Telecine is the historical process of converting 24 fps film to TV-compatible frame rates. Film cameras ran at exactly 24 frames per second; American TV broadcasts at 30 (technically 29.97) frames per second; the math doesn't divide evenly. The clever workaround is "3:2 pulldown" — show the first film frame across 3 video fields, the next film frame across 2, repeat. After every 4 film frames you've produced 10 video fields = 5 video frames, matching the TV cadence. Same length, just stretched out over more fields.
The visible cost of 3:2 pulldown is uneven motion cadence. Because some film frames are shown for 3 fields and others for 2, slow camera pans show a faint stuttery rhythm called judder. On fast action it's invisible; on slow scenes and panoramic shots, it's distracting once you notice it. Modern premium TVs with "true cinema" modes run their panels at 48 or 72 or 120 Hz (multiples of 24) specifically to eliminate this — they can show every film frame for the same duration.
For a product team in 2026, telecine is a legacy ingest concern. If you receive material that was originally 24 fps film telecined to 29.97 fps for TV broadcast, the right thing is to inverse telecine it back to clean 23.976 fps before encoding. FFmpeg's pullup filter and the fieldmatch filter do this. The pay-off is a smaller file (fewer redundant fields), a cleaner look on modern displays, and avoidance of the judder problem. Anything you produce natively today is 24p or 30p or 60p without any pulldown — telecine is only encountered on archival or broadcast contribution material.
