Frame Rate

帧率 (Frame Rate) is the number of complete images contained, displayed, or scheduled to be displayed in a video per second, typically measured in frames per second (fps). Film commonly uses 24 or 23.976 fps, while television systems commonly use 25, 29.97, 50, 59.94, or 60 fps. 帧率 affects the sampling of motion but does not specify resolution, scanning method, or shutter speed. 23.976, 29.97, and 59.94 originate from proportional adjustments made to the original integer rates in the NTSC color system; the exact values are approximately 24,000/1,001, 30,000/1,001, and 60,000/1,001, respectively. Rounding these values to 24, 30, and 60 is common in general descriptions, but precise fractions must be retained for synchronization, timecode, and long-program duration calculations.

Interlaced video also has a field rate. 1080i59.94 has approximately 59.94 time-staggered fields per second, but the complete frame cycle is approximately 29.97; if the source uses interlaced frames, the two fields may originate from the same moment in time. Players, containers, and analysis tools report “帧率” differently; this should be interpreted in conjunction with the scan type.

The display refresh rate is the number of times the screen refreshes per second; it is not equivalent to the content’s 帧率. 24 fps content can be repeated five times per frame on a 120 Hz screen, or displayed at approximately 60 Hz using the 3:2 pulldown; motion interpolation generates new intermediate frames, causing the displayed motion to differ from the original program.

A high 帧率 improves motion clarity and interactive responsiveness, but also increases data volume. Simply repeating a low 帧率 at a high 帧率 does not add temporal information, and frame interpolation may cause errors at object edges. Variable 帧率 files do not have a constant inter-frame time; a single average fps cannot fully describe the entire timing sequence.