Complete Guide to AV1 Encoding with FFmpeg — libsvtav1 / libaom-av1

What You’ll Learn

• What AV1 is and how it compares to H.264 and H.265
• When to use libsvtav1 (fast) vs libaom-av1 (high compression)
• CRF mode and bitrate-controlled encoding
• 2-pass encoding for precise bitrate targets
• Container and audio codec choices
• Browser compatibility and web delivery settings

Tested with: FFmpeg 7.0
Platform: Windows / macOS / Linux

What is AV1?

AV1 (AOMedia Video 1) is an open, royalty-free video codec developed by the Alliance for Open Media.

AV1 achieves half the file size of H.264 at equivalent quality. Major platforms like YouTube, Netflix, and Twitch are actively deploying AV1.

Check Available Encoders

ffmpeg -encoders 2>/dev/null | grep av1

Expected output:

 V..... libsvtav1            SVT-AV1(Scalable Video Technology for AV1) encoder (codec av1)
 V..... libaom-av1           libaom AV1 (codec av1)

If libsvtav1 is missing, install the latest FFmpeg from your package manager or the official FFmpeg website.

libsvtav1 — Fast AV1 Encoding (Recommended)

Basic Command (CRF mode)

ffmpeg -i input.mp4 -c:v libsvtav1 -crf 35 -preset 6 -c:a libopus -b:a 128k output.webm

CRF Values (libsvtav1)

Preset Selection

# Quality-first (slower)
ffmpeg -i input.mp4 -c:v libsvtav1 -crf 30 -preset 2 -c:a libopus -b:a 128k output.webm

# Balanced (recommended default)
ffmpeg -i input.mp4 -c:v libsvtav1 -crf 30 -preset 6 -c:a libopus -b:a 128k output.webm

# Speed-first (real-time use)
ffmpeg -i input.mp4 -c:v libsvtav1 -crf 30 -preset 10 -c:a libopus -b:a 128k output.webm

Output to MP4 Container

ffmpeg -i input.mp4 -c:v libsvtav1 -crf 35 -preset 6 -c:a aac -b:a 128k output_av1.mp4

Note: AV1+MP4 has more limited compatibility than AV1+WebM.

libaom-av1 — High-Compression AV1

libaom-av1 is the AV1 reference encoder. It produces slightly smaller files than libsvtav1 but is significantly slower.

Basic Command (CRF mode)

ffmpeg -i input.mp4 -c:v libaom-av1 -crf 30 -b:v 0 -c:a libopus -b:a 128k output.webm

Important: Always pair -crf with -b:v 0 when using libaom-av1.

Multithreading

ffmpeg -i input.mp4 -c:v libaom-av1 -crf 30 -b:v 0 -row-mt 1 -tiles 2x2 \
  -c:a libopus -b:a 128k output.webm

2-Pass Encoding (Bitrate Target)

Use 2-pass when you need a specific file size or streaming bitrate.

libsvtav1 2-pass

# Pass 1
ffmpeg -i input.mp4 -c:v libsvtav1 -b:v 2M -preset 6 -pass 1 -an -f null /dev/null

# Pass 2
ffmpeg -i input.mp4 -c:v libsvtav1 -b:v 2M -preset 6 -pass 2 -c:a libopus -b:a 128k output.webm

libaom-av1 2-pass

# Pass 1
ffmpeg -i input.mp4 -c:v libaom-av1 -b:v 2M -pass 1 -an -f null /dev/null

# Pass 2
ffmpeg -i input.mp4 -c:v libaom-av1 -b:v 2M -pass 2 -c:a libopus -b:a 128k output.webm

Platform-Specific Settings

YouTube (AV1)

ffmpeg -i input.mp4 \
  -c:v libsvtav1 -crf 32 -preset 6 \
  -vf "scale=1920:1080:force_original_aspect_ratio=decrease,pad=1920:1080:(ow-iw)/2:(oh-ih)/2" \
  -pix_fmt yuv420p \
  -c:a libopus -b:a 256k \
  output_youtube_av1.webm

Web Delivery (Lightweight)

ffmpeg -i input.mp4 \
  -c:v libsvtav1 -crf 40 -preset 8 \
  -vf "scale=1280:720" \
  -c:a libopus -b:a 96k \
  output_web.webm

Browser Compatibility

If iOS coverage is required, provide an H.264 fallback.

Troubleshooting

libsvtav1 not found

Unknown encoder 'libsvtav1'

Install the latest FFmpeg:

# macOS
brew install ffmpeg

# Ubuntu/Debian
sudo apt install ffmpeg

# Windows
winget install ffmpeg

Encoding is extremely slow

Switch from libaom-av1 to libsvtav1 — it is 10–50× faster:

# Slow
ffmpeg -i input.mp4 -c:v libaom-av1 -crf 30 -b:v 0 output.webm

# Fast
ffmpeg -i input.mp4 -c:v libsvtav1 -crf 35 -preset 6 output.webm

No audio / container error

WebM only supports Vorbis or Opus audio — not AAC:

# Wrong: AAC in WebM
ffmpeg -i input.mp4 -c:v libsvtav1 -crf 35 -c:a aac output.webm

# Correct: Opus in WebM
ffmpeg -i input.mp4 -c:v libsvtav1 -crf 35 -c:a libopus -b:a 128k output.webm

Related Articles

• Video Format Conversion
• Two-Pass H.265 Encoding
• YouTube Encoding Settings

Tested with ffmpeg 7.0 / Ubuntu 24.04
Primary source: ffmpeg.org/ffmpeg-codecs.html#libsvtav1