46 replies to this topic

[WanWizard]

I must say I am quite confused with this as well.

 

If a channel is in 1080i25, it means 25fps interlaced. So it will always deinterlace, and if the box doesn't do it, the TV will. SKY broadcasts all HD in 1080i.

 

MBAFF is about encoding interlaced material, it doesn't say anything about that material itself, that could be completely or partily progressive.

[Marko1305]

I must say I am quite confused with this as well.

If a channel is in 1080i25, it means 25fps interlaced. So it will always deinterlace, and if the box doesn't do it, the TV will. SKY broadcasts all HD in 1080i.

MBAFF is about encoding interlaced material, it doesn't say anything about that material itself, that could be completely or partily progressive.

It doesn't mean it is in 25fps interlaced but 25 fields. Those fields should be interlaced to 50fps for high frame rate content like sport channels, but by doing that you are sacrificing half of the vertical image resolution. Then there are movie/tv show channels which broadcast content in 25fps and that's where the problem rises. Receiver is acting like it's 50fps sport channel and trying to deinterlace it, causing the loss of full resolution (most noticeable moiré effect on certain patterns). It should instead detect film 2:2 cadence and play it as 25p which it does on MBAFF encoded channels. That's why I thought forcing it to act the same could fix the problem on 1080i25 channels.

Edited by Marko1305, 10 March 2024 - 16:07.

[WanWizard]

Either way, there isn't much you can do about it. you can tell the SoC what output you want at the HDMI end, and that's about it.

 

Using @Dimitrij's plugin, you can make a mapping from what the channel says is broadcasted (1080i25) to what you want at the HDMI end (which basically configures the SoC on a per-channel basis), and that is the end of the tuning abilities.

 

If the SoC does it wrong in your opinion, the only thing you can do is to use the plugin to make a mapping so that the SoC doesn't do anything (so you map 1080i25 to 1080i25, 1080p50 to 1080p50, and so on), and hope the TV deinterlacer does a better job.

 

Or find a box with a BCM SoC and see if that does a better job.

[Marko1305]

Yeah you are right currently the only viable solution is to map 1080i25 > 1080i and 1080p25 > 1080p . The only problem with that are constant resolution switches with providers which use MBAFF or interleaved for certain channels which are sometimes recognized as 1080i.
I thought maybe second solution to the problem could be making the receiver recognize mbaff channels as 1080i25 and let the TV,which have film mode cadence detection, do all the deinterlacing. Currently using 1080i resolution on 1080p25 channels makes the TV stuck in video deinterlacing 50fps mode unless you manually force it to film mode.

Edited by Marko1305, 10 March 2024 - 16:18.

[Dimitrij]

 

Using @Dimitrij's plugin, you can make a mapping from what the channel says is broadcasted (1080i25) to what you want at the HDMI end (which basically configures the SoC on a per-channel basis), and that is the end of the tuning abilities.

Absolutely right .

I made three different patches, but they are all based on the same principle (the original -->what we want as an output HDMI) .

Edited by Dimitrij, 10 March 2024 - 16:26.

[Dimitrij]

Maybe simple add seting "Enable 1080i25 Mode"?

Then you will supply the desired output value.

[Marko1305]

Yeah it would be an improvement