How to convert MP4 to ASF
To convert MP4 to ASF, upload your MP4 file, choose ASF as the output format and press Convert. The finished ASF file is ready to save to your phone or computer in seconds, free, with no watermark and no sign-up. Your file is deleted from our server about 30 minutes after the conversion.
This free online converter turns MP4 videos into ASF files in your browser, with no software to install and no watermark. When the video and audio inside your MP4 file can be placed in ASF as they are, the streams are copied without re-encoding, which is faster and keeps the original quality. Otherwise the video is re-encoded as Windows Media Video 8 with Windows Media Audio 2.
What you get with MP4 to ASF
- Built for streaming over networks
- Plays in Windows Media Player
- Can hold multiple tracks and metadata
- Plays on: Windows Media Player, VLC and legacy Windows tools
What to expect from this conversion
- Expect a larger file than the MP4 original, because ASF is a less efficient format for the same quality.
- ASF output uses Windows Media Video 8 and Windows Media Audio 2, the same streams WMV files carry.
- ASF is a legacy format. Convert to it only when an older player or device requires it, since MP4 is better for everyday use.
- The first audio track is kept. Subtitle tracks, extra audio tracks and chapters are not included in the converted file.
MP4 vs ASF
| Property | MP4 | ASF |
|---|---|---|
| Full name | MPEG-4 Part 14 | Advanced Systems Format |
| Released | 2001, ISO/IEC (MPEG) | 1999, Microsoft |
| Generation | Modern | Legacy |
| Typical file size | Small | Medium |
| Plays on | Windows, macOS, Android, iOS, smart TVs, game consoles and every major browser | Windows Media Player, VLC and legacy Windows tools |
| Best for | uploading to YouTube, Instagram, TikTok and WhatsApp; sharing a video that has to play everywhere | legacy Windows streaming; old media servers |
Steps to convert MP4 to ASF
- Drop your MP4 video file onto the converter, or click to choose it.
- Check that ASF is selected as the target and adjust the options if you want.
- Press Convert, then download your new ASF file when it finishes.
Tips for the best result
- Leave Fast mode on to keep the original quality whenever the streams can be copied.
- Pick a lower resolution if the file is for a phone or messaging app.
- Use Mute if you only need the picture.
Frequently asked questions
How do I convert MP4 to ASF?
Upload your MP4 file, make sure ASF is the selected target and press Convert. When the progress bar finishes, download the ASF file. No account or software is needed.
Is the MP4 to ASF converter free?
Yes. It is free, with no watermark, no sign-up and no daily limit on how many files you convert. The site is supported by ads.
Will I lose quality when converting MP4 to ASF?
Not necessarily. If the video and audio streams already fit inside ASF, they are copied without re-encoding, so quality stays identical. If the file has to be re-encoded, the High setting keeps almost all visible detail, while Small trades some detail for a smaller file.
Why is my ASF file larger than the MP4 original?
Expect a larger file than the MP4 original, because ASF is a less efficient format for the same quality. Choosing a lower quality or resolution reduces the size further.
Which devices can play ASF files?
ASF files play on Windows Media Player, VLC and legacy Windows tools.
How large a file can I upload?
You can upload videos up to 500 MB. Files are deleted from the server about 30 minutes after conversion.