VLC Deinterlace X question!
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Please post only Windows specific questions in this forum category. If you don't know where to post, please read the different forums' rules. Thanks.
VLC Deinterlace X question!
What are the main differences between the all the deinterlace settings? (Discard, Blend, Mean, Bob, Linear and X) X is new to me and how is X different from the other deinterlace settings?
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Guest
Re: VLC Deinterlace X question!
And why the selection of deinterlacing mode is not automatic ?What are the main differences between the all the deinterlace settings? (Discard, Blend, Mean, Bob, Linear and X) X is new to me and how is X different from the other deinterlace settings?
Re: VLC Deinterlace X question!
It's not automatic because it depends your needs ..... and the type of interlacing.
I may make some errors in my explanation but :
To understand it we need to go to the first age of TV. The thing is, at that time, we didn't knew how to transmit sufficiently fps thru radio.
So Interlacing has been invented. The principle basis is on your eye reaction. we can see distincly each image for around 16 to 25 frame per second. However, for having smooth movement and avoid flickering in the video we need for 50 to 60 frame per second (because we can see partial images until this rate).
The idea was to send half of the image instead it's full resolution. At the end you never have, on your TV, a full image. The tv works twice faster than the signal. Once it shows the first half image and then it fills the blank with the next half image.
So why we have it on our DVD ? a such old technology ? That's simple, to keep compatibility with some TV that still use interlacing.
We can see it with CRT or flat panel because they always use a full image on their signal.
Here is the basis interlacing.
Now what's up for deinterlacing..... As you understand interlacing destroys data ...... and deinterlacing needs to create an half image that doesn't exist.
Here is the explanation of those method that I know :
- Discard : discard one half of the image (odd or even) .... it doesn't respect the original size (due to the data loss)
- Blend : not sure, I think that's separating the two half and fuse them. it also doesn't respect the original size.
- Mean : it removes one half and create a new half thru a blur algorithm between each line
- Bob : Blend + Mean .....
- Linear : don't remember
- X : I'm really not sure : that's the algorithm available in your graphical system .......
Each depends on a particular situation.
The most used and most common is Mean. With it you will not have surprise. the others are here to keep the best image quality of particular situations.
I may make some errors in my explanation but :
To understand it we need to go to the first age of TV. The thing is, at that time, we didn't knew how to transmit sufficiently fps thru radio.
So Interlacing has been invented. The principle basis is on your eye reaction. we can see distincly each image for around 16 to 25 frame per second. However, for having smooth movement and avoid flickering in the video we need for 50 to 60 frame per second (because we can see partial images until this rate).
The idea was to send half of the image instead it's full resolution. At the end you never have, on your TV, a full image. The tv works twice faster than the signal. Once it shows the first half image and then it fills the blank with the next half image.
So why we have it on our DVD ? a such old technology ? That's simple, to keep compatibility with some TV that still use interlacing.
We can see it with CRT or flat panel because they always use a full image on their signal.
Here is the basis interlacing.
Now what's up for deinterlacing..... As you understand interlacing destroys data ...... and deinterlacing needs to create an half image that doesn't exist.
Here is the explanation of those method that I know :
- Discard : discard one half of the image (odd or even) .... it doesn't respect the original size (due to the data loss)
- Blend : not sure, I think that's separating the two half and fuse them. it also doesn't respect the original size.
- Mean : it removes one half and create a new half thru a blur algorithm between each line
- Bob : Blend + Mean .....
- Linear : don't remember
- X : I'm really not sure : that's the algorithm available in your graphical system .......
Each depends on a particular situation.
The most used and most common is Mean. With it you will not have surprise. the others are here to keep the best image quality of particular situations.
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Guest
Re: VLC Deinterlace X question!
I mean it seems that other players like PowerDVD and WinDVD are able to do that automatically, so I wonder why VLC can't do it...It's not automatic because it depends your needs ..... and the type of interlacing.
