I’ve been comparing outputs from a variety of sources into my Marantz AVR now that I seem to have reliable 4:4:4 support (combination of luck with a change of cable and settings). With 4K HDR10 content, I’m getting
12-bit/4:4:4 from both my Sony and Panny UHD disc players
10-bit/4:4:4 from the Vero
12-bit/4:2:2 from the Shield (tube version - Kodi and Plex) and the Apple TV (Infuse for playing mkv’s).
Is 10-bit/4:4:4 output from the Vero likely to be technically better than 12-bit 4:2:2 ? And is the 12-bit 4:4:4 from my disc players doing anything meaningfully different from the Vero, bearing in mind the material is 10-bit at source?
As a result of this experimenting, I’ve now figured out that 4:4:4 signals enable the so-called 4K pure direct option on my Panny OLED. I’ve noticed before that sometimes this option is enabled in the TV’s menu, but sometimes not, and it seems to be exclusively related to 4:4:4 input.
I’ve not come across 12-bit/4:4:4 before but I can’t imagine it’s a lot of use with current display panels 8-bit or 10-bit at most. Dolby Vision claims to be 12-bit but each layer is only 10-bits so the signal from disc player to your TV doesn’t have to handle 12 bits as far as I know.
12-bit/4:2:2 would similarly seem like overkill. But if you are reading this off the Marantz it probably isn’t really 12 bits. 4:2:2 can carry 8, 10 or 12 bits in the same bandwidth and the actual bit-depth isn’t always signalled. My guess is the lowest 2 bits are zero.
Difficult to say. It probably depends on your TV more than Vero. We have to convert it from 4:2:0 anyway and I don’t think we attempt to dither in the bottom two bits.
Thanks for your thoughts. I now have reliable 4:4:4 support at 1080/50p from my Marantz NR1711, so was exploring a bit more. Some months ago I posted on here how I would get blank screen issues with the Vero when playing my 1080/50 content. At first I found two workarounds for this: 1) connect the Vero to the AVR’s 8K input, and then 1080/50/4:4:4 worked, or 2) otherwise use a regular HDMI input and use the force 4:2:2 option on the Vero. I have now found that the Marantz video setting for “4K/8K Signal Format” by default does not allow 4:4:4 at 50p on any resolution, but if you set this to “8K Enhanced” (and ignore the warning), then 4:4:4 at 1080/50p works on all the HDMI inputs. I don’t know if previously the Marantz was falsely advertising 4:4:4 support to the Vero at 1080/50, but now it actually works.
Virtually all digital video is stored in 4:2:0 format. In order for it to be displayed on the screen, somewhere along the line it has to be converted to 4:4:4; the only question is whether the conversion (“chroma upsampling”) is done by the source, by the TV, or by a combination of both. So, it’s not a case of “4:2:2 vs 4:4:4” it’s a case of “4:4:4 that was upsampled by the source vs 4:4:4 that was upsampled partly by the source and partly by the TV”.
Which device does the upsampling can occasionally have a subtle impact on image quality, because not all devices use the same algorithm to do it. My 2017 Nvidia Shield, for example, has a particularly poor chroma upsampling algorithm, which is one of the many things that makes its image quality substandard. Panasonic UHD blu-ray players are supposed to have an unusually sophisticated algorithm, so in that case allowing the player to upsample rather than the TV might slightly improve the image.
But most devices (including, I think, the Vero, and quite likely also your TV) use a bilinear approach for chroma upsampling, so it’s unlikely that you’ll see any visible difference between the Vero handling it and the TV handling it.
As for the bit depth, I suspect it’s going to be sending exactly the same numbers, regardless of the nominal bit depth, it’s just that two of the digits in the 12-bit case will always be zero. (That’s if it’s really 12-bit at all - 4:2:2 tends to be identified as 12-bit even when it isn’t).
I think I read somewhere that the “native” output of the Vero’s video acceleration hardware is 4:4:4 and converting the signal back to 4:2:2 requires a little extra processing… but that’s obviously preferable to not getting a signal! So, all in all, I wouldn’t worry about it.
I agree, not sure if the Marantz is advertising 4:4:4 support @ 50p that is choked on default settings, but the long-standing mystery of my blank screens @ 50p from the Vero is now resolved. For some reason, full bandwidth is not enabled by default (see table below). Although 1080 resolution is not listed, I noticed that 4:4:4 @ 50p for 4K is disabled on the default “Enhanced” setting, and I wondered if that might have been carried over to 1080/50 as well. This turned out to be a good hunch, and 4:4:4 1080/50 is indeed disabled out of the box. An oversight in the manual and probably the firmware too.
Also noticed that 4:2:2 is only availble in 12 bit - is that a universal standard?
It appears Standard, Enhanced and 8K Enhanced correspond approximately to HDMI 1.4, 2.0 and 2.1 respectively. The reason 4k 50 (and 60)Hz is not supported at 10 and 12 bits 4:4:4 in HDMI 2.0 is they need more than 18GHz bandwidth - the limit for HDMI 2.0. There is no earthly reason why 1080p50Hz should not be supported at Standard setting. And certainly no reason if 1080p60Hz is supported. 1080p50Hz and 60Hz are practically the same signal.
Yes. 4:2:2 accommodates 12 bits, but if 8 or 10 bits are sent as 4:2:2 the low bits are just zeroed.
