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Need help?AV1 to AV1 — Before You Spend the Encode Time
AV1 is a codec, not a container. The Alliance for Open Media announced the release of the royalty-free AV1 1.0 bitstream specification on March 28, 2018, and the codec has since landed in every major browser and in a growing pile of hardware decoders. But there is no such thing as a standardised .av1 file — the extension is a shorthand people use for "AV1 video", and something still has to carry the frames, the timing and the sound.
This page takes .av1, .mp4, .mkv and .webm uploads, re-encodes the video with SVT-AV1, and writes a Matroska file under a .av1 name with an Opus audio track. That makes it useful for one specific job: taking AV1 video out of an MP4 or WebM and landing it in Matroska under a name that says what the codec is.
Be clear-eyed about the cost first. Every job re-encodes — our servers have no copy-through path — and re-encoding AV1 back into AV1 is the most expensive round trip on this site: slow to run, and it burns a generation of quality reproducing the artefacts the first AV1 encode already introduced. Free, no sign-up, no watermark; files upload over an encrypted connection and are deleted automatically after a few hours.
What the Download Actually Is
| Property | Value |
|---|---|
| Container written | Matroska (EBML), named .av1 |
| Video encoder | SVT-AV1 (libsvtav1) |
| Audio | Preserved as a re-encoded track, Opus by default |
| Accepted inputs | .av1, .mp4, .mkv, .webm |
| Default File Compression mode | Quality Preset at "Very High (Recommended)" |
| CRF slider range | 16-63. Switching to Constant Quality opens it at 30 |
| Qmin / Qmax controls | Only under Constraint Quality, both on a 16-63 scale |
| Default Video resolution | Keep original |
| Opens by double-click? | Usually not — .av1 is not a registered type on Windows or macOS |
| Fix | Rename the download to .mkv. The bytes are already Matroska; nothing is re-processed |
There is no raw OBU elementary stream on offer here, and no .ivf. If you need one of those for a decoder conformance test, extract it locally.
How to Convert AV1 to AV1
- Upload Your File: Drag and drop, or click "+ Add Files". An AV1 video already sitting inside an MP4, MKV or WebM is a supported starting point, not a problem. Batch uploads share one set of settings.
- Pick an Audio Codec: Video Codec has a single entry, AV1, because the target pins it. Audio is where the real choice is: Opus is preselected and is the efficient modern default, FLAC keeps the audio lossless, and AAC, AC3, EAC3, DTS (DCA), Vorbis, MP2 and MP3 cover compatibility cases.
- Set the Compression Mode: Quality Preset is preselected. Constant Quality exposes the CRF slider directly and opens it at 30. Constraint Quality is the only mode that also shows Qmin and Qmax, which let you fence the quantiser range as well as cap the bitrate. Specific file size takes a megabyte figure.
- Resize, Trim, then Convert: Video resolution starts on Keep original, with Resolution Percentage, height-based Presets from 4320p to 144p, a locked-aspect Width or Height, and exact Width x Height as alternatives. Trim takes a start time and a duration. Click Convert; expect AV1 encodes to take noticeably longer than H.264 ones.
Quality Preset to CRF, for AV1
AV1 is a CRF codec, so the preset resolves to a specific quantiser value calibrated at 1080p, then adjusted by up to two points for the output resolution. AV1's usable CRF range runs much higher than H.264's — a number that would be unwatchable on H.264 is ordinary here.
| Preset | AV1 CRF at 1080p | Character |
|---|---|---|
| Highest | 18 | Visually lossless, archival |
| Very High (default) | 20 | Near-lossless; the sensible setting for a re-encode |
| High | 25 | Transparent at normal viewing distance |
| Medium | 33 | Standard web quality |
| Low | 45 | Artefacts visible on inspection |
| Very Low | 50 | Noticeably compressed |
| Lowest | 55 | Heavy artefacts, smallest file |
Never carry a CRF number across codecs. CRF 23 is FFmpeg's H.264 default and roughly "standard web"; on AV1 the equivalent tier sits around 33. Setting 23 on AV1 asks for near-archival quality and a large file.
Frequently Asked Questions
Why is my .av1 download actually a Matroska file?
Because a codec name is not a container and something must hold the video, the audio and the timing together. .av1 has no registered muxer, so the pipeline picks Matroska, which accepts AV1 alongside any of the audio codecs offered here. Rename the file to .mkv and every player and file manager will treat it normally — the bytes do not change.
Does AV1 to AV1 lose quality?
Yes, and more wastefully than most round trips. Our servers always decode and re-encode. Feeding an already-AV1 stream back into SVT-AV1 means the encoder treats the first encode's ringing and blocking as detail worth preserving, so you pay bits for artefacts. If you have any less-compressed master, start from that instead.
Why does the encode take so long?
AV1 buys its compression advantage with a much larger search space than H.264 or H.265 — more block partitions, more prediction modes, more transform choices. Even SVT-AV1, which is the fastest production-quality AV1 encoder available, is well behind x264 on throughput. A long or high-resolution source is genuinely slow, and there is no setting on this page that changes that fundamental.
Should I use Constant Quality or Constraint Quality?
Constant Quality when you want a consistent look and do not care about the exact size — set a CRF and let the file land where it lands. Constraint Quality when there is a delivery ceiling: it pairs a CRF with a maximum bitrate, and on AV1 it also exposes Qmin and Qmax so you can stop the encoder wandering to either extreme on unusual scenes. Quality Preset is the shortcut for people who would rather not think about numbers.
Will my AV1 file play in a browser?
The codec will; the container might not, depending on how you name it. AV1 decodes in Chrome, Firefox, Edge and recent Safari. A file named .av1 will not be served or recognised sensibly, so rename it to .mkv for desktop players, or convert to a web container instead. AV1 to WebM targets the wrapper the web actually uses and AV1 to MP4 the one with the widest device support — on both pages AV1 is in the Video Codec dropdown but is not preselected (WebM opens on VP9, MP4 on H.264), so choose it explicitly if you want to keep the codec.
What happens to extra audio tracks and subtitles?
They do not survive. The output carries one video and one audio track, plus at most one subtitle track, and a text subtitle is rewritten into Matroska's native ASS form. If your source has multiple languages or a commentary track, extract them with a local Matroska tool before converting.
Is AV1 really royalty-free?
That is the design intent and the reason the Alliance for Open Media exists — the specification is published openly and AOMedia offers a royalty-free patent licence to implementers. It is the practical difference between AV1 and HEVC, whose patent pools are the main reason H.265 never became a universal web codec. For converting your own files it changes nothing; for anyone shipping a decoder or a streaming service it changes everything.
Can I put lossless audio alongside AV1?
Yes. Choose FLAC from the Audio Codec list and the Matroska output carries a lossless audio track next to the lossy video — a common archival pattern. It will grow the file considerably compared with the default Opus track, which is why Opus is preselected.
How long do my files stay on your servers?
Uploads and their outputs are deleted automatically after a few hours. They are never shared, published or indexed, and no account, email address or payment is required to use the tool.