YCbCr, RGB or RGB Enhanced

[Series1boy]

Hi,

my tv has been calibrated and my denon 3313 BD player is set to RGB normal and my calibrator said to leave it at this.

can any one explain what the difference is between the 3 because on various other sites and forums it advices to set to YCbCr. Would this cause any problems now that my tv is calibrated.

Thanks

 

[Glacialpath]

I can only suggest you switch it over and see. Does the player state if the YCbCr is 4:4:4 or 4:2:2?

Most if not all BDs are encoded at 4:2:2

Did the guy who calibrated the TV use a test signal generator or a BD disc with test patterns on? If he used a disc maybe the player was set to that when he was calibrating so that's the optimum setting for the player and TV.

I might be completely wrong but if you calibrate using test patterns from a BD then you rely on how well the player takes the data from the disc but if a signal generator was used it shuldn't matter what the player is set to and YCbCr might be best.

 

[thx1138]

Short answer: Use YCbCr.

Longer answer:

The video world, unlike the computer world use a video level of 16 for the blackest black and 235 for white. Values below 16 are usually still in the signal, but you shouldn't be able to distinguish different shades of grey below 16 - they should all look totally black when your display is calibrated in a dark room. Generally, better dynamic range is preferable, so it's usual to be able to distinguish levels of white between 235 and 255 without clipping, but technically speaking the brightest white should peak at 235 if the source material truly conforms to standards.

Rule of thumb:

Assume the primary use of the display is to watch HDTV (bt 709 is the world standard - it's often still referred to as rec 709). bt 709 uses YCbCr colour encoding.

Set your Blu-ray player to YCbCr and then use a calibration disc such as Spears and Munsil (2nd Edition or AVS HD 709 [free]) to set Brightness (black level) and Contrast (dynamic range). These are by far the most important settings on any display, and you don't need a chromameter to set them correctly, you can use a simple greyscale test pattern and your eyes.

The Blu-ray standard only supports bt 709 which limits chroma sub-sampling to 4:2:0. So generally it's fairly pointless to output anything more. Also, there's no Deep Colour on any Blu-ray discs. Sony's new Mastered in 4K discs support x.v.colour (xvYCC) which gives you a wider colour gamut, but only if ever device in the chain supports it - it's not the same as Deep Colour which is to do with the number of bits used to represent colour information.

If you have an XBOX or other games console, they have options to use 'Enhanced' RGB, but the term is very misleading. If you've setup your display for watching HDTV, then you should always ensure you are using standard video levels. If you engage Enhanced RGB, it will just make everything overly bright and the blacks will be crushed.

If, and only if you calibratre the display for use with a computer, then you could try RGB or Enhanced RGB modes. But I would alway advise calibrating to bt 709 and use video levels on your consoles.

It's a really complex subject, and there's quite a lot of misleading 'information' on the internet about it too.

If you want all the technical detail, read the Audioholics articles called: 'HDMI Enhanced Black Levels, xvYCC and RGB'.

Hope this helps.

James.
Certified THX Video Calibrator.

 

[Glacialpath]

Hi thx1138 how are you? Welcome to the mad house. Theres some great people on here though.

Great film that by the way. THX 1138

I'd like your opinion on my post above your's. I have worked in an authoring house and we encoded at 4:2:2 not 4:2:0 as you mentioned. I was only a QC op though not an author or ingest technician.

I may pick your brains on picture set up if that's ok with you. I do simple set ups on anyone's TV who wants it. Of course not as detailed as a full calibration and I don't have a meter to read the screen. I do have the THX calibration disc with the blue filter glasses. I have had the use of a D.V.E. disc before that had more test patterns on but that was at an old job and it wan't mine.

I'd love to do either a ISF course or the THX one one day when I have the money. Also getting my Kuro LX5090 calibrated is high on my list when I have the money and a darker room too.

 

[Series1boy]

This is interesting because the calibrator I used has confirmed it should be set to RGB because it wasn't showing the test patterns correctly on the other settings.

 

[Glacialpath]

Hmmmm. Strange. What disc did the calibrater use. Something seems wrong if the other settings didn't give the full range of the test patterns. Maybe it was something to do with what the AVR was doing with the signal?

If you are happy with the picture then RGB must be fine.

 

[thx1138]

Feel free to pick my brains. Always happy to share & learn.

