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View Full Version : Questions on chroma subsampling by my devices

Dodgexander
9th June 2014, 17:20
I'm still trying to get to the bottom of what is going on between my devices and chroma sub-sampling. Last night I made a collection of photos of the chromares.png test image.

I took photos in each test in the following order RGB 4:4:4>RGB 4:4:4 Limited>YCbCr 4:2:2>YCbCr 4:4:4

A set of tests were done when directly connected to my display; a Samsung LE40M86BD (European Version of the 65F series in North America) and also when connected via my AVR; an Onkyo TX-SR608.

I tested the following TV display modes. Once directly connected to the TV and Once connected via the receiver. Everything from the receiver tests are set as Through.

With PC Mode enabled and Colour Space set to AUTO
Direct (http://imgur.com/a/a8mbt#0)
Receiver (http://imgur.com/a/NWOsa)

With PC mode enabled and Colour Space set to WIDE
Direct (http://imgur.com/a/n14Oq#0)
Receiver (http://imgur.com/a/cqoIN#0)

With PC mode enabled and Colour Space set to AUTO + xvYCC enabled
Direct (http://imgur.com/a/2AIPa#0)
Receiver (http://imgur.com/a/NmbGG#0)

With PC mode enabled and Colour Space Set to WIDE + xvYCC enabled
Direct (http://imgur.com/a/rGJtK#0)
Receiver (http://imgur.com/a/oXZEV#0)

Without PC Mode enabled and Colour Space set to AUTO
Direct (http://imgur.com/a/M3Ixj)
Receiver (http://imgur.com/a/EDhaz)

Without PC Mode enabled and Colour Space set to WIDE
Direct (http://imgur.com/a/eHMp1)
Receiver (http://imgur.com/a/wa81Q)

Without PC Mode enabled and Colour Space set to AUTO + xvYCC enabled
Direct (http://imgur.com/a/JH3dx)
Receiver (http://imgur.com/a/G7bBz)

Without PC Mode enabled and Colour Space Set to WIDE + xvYCC enabled
Direct (http://imgur.com/a/47CVx)
Receiver (http://imgur.com/a/qEXPQ)


It seems its not just PC mode that effects the chroma, but xvYCC mode and Colour Space.

Also, it doesn't matter what mode, but there is large degredation when going through my receiver.

What I don't understand is Onkyo say the receiver passes 10bit 4:2:2 but not 12bit 4:4:4. Why is the display info showing 24/30bit?

If it does pass 4:2:2, why are the images so different even with 4:2:2 set in the PC driver?

Furthermore, it seems xvYCC and Colour space settings interfere with the receiver, I'm still not sure which of these settings I should use.

As far as I know xvYCC shouldn't affect as it only activates if the source is supporting it.

As for colour space, am I right in thinking this is samsungs own way of increasing the colour gamut? All the reviewers of the television have it set to on, to get best gamut readings, yet here it seems to also interfere.

I never thought I would see such a difference between pictures when I bought the receiver, even in through mode. What a shame, because now I don't know which mode I should be using on the PC or the Televsion. Maybe someone with more experience can explain why the images look the way they do, its hard to tell which is a 4:2:2 or 4:4:4 or even 4:2:0.
huhn
9th June 2014, 18:46
I never thought I would see such a difference between pictures when I bought the receiver, even in through mode. What a shame, because now I don't know which mode I should be using on the PC or the Televsion. Maybe someone with more experience can explain why the images look the way they do, its hard to tell which is a 4:2:2 or 4:4:4 or even 4:2:0.

direct auto (first screen) is 4:4:4 and the color doesn't look totally wrong.
the colorspace of a pc is sRGB (bt 709) with default the TV should use bt 709 too.
think about opening a new thread because this is leaving the topic of MadVR.
cyberbeing
9th June 2014, 21:28
What I don't understand is Onkyo say the receiver passes 10bit 4:2:2 but not 12bit 4:4:4. Why is the display info showing 24/30bit?

8bit/channel = 24bit
10bit/channel = 30bit
12bit/channel = 36bit
16bit/channel = 48bit
Dodgexander
10th June 2014, 00:29
Thankyou guys.

