name: ffmpeg description: Extract audio and transcode MP4 to WebM using ffmpeg.

ffmpeg

Use when

• Extract audio from a video file.
• Transcode an MP4 video to WebM.

Don't use when

• A higher-level video-editing skill or tool is already in use for complex edits.
• The task is purely file transfer or metadata inspection (no transcoding needed).

Outputs

• Output files should be written to artifacts/ when possible (e.g., artifacts/output.webm).

Templates or Examples

• Use the command blocks below as templates, swapping inputs/outputs and codecs as needed.

Requirements

• Prefer safe defaults and explicit codecs.
• Keep commands minimal and reproducible.
• Use ASCII-only output unless file already uses Unicode.

Commands

Extract audio (MP4 → MP3)

ffmpeg -y -i input.mp4 -vn -c:a libmp3lame -q:a 2 output.mp3

Extract audio (MP4 → WAV, lossless)

ffmpeg -y -i input.mp4 -vn -c:a pcm_s16le -ar 44100 -ac 2 output.wav

Transcode MP4 → WebM (VP9 + Opus)

ffmpeg -y -i input.mp4 -c:v libvpx-vp9 -crf 32 -b:v 0 -row-mt 1 -c:a libopus -b:a 128k output.webm

Transcode MP4 → WebM (VP8 + Vorbis)

ffmpeg -y -i input.mp4 -c:v libvpx -crf 10 -b:v 1M -c:a libvorbis -b:a 128k output.webm

Notes

• -y overwrites output files. Remove if you want interactive prompts.
• Lower -crf means higher quality (and larger files).
• If audio-only extraction is desired, use -vn to drop video.