Mind Your i’s and p’s

 

What is the difference between 24p, 25p and 50p in video? Which one should I be using?    
Ravi Ghosh, Kolkata, via email

The number indicates the frame rate (number of frames per second) at which you are recording video. Filmmakers used 24 frames per second as the standard for making movies. There is no significant difference in the output quality at 24p, 25p or 30p except when it comes to direct output to TV screens. 30p and 60p is used in countries (USA and Canada) that use a 60Hz power grid to run TVs. In most other countries, including India, the power supply is 50Hz. Here, you should shoot at 25p and 50p. 50p and 60p will allow you to make slightly slo-mo videos. However, for realistic slow motion, you will need a camera that shoots at 120fps and higher.

Whether the number is followed by an ‘i’ or a ‘p’ tells you if the video being shot is an interlaced or progressive scan. With progressive scans the video shoots 25 individual frames. In the case of interlaced scans, though the video has only 25 frames, it shows you only half a frame at a time thus giving the impression of 50fps. This was done to have less flicker when recording fast moving subjects while simultaneously saving on bandwidth. However, as a result the clarity is hampered when you compare it to 25p video.

Tags: better photography, fps, Frame Rate, May 2015, output