Tall phone screen recording to 9:16: crop height 0.8215 and a y offset

Some phone screen recordings are taller than 9:16. A 1170x2532 recording, for example, is about 9:19.5. To make it 9:16, keep the full width and crop the height to 0.8215 of the frame. Setting y to 0.1785 keeps the bottom and removes the top 450 px or so, where the status bar sits; y of 0.0893 would trim top and bottom evenly. Then scale=1080:1920.

The numbers

This case flips the usual formula, because the source is taller than the target. For a full-width crop the height must be 16/9 of the width: 1170 x 16 / 9 = 2080 px. 2080 / 2532 = 0.8215. The remaining 452 rows are the part you choose to lose, and y decides where. The values below use y = 0.0893, centered.

Choosing y

A screen recording has chrome at both ends: a status bar with the clock and battery at the top, and a home indicator or tab bar at the bottom. Which you keep depends on the story. For an app walkthrough, keep the bottom tab bar and drop the status bar; use y near 0.1785 (the largest allowed here, since y + height must be at most 1). For a feed or chat, the opposite.

The recording also gives you a privacy reason to crop: the status bar can show a clock, carrier and notifications. Cropping it out is not a guarantee that nothing sensitive remains in the frame, so check stills with video frames before you post.

# 1) free contract check, no job, no charge
curl -X POST https://api.sume.com/v1/video-filter/check \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "video_url": "https://media.sume.com/artifacts/artf_demo/screen.mp4",
    "ops": [{"op":"crop","x":0.0,"y":0.0892,"width":1.0,"height":0.8215}],
    "filtergraph": "scale=1080:1920,setsar=1"
  }'

# 2) same body to /v1/video-filter, with an Idempotency-Key header, to encode

What not to do

At the documented public rate the encode is $0.02 per job and the check is free; confirm the live rate in GET /v1/catalog. The clip must already be a media.sume.com file of your workspace, so import it first with POST /v1/media-imports, and send an Idempotency-Key on the encode.

• Do not stretch a 9:19.5 recording into 9:16. stretch distorts the UI; crop instead.
• Do not pad it with black bars to reach 9:16; fill the frame.
• Do not crop below 0.05 on any side or let y + height exceed 1; the check refuses both.
• Keep the source under 300 seconds, or trim it first.

Three values of y

With the crop height fixed at 0.8215, only y moves the window. The table shows which rows of the 2532-row frame each choice keeps. Rows are approximate because the compiler rounds to even pixels.

Note that this recipe uses the full width of the recording, so no sideways content is lost; only rows are removed. The scale to 1080x1920 is then a reduction from 1170x2080, about 0.92 times, so on-screen text stays sharp, which is an advantage over cropping a horizontal source.