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ATI HD 5000 Series Known Problems (5870 5850 5770 5750 5670 5570 5450)

510K views 3K replies 387 participants last post by  soulkeeper 
#1 ·
OK so the 5000 series definitely has some problems especially with HDMI audio, but I and others have worked around them for the most part, and sometimes fixed them. [There's several of us who had been waiting for these cards for a while and have followed their progression since the beginning. You might wanna pay extra attention to what renethx, vladd, SamuriHL, Tulli and other "olds" from the original thread have to say (sorry if I forgot someone!)]


If you don't understand some terms, please search for them in order to keep this post as short and clear as possible. I will keep updating this post with other people's contributions (esp. Tulli, I hope, cause I know practically nothing about fixing EDID!).


All this is tested on Windows 7 64-bit, it should be the same on 32-bit and maybe Vista. If you got XP you might have some more trouble (you probably won't be able to bitstream HD-disc audio at all). I think it's time to let XP go.

Original thread pertaining HTPC use.


First of all, the Realtek HDMI driver is recommended as opposed to the ATI HDMI audio driver that comes with the Catalyst installation. After accepting, download the ATI HDMI Audio Device in red fonts. Current version is 2.39 as of 2010/02/06. The other ones (usually higher, newer versions) are for the Realtek analog motherboard devices. This is about the most common mistake people make. The main difference between these two drivers is that the Realtek one doesn't suffer from the " silent stream bug ".

[2010/02/14] The Realtek driver is now at version 2.42. ricabullah points out that there is a problem with the both the 2.39 and 2.42 drivers with DVBViewer.

[2010/03/12] There are other small differences. Go below (next post) to see the details please.



OK so the most common problems are:

-
1) No Dolby TrueHD or DTS-HD (or both) bitstreaming to an AVR that should be capable. FIXED!

This is most probably due to an EDID error. You will need to override your monitor's driver with a driver with its EDID information modified.Tulli is the man for this, and many people have already benefited from his EDID modifications. Start with Tulli's post below.

[2010/02/15] There have been so many requests for Tulli's patches that he opened a thread just for them. Go there for info on how to do the EDID overrides. Thanks Tulli!

[2010/04/29] As reported on Tulli's thread, this issue is fixed with Catalyst 10.4.
-
2) Dropouts (or pops) with DXVA disabled. FIXED!

This was discovered at this thread at Doom9. It happens with legacy DD and DTS but it might happen with other audio too. It is caused by Powerplay, an energy-saving feature that downclocks the GPU and memory when the card isn't being stressed. This is most likely a graphics driver problem (not an audio driver one). I'm not sure if it could be a hardware problem though, let's hope not.


The workaround is here .
 
[2010/06/16] This Powerplay issue is fixed with Catalyst 10.6.
-
3) Channel switching (to/from fronts/rears/center) or crackling, horrible distortion. FIXED!

Channel switching happens when audio is set to5.1 and higher than 48 kHz (96 or 192 kHz) and 24-bit in the Windows mixer, and in 16-bit 176.4 kHz. I don't get it in 16/88.2 or 16/96. Also happens when using WASAPI exclusive with content with equivalent settings.


When setting it to 7.1 and similar bit-depth/sampling-rate settings, there might be crackling and bad distortion, but I'm not getting this anymore. I'm on the 8.70RC2 drivers (presumably Cat 10.2 RC2), so that may have fixed it.


This is also caused by graphics drivers. Powerplay triggers it (see above #2 on how to disable it). Or you can also just set the windows mixer to 24-bit 48 kHz or any other unaffected mode.
 
[2010/06/16] This Powerplay issue is fixed with Catalyst 10.6.
-
4) 23, 29 and 59 Hz revert to 24, 30 and 60 in CCC.

This is not a big problem. When you set it to 23, it will be 23 even though the number will show 24. There is a trick though. If you are switching form 23 to 24 or vice versa, it won't switch. You need to switch to something completely different first (like 59 or 60) and then back to 24 (or 23). Same goes for 29/30 and 59/60.


