NTSC and PAL

NTSC and PAL

• PAL: Phase alternating line 

• NTSC: National Television System Committee

• PAL countries run on 50Hz A/C power while NTSC countries run on 60Hz

NTSC video (black-and-white) originally had a frame rate of 30 fps, so the timecode counted at 30 fps. However, NTSC color video (the only kind of NTSC video in use today), has a frame rate of 29.97 fps

Interesting:

Shooting video in a NTSC country using pal settings and a 1/50 shutter you will see flicker if under florescent lighting. 

• NTSC is used with a frame rate of 60i or 30p whereas PAL generally uses 50i or 25p; both use a high enough frame rate to give the illusion of fluid motion.

• PAL has a closer frame rate to that of film, so most films are sped up 4% to play on PAL systems, shortening the runtime of the film as well as slightly raising the pitch of the audio track

•  Film conversions for NTSC instead use 3:2 pull down to spread the 24 frames of film across 60 interlaced fields. This maintains the runtime of the film and preserves the original audio, but may cause worse interlacing artifacts during fast motion.

• The 3:2 pulldown used to convert film to NTSC 29.97.
• Slow down the film motion by 1/1000 to 23.976 frames
• For a two-hour film, play time is extended by 7.2 seconds
• Distribute cinema frames into video fields. At 23.976 frame/s, there are four frames of film for every five frames of 29.97 Hz video

• Every original film frame can be considered to consist of two incomplete images or fields
• One field for odd lines and one for even.
• There are eight fields for every four film frames, which are called A, B, C, and D.
• These eight fields have to be "stretched" to ten fields by repeating two of the fields
• The telecine alternately places A frame across two fields (A1, A2), B frame across three fields (B1, B2, B2), C frame across two fields (C1, C2), and D frame across three fields (D1, D2, D2).