Optimize a video file for web with ffmpeg

decode_for_web.sh

# params
VF="scale='min(1280,iw)':'min(720,ih)':force_original_aspect_ratio=decrease"

# Pass 1
ffmpeg -y -i main.mp4 -map 0:v:0 -an \
  -c:v libx264 -pix_fmt yuv420p -profile:v high -level 4.1 -preset slow \
  -vf "$VF" -g 60 -keyint_min 60 -sc_threshold 0 \
  -b:v 1150k -maxrate 1500k -bufsize 3000k \
  -movflags +faststart -pass 1 -f mp4 /dev/null

# Pass 2
ffmpeg -i main.mp4 -map 0:v:0 -map 0:a:0? \
  -c:v libx264 -pix_fmt yuv420p -profile:v high -level 4.1 -preset slow \
  -vf "$VF" -g 60 -keyint_min 60 -sc_threshold 0 \
  -b:v 1150k -maxrate 1500k -bufsize 3000k \
  -c:a aac -ac 2 -b:a 96k \
  -movflags +faststart -pass 2 output.mp4

ls -lh output.mp4