[vladd below points out that it's a CCC problem, you can still change at will with the Windows interface (see his post if you don't know how).]



The next two aren't as common but I suspect it's because not many people use these options. If you do please leave a post confirming, thanks.
-
5) When using CCC profiles/hotkeys, 23, 29 and 59 Hz aren't set.

Even if you save your profile after setting 23, 29 or 59, when you call up the profile (via a hotkey or otherwise), it will set the refresh to 24, 30 or 60 respectively. You have to edit the xml of your profiles like indicated here .
-
6) Win 7 Media Center won't work with 29 Hz.

I use 29i with MC because my TV can only apply reverse pulldown up to 1080i, so this is a rather unique case, not many are using interlaced. In any case, MC for me automatically changed to 30i. For all other rates (including 23 and 59) it would work OK. This can be fixed with this registry settingCode:
Code:
HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Media Center\\Settings\\DisplayService
Change theRefreshRate value to 29. This means though that MC will always change to 29 when opening full screen.


Side note: You can also erase that value to reset MC to not change refresh rates when opening (which will do if you set up your display for a certain resolution/rate within MC).

-
[2010/03/04] 7) Pixel Format Output Problems.

For the past few days, there's been a lengthy and somewhat confusing discussion about the different Pixel Format (YCbCr, RGB Full and RGB Limited), that these cards offer. As of now, this is the last post of this thread, and this the last on the subject on the main 5000 thread. You can go back a few days and see what's been going on. Basically, we have two problems:


- Pixel Format RGB Full in some systems is broken, it seems to output desktop colors at the same levels as Limited. For some others (like me) this doesn't happen and RGB Full and Limited work as expected (Full outputs 0-255 and Limited 16-235). We don't know yet if the display affects the cards' output, but we're trying to test that.


- Pixel Format YCbCr yields a greenish cast especially in the darker areas. This affects everything except video in the protected video path (PVP) such as bluray in the commercial bluray players (when playing from disc or ISO). For PVP video, it seems YCbCr is being output without conversion to RGB first, so there's no green cast. See the measurement graphs sotti posted in this thread, and here for a more visual representation of the problem.


There might be smaller problems for other people. Two things though.


First of all, none of these is resolved as of now, nor there are workarounds for the YCbCr issue or something that always works for the RGB issue. I'm putting this here cause I've been asked to by some people, but the information will be updated when we know more what's causing the RGB problem. The YCC problem seems to be straightforward, just a bad conversion.


Secondly, all this talk (especially the banding discussion therein) is not a problem everyone will notice, or everyone will care about. See if it applies to you, and if you're satisfied with what you're getting, then you don't have to worry about this.

-
[2010/04/21] 8) DXVA profiles support limitations
ter9999 explains :
Quote:
ATi cards don't support BSP for MPEG2. There is only IDCT profile support for MPEG2. There is a tweak in register "ModeMPEG2_VLD", but when setting it to 1, green screen will be there when watching MPEG2 using DxVA.


Details, please refer to:
http://www.avsforum.com/avs-vb/showthread.php?t=1227157
 
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#977 ·

Quote:
Originally Posted by Andy o /forum/post/18298271


Do you have GPU scaling turned on? Also, I had about the worst experience I've ever had with electronics with an AVR254 and HTPC. Harman Kardon receivers don't pass through the HDMI video, that's probably why it works with your projector. The HK must have its own video EDID, and will reprocess the video before sending to the display.

No, I didn't touch anything in the drivers except the refresh rate. On avforum.no, other users have the exact same graphics card and receiver, but no problems. Maybe I need to recheck the firmware of the AVR.
 
#978 ·

Quote:
Originally Posted by Andy o /forum/post/18298282


Yeah, that would be the most hassle-free combination. All your levels will be consistent. BTB and WTW are not supposed to be seen anyway, when you pass them through, usually your display will cut them anyway (or you'll see gray blacks and whites). Some people like to pass WTW cause there's a little information there sometimes, but I don't think it's really necessary.

