ASF to AV1 Converter

Convert ASF to AV1 Online

ASF is Microsoft's Advanced Systems Format — the Windows Media container that usually wraps WMV video and WMA audio, awkward to play outside Windows and inefficient by modern standards. This converter re-encodes those clips to AV1, the royalty-free AOMedia codec finalized in 2018 that is roughly 30-50% smaller than H.264 at the same visual quality. AV1 output is the modern, portable replacement for legacy WMV — far smaller and playable in current browsers — though the trade-off is slow encoding and no quality regain from a lossy source.

How to Convert ASF to AV1

1. Upload Your ASF File: Drag and drop or click "Add Files" to add .asf or .wmv clips — old Windows Media exports, screen recordings, or streamed-content captures. Batch is supported; queue a whole folder and each file is encoded on our servers.
2. Pick Quality Preset or Bitrate Mode: The default is the "Very High (Recommended)" Quality Preset, producing AV1 video with Opus audio. Switch to Specific file size to cap the result at a fixed MB target, Constant Quality for a fixed perceptual quality (the cleanest way to control AV1 size), or Constant / Variable Bitrate when you need predictable bitrate.
3. Resize or Trim if Needed (Optional): Under Video Resolution keep original, pick a Preset Resolution (2160p / 1440p / 1080p / 720p / 480p), scale by Resolution Percentage, or set a custom Width × Height. Use Trim with a Time Range — start time plus duration in seconds or HH:MM:SS.sss — to cut intros before encoding (a good idea, since AV1 encoding is slow).
4. Convert and Download: Click Convert. Files are uploaded over an encrypted connection, processed on our servers, and deleted automatically after a few hours — no sign-up, no watermark, never shared.

ASF vs AV1 at a Glance

If your priority is the fastest, most universally-playable result rather than the smallest file, ASF to MP4 produces H.264 that plays on virtually every phone, browser, and editor. To shrink an MP4 afterward, use Compress MP4.

Frequently Asked Questions

Does ASF to AV1 lose quality?

Yes — it is a lossy-to-lossy re-encode. The .asf holds WMV/VC-1 video and WMA audio; AV1 is a different codec, so the video is fully decoded and re-encoded with no lossless remux path. You cannot recover detail the original WMV encode already discarded, but AV1 is efficient enough that a high-quality setting looks visually near-identical to the source while producing a much smaller file. To keep loss minimal, leave the Quality Preset on "Very High (Recommended)" or use Constant Quality at a high setting, and avoid repeated round-trip conversions.

Why is AV1 encoding so much slower than converting to MP4 (H.264)?

AV1 uses far more complex coding tools — larger block partitions, more prediction modes, refined motion estimation — to squeeze more compression out of every frame. In practice that makes AV1 encoding often 5-10× slower than H.264 at comparable quality. The payoff is a much smaller file at the same visual quality. For a one-off archive conversion the wait is usually worth it; when speed matters more than size, ASF to MP4 with H.264 finishes far faster.

Will my AV1 file actually be smaller than the original WMV/ASF?

Usually yes. WMV 9 / VC-1 is a 2006-era codec; AV1 is roughly 30-50% more efficient at the same quality, so a typical WMV-in-ASF clip converts to a meaningfully smaller AV1 file. The exact ratio depends on source bitrate and content — animation and screen recordings compress better than grainy live action. In our testing, a standard-definition .asf clip re-encoded at the default Very High preset produced an AV1 MP4 noticeably smaller than the source while staying visually close.

Can my device actually play AV1?

AV1-in-MP4 plays in Chrome 70+, Firefox 67+, Edge 121+, and Safari 17+ on AV1-capable Apple silicon, plus VLC, MPV, and most current players. Hardware decode is widespread on 2022-and-newer devices (Intel 11th-gen+ and Arc, NVIDIA RTX 30/40, AMD RDNA2+, Apple M3 / iPhone 15 Pro and newer, Snapdragon 8 Gen 2+). Older hardware falls back to software decode, which handles 1080p fine on a modern desktop CPU but can stutter at 4K. If you need guaranteed playback on any device today, ASF to MP4 with H.264 is the safer pick.

What container and audio codec does the AV1 output use?

XConvert wraps the AV1 video stream in an MP4 container by default, with Opus audio — AV1-in-MP4 is supported by every modern browser and player listed above. The WMA audio inside the .asf is decoded and re-encoded to Opus (or AAC if you choose it) and stays in sync with the video. If you prefer AV1 inside a different container, see ASF to MKV or ASF to WebM.