The AV receiver can influence the display image. Many AV receivers will upscale and reprocess video and some even have options to adjust bightness levels or control DNR (switch it off!). It's always best to do a test and remove the AV receiver from the display chain and compare how it looks going direct. Some AV receivers run really hot - and it's not due to audio amplifcation, but it is due to video processing. Some AV receivers allow *ALL* video processing to be completely disabled. The plus side is they run much, much cooler, and your HDMI/video processing board is unlikely to die! The downside is you won't get any deinterlacing, or video upscaling or any on screen graphic overlays (such as volume) from the AV receiver. Most display devices handle deinterlacing and upscaling suprising well these days. If you have an older Onkyo (TX-NR808 for example) with Faroudja DCDi processing, you have to disable the onboard processing completely, otherwise you'll get a frame stutter every 48 seconds or so, when watching 24P material (it's a fault in the Faroudja DCDi processing)... But I've gone a bit off topic.

Chroma sub-sampling is a means of throwing away colour resolution, to reduce the amount of bandwidth used to make up the image (it's a form of lossy compression affecting colour, not detail). Our eyes are far more critical of black & white detail, and can live with this reduction in colour resolution quite well. Studios will work at 4:4:4 (full colour resolution) or 4:2:2 (half colour resolution - this does *not* mean that the colour pallete in the image is halved). BT 709 mandates 4:2:0 which is a further drop in colour resolution. If your Blu-ray player has an option to output anything higher than 4:2:0, then you need to know that this is only an appoximation - the full colour resolution is not present on the disc. Usually the display device will receive 4:2:0 colour resolution and will up-sample it back to 4:4:4. Some people argue that a highend Blu-ray player makes a better job of the colour upsampling than the display device - I've never been able to see any visible difference and prefer to stick to BT 709 standard all the way along the display chain. But this may not be true for everyone.

It is correct to say that your Blu-ray player can affect the way the test pattern from BD disc will look, in just the same way as your AV receiver can affect the image properties. A signal test generator will always give you the absolutely best YCbCr reference image - however they are prohibitively expensive for most people. Most highend Blu-ray players give you the option of using YCbCr and you can accurately calibrate to 16-235 video levels as per the BT 709 standard.

Someone mentioned the 'blue filter' that is provided with the THX calibrator disc (amongst others). You need to be careful, as these cheap filters are not always accurate themselves! When I've used the 'blue filter' method for calibration, I've never been satisfied with the results and have always had to make manual colour adjustments. While there's no substitute to having a chromameter, you can use images such the BBC Test Card (if you can find it these days) or just good quality static colour images to adjust the basic colour control pretty well by eye - always get brightness (black level) and contrast (dynamic range) right first. It's *not* possible to adjust individual R,G,B and Y,M,C saturation and cutoff levels etc by eye (so don't try!).

Always use Professional or Cinema mode on your display device. These modes should have the most accurate colour temperature. Many TVs are 'cool' out out of the box, so colours will shift towards blues and whites. This also tends to make red look over saturated and unnatural. When you first select Professional or Cinema things may initially look too brown or green - but it's only because you're used to seeing it wrong.

Calibration and home cinema setup isn't a destination - it's a journey.

James.

Certified THX video calibrator.

 

[Glacialpath]

Ah thanks for the tips. I have always found setting a display mode to Standard or Natural the best for doing a simple disc set up. It maks sence though that I don't actually know what the correct setting look like as I not using a meter to calibrate.

The blue filter glasses with the THX disc work pretty well for adjusting the colour and hue for an over all setting but yes I guess setting the chroma levels correctly with a meter and adjusting all 6 colours is much more acurate.

I might try my LX5090 Kuro on Cinema or Pro and see if I feel the picture looks better after a week of viewing to allow me to get used to it. I have always felt the skin tone look a little red even though I've set the colour and hue correctly according to the test pattern and the blue glasses. That's why one day I want a full calibration done as I'm sure the skin tones will look better.

My Pioneer LX71 Bluray player has an option for 4:4:4 which is what I set it to. Are you saying the player is then upscaling the colour to 4:4:4 from what it is on the disc? Should I set it to 4:2:2 to match the BD?

I'm not sure if I am bypassing all the video processing in my AVR as I do get some on screen graphics from time to time. I'm guessing it doesn't stop you seeing the GUI if you need it with all video processing off?

I will try connecting my BD player straight to the TV and have a play with the setting on the player. There are quite a fiew video setting in the player like Chroma level, Contrast, Black level, Gamma and so on. I'll try that with all the TV setting in a neutral position and the player ones in a neutral setting to to see what my playey gives me through my TV. Of course I won't be adjusting any of the colour managment cause I don't have a meter and though I have test patterns for gamma I don't know how to use them. They are grey squares with a % of brightness I think. I guess you need a metter to read them too?