WTW is much more important than people think. It's not only the info on that range, but the info that you'd lose when converting YCbCr to RGB. Read this posts of Don Munsil and specially Chris Wiggles ( http://www.avsforum.com/avs-vb/showp...postcount=34):

Quote:
Originally Posted by dmunsil /forum/post/0


I honestly think clipping below reference black is not nearly as big a deal as clipping above reference white. I've seen some content that looks visibly changed when below-reference is clipped, and I assume mostly it's because those lower values affect the scaling and processing algorithms. On a CRT, a really low below-black value has the potential to affect the next pixel, pushing it up just a tad because of filtering, internal ringing, etc. On a fixed-pixel display, that's not necessarily going to happen if you get 1:1 pixel mapping, and I can't honestly say I've seen any visible artifact because of below-reference clipping in a situation like that. I still think there's no good reason to clip below 16; it's not like it's helpful in any way. The player/display shouldn't throw away the below-reference values and refuse to display them, even if you turn the brightness up. Certainly it makes calibration somewhat harder, and I'm at least open to the possibility that there could be subtle second-order effects of clipping those values.


But post-calibration all the values from 1-16 should end up producing the same value on your display and that value should be the blackest value the display can produce. Again, modulo some subtle potential effects when scaling and so forth.


Bottom line is simple: make the display act like a BVM. If there's any controversy, just check what a BVM does and copy that. But whether or not displays should show the above-reference signal is an easy question. They should. The content was viewed all throughout the video production and mastering process on BVMs that do not clip above reference. And ALL content has some above-reference material. All of it. You can see the difference by switching from clipped to not-clipped. The not-clipped is correct, and the clipped is incorrect.


Some of the above-reference material is basically unimportant. It just doesn't change the image in any visible way. Some of it, on the other hand, is easily visible when you compare clipped to not-clipped. Does the image look basically OK if you clip? Yes, most of the time it does. But that proves nothing. If you clipped at 225 the image would still look OK most of the time. You could clip black at 25 instead of 16 and I bet a lot of viewers would say the image looked punchier. And in fact it would be punchier, with more contrast. But it would still be wrong, and it would still look different from a reference monitor. And making the video look like it does on a reference BVM is the goal.


Bottom line: there are visible differences in the image when you clip above 235. No professional monitor clips above 235. If you want your home system to look as close as possible to a pro monitor you will not clip above 235. Q.E.D.

Don
Quote:
Originally Posted by ChrisWiggles /forum/post/0


Video is not supposed to stop at 235. It is expressly designed to extend to 254, and that is explicitly stated in the video standards. Further, this discussion we've had before is something of a simplified version that only deals with RGB. The YCbCr that's on the disc is 16-240 for chroma, and even assuming a hard clip right at 240 and at 235 for Y, this will still yield RGB values that are outside the nominal range upon conversion to RGB.


This occurs with a great deal of content, probably all content that has been handled well and has not been errantly clipped off. And even content that may have been hard-clipped in component will still yield values that are beyond 235.


YCbCr triplets that are clipped (to 16-235 for luma and 16-240 for chroma) will still yield RGB triplets that exceed 16-235 RGB range.


For instance, the perfectly legal YCbCr triplet of (200, 160, 150) in Rec.709 decodes to an RGB triplet of (250,181,240). Note that the component values don't even come anywhere close to the legal limit for video luma or chroma, yet they already exceed the nominal range in RGB for both red and blue. Unless an additional clip is imposed on the playback side in RGB (for no good reason), video values will regularly fall outside the nominal RGB range. An imposed clip at the playback side in RGB would change the color that was encoded on the disc, and I would argue that this is a detriment and a deviation from accuracy since this is not how it was observed(arbitrarily clipped) when mastered.


