When playing a standard definition video, or a 720p/24 video, is there any way to completely avoid upscaling?

Help and Support
1

This may be more of a Kodi question than an OSMC question, but I’ll chance my arm anyway. :slight_smile:

I find the upscaling on my Vero 4K+ isn’t the best. It’s not bad; but I also own a Lumagen RadiancePro video processor, and its upscaling is definitely better. So, if possible, I’d like to have the 4K+ output all videos at native resolution and have the RPro do the scaling. This works okay for 1080p streams - 4K+ switches automatically between 1080p and 2160p - but there are two situations where I have trouble with this.

The first is that I have a few videos which are encoded as 720p/24. Is there any way to force the 4K+ to output 720p/24 (or rather 720p/23.976)? It doesn’t seem to want to. (I could output it as 720p/60, but the RPro and TV can’t reliably convert 60Hz to 24Hz, so this gives 3:2 judder).

The second case is when we’re dealing with a DVD rip. The 4K+ doesn’t seem to support 576p/50 or 480p/60 output. (If it actually does, that’s probably the solution to my problem!).

I wondered about using the “original size” scaling option during playback. SD video doesn’t always look that good scaled up to full screen on a 65" TV anyway. So I figured, if I don’t mind having a smaller picture, I can output 720p or 1080p, with Kodi’s zoom mode set to “Original Size”: I should then get the unaltered video in the middle of an otherwise black screen… but of course I don’t: there’s always some scaling, because SD video has rectangular pixels.

For 720x576, if the video is supposed to be 4:3, “original size” gives you (I think) 768x576; for 16:9, it gives you 1024x576.

For 720x480, 16:9 original size gives you (I think) 853x480; and for 4:3 it actually downscales horizontally and gives you 640x480. (I guess I could use 50% zoom instead with 1080p output - that should give 720x540).

So, in each of these cases, the 4K+ is still doing some scaling, and the RPro is then re-scaling, which is not optimal.

The RPro does support applying different horizontal and vertical scaling factors; so, is it possible to get the 4K+ to output a completely unscaled 720x576 or 720x480 image (with initially incorrect aspect ratio) within a 1080p or 720p image, so I can then get the RPro to scale everything to the right size? If so, what combination of settings on the 4K+ gives me that?

2

This is currently not possible, but it has been discussed before. Although outputting the image pixel-perfect in a 1080p frame is new. There hasn’t been a lot of demand for any of this until now and it would also bring difficulties: What would the GUI look like with native resolution output or when taking your approach, @angry.sardine? That’s probably one of the more obvious ones. The other might be that Kodi seems to only like 720p as the lowest output resolution.

Native resolution output (of formats supported by HDMI) might be possible with Kodi v18’s resolution whitelisting.

3

On a Raspberry Pi running OSMC you can actually set the output to 576p or 480p - try it and see what it looks like. :slight_smile:

The fact that this is not an option on the Vero 4K+ made me wonder if it was a hardware limitation.

I’m always surprised that I seem to be the only person on the planet who prefers not to upscale SD to full screen - I think it’s looks so much better that way. :slight_smile:

5

Setting the whole GUI to that resolution isn’t what we’re discussing here. It’s just downgrading the output resolution to the native source resolution with the GUI set to 1080p.

6

Well, no: what I want is for the video to play at 576p or 480p; I don’t care that much about what the GUI is doing. :slight_smile:

But my point was that you can actually run OSMC with 480p or 576p output on the Raspberry Pi right now, and the GUI is still usable (if not exactly pretty); so I don’t think that’s a major obstacle.

So (reverting to a previous subject) is 720p/24 output possible?

And is there any way to get an exact 720x576 or 720x480 image embedded in 1080p or 720p output? It looks like it ought to be possible by ticking the Non-Linear Scaling box and then carefully adjusting the Zoom and Pixel Ratio settings; but because you can only adjust those to two decimal places, I’m not sure you can get the exact number of pixels you need to avoid scaling.

7

If your intention is to get pixel-for-pixel output you are really swimming against the tide. I don’t think anyone involved with kodi ever thought that would be worth providing for.

Besides, you should know that SD material is rarely square pixels so there’s always going to be some scaling at least in one direction.

8

Someone must have, or they wouldn’t have added the “Original Size” zoom option. I sometimes use that for 720p/24 videos - output it as 1280x720 within a 1080p/24 stream.

Yes, I know, I already said that. :slight_smile: It’s for precisely that reason that I’m exploring the Non-Linear Scaling function. If I can persuade the thing to actually give me an unscaled 720x480 image, I can then use my Lumagen processor to scale non-linearly to the correct aspect ratio.

The end goal is just to get the video out in the most raw state possible so all the processing (including scaling) can be done by an external device.

