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Install the Recharm video effects skill: download https://recharm-growth-staging.s3.us-east-2.amazonaws.com/website/downloads/recharm-video-effects.zip and unzip it into ~/.claude/skillsAsk for the effect
Join clipA.mp4 and clipB.mp4 with a barn door transition How long the doors take to open, in seconds: 0.6
Several videos, several effects, one ask
Put your clips in the folder, mention them with @, and ask for everything at once. Claude runs one tested script after another on each clip, then joins them.
Put a sale badge on @clip1.mp4, give @clip2.mp4 a VHS look, then join them with a barn door transition.
Settings you can change
Ask Claude to change any of these, or edit them at the top of the command.
| Setting | Default | What it does |
|---|---|---|
D | 0.6 | How long the doors take to open, in seconds. |
Without the skill
Don’t want to install the skill? Paste this prompt into Claude Code and Claude writes the command itself.
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Join clipA.mp4 and clipB.mp4 with a 0.6 second barn door transition. The transition starts 0.6 seconds before A ends: from then on clip B plays full frame underneath, while A's left half (x 0 to half the width) slides left and A's right half slides right until both are fully off-screen, with smoothstep easing (progress p from 0 to 1, moved by p*p*(3-2p) of a half-width). Each half keeps showing A's own picture as it moves; there is no seam, border or fade. Crossfade the audio over the same 0.6 seconds. Fit B to A's size and frame rate first. The output is 11.4 seconds at 30fps. Use ffmpeg, keep the audio and save it as output.mp4.Run it without Claude
This is the exact command we tested. Save it as barn-door.sh and run:
sh barn-door.sh clipA.mp4 clipB.mp4 output.mp4Show the command
#!/bin/sh
# Barn door: clip A splits down the middle and its two halves slide out to the sides over 0.6s, opening onto clip B. The sound crossfades underneath.
# Usage: sh barn-door.sh clipA.mp4 clipB.mp4 output.mp4 (both clips need an audio track)
set -e
A="$1"; B="$2"; OUT="$3"
D=0.6 # how long the doors take to open, in seconds
LEN=$(ffprobe -v error -show_entries format=duration -of csv=p=0 "$A")
OFFSET=$(echo "$LEN - $D" | bc)
SIZE=$(ffprobe -v error -select_streams v:0 -show_entries stream=width,height -of csv=s=x:p=0 "$A")
FPS=$(ffprobe -v error -select_streams v:0 -show_entries stream=r_frame_rate -of csv=p=0 "$A")
W=${SIZE%x*}; H=${SIZE#*x}
# 0 -> 1 over the transition, eased in and out (smoothstep)
EASE="st(0,clip((t-$OFFSET)/$D,0,1));ld(0)*ld(0)*(3-2*ld(0))"
# B is fitted to A and starts at OFFSET; A's left and right halves are laid on top and pushed off-screen
ffmpeg -y -i "$A" -i "$B" -filter_complex "\
[0:v]fps=$FPS,format=yuv420p,setsar=1,split[a1][a2];\
[a1]crop=iw/2:ih:0:0[left];\
[a2]crop=iw/2:ih:iw/2:0[right];\
[1:v]scale=$W:$H:force_original_aspect_ratio=increase,crop=$W:$H,fps=$FPS,format=yuv420p,setsar=1,tpad=start_duration=$OFFSET[b];\
[b][left]overlay=x='-w*($EASE)':y=0:eof_action=pass[bl];\
[bl][right]overlay=x='w+w*($EASE)':y=0:eof_action=pass[v];\
[0:a][1:a]acrossfade=d=$D[au]" \
-map "[v]" -map "[au]" -r "$FPS" -c:v libx264 -crf 18 -pix_fmt yuv420p -c:a aac "$OUT"
