How to set up a projection on your window, wall or garage

Every HollowlightFX loop works on a window, wall or garage door. Jump to: Window · Wall · Garage door · Outdoor power, weather & safety.

A window projection (also called rear projection) puts a glowing video on a screen inside your window so it looks like a ghost, horseman or talking pumpkin is in your house. Here's everything you need, from the projector to sound. You don't need expensive gear: most people use a budget home projector and a white sheet.

What you need

• A projector that plays MP4 files (USB, HDMI or built-in apps)
• A rear-projection screen, window film, or a white sheet/shower curtain
• A projection video with a black background (like ours)
• A USB stick, laptop, phone or streaming stick for playback
• Optional: a Bluetooth speaker

Projector specs that matter

Sheet vs. rear projection screen vs. window film

Window setup (rear projection), step by step

1. Pick a projector. Any projector that plays MP4 from USB works. Aim for at least 720p native resolution (1080p is nicer) and 3,000+ advertised lumens if there is any streetlight. A short-throw projector fits tight spaces between the window and furniture.
2. Choose your screen. A rear-projection screen gives the brightest, crispest image. A plain white flat sheet or shower curtain is a cheap alternative. Window film (rear-projection film) sticks to glass for a 'floating' look.
3. Hang it inside the window. Mount the screen or sheet tight against the inside of the window so it is flat and wrinkle-free. Use tension rods, removable hooks or tape.
4. Place the projector behind. Put the projector inside the house behind the screen, centered and level, and use rear-projection mode (or flip the image horizontally) so it reads correctly from the street.
5. Size and focus. Move the projector closer or farther until the image fills the window, then focus. Keep keystone correction minimal for the sharpest picture.
6. Loop the video. Copy the MP4 to a USB stick and turn on repeat in the projector's media player, or loop it from a laptop, phone (HDMI adapter) or streaming stick. Turn off sleep/screensaver settings.
7. Add sound (optional). Place a Bluetooth speaker near the window or outside the door so trick-or-treaters can hear the jokes, chants and screams. Keep the volume neighbor-friendly.
8. Make it dark. Turn off the room lights behind the screen and porch lights that shine on the window. Black backgrounds in our videos disappear, so only the glowing figure shows.

Wall setup (front projection)

1. Pick the wall. A flat, smooth, light-coloured wall works best. White or light grey gives the brightest image; dark, red or heavily textured walls (brick, stone, siding grooves) soak up light and blur detail. A white sheet or projector screen hung on the wall is an easy fix for a dark or rough surface.
2. Placement and throw distance. Put the projector in front of the wall, centred and level with the middle of the image. Picture size depends on your projector's throw ratio (in its manual or spec sheet): image width ≈ distance ÷ throw ratio. For example, a 1.2:1 projector 12 ft from the wall makes an image about 10 ft wide. Moving it back makes the picture bigger but dimmer.
3. Square it up. Aim straight at the wall rather than up at an angle, and use keystone correction only for small fixes so the image stays sharp.
4. Light and darkness. Turn off lights that shine on the wall. Our videos use black backgrounds, so in a dark space only the glowing figure shows.
5. Normal mode, not rear mode. For a wall you are projecting from the front, so leave the image un-flipped (front/desktop mode).

Garage door setup

1. Surface colour. White or light-coloured garage doors make the brightest, most colourful picture. Darker doors still work with a brighter projector, or hang a white sheet or outdoor projection screen over the door.
2. Placement and throw distance. Set the projector on a stable table or stand in the driveway or yard, or on a sheltered porch, aimed square at the door. Use the same rule: image width ≈ distance ÷ throw ratio. A single-car door is about 8–9 ft wide and a double door about 16 ft, so a typical 1.2:1 projector needs roughly 10–11 ft of distance for a single door and about 19–20 ft for a double. A short-throw projector needs much less room.
3. Panels and lines. Door panels and seams show through the picture. Centre the main figure on a smooth area, or cover the door with a sheet or screen for a cleaner look.
4. Light and darkness. Turn off porch and driveway lights that hit the door, and start after full dark. Streetlights reduce contrast, so more lumens help.
5. Sound. Put a weather-protected Bluetooth speaker near the door so passersby hear the audio.

Outdoor power, weather & keeping the projector safe

• Power: use an extension cord rated for outdoor use, plugged into a GFCI-protected outlet. Keep connections off the ground and out of puddles, and tape or cover cords so nobody trips.
• Weather: most home projectors are not waterproof. Check the forecast, keep the projector under cover (a porch, an open garage, or a ventilated projector enclosure), and bring it inside if rain, snow or heavy dew is expected.
• Ventilation: never wrap or seal a running projector in a bag or box without airflow. Leave the vents clear so it doesn't overheat.
• Condensation: when bringing a cold projector inside, let it warm up to room temperature before turning it on again.
• Stability and theft: place it on a stable, level surface where it can't be knocked over, and keep it close to the house or behind a window if you're worried about theft. Projecting from inside through a window onto the garage or yard is not recommended because glass reflects and dims the image; open the window instead or stay outside under cover.
• Timer: a plug-in outdoor timer can switch the show off at night. Check your projector's manual, since some need to cool down before power is cut.

Brightness tips

• Projection looks best after full dark; start the show about 20 minutes after sunset.
• Turn off lights between the projector and the screen, and porch lights aimed at the window.
• Use the projector's brightest picture mode; disable eco mode.
• Upstairs windows and windows facing the sidewalk get the most views.

Looping playback

• USB stick: easiest. Copy the MP4, open the projector's media player, set repeat to "one" or "all."
• Phone: use an HDMI adapter or screen casting and a looping video player. Turn off auto-lock and notifications.
• Laptop: VLC or any player with loop enabled, full screen, sleep disabled.
• Our videos start and end on the same frame, so the loop is seamless.

Make an extra-long loop

Some projectors briefly show a play bar or file name every time a video repeats. A longer file means fewer restarts and fewer pop-ups, so you can start it once and let it run all night.

1. Get ffmpeg (free): download it for Windows or Mac from ffmpeg.org.
2. Run one command in the folder with your video (Command Prompt on Windows, Terminal on Mac):
   ffmpeg -stream_loop 11 -i "Your Loop.mp4" -c copy "Your Loop - 30 min.mp4"
3. Pick the number: it's how many extra times the clip repeats. 11 gives 12 plays in total, about 30 minutes from a 2.5-minute loop. For a 20-second clip, 89 gives about 30 minutes.
4. No quality loss: -c copy joins the video without re-encoding, so it takes seconds and looks exactly like the original.
5. Prefer no command line? In the free Shotcut or Clipchamp editor, place the clip on the timeline several times back-to-back and export as MP4.

Tip: in your projector's player, choose "Repeat one" or "Single loop" and turn off any on-screen info display if available (menu names vary by brand).

Sound tip

Projectors' built-in speakers stay inside the house. For talking or screaming projections, put a Bluetooth speaker by the door or in a cracked window so the audio lines up with the action.

Ready to try it? Browse HollowlightFX projection videos or visit the Etsy shop. Every download includes a printable Projector Setup Guide.