Obviously, if the Vero 4K+ could actually output 576p and 480p, I wouldn’t need to try something this convoluted. That would be a much better solution.

9

since you mentioned Lumagen

Does the vero 4k + work with a video processor such as Lumagen RadiancePro? I don’t have mine yet so I didn’t go into detail on how to use it with vero but in any case with if you have a Lumagen it would be a waste of money if you wouldn’t or couldn’t let it handle all the video processing I guess we’d need some kind of Passthrough mode for video

10

Kodi v18 adds support for outputting content at its native resolution.
I think this will meet your requirements.

Sam

11

Oh, cool. :slight_smile:

I don’t suppose that includes 576i and 480i output (as opposed to 576p and 480p) does it?

Also: do you OSMC people ever sleep?! :grinning:

12

576/480 requires some changes to add support for these modes, but it’s possible.

If I remember correctly, supporting 480/576 modes was only possible for CVBS output to avoid conflict. We can definitely revisit this and I can’t see why both use case scenarios cannot be made to work.

Cheers

Sam

13

Certainly the ability to output 576p and 480p from the Vero 4K+ via HDMI (and thus have SD video playing at native resolution) would make the device much more useful from my perspective.

14

I doubt it. We would have to bypass the deinterlacer. I’ve just spent some time playing with Leia, whitelisting and various viewmodes. There appear to be some strange decisions being made by Kodi and/or Vero when it comes to handling non-square pixels but these will be ironed out to get it right for normal viewing.

I re-read your OP and now appreciate better what you want to achieve. As I said, no-one at Kodi seems interested in pixel-for-pixel throughput. I don’t know what the intended use for ‘original size’ was but you are right, it means 576 or 480 lines but 4:3 or 16:9 as appropriate. That’s exactly what TVs do: effectively 704->768 or 704->640 for 4:3 for example. We can have a look at overriding that, I guess, but exposing a setting in the GUI for it would baffle most users.

15

Well, that’s not too big a deal - my RadiancePro is supposed to be be able to reinterlace 480p and 576p; so if it were up to me (and I’m sure you’re happy that it isn’t up to me :slight_smile: ) allowing 480p and 576p video playback would be a high priority; 480i and 576i very low priority.

16

Why would you do that? Unless you knew the exact algorithm AML use and reversed it.

17

There must surely be plenty of settings in Kodi that most users would never want to touch, but a few do?

You can put a scary warning on it saying “don’t change this unless you’re 100% certain you know what you’re doing”. :slight_smile:

In case this wasn’t clear: if you could enable 480p and 576p video playback (so the Vero 4K+ produces a deinterlaced but completely unscaled image) that would completely solve my issue; messing around with Original Size, Non Linear Scaling, and Pixel Ratio would then be pointless. I was looking at those only as a possible fall-back strategy if native-SD-resolution output turned out not to be possible.

18

It was clear. Or is today, anyway!

1 Like
20

When you deinterlace something, all of the pixels in the original interlaced stream should still be there. The original odd field contains pixel rows 1, 3, 5, etc. and the even field has rows 2, 4, 6, etc. When constructing a progressive frame corresponding to the first field, all of pixel rows 1, 3, 5, etc. are left intact; the even pixel rows are then generated - how you generate them depends on the algorithm.

So, regardless of the algorithm, so long as you know the frame was based on an odd field, all you have to is grab the odd pixel rows and ignore the even ones. Then you do the reverse for the next frame (grab even rows).

Keep going and you’ve perfectly reconstructed the original interlaced video - meaning you can then apply a different and potentially better deinterlacing algorithm.

25

I decided to live dangerously and install the latest Leia test build on my 4K+.

Intriguingly, it actually does support 576p and 480p output resolutions, and even switches to those resolutions automatically at playback if you whitelist them. But, frustratingly, if you play a DVD rip with the output set to 480p or 576p, it screws up the aspect ratio. :rage:

You can get it nearly correct by setting a pixel ratio of 1.13 for an NTSC DVD, or 0.94 for PAL; but to get it exact would require a pixel ratio of 1.125 or 0.9375, which you can’t enter. (And I’m not sure I trust Kodi to completely bypass the scaling process even under those conditions).

If a video is 720x480 and the output resolution is also 720x480, it’s not clear to me why “no scaling at all” isn’t the default. :roll_eyes:

Of course, this is probably a Kodi issue rather than an OSMC one :slight_smile: but as it affects the usefulness of the Vero 4K and (presumably) other OSMC-made devices, it might be worth looking into at least briefly…?

26

Yes, this is exactly what I found. Unwhitelist those 480 resolutions and pick original size to get rid of the aspect ratio screw-up until an answer is found for that.

If I play a 576 4:3 vid with 576 whitelisted at original size my TV blows it up to 2304 high so it goes off the top and bottom of the screen. Makes some sense, I suppose.