I think the 23.98 frame rate that most BDs are converted to now causes some of the jitter as it's not true 24fps I might be wrong though. I know it's best to watch and 1080i as a 1080i and not try watching it in 1080p and when I upscale DVD 576i to 1080 I only take it up to 1080/50i

I just thought. I'll want the BD player setting on neutral when setting the TV up as I'll want the test patterns a pure as possible so when I'm watching TV broadcast I'm seeing the broadcast as unchanged as possible. I'll only change the BD settings if I feel I can get more from the BDs using them.

Cheers James.

 

[thx1138]

The Pioneer BDP-LX71 is a nice piece of kit. I had a BDP-LX70A for a while. Slow, but very well built, and very nice picture and sound. I used 7.1 analogue outputs and component video back then with my first projector.

So, yes when you tell the player to output 4:4:4, it's doing it's own colour resolution (chroma) upsampling - because on the disc it's 4:2:0 (not 4:2:2). If you output anything less than 4:4:4, then the display device will do the upsampling back to 4:4:4 - but it's all an approximation, because you can't create something that wasn't there to begin with. The worse of all worlds is to do the upsampling twice 4:2:2 from the player, then up to 4:4:4 in the display.

My Pioneer BDP-LX55 can do YCbCr, YCbCr 4:2:2, RGB and Enhanced RGB. I have it set to YCbCr which is 4:2:0 using video levels.

Trust your eyes. Set your player to YCbCr 4:2:0 then watch some content. Then try it set to 4:4:4. Try to use something that has lots of shades of the same colour (the sky). I'll say with a high degree of certainity that you won't see any difference.

I calibrate using my Blu-ray player as reference source, but I also have Sky+ HD, and Freeview HD, so I want these to look the best they can as well. That's why I like to get everything to comply with BT. 709 and use YCbCr 4:2:0 video levels thoughout. You need to be careful with the 'look' of some entertainment programmes (Striclty Comes Dancing comes to mine) - a lot of programmes are going for a 'blown out' over saturated, high constrast look for artistic reasons. It should go without saying that you shouldn't make any picture adjustments using this sort of material, always use your reference disc, to set brightness, contrast and colour levels.

Yes, it's BDs that are actually encoded at 23.976 frames per second that cause the problem with Faroudja DCDi. The few that are exactly 24 are fine. The problem is seen as a very pronouced stutter (almost a pause), not jitter. Poor de-interlacing with 3:2 (some call it 2:3) pull down tends to cause jitter and tearing (a problem in parts of the world that use 60 fields per second), but if you are watching 1080/24p then you shouldn't be seeing any jitter.

TV 'enhanced' settings such as frame-interpolation / video smoothing attempt to compensate for *slow* frame rates, by creating new frames - these might eliminate jitter (depends what you meam), but unwanted motion artifacts are always created because again, you can't accurately create information that isn't there in the first place!

Regards,

James.

 

[Glacialpath]

Hi James

So either way you can't avoid the colour levels being upscaled back to 4:4:4? I would have thought the TV would play what it is sent?

When in my last job they would convert from 4:4:4 off the HD CAM SR tapes to 4:2:2. Now this may have been just for file bassed content that would end up as an HD download. I can't remember if it was the same for BD. Saying that, the fact they now use the same source to make the BD and DVD, it would make sense to reduce it to 4:2:0

Just looking at my player settings. In HDMI colour space it has AUto, 4:4:4, 4:2:2, RGB (16 to 235) and RGB ( 0 to 255)

When I set it to either RGB the screen goes mostly green. Is this used when connected via componant?

So is auto fine or shall I leave it on 4:4:4?

 

[Series1boy]

Extract from my calibration report, any thoughts?

Pre-calibration Checks
I discovered the Pioneer LX71 Blu-ray player’s HDMI output was incorrectly set to RGB (0-255), thus clipping BTB (blacker-than-black) detail for video content (16-235). When calibrated through RGB 0-255, it will compress the dynamic range, resulting in a flat look. In my opinion, this is the primary reason for the washed-out appearance and crushed near-black detail noticed on Sky HD which is 16-235.Proceeded to switch the LX71’s HDMI output to the correct RGB (16-235) setting (pictured below) before further calibration:

 

[thx1138]

RGB (16-235) is an odd term and isn't terminology I've seen before. I think they mean YCbCr (16-235), and have just called it RGB (16-235) in error (lots of manufacturers use misleading or plain wrong terms all the time).

It sounds like the mode you should be using for Standard Video. If the overal brightness and dynamic range now looks comparable to what your seeing from Sky, then I'd say you've got it right.

Regards,

James.