Frame Rate

Another term that can has been used to mean two different things in our industry. The literal definition of frame rate is the same as “frame speed.” Some engineers call it frame speed just to avoid possible confusion. Frame speed is the number of frames that go by in audio, film, or video per unit of real (actual) time (usually one second). 30 fps means that 30 frames occur per second, while 24 fps means 24 frames occur per second. Pretty simple. Unfortunately another distinction, “frame count,” can work its way in here too. Frame count is the number of frames that are COUNTED in one running second of audio, video, or film regardless of the actual running speed. Film, audio, and all different types of video use different frame counts. Drop frame time code is an example of a frame count where the number of frames that occur per second of video (not real) time are altered to account for slightly slower running speed of color NTSC video. Non-drop is another frame counting scheme. The 24 frames per second used in film is both its frame count and its frame rate. So when video guys refer to 30 drop frame they are speaking in terms of frame count. When they say 29.97 they are speaking in terms of frame rate. Unfortunately both get called frame rate, which has served to make the issue even more confusing than it already is.