Download YouTube video and re-encode for playback on web and iOS (requires yt-dlp and ffmpeg)

download-mp4.sh

#!/usr/bin/env bash

# Usage: download-mp4.sh <YouTube_URL>

if [ -z "$1" ]; then
  echo "Usage: download-mp4.sh <YouTube_URL>"
  exit 1
fi

URL="$1"

# Download video using yt-dlp and store the exact filename
FILENAME=$(yt-dlp --no-simulate \
  -f "bestvideo[ext=mp4][height<=720]+bestaudio[ext=m4a]/best[ext=mp4]/best" \
  --merge-output-format mp4 \
  -o "%(title)s.%(ext)s" \
  --print filename \
  "$URL")

# Verify the downloaded filename
echo "Downloaded filename: $FILENAME"

# Re-encode with FFmpeg using hardware acceleration (if available) + Progress Indicator
ffmpeg -y -i "$FILENAME" \
  -c:v libx264 -preset veryfast -profile:v baseline -level 3.0 -pix_fmt yuv420p \
  -c:a aac -b:a 128k \
  -movflags +faststart \
  -progress pipe:1 -stats \
  "${FILENAME}.tmp.mp4" | awk '/out_time_ms/ { printf "\rProgress: %.2f%%", $2 / 1000000 }'

# Replace the original file with the faster-encoded version
mv "${FILENAME}.tmp.mp4" "$FILENAME"

echo -e "\nDone: $FILENAME"