Examples:
http://www.avsforum.com/avs-vb/showp...6&postcount=23
http://www.avsforum.com/avs-vb/showp...6&postcount=29
 
#979 ·

Quote:
Originally Posted by cyberlolo /forum/post/18299106


WTW is much more important than people think. It's not only the info on that range, but the info that you'd lose when converting YCbCr to RGB. Read this posts of Don Munsil and specially Chris Wiggles ( http://www.avsforum.com/avs-vb/showp...postcount=34):

To each his own but if you choose to display WTW than you are cutting your on/off contrast ratio quite a bit.
 
#981 ·

Quote:
Originally Posted by cyberlolo /forum/post/18299246


Yes, but if not, you're simply deviating from accuracy. What you'd be watching is not as supposed to be.

To each his own. To get things to look like they do on a studio monitor, you need a studio monitor. Teleciners know that a variety of displays will be used by consumers to watch a given disk. Most would be surprised at the things that many of us do to be "accurate."
 
#982 ·

Quote:
Originally Posted by Lawguy /forum/post/18299370


To each his own. To get things to look like they do on a studio monitor, you need a studio monitor. Teleciners know that a variety of displays will be used by consumers to watch a given disk. Most would be surprised at the things that many of us do to be "accurate."

Nop, the goal is to get things to look AS CLOSE AS they do on a studio monitor. And to get that, you need to preserve all WTW. Period.


Now, if you don't worry about getting the most possible accuracy from your display, then of course you can do whatever you want.
 
#985 ·
Currently my gaming HTPC has GTX260 connected to Pioneer VSX-21. AVR is connected to HD20 projector. I'll get my HD5770 to replace GTX260 next week. I am reading this forum to understand the issues that is awaiting for me. I am using TM3 for playing ISOs and MPC



Issue 1: No Dolby TrueHD or DTS-HD

=> I have Pioneer AVR. Hopefully i don't get into EDID problem. I'll use the Realtek audio driver.

Issue 2 & 3: Channel Switching, distortion

=> I need to disable powerplay.

Issue 4,5&6: Pertaining to refresh rate

=> The Optoma Hd20 projector always project with 60Hz even when the input is 24Hz
. So, unfortunately i won't face the refresh rate issue as i will always be using 60Hz refresh rate


Issue 7: Pixel format output problems

I am not a videophile. Hopefully i don't get a problem with this. Fingers crossed.


Andy, Thanks for composing this very informative thread. I think i have understood what i need to do. Let me know if i am missing any.
 
#986 ·

Quote:
Originally Posted by Andy o /forum/post/18085546


As per the reviews, you will still be able to choose VA, and as long as you're not getting dropped frames or sync issues, the ESVP option won't make a difference. As one of the reps said, you can trade processing for VA. And many don't use most or all processing like Skin Tones, Brighter Whites, Edge Enhancement, De-noise, and the worst of all (to me), Dynamic Contrast.

From page 1 of this thread, in my view the alert to disabling dynamic contrast in the catalyst drivers cannot be overstated.


I'm not sure if this setting is enabled by default in the catalyst 10.2 drivers but it was for me after using the restore to factory defaults button.


With dynamic contrast enabled on my system (ati 5850 win 7) I saw flashing in brightly lit scenes or when any white color appeared in the image. Note that I don't have cablecard like the author from the quote. I saw the flashing in media center with both my qam tuners from different manufacturers (silicondust hd homerun and ati theatre 650 pci). Slightly off topic but to any other ati theatre 650 pci users I used the driver from the 750 set which worked. There is currently no official ati supported 650 win 7 driver though it's promised for the first quarter of this year.


I would think this setting alone would account for plenty of tech support hours for media center users unless less people than I suspect are seeing it. For me it was a major annoyance in media center until I figured out what was causing it.


Other behavior I noted like others was loss of any other refresh rates than 60 Hz after enabeling gpu scaling and loss of my underscan/overscan settings on resume from sleep after checking the box on the scaling options ccc page 'use the scaling values instead of the customized settings..."


