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Install the skill (once)
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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 shape wipe Length of the wipe in seconds: 0.8 Width of the white outline, as a share of the frame (about 4px on a 540px-wide video): 0.008
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 shape wipe.
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 | 0.8 | Length of the wipe in seconds. |
EDGE | 0.008 | Width of the white outline, as a share of the frame (about 4px on a 540px-wide video). |
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 0.8 second diamond wipe that starts 0.8 seconds before the end of A: B shows inside a diamond centered in the frame that grows until it fills it, with a white outline about 4 pixels wide. Use ffmpeg xfade with transition=custom and expr='if(lt(abs(X-W/2)/W+abs(Y-H/2)/H,1-P*P),B,if(lt(abs(X-W/2)/W+abs(Y-H/2)/H,1-P*P+0.008),if(eq(PLANE,0),235,128),A))', so the diamond's points touch the middle of each edge halfway through and its sides reach the corners at the end. Crossfade the audio over the same 0.8 seconds. Match B's size and frame rate to A. Save it as output.mp4.Run it without Claude
This is the exact command we tested. Save it as shape-wipe.sh and run:
sh shape-wipe.sh clipA.mp4 clipB.mp4 output.mp4Show the command
#!/bin/sh
# Shape wipe: clip B opens out of a diamond in the middle of clip A that grows to fill the frame over 0.8s. The sound crossfades underneath.
# Usage: sh shape-wipe.sh clipA.mp4 clipB.mp4 output.mp4 (both clips need an audio track)
set -e
A="$1"; B="$2"; OUT="$3"
D=0.8 # transition length in seconds
EDGE=0.008 # white outline on the diamond, as a share of the frame (0.008 is about 4px wide on 540px)
LEN=$(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=${SIZE#*x}
# xfade's P runs from 1 to 0, so 1-P*P is the diamond's size, easing out. A pixel shows B once
# its distance from the center, measured across the frame's width and height, is inside that size
# (at 1 the diamond reaches the corners), and turns white in a thin band just outside it.
# White is 235 on the brightness plane and 128 on the two color planes.
DIAMOND="if(lt(abs(X-W/2)/W+abs(Y-H/2)/H,1-P*P),B,if(lt(abs(X-W/2)/W+abs(Y-H/2)/H,1-P*P+$EDGE),if(eq(PLANE,0),235,128),A))"
# xfade needs both clips at the same size and frame rate, so B is fitted to A first
ffmpeg -y -i "$A" -i "$B" -filter_complex "\
[0:v]fps=$FPS,format=yuv420p,setsar=1[a];\
[1:v]scale=$W:$H:force_original_aspect_ratio=increase,crop=$W:$H,fps=$FPS,format=yuv420p,setsar=1[b];\
[a][b]xfade=transition=custom:expr='$DIAMOND':duration=$D:offset=$OFFSET[v];\
[0:a][1:a]acrossfade=d=$D[au]" \
-map "[v]" -map "[au]" -c:v libx264 -crf 18 -pix_fmt yuv420p -c:a aac "$OUT"
