transcode

name	transcode
description	Ad-hoc transcode of a video file or folder — pick codec, container, resolution, framerate, and rate-control on the spot. Uses the hardware encoder detected by profile-system when available, falls back to libx264/libx265. Use when the user says "transcode this", "convert these to h.265", "change the framerate to 30", "make these smaller", or "VBR to CBR".
disable-model-invocation	false
allowed-tools	Bash(ffmpeg *), Bash(ffprobe *), Bash(test *), Bash(mkdir *), Bash(ls *), Bash(find *), Bash(jq *), Bash(stat *), Bash(basename *), Bash(dirname *), Bash(realpath *), Read, Write

Transcode

Generic, on-demand transcoding. Unlike render-with-profile (which uses a saved preset), this skill takes parameters per invocation. Use it for one-offs, format conversions, framerate changes, or fixes (VBR → CBR).

Procedure

1. Resolve system profile

DATA_DIR="${CLAUDE_USER_DATA:-${XDG_DATA_HOME:-$HOME/.local/share}/claude-plugins}/video-editing"
SYS_FILE="$DATA_DIR/system-profile.json"
test -f "$SYS_FILE" && HAVE_SYS=1 || HAVE_SYS=0

If missing, warn the user that the skill will fall back to libx264/libx265 (slower, CPU-only) and offer to run profile-system.

2. Inputs

Ask if not provided:

Field	Example
Source	file or folder
Codec	h264 / hevc / av1 / copy (stream-copy)
Container	mp4 / mkv / mov
Resolution	source / 1920x1080 / 1280x720
Framerate	source / 24 / 30 / 60
Rate control	crf / qp / cbr / vbr — with value
Output dir	default: sibling transcoded/ folder

3. Pick encoder

If HAVE_SYS=1, read .encoders.<codec>.preferred from system-profile.json. Otherwise:

Codec	Software fallback
h264	libx264
hevc	libx265
av1	libsvtav1

For codec=copy, skip encoder selection — just -c:v copy -c:a copy (useful for container changes).

4. Build the ffmpeg command

VAAPI hardware path:

ffmpeg -hide_banner -i "$IN" \
  -vaapi_device "$RENDER_NODE" \
  -vf 'format=nv12,hwupload[,scale_vaapi=...]' \
  -c:v "$ENCODER" -qp "$QP" \
  -r "$FPS" \
  -c:a aac -b:a 192k \
  -movflags +faststart \
  "$OUT"

Software path:

ffmpeg -hide_banner -i "$IN" \
  [-vf scale=...] -r "$FPS" \
  -c:v "$ENCODER" -crf "$CRF" -preset medium \
  -c:a aac -b:a 192k \
  -movflags +faststart \
  "$OUT"

For CBR: -c:v libx264 -b:v <rate> -minrate <rate> -maxrate <rate> -bufsize <2*rate>.

Show the resolved command before running. Ask for confirmation when transcoding more than 1 file.

5. Loop and report

mkdir -p "$OUT_DIR"
for in in <inputs>; do
  out="$OUT_DIR/$(basename "${in%.*}").$CONTAINER"
  ffmpeg -hide_banner -y -i "$in" <args> "$out"
  echo "$in -> $out ($(stat -c%s "$out") bytes)"
done

Originals are never modified. Summarize input vs. output total bytes at the end.