The help file isn't exactly crystal clear on why or why not one might want to use or not use these settings or their specific interaction with each other, but they have clearly caused confusion amongst users (see ATI forums).


I can't help but wonder if the ati 'crew' really checks various stuff like this out when they ship a driver revision. This is the kind of thing only someone who actually uses the card in day to day htpc use would ever see....


I do plan to let ati know as they apparently ain't gonna fix this stuff if they don't hear from people.....


ps the ccc treasure map to the dynamic contrast setting is graphics,avivo video,all settings


What maniac designed that interface? The progammer for the CCC menuing deserves a special place in hell....
 
#987 ·

Quote:
Originally Posted by racerxnet /forum/post/18296791


Xp may be "crotchety" but is still the dominant OS in use today. It requires less overhead than Vista or 7 and does all that is requires as a media box. What more can you ask for. Just because MS is not supporting it does not mean it is a relic.


Those reasons and its ability to overcome the expansion levels problems seem to make it a worthwhile investment. Care to elaborate....


MAK

Under normal circumstances I would agree with you,

and 5XXX cards even have better DXVA format support in XP (for some unknown reason).


The problem is, mostly in XP The 5XXX series also has a very serious DPC latency bug that kills the system & audio performance when using software playback, under any video renderer, especially VMR9.
 
#988 ·
Hmm the GPU scaling and 60 Hz issue seems common enough, I'll add it to the second post. I wouldn't have thought people would enable that. I'm still not clear what purpose it serves with the great majority of current HDMI TVs and it's disabled by default (and it's in that menu you have to be Indiana Jones to discover), so I thought almost nobody would have it enabled.
 
#989 ·

Quote:
Originally Posted by cyberlolo /forum/post/18299246


Yes, but if not, you're simply deviating from accuracy. What you'd be watching would not look as supposed to.

The problem with WTW is you are not supposed to SEE WTW. If you can see it, you're display is incorrectly calibrated and thus "what you'd be watching would not look as supposed to".


Now, as far as the drivers clipping this info. If and only if that causes other impact within the image you are supposed to view, that would be an issue. But I have yet to see any evidence of that.
 
#990 ·

Quote:
Originally Posted by beaups /forum/post/18306333


The problem with WTW is you are not supposed to SEE WTW. If you can see it, you're display is incorrectly calibrated and thus "what you'd be watching would not look as supposed to".


Now, as far as the drivers clipping this info. If and only if that causes other impact within the image you are supposed to view, that would be an issue. But I have yet to see any evidence of that.

Wrong. WTW is not only supposed to be viewed, but it MUST be viewed. If you're clipping it, or if you're getting peak white at 235 level, you're getting a less accurate image than if you get all WTW up to 254. That's a fact, and you have the evidence and a detailed explanation in the links I posted before.


Have you read the example of converting YCbCr to RGB and having the resulting triplets exceeding the "legal" values? If you clip at 235, any value on the triplet that falls over 235 (and a lot of triplets will have at least one value over 235, as shown in the example), will be clipped too at 235, and then you'd be getting a different color than it really is. This is what I mean when I say "what you'd be watching would not look as supposed to".


If you need more information, please take a look here (very well explained): http://www.spearsandmunsil.com/artic...stcontrol.html
 
#991 ·

Quote:
Originally Posted by beaups /forum/post/18306333


The problem with WTW is you are not supposed to SEE WTW. If you can see it, you're display is incorrectly calibrated and thus "what you'd be watching would not look as supposed to".


Now, as far as the drivers clipping this info. If and only if that causes other impact within the image you are supposed to view, that would be an issue. But I have yet to see any evidence of that.

My understanding is this is not correct.


I'm going to the THX Calibrator certification in two weeks, so you can bet I'll be confirming it then.


But since I work for the company that writes the software THX uses to teach it's calibrators and my current project is writing the next version of that project, that my assumption that WTW is important is likely accurate (althought how important is deffinetly debateable).


