VP9 · CRF 31 · 720p · Opus · WebM

The scenario

Web-first delivery for a news site targeting mobile browsers. VP9 for broad browser support without licensing fees, 720p for mobile-first, CRF 31 with -b:v 0 for pure quality mode. Opus + WebM for the open-source stack.

The answer

Video Codec	VP9
CRF	31
Resolution	720p
Audio	Opus
Container	WebM

The command

ffmpeg -i input.mp4 -c:v libvpx-vp9 -crf 31 -b:v 0 -c:a libopus output.webm

Why

The -b:v 0 flag is required with VP9 CRF mode. Without it, FFmpeg defaults to a target bitrate of 200kbps, which overrides CRF and produces terrible quality — a common VP9 gotcha.

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