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# Use the ultrafast preset when encode speed matters more than size
- URL: https://ffmpeguru.com/use-the-ultrafast-preset-when-encode-speed-matters-more-than-size/
- Published: 2026-10-29T09:00:00.000Z
- Updated: 2026-10-29T09:00:00.000Z
- Author: FFmpeguru
- Tags: ffmpeg

FFmpeg's H.264 presets control how aggressively the encoder searches for compressible patterns. `ultrafast` is the minimum-search preset: it runs at near real-time, produces the largest file for a given quality target, and is the right choice when you need to encode fast, not efficiently.

## The command

```
ffmpeg -i input.mp4 -c:v libx264 -preset ultrafast output.mp4
```

## What it does

libx264's preset controls motion estimation, mode decision, and partition search. `ultrafast` turns off all of that: it uses the simplest possible encoder decisions, encodes frame by frame with no lookahead, and produces output that is typically 2 to 10 times larger than the medium preset at the same CRF.

## When to use it

For real-time or near-real-time encoding, screen recording, video conferencing, and any time you need the encode to keep up with the input. `ultrafast` is also a debugging preset: if something does not encode at ultrafast, it is a fundamental issue, not a preset issue.

## Video and audio requirements

Any input. `ultrafast` disables B-frames, which means the output is not as compressible in streaming. For real-time delivery, use a faster preset plus a higher CRF to control size. For example, `-preset ultrafast -crf 28` gives a small, real-time file at the cost of quality.

## Things to avoid

- Using `ultrafast` for delivery encodes. The files are 2 to 10 times larger than medium at the same quality. Use it for real-time or near-real-time only.
- Forgetting that `ultrafast` disables B-frames. The output is I-frame and P-frame only, which inflates bitrate and reduces compression efficiency.
- Combining `ultrafast` with high CRF. The preset already produces large files; CRF 28 makes them larger. For real-time at smaller size, use `superfast` or `veryfast` with a higher CRF.
- For live streaming, `ultrafast` is fine, but for recording-then-uploading, prefer a slower preset and let the upload time absorb the encode cost.