How to Use -preset in FFmpeg
ffmpeg -i input.mkv -c:v libx264 -preset slow -crf 23 -c:a aac -b:a 192k output.mp4— H.264 (x264).ffmpeg -i input.mkv -c:v libx265 -preset medium -crf 28 -tag:v hvc1 -c:a aac -b:a 192k output.mp4— H.265 (x265) uses the same preset names.ffmpeg -i input.mkv -c:v h264_nvenc -preset p5 -rc vbr -cq 23 -b:v 0 -c:a aac -b:a 192k output.mp4— NVIDIA GPU encoding uses presets p1 (fastest) to p7 (best quality).-tune film,animation,grain,stillimage,fastdecodeorzerolatency— an optional x264 tune adjusts the settings to the content; it works on top of the preset.
Old .ffpreset files (for example libx264-ipod640.ffpreset, loaded with -vpre or -fpre) are a separate, legacy mechanism. For x264 and x265, use -preset.
What Are FFmpeg Presets?
When encoding video with x264 (H.264) or x265 (H.265), the preset controls how many compression algorithms the encoder uses. More algorithms = better compression = smaller files, but slower encoding.
The 10 x264 presets, from fastest to slowest:
ultrafastsuperfastveryfastfasterfastmedium(default)slowslowerveryslowplacebo(not recommended — negligible improvement over veryslow)
A critical point: at the same CRF, all presets aim for about the same visual quality. The main difference is file size and encoding speed. Slower presets don't look better — they compress better.
Benchmark Table: All Presets Compared
Encoding a 1-minute 1080p video at CRF 23 on an 8-core CPU (representative benchmarks):
| Preset | Speed (fps) | Encode Time | File Size | Size vs Medium |
|---|---|---|---|---|
ultrafast |
~120 fps | ~15s | ~95 MB | +58% |
superfast |
~90 fps | ~20s | ~80 MB | +33% |
veryfast |
~70 fps | ~25s | ~70 MB | +17% |
faster |
~55 fps | ~33s | ~65 MB | +8% |
fast |
~42 fps | ~43s | ~62 MB | +3% |
medium |
~30 fps | ~60s | ~60 MB | baseline |
slow |
~15 fps | ~2 min | ~52 MB | -13% |
slower |
~8 fps | ~3.5 min | ~50 MB | -17% |
veryslow |
~4 fps | ~7.5 min | ~48 MB | -20% |
The Sweet Spots
Three presets stand out as the best choices for different scenarios:
medium — General Use (Our Default)
The default for a reason. It offers the best balance of encoding speed and file size. For an online converter where users are waiting for results, medium provides fast turnaround without excessive file bloat.
slow — Best Size Savings Worth the Wait
Compared to medium, slow takes about 2x longer but produces files 10–15% smaller. If you're encoding a large library for archival and time isn't a factor, slow is the best preset. The savings compound across many files. If each file must hit an exact size, read about two-pass encoding vs CRF.
veryfast — When Speed Is Critical
About 2.3x faster than medium at the cost of 17% larger files. Ideal for batch processing, quick previews, or when encoding speed is the bottleneck. The quality is identical — only file size increases.
Diminishing Returns
The critical insight: the slower you go, the less you gain per step.
veryfast→medium: -17% size (significant, worth the 2.3x slower encoding)medium→slow: -13% size (still significant, worth it for archival)slow→slower: -4% size (marginal, 2x slower for little gain)slower→veryslow: -3% size (marginal, 2x slower for almost nothing)
This is why veryslow and placebo are rarely worth using. The encoding time doubles or triples for single-digit percentage improvements in file size.
Practical recommendation: Use medium unless you have a specific reason not to. If file size matters and you have time, use slow. Never use placebo — it's effectively identical to veryslow at 3–5x the encoding time.
Preset + CRF Interaction
Presets and CRF work together but control different things:
- CRF controls quality level (what you see)
- Preset controls compression efficiency (how many bytes it takes to achieve that quality)
At CRF 23 with ultrafast, the video looks nearly the same as CRF 23 with veryslow. But the veryslow file is 40–50% smaller because the encoder spent more time finding efficient ways to represent the same visual information.
This means you can achieve smaller files in two ways:
- Increase CRF (e.g., 23 → 28) — reduces quality and file size
- Use a slower preset (e.g., medium → slow) — reduces file size only, quality stays the same
Our Converter Settings
Our online converter uses the medium preset with CRF 23. This was chosen for the best user experience:
- Fast processing: Users don't want to wait 10 minutes for a 1-minute video
- Excellent quality: CRF 23 produces visually indistinguishable output
- Reasonable file size:
mediumprovides good compression without excessive encoding time
For users who need maximum compression, downloading FFmpeg and running the slow preset locally is the best option for large file libraries. For the other levers, such as CRF, resolution and codec, see how to compress video without losing quality.
Which Presets CleverUtils Video Tools Use
| Tool | x264 preset | CRF |
|---|---|---|
| Video to MP4, MOV and MKV converters | medium | 23 |
| Compress Video | veryfast | 18 / 23 / 28 / 32 (Highest to Smallest) |
| Resize Video, Trim Video | fast | 18 |
| Reverse Video | fast | 23 |
In the benchmark above, veryfast files are about 17% larger than medium at the same CRF, so in the compressor the CRF choice is what really sets the output size.