I managed to solve my problem by using a trick (https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CCYQFjAA&url=http%3A%2F%2Fwww.avsforum.com%2Ft%2F1236522%2Fthe-official-onkyo-tx-sr608-thread-no-price-talk&ei=-kKWU9WxEcmxO-e9gZAM&usg=AFQjCNGeea0ViK2bzZXT_hVYLntvDQxWzQ&sig2=h1t4InkBC1H7Mqke_HoPHA&bvm=bv.68445247,d.ZWU)to completely disable the video processing of my TX-SR608. With this setting the video is passed as it is directly. Unfortunately this also means no OSD.

My question left now again is off-topic. It seems recommended to keep xvYCC and Colour Space Wide both on according too the test on my television at HDTV Test (https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0CDoQFjAC&url=http%3A%2F%2Fwww.hdtvtest.co.uk%2FSamsung-LE40M86BD%2F&ei=fkGWU6KcA4KwPL-ygZAM&usg=AFQjCNEeyBERmtz7IA4fs0fskYbfZxwLmA&sig2=gPbnUdVgiNR3G5g52dk_qg&bvm=bv.68445247,d.ZWU) I'm using their calibration settings they used when measuring with a meter so don't want to differ from their recommendation, but I'm not sure how the settings apply to 4:4:4 and a PC input compared to 4:2:2.

It makes me wonder the best way though since looking at that test image, the colour seems to change oddly with these two enhancements on (even with xvYCC which is only suppose to affect the image if the source outputs it). The test shows with Wide enabled the colour gamut is significantly better, which is why they have enabled it.

Short of calibrating myself, is it worth keeping these settings on, or could it be interfering and making the picture worse?
QBhd
10th June 2014, 00:49
both 4:2:2 and 4:4:4 will be un-mistakable... if you can't see these two clearly then you are in 4:2:0

From the looks of things your AVR is doing a down conversion to 4:2:0. From what I understand of AVRs (I personally don't own one, but I have done some research for my brother), the "through" setting only pertains to the HDMI audio... okay I just googled your AVR and looked at the manual, the "Through" setting for video just keeps the source resolution, it doesn't say anything about conversion of chroma resolution. Also I found this little tid-bit:

http://i.imgur.com/IzSuhsa.png

QB
Dodgexander
10th June 2014, 03:33
both 4:2:2 and 4:4:4 will be un-mistakable... if you can't see these two clearly then you are in 4:2:0

From the looks of things your AVR is doing a down conversion to 4:2:0. From what I understand of AVRs (I personally don't own one, but I have done some research for my brother), the "through" setting only pertains to the HDMI audio... okay I just googled your AVR and looked at the manual, the "Through" setting for video just keeps the source resolution, it doesn't say anything about conversion of chroma resolution. Also I found this little tid-bit:

http://i.imgur.com/IzSuhsa.png

QB

Thanks, it does seem that way. But why put the option "through" under video? Even in the HDMI output section through is next to resolutions you can choose. Onkyo did tell me the receiver is capable of passing 4:2:2 though, only the new range are capable of 4:4:4 though. I even have a case open with them about it. Although I'm not certain how much the person I'm dealing with actually knows for certain. Clearly it seems onkyo have little control over the processing chip if they can't disable enhancements whilst using the osd with through mode. What's interesting is what the other modes do compared! Maybe they should have renamed through to copy or match input instead.

I'm pretty sure that section in the manual relates to the VGA PC connection, not connection via hdmi which I have for HD audio. That section is for assigning names to each input, it seems if you use vga you need to rename hdmi5 to something else first. Using vga may be interesting, but I don't think it is possible to have hd audio then.

Thanks for taking the time to look though, very kind.

Sent from my Nexus 5 using Tapatalk
QBhd
10th June 2014, 05:41
You could very well be correct... are you at least using HDMI5? It does seem that particular HDMI is for PC input, and I know certain TV's require specific HDMI ports to be used with a PC

QB
Dodgexander
10th June 2014, 20:54
Yeah I'm using 5. The screen mentioned just let's you set different names for the assignments. The name is PC. I've encountered the different port problem before. Even my tv needs to be on hdmi2. Hdmi1 doesn't work.

It's a shame you have to disable the osd and video processing to achieve correct gamma.

It makes me wonder how many people have been using it without realising what it does to their image.

Without it the picture I get is noticeably sublime in comparison. It's almost like having a new tv. Anyway it will be interesting to see what onkyo have to say about my experiences:p

Sent from my Nexus 5 using Tapatalk