Also remember video standards revolve around YCrCb encoding. For that standard Y's range is from 16-235, but Cr and Cb range from 16-240 with 128 being neutral.


So YCrCb - 235,240,240 which is completely legal and not out of range or WTW for video transforms to RGB 255,162,255, wich would be subastationally different if you simply clipped above 235.
 
#992 ·
sotti,

I would be VERY interested in your thoughts concerning that experience. Please post. Thanks
 
#993 ·

Quote:
Originally Posted by sotti /forum/post/18307335


My understanding is this is not correct.


I'm going to the THX Calibrator certification in two weeks, so you can bet I'll be confirming it then.


But since I work for the company that writes the software THX uses to teach it's calibrators and my current project is writing the next version of that project, that my assumption that WTW is important is likely accurate (althought how important is deffinetly debateable).


Also remember video standards revolve around YCrCb encoding. For that standard Y's range is from 16-235, but Cr and Cb range from 16-240 with 128 being neutral.


So YCrCb - 235,240,240 which is completely legal and not out of range or WTW for video transforms to RGB 255,162,255, wich would be subastationally different if you simply clipped above 235.

Would you agree that it depends when in all of the conversion processes that the BTB and WTW is clipped? Meaning if it is only clipped at the output stage, after all of the conversions, it would be insignificant?
 
#994 ·
With all the s__t that goes wrong with HTPC's, if I see a vaguely recognizable image on my screen I'm ecstatic, clipped or not...



Actually, when this is all sorted out, perhaps a thread can be started, sort of a FAQ, for ATI users with best practices/optimal settings for HT use...There's some great information sprinkled throughout a few different threads, but not easy to find, and information/advice changes over the life of a thread, making searches not the ideal way to get the latest.


For example, this conversation about clipping, while legitimately interesting to me, would. at its conclusion, be best as part of a step-by-step guide because I'm guessing a vast majority of readers have no idea where to go and what to set (given all the interactions of different settings, as well as different software players, OS, etc) for proper playback.


Or even a thread where members having generally positive experience post the details of their setup, what's working (and what's not), and what workarounds/enhancements have been tried. Maybe something in the format of:


Thread name: ATI 5xxx User Configurations


Post Title: 's HTPC Configuration with ATI 5

CPU/Motherboard:

RAM:

Boot/Media Drive Configuration (HW/SW)

Video Card:

Video Driver:

Audio Card:

Audio Driver:

OS Version:

OS Performance Tweaks (if applicable, ie Power Settings, Windows Performance Settings, disabling Indexing/Searching, etc.)

Media Interface (ie WMC, XBMC):

Media Player (s):

Additional Software:

AVR Model:

Display/Projector Model:

EDID Override (Y/N, which one)
Then, player specific configurations:

Media Player: (i.e)Total Media Theater 3 .170

Video Settings:

- Windows

- Driver

- Media Interface

Audio Settings

- Windows

- Driver

- Media Interface

- Player (1, 2, etc.)

Additional Software Settings:


Experiences/Usage:


Outstanding Issues:


Experimentation/Results: (ie, "I installed ReClock version xxxx in this configuration in an attempt to zzzz, but could not successfully do yyyy despite the following workaround attempts....)

...then repeated for each player type if you have more than one player.


If other's think this is a good idea, I'll start a thread and post my setup to start. I would suggest if we do this, that any updates to your configs, settings, experiences be reflected back into the initial posting you make, highlighted/dated, and the reason for editing added to original configuration post, so everything is traceable in one spot.


If there are elements I'm missing or overstating, let me know here or in a PM - conversely, without feedback, I'll assume the interest is low and won't start the thread...
 
#995 ·

Quote:
Originally Posted by sotti /forum/post/18307335


My understanding is this is not correct.


I'm going to the THX Calibrator certification in two weeks, so you can bet I'll be confirming it then.