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Guest
Perhaps suggesting this to the standards committee so that a flag is written by the encoders for the type of interlacing that was used would allow the library to sense what filter would be best. 
Generally there are user flags that are almost never used in any given format, one certainly wouldn't be missed if designated specific. Now it just a matter of getting all of the encoders updated and the users to set the flag. 
Of coarse all of the players would need to be updated too! But that wouldn't be many because most of them don't have these features.
Generally there are user flags that are almost never used in any given format, one certainly wouldn't be missed if designated specific. Now it just a matter of getting all of the encoders updated and the users to set the flag. Of coarse all of the players would need to be updated too! But that wouldn't be many because most of them don't have these features.1 - because there is a lot of interlacing type
2 - because, as guest said, it's not said in advance .... and none say that they are interlaced or not.
3 - because it's impossible to know before it occurs (witch can be far after the start of your movie)
4 - no player have automatic detection, just deinterlacing always activated ....
5 - some technics needs a subjective choice ...... so it needs an AI that exist only on high research labs at experimental stage or in design stage .......
That's why it needs to be manual ....... because the system need your brain to say witch is the best for your video.
Interlacing is an analog trick .... not a digital ......... things done easily in analog can be troublesome in digital (or impossible for the moment). And the reverse is also true
2 - because, as guest said, it's not said in advance .... and none say that they are interlaced or not.
3 - because it's impossible to know before it occurs (witch can be far after the start of your movie)
4 - no player have automatic detection, just deinterlacing always activated ....
5 - some technics needs a subjective choice ...... so it needs an AI that exist only on high research labs at experimental stage or in design stage .......
That's why it needs to be manual ....... because the system need your brain to say witch is the best for your video.
Interlacing is an analog trick .... not a digital ......... things done easily in analog can be troublesome in digital (or impossible for the moment). And the reverse is also true
Last edited by Mimiru on 04 Jul 2006 22:36, edited 1 time in total.
To make it easy to understand :
for a played interlaced video :
In a computer view :
Deinterlacing alters the quality, it does not enhance it. He can't say witch image is best thru this or this deinterlacing algorithm .... because he can't recognise what is inside the picture. When you see a picture with someone that is walking ..... the computer only see pixels. He needs an image recognition system to recognise forms and errors on those forms ....... and a big database to recognise everything on earth ........ This does not exist for the moment ......
You can also say that he can do it via pattern comparison ...... but you need the original ........ but this system, in our case, lead also to AI.....
In a TV view : the trick is done thru the latency of your eye and the latency of the phosphorous layer (two things impossible to reproduce in digital way for the moment).
for a played interlaced video :
In a computer view :
Deinterlacing alters the quality, it does not enhance it. He can't say witch image is best thru this or this deinterlacing algorithm .... because he can't recognise what is inside the picture. When you see a picture with someone that is walking ..... the computer only see pixels. He needs an image recognition system to recognise forms and errors on those forms ....... and a big database to recognise everything on earth ........ This does not exist for the moment ......
You can also say that he can do it via pattern comparison ...... but you need the original ........ but this system, in our case, lead also to AI.....
In a TV view : the trick is done thru the latency of your eye and the latency of the phosphorous layer (two things impossible to reproduce in digital way for the moment).
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DeadlyNinja
X Deinterlace Method
The source code (modules/videofilter/deinterlace.c) says:
I only looked at it for a few minutes, but the code itself is somewhat cryptic.
Code: Select all
/*****************************************************************************
* RenderX: This algo works on a 8x8 block basic, it copies the top field
* and apply a process to recreate the bottom field :
* If a 8x8 block is classified as :
* - progressive: it applies a small blend (1,6,1)
* - interlaced:
* * in the MMX version: we do a ME between the 2 fields, if there is a
* good match we use MC to recreate the bottom field (with a small
* blend (1,6,1) )
* * otherwise: it recreates the bottom field by an edge oriented
* interpolation.
*****************************************************************************/
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