Originally published at ffmpeg-micro.com Every video encoder faces the same tradeoff: quality vs. file size. CRF (Constant Rate Factor) is how FFmpeg lets you control that tradeoff with a single number. Most guides say "just use CRF 23." That's fine for a quick transcode, but CRF 23 means completely different things depending on your codec, your content, and where you're delivering. This guide covers what CRF actually does, how the scale works across codecs, and how to pick the right value. What Is CRF in FFmpeg? CRF is a rate control mode that targets consistent perceptual quality across an entire video, letting the bitrate float as needed. Simple scenes (static shots, solid colors) get fewer bits. Complex scenes (fast motion, fine detail) get more bits. The result is a file where quality looks consistent to your eyes, even though the bitrate varies frame to frame.…