MP4 to ASF - Online Video Converter

Convert MP4 to ASF online. Private, client-side - no uploadrequired. Batch conversion, quality presets, codec control.

Convert MP4 to ASF

[+] Drop MP4 video here or click to select MP4

Output format

ASF (WMV2 / WMA)

No transcoding (remux only)[i]

Mode[i]

Simple Advanced

Quality[i]

Resolution[i]

About MP4 to ASF

Convert MP4 to ASF. MP4 pairs H.264 video with AAC audio in the ISO base media container. ASF is Microsoft's streaming container that usually wraps WMV and WMA. Live-archive headers can confuse players; remuxing usually repairs them..

Why convert MP4 to ASF?

Smaller files with ASF lossy compression.
Keep animation and transparency where supported.
Private, no upload - runs in your browser.

MP4 vs ASF

Animation	Yes	Yes
Transparency	No	No
Compression	lossy	lossy
Typical use	MP4 pairs H.264 video with AAC audio in the ISO base media container.	ASF is Microsoft's streaming container that usually wraps WMV and WMA.

When not to convert MP4 to ASF

Skip ASF for archival masters: lossy compression discards detail, so keep the MP4 original.
Keep a master copy: repeated exports stack small losses, so archive MP4 before batch ASF shares.

Limits

Starting point: MP4 - H.264 video with AAC audio in one file. H.264 has no alpha channel, so transparency is dropped. Live-archive headers can confuse players; remuxing usually repairs them. Encode ASF (WMV2 / WMA) from MP4 at a bitrate near the source, and confirm the audio track before converting.

How conversion works

Conversion runs entirely in your browser with FFmpeg WASM. Files never leave your device.

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FAQ

How do I convert MP4 to ASF?

Drop your MP4 file onto this page, choose quality and codec settings, then click Convert. The result downloads as ASF instantly. All processing runs in your browser.

What codec is used for ASF?

The default codec for ASF is WMV2 / WMA. You can change the video and audio codec in Advanced mode.

How do you store my files?

We do not store any processed videos. All conversion happens entirely in your browser using FFmpeg WASM.