Reel Export skill

Reel export

Most motion is built wide. This turns it into a vertical file with a hook on top that the apps accept without washing out the colours.

Before you start: read brand.md and MOTION.md if they exist. If not, run brand-intake first, or ask for hex codes, a font and a logo file. Never call a result on-brand without them.

Step 1: Ask for four things, then wait

1. The video. Any MP4, any size.
2. The headline, two short lines, word for word. It is the hook people read with the sound off.
3. Logos, as attached files, if the video names a product or company.
4. The background colour around the video. Default: near-black #0B0B0F.

Step 2: The safe zone

The app draws its own buttons, caption and profile over the edges of a Reel. Keep every word and logo:

• between y 360 and y 1420 (nothing in the bottom 500px)
• out of the right 120px

Put the headline at the top of that zone, then the video under it. A 16:9 video scaled to 1080 wide is 608 tall, so it sits well at y 660.

Step 3: Build the overlay, then encode

Build a transparent 1080 x 1920 overlay.png in HTML with the headline and any logos, and screenshot it. Text you can style beats text burned in by ffmpeg. Then:

ffmpeg -y -i in.mp4 -loop 1 -i overlay.png -f lavfi -i anullsrc=r=48000:cl=stereo -filter_complex "color=c=0x0B0B0F:s=1080x1920:r=30[bg];[0:v]fps=30,scale=1080:-2,setsar=1[v];[bg][v]overlay=0:660:shortest=1[o];[o][1:v]overlay=0:0:shortest=1,scale=out_color_matrix=bt709:out_range=tv,format=yuv420p[out]" -map "[out]" -map 2:a -shortest -c:v libx264 -profile:v high -crf 18 -pix_fmt yuv420p -color_range tv -colorspace bt709 -color_primaries bt709 -color_trc bt709 -c:a aac -b:a 128k -movflags +faststart reel.mp4

This adds a silent AAC track. If the video has its own sound, swap -map 2:a for -map 0:a.

Step 4: Check before upload

ffprobe -v error -show_entries stream=codec_type,codec_name,width,height,pix_fmt,color_range,color_space -of compact reel.mp4

Pass means: video h264, 1080 x 1920, yuv420p, color_range=tv, bt709, plus one aac audio stream. If you see hevc or color_range=pc, encode again. Then pull one frame from the middle and look at it at phone size.

What I learned the hard way

• A phone recording is often HEVC and full range. Uploaded as is, it can come out washed out or re-encoded badly. Always export a fresh H.264, limited-range file, including after any edit.
• A logo over footage vanishes on light frames. Put each logo (and its label) on its own dark rounded tile.
• faststart matters. Without -movflags +faststart the file cannot start playing until it has fully loaded.
• Keep the hook to two lines. Mine were short enough to read in a second: "This Mac launch" / "is 100% code".