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
- The video. Any MP4, any size.
- The headline, two short lines, word for word. It is the hook people read with the sound off.
- Logos, as attached files, if the video names a product or company.
- 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 +faststartthe 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".