But since I work for the company that writes the software THX uses to teach it's calibrators and my current project is writing the next version of that project, that my assumption that WTW is important is likely accurate (althought how important is deffinetly debateable).


Also remember video standards revolve around YCrCb encoding. For that standard Y's range is from 16-235, but Cr and Cb range from 16-240 with 128 being neutral.


So YCrCb - 235,240,240 which is completely legal and not out of range or WTW for video transforms to RGB 255,162,255, wich would be subastationally different if you simply clipped above 235.

Yes, that's absolutely correct.
 
#997 ·

Quote:
Originally Posted by beaups /forum/post/18309153


But....is it an issue if the BTB and WTW is clipped AFTER all of the conversions/transforms are completed? Meaning if the BTB and WTW is lost closer to the output stage would it still be an issue?

Clipping BTB is adviced to be done at the end of the chain, but it can be done before with (almost) no problems.

WTW doesn't have to be clipped. It doesn't matter if you clip it at the beggining or at the end of the chain, but if you do, you will be getting away from accuracy.
 
#998 ·

Quote:
Originally Posted by thrang /forum/post/18308856


With all the s__t that goes wrong with HTPC's, if I see a vaguely recognizable image on my screen I'm ecstatic, clipped or not...



...I'm guessing a vast majority of readers have no idea where to go and what to set (given all the interactions of different settings, as well as different software players, OS, etc) for proper playback.


Or even a thread where members having generally positive experience post the details of their setup, what's working (and what's not), and what workarounds/enhancements have been tried...


I would suggest if we do this, that any updates to your configs, settings, experiences be reflected back into the initial posting you make, highlighted/dated, and the reason for editing added to original configuration post, so everything is traceable in one spot....

I think this would be great. It is so hard to come up with good recommendations, pulling stuff out from here and there. Too bad this approach is not used much.
 
#999 ·

Quote:
Originally Posted by beaups /forum/post/18308663


Would you agree that it depends when in all of the conversion processes that the BTB and WTW is clipped? Meaning if it is only clipped at the output stage, after all of the conversions, it would be insignificant?

No I wouldn't.


235,240,240 YCrCb is valid, not WTW, and gives 255,162,255 RGB. If you clip that to 235,162,235 then its the YCrCb encoding of the rendered color is 183,161,156.


so no I don't think that YCrCb 235,240,240 should look exactly the same as YCrCb 183,161,156.


If possible always preseve WTW.

It's not always possible.
 
#1,000 ·

Quote:
Originally Posted by sotti /forum/post/18310384


No I wouldn't.


235,240,240 YCrCb is valid, not WTW, and gives 255,162,255 RGB. If you clip that to 235,162,235 then its the YCrCb encoding of the rendered color is 183,161,156.


so no I don't think that YCrCb 235,240,240 should look exactly the same as YCrCb 183,161,156.


If possible always preseve WTW.

It's not always possible.

In your example you are clipping the YCC values before the RGB conversion. What I am suggesting is that the 235, 240, 240 is converted as-is into RGB (to 255, 162, 255 per your example) and then compressed into the 235-max range (say 235, 150, 235). I don't know the conversions as you do, but it does appear that the wtw and btb are expanded out of existence before the compression back to 16-235....meaning they aren't actually "clipped" persay.
 
#1,001 ·

Quote:
Originally Posted by beaups /forum/post/18310483


In your example you are clipping the YCC values before the RGB conversion. What I am suggesting is that the 235, 240, 240 is converted as-is into RGB (to 255, 162, 255 per your example) and then compressed into the 235-max range (say 235, 150, 235). I don't know the conversions as you do, but it does appear that the wtw and btb are expanded out of existence before the compression back to 16-235....meaning they aren't actually "clipped" persay.

Nop, in his example, he's clipping after the conversion. Anyway, clipping WTW in any stage of the chain is not a good idea. Just be sure that it's preserved entirely up to 254 and you'll be ok.
 
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