Pad to 16:9, centred
job_8fd9c90928c54eafThe standard letterbox. Scale first, then pad.
ffmpeg -i https://cdn.rendobar.com/assets/examples/sample.mp4 -vf "scale=1280:-2,pad=1280:720:(ow-iw)/2:(oh-ih)/2" -t 5 out.mp4video filter
The FFmpeg pad filter
Adds bars around the frame to reach a target size without cropping the picture.
3 of 3 variants measured Measured 2026-08-20
The part that catches people
pad places the source at 0,0 unless told otherwise, so a naive pad puts your video in the top-left with all the padding on the right and bottom. Centring needs the (ow-iw)/2 expressions, which is the form almost every real command uses.
Measured, not described
Every row below is a real job. The same 1280x720 five-second H.264 source went through each variant, so the numbers are comparable to each other and to every other filter page on this site. Encode time is the FFmpeg step on its own, separated from the download and the upload.
| Variant | Encode | Output | Cost |
|---|---|---|---|
| Pad to 16:9, centred | 1093 ms | 514.0 KB · 1280x720 | $0.0025 |
| Pad to 1:1, centred | 636 ms | 298.0 KB · 720x720 | $0.0021 |
| Pad with white bars | 1208 ms | 514.0 KB · 1280x720 | $0.0026 |
The exact commands
Pad to 1:1, centred
job_e697435ed4df4538Square output for feeds that crop to it.
ffmpeg -i https://cdn.rendobar.com/assets/examples/sample.mp4 -vf "scale=720:-2,pad=720:720:(ow-iw)/2:(oh-ih)/2" -t 5 out.mp4Pad with white bars
job_f13cd6e3710d4cfaThe colour argument is positional and comes last.
ffmpeg -i https://cdn.rendobar.com/assets/examples/sample.mp4 -vf "scale=1280:-2,pad=1280:720:(ow-iw)/2:(oh-ih)/2:white" -t 5 out.mp4How these numbers were produced
Each variant was submitted to the Rendobar API as an ffmpeg job against the same public source file, and the response was recorded verbatim. Encode time is the API's own per-step timing for the FFmpeg step. Output size is the byte count of the file the job produced. Cost is what the job was actually billed.
Nothing here was estimated, and the whole set is re-runnable, so if a figure looks wrong it can be checked rather than argued about. The 72 variants behind this filter reference cost $0.193082 in total to measure.
Frequently asked questions
What does the FFmpeg pad filter do?
Adds bars around the frame to reach a target size without cropping the picture.
What is the most common mistake with pad?
pad places the source at 0,0 unless told otherwise, so a naive pad puts your video in the top-left with all the padding on the right and bottom. Centring needs the (ow-iw)/2 expressions, which is the form almost every real command uses.
How long does pad take to run?
On a 1280x720 five-second H.264 source, the fastest variant on this page (Pad to 1:1, centred) spent 636 ms inside FFmpeg. That figure is the encode step alone, measured separately from the download and the upload, so it is the filter's own cost rather than the round trip.
Do I need FFmpeg installed to use pad?
Not with Rendobar. Every command on this page ran through the Rendobar API against a URL, with no local FFmpeg install and no server. The job id next to each row is the real job that produced the numbers.
Other filters, measured the same way
scale Resizes video to a target width and height, with optional aspect-preserving arithmetic. crop Cuts a rectangle out of each frame, positioned from the top-left corner. fps Resamples video to a constant frame rate by duplicating or dropping frames. transpose Rotates video by 90 degree steps, optionally flipping as it goes. overlay Composites one video or image on top of another at a chosen position.
Run pad without installing FFmpeg
Every command on this page ran through the API against a URL. No binary, no server.