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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
Add a seamless loop to input.mp4 Seconds over which the end dissolves into the start; the output is this much shorter than the input: 1.0
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.
Add a seamless loop to @clip1.mp4, put a sale badge on @clip2.mp4, give @clip3.mp4 a VHS look, then join all three with crossfades.
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 |
|---|---|---|
BLEND | 1.0 | Seconds over which the end dissolves into the start; the output is this much shorter than the input. |
Without the skill
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Make input.mp4 (540x960, 30fps, 6 seconds) loop seamlessly with ffmpeg. The output is 5 seconds long: output 0-4s is input 1.0-5.0s played normally; over output 4.0-5.0s, input 5.0-6.0s fades out linearly while input 0.0-1.0s fades in over it (a 1-second crossfade, 50/50 at output 4.5s), so the last frame of the output is input 0.97s and leads straight into the first frame, input 1.0s. Crossfade the audio the same way (the input's audio from 1s to the end, with its last second crossfading into the first second of the input's audio). Don't crop, zoom, change colors or add any text. Keep the size, 30fps and audio, encode H.264 yuv420p, and save it as output.mp4.Run it without Claude
This is the exact command we tested. Save it as seamless-loop.sh and run:
sh seamless-loop.sh input.mp4 output.mp4Show the command
#!/bin/sh
# Seamless loop: the clip's last second dissolves into its first, so the end flows straight back into the start.
# Usage: sh seamless-loop.sh input.mp4 output.mp4 (the output is BLEND seconds shorter than the input)
set -e
IN="$1"; OUT="$2"
BLEND=1.0 # seconds over which the end dissolves into the start
LEN=$(ffprobe -v error -show_entries format=duration -of csv=p=0 "$IN")
FPS=$(ffprobe -v error -select_streams v:0 -show_entries stream=r_frame_rate -of csv=p=0 "$IN")
OFFSET=$(awk "BEGIN{print $LEN - 2 * $BLEND}") # where the dissolve starts in the output
# The output plays the input from BLEND to the end, and over its last BLEND seconds fades into the input's
# first BLEND seconds. Those end on the frame the output opens with, so the last frame leads into the first.
ffmpeg -y -v error -i "$IN" -filter_complex "
[0:v]fps=$FPS,format=yuv420p,setsar=1,split[v1][v2];
[v1]trim=start=$BLEND,setpts=PTS-STARTPTS[body];
[v2]trim=duration=$BLEND,setpts=PTS-STARTPTS[head];
[body][head]xfade=transition=fade:duration=$BLEND:offset=$OFFSET[v];
[0:a]asplit[a1][a2];
[a1]atrim=start=$BLEND,asetpts=PTS-STARTPTS[abody];
[a2]atrim=duration=$BLEND,asetpts=PTS-STARTPTS[ahead];
[abody][ahead]acrossfade=d=$BLEND[a]" \
-map "[v]" -map "[a]" -r "$FPS" -c:v libx264 -crf 18 -pix_fmt yuv420p -c:a aac "$OUT"
