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Live TV Deinterlace Method Option


roberto188

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This is a "solution" left in limbo with no way for an admin to create an environment that works best for each device in their system.

 

Right now unless someone reads the forums religiously they won't know there is even an option to set or change it.  The de-interlace options have been removed.

 

The "fix" for not needing to probe is simply a switch used for the filter as I explained above.  That leaves only old devices that can't display 1080/60.  That is the only problem I know of with 1080/p.

 

All we need is a text box that the admin can input devices not to use 60 such as: Roku 1;Roku 2; Roku 3, Chromecast 1

This would allow the admin to adjust the list if needed with any new device that find or don't want to use 60 frames when deinterlacing.

 

Us users who test could report back what new devices we have add to add to our own systems which could then be added to new Emby releases as the default device string.

 

That makes this a simple change that allow the use of 60 frames for every device (if turned on) but allow a blacklist for older devices so they use 30 frames.

 

These would be ADVANCED SETTING that are hidden by default like many other features/options.

 

I personally don't like having to change config options.  I help people a lot view web access to help correct options and tune their systems.  Can't add/change what I can't see or have easy access to.  In order to even check these, I'd need remote access to the system.  That also means if I'm using my own system from remote and find an issue I can't log into the web interface to make the change either.

 

I bet many people reading this thread don't even know what their settings are or how to customize them in the config to test this.

 

I bring this back up because I was just in the forums at the other media server platform and many users are wanting 60 frames for 1080 but have mixed environments. I'd want to introduce them to Emby if it could solve their problem but we can't at present.  So close but missing the ability to blacklist certain devices.

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unisoft

All TV is effectively 60fps. 30fps for any sports is brutal to watch.

No it's not!

 

In the UK it's 25 frames at 50 Hertz interlaced for OTA broadcasts!

 

For HD it's 1920x1080i 25 @ 50hz

(Historically, 1440x1080 was used for a while too but retired now).

 

SD is normally 720x576 25 frames @ 50hz

(there are variations on 720, may sometimes be 704, depends on broadcaster).

 

Different countries = different frame rates.

Edited by unisoft
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Yep, differently electrical system with different hertz so different standards were needed back in the day for the CRTs.

 

The same principle applies however in that using only 25 or 30ish fps vs 50 or 60ish fps is only half the temporal resolution.

 

It's important to understand what "temporal resolution" means so skip this if you already know what it is.

High level description to follow:

 

Back in the day the CRTs could not redraw the screen fast enough because once you "lit up" the dot and then turned it off it wasn't instantly off but quickly dimmed.

So designers figured out that if they did something clever they could overcome this and make it look much better.

What they did was come up with the idea of drawing all ODD NUMBER lines on the first pass, then drawing all EVEN NUMBER lines on the second pass.  ODD, EVEN, ODD, EVEN, over and over again.

 

Sitting at a slight distance from the TV the ODD, EVEN line drawing would look natural.  In the UK this would paint the screen 50 times per second (25 odd & 25 even). HOWEVER this wasn't the end of the story.  One frame IS NOT broken up into odd and even lines.  It's a bit more complicated then that.

 

To better understand this lets assume you're the Flash and walk very fast. :)  In one second you step 50 times (25 with your left foot and 25 times with your right foot).  So in order to fully see each step you would need 50 frame per second.  However in the old CRT days using INTERLACED video we need to cheat.  So the first ODD pass will get you taking your first step with your left foot, the first EVEN pass will get your right foot, next ODD pass your left foot, next EVEN pass your right foot.  Over and over again for the full second.

 

Now lets assume instead of one second we did one minute of this.  Now hopefully you get where I'm going with this.  The ODD and EVEN lines together don't make one sequence of motion but two sequences of motion.

 

Now assuming our film was properly setup for broadcast with interlacing it would work just like above.

 

Jumping forward to today's technology and our present challenges.  Since we don't use CRTs anymore we need to to deinterlace this image and use some type of algorithm to "combine" or use the ODD & EVEN lines.

 

One simple type of deinterlacing will use only the ODD or EVEN lines and throw out the other.  If this is done you will end up with 25 frames per second.  However as you can probably guess if we kept the ODD lines and throw out the EVEN lines using our example above the video would show the Flash "walking" but his left foot would ALWAYS be in front.  That would look funny as hell.  Keep the EVEN line and throw out the ODD lines and only his right foot would be in front.  <-- In either case you only have half the "temporal resolution" or motion of what was intended by the interlacing algorithm that was applied to the film to digitize it.

 

The full motion being conveyed needs both the ODD and EVEN lines to form the motion correctly.  Show only "half" and fast motion scenes like sports look "jerky" with missing motion.

 

There are many different ways to "trick" or try to combine this data back into frames that convey the motion properly but as you can imagine by now there is no substitute for changing this back to 50 fps for display of the full motion.

 

Often times with scenes that don't have a lot of motion you can get by with only 25 fps.  It's not proper by "passable" in many situations.  However, once you understand how it should look then watching anything at 25 fps will look bad regardless of show or movie but fast scenes are just intolerable.

