[http://en.wikipedia.org/NTSC NTSC] is a television broadcast system created by the National Television Standards Comittee in USA. While an analog system, NTSC is used as a reference for digital video for the screen size and number of frames per second. It has the following characteristics:
* 352x240 pixels screen size (720x480 for DVD)▼
* 30fps. More precisely, 30000/1001fps or 29,97fps.▼
pixels screen size
. More precisely
The strange rate of frames per second in NTSC makes necessary the use of the commonlly called '''drop frame''' technique in video editors like Kdenlive. Every 2 minutes, except each 10th minute, two frames are simply ignored in the time count, so the video seems to run in 30fps. Without this trick, the audio at "real 30fps" would slightly slip out of sync with the video in some minutes.