Video quality

General Discussion
1

Chaps, hello.
Let me tell you a story, will ya?

I’ve been using a PC as my main movie player for as long as I can remember. Why? Because I like having everything in one place, and the PC just does that perfectly. On top of that, the video quality you get out of a PC has always been better than anything else, at least in my experience. MadVR was the big reason back in the day, but since I moved from Windows to Linux, MPV has been my hero.

Well, that illusion got shattered with HDR. I only jumped into HDR this year (believe it or not) because, first, I’m on Linux now, and second, I’m stuck with NVIDIA GPUs. None of the other options give me HDMI 2.1 + VRR, and only recently has HDR been simple enough to actually enable and use. DisplayPort isn’t an option, there are no DP AVRs, and every DP-to-HDMI adapter I tried (and I swear I tried them all) failed one way or another. So yeah, NVIDIA it is.

Alright, context out of the way, back to HDR.

KDE desktop HDR support for proper movie playback has been such a mess that I gave up. What I need is an external player I can trust not to mess with HDR at all. There’s no point in calibrating my display if the player/KDE compositor is just going to ruin it afterwards. When it comes to EOTF, gamut, etc, I don’t want any kind of signal remapping happening.

If you’re curious about the drama:
Plasma 6.3 broke HDR brightness
HDR calibration tool - KDE 6.4

I’m waiting for my Vero V to arrive, but in the meantime I’ve been playing around with both OSMC and LibreELEC on a Raspberry Pi 4.

The Pi actually runs better on LibreELEC. The Kodi GUI there looks hardware accelerated, while on OSMC it feels software rendered, so one’s smooth and the other’s choppy. Not the main issue though. Both can play HDR H.265 just fine, which at least gives me a taste of what I’m in for. (Also, on OSMC, switching RGB full/limited seems to do nothing, is that a bug?)

Anyway, venting over. Now that I’ve got a player I can trust not to touch HDR, I’ve realized there’s no point trying to force KDE + MPV into that role if I want the signal to stay completely untouched all the way to the display.

But circling back to my original point: “the video quality you can get out of a PC is in my experience always superior to anything else.”

Same goes for banding. My TV’s an OLED, and as everyone knows, OLED banding is notoriously hard to get rid of. MPV makes it basically disappear, while on the Pi it’s clearly there. Skies especially stick out like a sore thumb. Thankfully, LG’s “smooth gradation” helps, but still… MPV playback is just on another level.

So, after all this rambling (sorry), here’s the actual question:
Is the Vero V’s video output any better than the RPi4?

I’m getting the Vero V either way (order’s already in, I want AV1 playback), but I’d rather set my expectations before I actually test it.

I also tried digging into video processing add-ons and tweaks, but since I’m still new to this whole “external media player with Kodi” thing, I’m kind of lost.

Are there filters like deband, dithering, or other processing tricks similar to what MPV offers available?

Thank you for having given me some minutes of your life (I’m sorry :smiley: ).

Adolfo

2

If you switch to full, OSMC will output full-range and signal to your TV it’s full-range so you shouldn’t expect to see a difference. You may see a difference when outputting YUV as some (most?) TVs don’t do YUV full-range.

I don’t know whether the Pi can output 10 bits, or if it can whether it is in your testing. Vero certainly does output 10 or 12 bits and with that I’ve never been bothered by banding on LED or OLED screens. I think we would have heard from users if there was a problem.

These functions are built in to the video chain. There are no user adjustments available - it just works.

In fact ‘just works’ should be the biggest difference you see coming from the mess which is video on PC.
Let us know how it goes, and welcome!

3

I’ll confirm, but I’m pretty sure the signal stayed as RGB Limited.

The Pi 4 can output 10-bit in both RGB and YCbCr. I use it as a pattern generator for calibration purposes with ColorSpace software. Both LibreELEC and OSMC output RGB 12-bit by default when playing an HDR movie in my setup. If I force YCbCr on OSMC (LibreELEC does not have this option, or I’m missing it), it only outputs 8-bit HDR, but I’m sure it is capable of outputting 10-bit YCbCr at 4K.

Thank you and I will :smiley: If I spot banding, I’ll try to show it. The Pi 4 definitely has it with RGB 12-bit output where’as with my PC it’s not there.

4

@grahamh I confirmed. PI 4 set to RGB Full, it still outputs RGB Limited.

5

OK. I don’t have a Pi4 but it certainly works correctly on Vero.

6

@grahamh I’m sure it will, but I’ll keep it stock, and I’m assuming it’ll be limited, not full. The banding I mentioned does not occur with the Pi 4 running OSMC, it only happens with LibreELEC. The difference I noticed between LibreELEC and OSMC on the Pi 4 regarding video playback is that LibreELEC outputs in RGB, while OSMC outputs in YCbCr. I’m hesitant to say that’s the problem, but for whatever reason, OSMC produces a clean sky in the same scene, whereas on LibreELEC it’s a color-banding mess with my gear.

7

FYI, there is a big difference in banding between playing HDR and Dolby Vision on my LG OLED. I used to notice banding all the time when playing 4k HDR videos on my Vero 4k+, now I have a Vero V which supports player led DV and I have switched almost entirely to 4k HDR/DV hybrid videos the banding, if their is any, is no longer noticeable.

I think it’s to do with DV being in an 8 bit RGB wrapper over hdmi and being decoded as 12 bit while the HDR was being sent over hdmi as 10 bit.

8

Following my tests with the Pi 4 while waiting for my Vero V, I found that the culprit was having the 4kp60 option enabled in config.txt when using LibreELEC. OSMC does not have that option enabled by default. For some reason, enabling 4K60 makes the Pi 4’s output look really bad in some scenarios.

The banding I see, if I can even call it banding, almost looks like an actual rendering error. There’s color in every gradient, but it gets fixed by disabling 4K60 output. When I do that, the Pi 4’s HDR output changes from RGB to YCbCr, though I believe that’s just a side effect, not the actual cause.

Anyway, once the Vero V arrives, this shouldn’t be a problem. In the meantime, I’m just using the Pi for practicing with Kodi.

I have never seen dolby vision first hand, so that’s on my todo list.

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