 

It's exactly the same for US TVs but we use 29.97 and 59.94 fps.

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Nah, pass.  These days that solution isn't the easiest to keep working/running well when you need to use multiple "apps".  Try controlling that with a remote using other services such as ESPN, NFL Game Rewind, HBO, CBS All Access, etc.

 

If all you need to use is Emby then OK but something like the Shield TV can give it a good run for it's money at many levels far cheaper and a lot easier.

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Everyone should just use HTPCs and Theater with mpv, and you can do pretty much anything you want :D

 

Except be sure that everything will "just work" every time you turn it on  :P

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Back in the day my HTTPs would always work flawlessly until I had a business trip and sure enough would have an issue when I'm not there. :)

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unisoft

Yep, differently electrical system with different hertz so different standards were needed back in the day for the CRTs.

 

The same principle applies however in that using only 25 or 30ish fps vs 50 or 60ish fps is only half the temporal resolution.

 

It's important to understand what "temporal resolution" means so skip this if you already know what it is.

High level description to follow:

 

Back in the day the CRTs could not redraw the screen fast enough because once you "lit up" the dot and then turned it off it wasn't instantly off but quickly dimmed.

So designers figured out that if they did something clever they could overcome this and make it look much better.

What they did was come up with the idea of drawing all ODD NUMBER lines on the first pass, then drawing all EVEN NUMBER lines on the second pass. ODD, EVEN, ODD, EVEN, over and over again.

 

Sitting at a slight distance from the TV the ODD, EVEN line drawing would look natural. In the UK this would paint the screen 50 times per second (25 odd & 25 even). HOWEVER this wasn't the end of the story. One frame IS NOT broken up into odd and even lines. It's a bit more complicated then that.

 

To better understand this lets assume you're the Flash and walk very fast. :) In one second you step 50 times (25 with your left foot and 25 times with your right foot). So in order to fully see each step you would need 50 frame per second. However in the old CRT days using INTERLACED video we need to cheat. So the first ODD pass will get you taking your first step with your left foot, the first EVEN pass will get your right foot, next ODD pass your left foot, next EVEN pass your right foot. Over and over again for the full second.

 

Now lets assume instead of one second we did one minute of this. Now hopefully you get where I'm going with this. The ODD and EVEN lines together don't make one sequence of motion but two sequences of motion.

 

Now assuming our film was properly setup for broadcast with interlacing it would work just like above.

 

Jumping forward to today's technology and our present challenges. Since we don't use CRTs anymore we need to to deinterlace this image and use some type of algorithm to "combine" or use the ODD & EVEN lines.

 

One simple type of deinterlacing will use only the ODD or EVEN lines and throw out the other. If this is done you will end up with 25 frames per second. However as you can probably guess if we kept the ODD lines and throw out the EVEN lines using our example above the video would show the Flash "walking" but his left foot would ALWAYS be in front. That would look funny as hell. Keep the EVEN line and throw out the ODD lines and only his right foot would be in front. <-- In either case you only have half the "temporal resolution" or motion of what was intended by the interlacing algorithm that was applied to the film to digitize it.

 

The full motion being conveyed needs both the ODD and EVEN lines to form the motion correctly. Show only "half" and fast motion scenes like sports look "jerky" with missing motion.

 

There are many different ways to "trick" or try to combine this data back into frames that convey the motion properly but as you can imagine by now there is no substitute for changing this back to 50 fps for display of the full motion.

 

Often times with scenes that don't have a lot of motion you can get by with only 25 fps. It's not proper by "passable" in many situations. However, once you understand how it should look then watching anything at 25 fps will look bad regardless of show or movie but fast scenes are just intolerable.

 

It's exactly the same for US TVs but we use 29.97 and 59.94 fps.

I'd hope I'd understand is this is my bread and butter stuff for work :)

 

For PAL 50, you need to decide interlace as you said to 50 frames to capture motion properly. It's multiples of 25, so the next nearest is 50. If you did it at 25p, the motion would suffer in that scrolling text like credits would be juddery, and studio video shot material would look washed out and lose live look.

 

iTunes gets it wrong with UK TV content because this is exactly what their encoding suppliers do to 25p, but they get 24p films pretty much right.

Edited by unisoft
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  • 1 month later...

@@Luke

I'm just getting into live tv and find the interlacing issue really annoying.  I'm running on a Synology so getting into the folders for emby will be a bit of a pain.  I'd appreciate these options being returned under some kind of super user mode.  My synology is i3 dual core 3.5ghz so can take a full re-encode.  Is there a way to this via the UI or am I destined to SSH to the encoding folder?

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You are destined to editing the config file for right now. The problem if you read earlier in this topic is that it's not so simple to just add the option and be done with it. If it were, we'd keep it. But in order to add the option, we then have to do quite a bit of other work in order to actually make it work right. Until such time when we might be able to do that, it will stay as a hidden config switch.

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