Auto Frame Rate Synchronization

From NMTWiki

With the auto frame rate feature, the NMT player will detect the frame rate of the source file, and then change the output frame rate so that it matches the frame rate of the source file.

A video frame rate is how many picture frames are shown during the course of one second. The measuring unit for frame rate is "frames per second" or fps.

Typical FPS settings

• PAL (50Hz), the TV system used in Europe and Asia, has a basic frame rate of 25 frames per second.
• NTSC (60Hz), the TV system used in North America, has a basic frame rate of 29.97 frames per second.
• Movies from Europe and Asia have a basic frame rate of 25 frames per second.
• Movies made in the USA have a basic frame rate of 23.976 frames per second, some European releases are actually 24 frames per second.
• Some TV's claim 24fps compatibility. Most sets that are 37" or larger are fine and will have the required pixel to natively display 24fps material. However some smaller screens that claim this or lower spec larger screen models cheat by actually accepting the signal but then post-processing and displaying at NTSC(60Hz) which introduces judder. Make sure your TV has 1920x1080 pixels if you want true judder free playback on the NTSC/24 or NTSC/PAL/24 settings.

Why Bother?

When you play back a source file that has a different frame rate than the output setting you have chosen, then the result on your TV will be what is called judder, the picture will have small regular stutters to compensate for the difference between the source material's frame rate, and the video resolution refresh rate based on the source material frame rate and the available TV video resolutions.

Some people are more susceptible to perceiving judder than others, in addition the type of video material can make a big difference - action movies with lots of camera panning will show more judder than static drama.

Before the auto frame rate feature was introduced, you would have to select the output manually to make sure that the correct resolution for the source material's frame rate was used, thereby avoiding judder.

Some may prefer to leave the autoframerate feature turned OFF, particularly those with expensive scalers, and continue to select the correct resolution setting for each video, remember it is not compulsory to use autoframerate.

With the auto frame rate feature, the NMT player will detect the frame rate of the source file, and then change the output resolution to the best setting that your TV can accept. Based on what settings you have chosen in SETUP on your NMT.

What Setting Should I choose?

This depends mainly on 2 things:

• What frame rate does your TV support?

If you don't know, read the manual or google the model name.

If your TV does not support 24fps (sometimes called "RealCinema" by TV manufacturers), then you should choose the PAL/NTSC setting in the auto frame rate drop down - this will play the 24fps video at 60fps, which will be imperfect, but the best setting for your TV.

However if you are in the USA, you may have a TV that does not support PAL 25fps either! If so, you should disable the Auto frame rate setting completely and set your TV output to 1080p60/720p60 depending on your screen size.

• If your TV supports both NTSC & PAL and in addition also has 24fps, then you use the NTSC/PAL/24psetting in the auto frame rate box.

Again if you in the USA you may have a TV that doesn't have PAL. Therefore select NTSC/24p.

Some TVs claim to support 24fps, but in fact display at 60Hz after processing the 24fps signal. Use the "info" button on the handset during playback to check the frame rate that the NMT is using. A substantially more detailed explanation of the different frame rates used, and in particular the approach used to convert movies from 23.976 fps to 29.97 fps using 2:3 pulldown can be found here Telecine

Files that are 23.976fps will be played at 23.976 fps, files that are 24fps will be played at 24 fps. The display will however show 24fps for both 23.976 and 24 fps.