How to use properly anti-aliasing modes and increase the video rate in LCD TVs when connecting to PC
Today's LCD TVs that are in the medium price ranges often have the mode of expansion rate up to 100-200 Hz due to the technical tricks of picture perception by person.
For example, TrueMotion technology in LG TVs, Motion Plus in Samsung, Perfect Natural Motion in Philips, and RealCinema in Panasonic.
How can we use them properly when connecting to a PC?
If you know what the scanning expansion and the video smoothing technologies are in TVs just skip it.
When receiving an input signal (let’s say 50Hz) a TV set simply shows each frame twice that would stretch the entire process up to 100 Hz in regular mode. This does not make a lot of sense. How does technology affect the image smoothing to make us believe in the real 100Hz picture? The technology is not new and is quite simple. When receiving an image of input signal TV delays 1-2 frames before the showing and begins to compute the shift difference between adjacent frames to create its own, an intermediate image between them.
TV processor, depending on the algorithms computes scene shift objects, background and other parameters, creating on the basis of all data a frame, which will smooth the changeover between two real frames received from the source. Especially, this effect becomes noticeable when there is the panoramic shooting with shifting background, the computation of intermediate frames allow reducing the shift background gaps between frames, which makes the resulting image is much smoother (in 2-4 times).
But there is one difficulty that made me to write this article.
It would seem that we have a computer and a graphics card with HDMI output, let them deal with anti-aliasing and other processing, why do we need all these tricks with the TV set? Everything is fine, but that's just depending on the graphics card and TV the signal can be transmitted over HDMI cable with the maximum possible frequency 50-60Hz (in expansion of 1080p). 60Hz is quite far from 100 Hz. It is foolish not to use all the equipment. Okay, let's say we have a ceiling of 50 Hz; we can also enable anti-aliasing at this frequency. Here begins the main trick. Basically, all digital movies have only ~ 24 frames / second (even Mega Blu-ray Remux of 40GB). A final picture of the video is received by the same simple trick – smearing frames to get the desired frequency, but in this case, all those things are done by the graphics card with a video processor and software video players.
So, let’s take a look at the result - we took the film in ~ 24Hz (frames per second) - stretched it using a PC up to 50Hz, and then it gave the TV that is trying to stretch it even before receiving the 100Hz. The result is a funny image. The image begins to floating. It slows down then speeds up, and periodically it freezes for a split second. Watching the video in this mode is close to the hell, although the picture gets smoother and bumpless, but the constant change of speed and jerks after 10 minutes of watching cause strong desire to turn this nightmare. What's the problem? It is a double work on the video. Working algorithms on the PC and the TV are not synchronized with each other and they get the output of the mutant made of the different pieces.
Hence we get a bunch of negative comments about TVs on the forums.
Here we come to the most interesting point. What do you do? There are a few options, but the right ones are much less. The obvious one is to enable the TV technology of smoothing and watch 50-60Hz received from the PC. It is not a very rosy outlook, knowing that the TV can produce twice as much. Here is more proper method such as to disable image processing on the PC, and let the TV to deal with the picture. In practice, this means that when we open the movie file, the player recognize that the frame rate is 24Hz in this file and automatically converts HDMI output video card in this mode. As a result, we have on the TV almost raw video stream at 24 frames / sec that is not spoiled by any processing. Here is the smoothing technology does a great job in the TV, we turn on anti-aliasing mode and watch a smooth picture without jerks and decelerations. Take my word for it, it is worth just to try and understand the difference. Considering that the experiment itself does not take much time, and it requires only a couple of checkmarks in the settings, I strongly recommend if you are the owner of the TV with the pseudo-hertz like 100-200-500Hz just to try this method. I think that you just will not come back to the old one.
Now I say a few words about disadvantages. Actually, there are not many. First of all, it becomes difficult to watch video in the window. Due to the fact that the image is switched to 24Hz mode, the interface and the program will look like retarded. This technology is designed strictly for a video, and not for gaming or work. Secondly, there are some problems with the TV rate change, for example, they can automatically switch it to regular TV mode, losing HDMI (considering that the source is gone), and then you have to switch back to the remote control. What can I say? You just have to try it by yourself!
I have a few words for those who are too lazy or do not have time. To enable a full mode of pseudo-hertz on today's LCD TVs, it is needed to enable their anti-aliasing modes, and as for a computer you need to enable in the video player the setting of image frequency control at the output according to the original frequency of a video file. Why it helps - see above.
To enable an output auto-switching in the same mode that is the video file can be done by a player (I use for this built-in player in xbmc where there is a such option), or a third-party software such as autofrequency - www.homecinema-hd.com/autofrequency_en.html that recognizes the frequency of the video, switches the screen and then starts the video in the player (like MPC-HC). Unfortunately, I cannot list these menu options for all the players, I'll be grateful if you could help in the comments.
For example, in xbmc video output settings it is done like this:
We may have a little play around with the rest of the menu options to get a clean sound and correct vertical sync with the TV set.
Manual switching of the screen modes also should work, even though the frequency in the video is not always exactly 24 Hz, and it may often be 23.976 Hz, but there always should fit 24Hz mode.
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