16 replies to this topic

[Marko1305]

Hi, I always have doubt when watching 1080i25 sport channels should I set 1080i50 or 1080p50 in autoresolution plugin, which one would provide optimal picture quality. Also deinterlacer mode for interlaced content auto, bob or off? If tv is high-end should I change some settings to let tv deinterlace content?

[WanWizard]

I decided against using the plugin.

 

I couldn't see much (if at all) difference between the scaler of the box and of the TV, and I quickly got annoyed by the extra seconds of zap time every time my TV needed to switch resolutions.

 

I you do want to use it, I suggest you set all relevant resolutions in the plugin to pass-through as is (so 1080i25 -> 1080i25), to avoid setting two scalers to work.

[Marko1305]

My setup is simple 2160p auto (24/50/60hz) for 4k channels and 1080p auto (24/50/60hz) for everything else. I think that stbs are generally not able to set refresh rate to 25hz only 24 50 and 60hz. It is probably because tv's struggle with 25hz and display 50hz better. Should I set 1080i50 or 1080p50, what's considered more correct?

Edited by Marko1305, 16 January 2023 - 13:47.

[WanWizard]

You have to be careful not to mix refresh rate and frames-per-second.

 

24 comes from the movie industry (35mm film), in which 24 fps is used. 50 is used in countries where the AC network uses 50Hz, and 60 from countries where the AC network uses 60Hz.

 

25 and 30 fps are always because interlacing is used, so there is no 1080p25 or 1080p30. For the same reason, there is no 1080i50 or 1080i60.

 

If you set the box output mode to 1080i, it will leave the deinterlacing to the TV, it you set it to 1080p, the box will do the deinterlacing.

 

But in both cases, the refresh rate of the signal going to the TV will be 50Hz or 60Hz (according to your refresh rate setting)

 

This is because you always have 50 or 60 frames, the only difference is that with interlacing, each frame contains only half the image information (in the analog world half the lines).

[Marko1305]

I understand the difference between fps and hz, but when I set the stb to 1080i tv reports signal as 1080 i50 not i25.

[WanWizard]

The two are mixed up everywhere.

 

1080i25 50 Hz contains 50 fields, each field with half a frame, giving 25 full frames after deinterlacing.

 

Is the TV displaying frames, or fields (Hz)?

[Marko1305]

Fields(hz)

[WanWizard]

In which case 1080 i50 is correct.

[Marko1305]

Will motion in sports now be smoother? Is tv scaler better than the box? Watching tennis right now and balls seems smoother but that may be placebo effect. One annoying thing with 1080i is GUI fluidness which is like flickering/lagging a little bit as expected.

Edited by Marko1305, 16 January 2023 - 16:31.

[Marko1305]

In which case 1080 i50 is correct.

Do I need to change deinterlace mod for interlaced content to off or bob now in autoresolution plugin?

[WanWizard]

I don't use the autoresolution plugin, as I don't see a difference between the scaler in my VU+ Solo 4K and the one in my TV (which is high-end by only HD, no 4K).

 

What the best approach is, is highly depending on what box, what TV, what you watch, and your perceptions, so it is difficult to give generic advice.

[Marko1305]

But it should be a general rule whether you should turn off deinterlace mode or set it to auto if you choose to let the tv do the deinterlacing. My assumption is off or auto as safer option.

Edited by Marko1305, 16 January 2023 - 17:47.

[WanWizard]

auto means the box will decide what the best method is, so use off if you want to TV to deinterlace.

[Marko1305]

That's what I thought as well thanks for the help.

[Dimitrij]

root@lunix3-4k:~# cat /proc/stb/vmpeg/deinterlace
off on auto
root@lunix3-4k:~# echo auto > /proc/stb/vmpeg/deinterlace
root@lunix3-4k:~# cat /proc/stb/vmpeg/deinterlace
off on auto
root@lunix3-4k:~# echo on > /proc/stb/vmpeg/deinterlace
root@lunix3-4k:~# cat /proc/stb/vmpeg/deinterlace
off on auto
root@lunix3-4k:~#

In my opinion, in modern receivers, this option does not affect anything.

[Marko1305]

I did some testing on the news channels with horizontal moving bar and I can truly see the difference between tv scaler and box scaler. When box is deinterlacing there is little lag on moving objects every 2-3 seconds and the picture is totally smooth when the tv does it.

[Trial]

Hi,

as there will never be a general answer what is best my advise was always: Test it and choose what you like more. News ticker is always a good test for interlaced material.

 

Keep in mind that there was no real progress in developing STBs but a lot on TV.

 

Ralf