ATI settings, it was set to output Full RGB (0-255) by default. However playback of a calibration file shows that nothing below 16 is being displayed (no matter how high I set Brightness), and nothing above 235 is being displayed (no matter how low I set the contrast). Also I had to set the brightness on my TV to a ludicrous level (something like 75) just to get 17-25 to flash. I've tried 'forcing' Full RGB through ffdshow as per the advice here but no luck. The only way I can get my TV to display 0-255 is by setting ffdshow to 16-235 and setting YCbCr 4:4:4 in the ATI control utility.

Is sending YCbCr 4:4:4 and letting my TV do the RGB conversion just as good as sending RGB?

Same problem here but I solved it by manually adjusting the settings in AVIVOS's "Basic Colors" : Brightness and Contrast !
I'm using full RGB and Brightness = 1 and Contrast = 98 And VERY IMPORTANT DISABLE DYNAMIC CONTRAST in "All Settings"

Delerue · 9th December 2009, 02:57

I found a way to workaround the problem with Nvidia drivers after 180.42 version that bugs the black color with VMR 7 Windowed render. The problem seems to be with 'nvapi.dll' (or 'nvapi64.dll' if you use Windows x64). This DLL handles the interface of the Nvidia Control Panel, but not the driver itself. So, you can use a new driver with an old interface and everything works flawlessly. I'm sharing with you both x32 and x64 version of this DLL from ForceWare 180.42. Just find the '%windir%\system32' folder, make a backup of the current 'nvapi.dll' (or 'nvapi64.dll' if you use Windows x64) and finally copy the version below. I hope it'll help someone.

http://www.mediafire.com/?lnniezmnj1y

ears1991 · 17th December 2009, 22:34

HALLELUJAH 9.12 fixes the cruddy luminance levels at last!!!!
if im right in saying its been broken since 9.2, that makes it that it took ati 10 months to fix... nice

THX-UltraII · 21st January 2010, 16:19

I just switched from my good old ATI 4350 to a new HD 5670 to finally have to possibility to bitstream HD audio.

However, what I already knew, the new 5xxx series has a bug. When you select 'Pixel Format PC Standard (Full RGB)' it is NOT sending this out actually. With the 4xxx series this was ok and I always had my projector set to 'Enhanced'. But now with the 5xxx series this doesn t work anymore. I already contacted ATI and they are aware of the problem and it will take a few drivers to fix it.

So I now set my projector back from 'Enhanced' to 'Normal', do I just have to choose Limited RGB now? Will the BTB and WTW be ok this way?

27th September 2009, 16:24	#261 \| Link
Keiyakusha 契約者 Join Date: Jun 2008 Posts: 1,576	thewebchat AFAIK input range is something that can be changed only by reencoding and output is the range after decoding, which can be TV or PC depending on circumstances. So all is right here. EDIT: For example when using CoreAVC and video is h264 with any range and properly set --fullrange flag (if needed), then it's shouldn't be necessary to change anything regardless of input content. But in other cases if you have fullrange yuv as input - you should correct levels. I believe MPC-HC with EVR-CP renderer allows correcting levels in renderer (not using shader). And Haali's renderer too. Last edited by Keiyakusha; 27th September 2009 at 16:34.

17th October 2009, 18:39	#271 \| Link
ACrowley Registered User Join Date: Apr 2006 Posts: 1,008	anybody use Windows 7 ? Looks like W7 outputs correct liminacne Levels by default. I dont have to adjust it manually ,for all codecs/formats. All Streams are displayed as 0-255, from all Decoders with EVR I use a ATI HD4870. Last edited by ACrowley; 17th October 2009 at 18:46.

9th December 2009, 02:57	#276 \| Link
Delerue Registered User Join Date: Jun 2005 Posts: 365	I found a way to workaround the problem with Nvidia drivers after 180.42 version that bugs the black color with VMR 7 Windowed render. The problem seems to be with 'nvapi.dll' (or 'nvapi64.dll' if you use Windows x64). This DLL handles the interface of the Nvidia Control Panel, but not the driver itself. So, you can use a new driver with an old interface and everything works flawlessly. I'm sharing with you both x32 and x64 version of this DLL from ForceWare 180.42. Just find the '%windir%\system32' folder, make a backup of the current 'nvapi.dll' (or 'nvapi64.dll' if you use Windows x64) and finally copy the version below. I hope it'll help someone. http://www.mediafire.com/?lnniezmnj1y Last edited by Delerue; 9th December 2009 at 02:59.

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27th September 2009, 16:47	#262 \| Link
thewebchat Advanced Blogging Join Date: May 2009 Posts: 480	I don't understand what you are trying to say. EVR/CP will only convert using TV->PC range expansion. I don't even know what the option in MPC-HC to change the "output range" does, as it produces no difference and the output is RGB (converted with TV-PC of course) anyway. It is true that CoreAVC, on detecting the full range flag, will clamp the output levels to 16-235 when passing the decoded stream to the renderer. However, like I said, this removes 14.2% of the detail in the stream. Is there a way to force EVR-CP to use PC->PC for RGB conversion.

