[Rohan]

When all you guys talk about how you have your CRT PJs setup and reference your resolution like 1440x720 @ 48mhz or whatever, what does that really mean?


Isn't 48mhz 48 frames per second?


I thought 480p = 60 frames per second -- why do you drop your frames per second? Because of RGBHV bandwidth limitations?


When you drop frames per second, aren't you losing data?

 

[Mooneyass]

it's 1440 x 720 @48 Hz (not mhz). The 48Hz refers to the frame rate at which the image is refreshed, like frames per second. Keep in mind that this is progressive scan, meaning the entire frame (all scan lines) is drawn every 1/48th of a second. Regular TV is interlaced at 60 Hz, meaning half the frame (every second line) is drawn every 1/60th of a second. 480p is called line doubling, when you refer to NTSC video. Essentially you de-interlace the image or recombine ever second frame back into one (which would sort of equal 30Hz now). Then you display it twice as many times (if you're running @60Hz still).


Movies/DVD's are filmed at 24 fps progressive. This is why most every one runs their PJ's at 48 Hz or 72 Hz, as it is a multiple of the original source fram rate.


MHz refers to the video bandwidth, or throughput if you prefer....


Clear as mud?

 

[Drew Eckhardt]

1. It's 48Hz, as in 48 frames-per-second. 48MHz would be 48 million frames per second.


2. While 480p is 60 frames per second, film is 24 fps. To go between the two, a frame of film becomes 3 video frames, the next film frame 2 video frames, the next 3, etc. This creates a certain amount of motion judder that's not present when you run an integral multiple of the 24fps film frame rate. Information is not lost for film sources.


3. People run 48Hz instead of 72Hz (or 120Hz, which is an integral multiple of both 24fps from film and 60fps from video) because many projectors don't have the bandwidth for 72Hz and start getting soft.