27th September 2009, 16:55	#263 \| Link
Keiyakusha 契約者 Join Date: Jun 2008 Posts: 1,576	Ahh I see what do you mean. Well I not sure what output range in EVR-CP does, but I thought its something like: 0-255 -> convert to PC 16-235 -> do not convert anything

5th October 2009, 18:05	#264 \| Link
Jackie Registered User Join Date: Dec 2001 Posts: 48	Hi, just for my understanding: I have an ATI HD 4850 and a Samsung LCD TV that can be set to limited and full range. I can use both 0-255 and 16-235 setups correctly, the question is which one is the very best. To my understanding, most studio material is produced using YCbCR 4:2:2 with 16-235, ist that right? So isn't that the best setting to chose if your components all support it?

5th October 2009, 18:12	#265 \| Link
mark0077 Registered User Join Date: Apr 2008 Posts: 1,106	Will you use your PC for anything else, like webpages, desktop work etc. If so, full range is the way to go for your tv setting, desktop set to output full range. ATI drivers should do 16-235 -> 0-255 for you automatically, if not some ATI users will surely be able to help with that. If all you use is 16-235 then you can set everything to limited range, but I don't see any advantage, your TV is going to have to do a conversion from 16-235 to 0-255 internally anyways. At the end of the day your LCD will be outputting 0-255, so its a matter of whether you want your TV doing the 16-235 conversion, or your PC. I trust my Pc much more than my own Samsung TV, even for things like de-interlacing. Series 9 does a horrible job compared to software de-interlacers like yadif, and much much worse again than hardware de-interlacers. Personally I would set your TV to full range, and output 0-255 from PC, just verify your ATI drivers are doing 16-235 conversion for you when watching movies. (I use ffdshow for this rather than my graphics card, both should do a great job)

5th October 2009, 18:32	#267 \| Link
mark0077 Registered User Join Date: Apr 2008 Posts: 1,106	Well if your watching content thats 16-235 (which is like 99% of material out there), you shouldn't be able to see the detail below 16 or above 235. Your graphics drivers should scale 16-235 to 0-255 removing those details. If it doesn't you'll need to figure out what setting in your drivers does this, or you can use ffdshow and set it to output RGB32, and it will then instead do this conversion for you. Your graphics card in this case won't do any conversions as its getting RGB32. This is what I use and get excellent conversions. There are various threads about the settings to use here but enabling "dithering" and "high quality yv12 to rgb conversion" enabled in the Output options in ffdshow should almost do the trick.

5th October 2009, 18:53	#268 \| Link
Jackie Registered User Join Date: Dec 2001 Posts: 48	Thanks alot mark, I think I have figured out how it works now: I have set Full RGB as Pixel Format, and my Samsung TVs HDMI settings to "normal" instead of "low", I think now the results are correct. Can anybody tell me in detail what "HDMI setting" normal/low on Samsung LCD does, since it is not really clear from the manual.

5th October 2009, 19:02	#269 \| Link
mark0077 Registered User Join Date: Apr 2008 Posts: 1,106	The normal / low from using my own TV is Normal - Assume input is 0-255, basically just outputs what its given to screen Low - Assume input is 16-235, therefore converts internally to 0-255 to give correct contrast

12th October 2009, 13:54	#270 \| Link
iSeries Registered User Join Date: Jan 2009 Posts: 625	Hi, I'm having trouble getting Full RGB from my ATI 4550 to my LCD TV. In the ATI settings, it was set to output Full RGB (0-255) by default. However playback of a calibration file shows that nothing below 16 is being displayed (no matter how high I set Brightness), and nothing above 235 is being displayed (no matter how low I set the contrast). Also I had to set the brightness on my TV to a ludicrous level (something like 75) just to get 17-25 to flash. I've tried 'forcing' Full RGB through ffdshow as per the advice here but no luck. The only way I can get my TV to display 0-255 is by setting ffdshow to 16-235 and setting YCbCr 4:4:4 in the ATI control utility. Is sending YCbCr 4:4:4 and letting my TV do the RGB conversion just as good as sending RGB?

17th December 2009, 22:34	#277 \| Link
ears1991 Registered User Join Date: May 2009 Posts: 7	HALLELUJAH 9.12 fixes the cruddy luminance levels at last!!!! if im right in saying its been broken since 9.2, that makes it that it took ati 10 months to fix... nice

21st January 2010, 16:19	#278 \| Link
THX-UltraII Registered User Join Date: Aug 2008 Location: the Netherlands Posts: 851	I just switched from my good old ATI 4350 to a new HD 5670 to finally have to possibility to bitstream HD audio. However, what I already knew, the new 5xxx series has a bug. When you select 'Pixel Format PC Standard (Full RGB)' it is NOT sending this out actually. With the 4xxx series this was ok and I always had my projector set to 'Enhanced'. But now with the 5xxx series this doesn t work anymore. I already contacted ATI and they are aware of the problem and it will take a few drivers to fix it. So I now set my projector back from 'Enhanced' to 'Normal', do I just have to choose Limited RGB now? Will the BTB and WTW be ok this way?