How to convert ASF to Y4M
To convert ASF to Y4M, upload your ASF file, choose Y4M as the output format and press Convert. The finished Y4M 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 ASF videos into Y4M files in your browser, with no software to install and no watermark. When the video and audio inside your ASF file can be placed in Y4M 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 raw uncompressed YUV4MPEG2 video (no audio, up to 720p).
What you get with ASF to Y4M
- Perfect, uncompressed picture
- Handy as an input to encoders
- Simple format that any tool can read
- Plays on: ffmpeg, x264, x265, aomenc, VLC and other video tools
What to expect from this conversion
- Expect a larger file than the ASF original, because Y4M is a less efficient format for the same quality.
- Y4M stores raw frames without compression and without audio. To keep the file manageable, output is limited to 720p, and it is still very large.
- The first audio track is kept. Subtitle tracks, extra audio tracks and chapters are not included in the converted file.
ASF vs Y4M
| Property | ASF | Y4M |
|---|---|---|
| Full name | Advanced Systems Format | YUV4MPEG2 |
| Released | 1999, Microsoft | 2000, MJPEG Tools / Xiph.Org |
| Generation | Legacy | Niche |
| Typical file size | Medium | Huge |
| Plays on | Windows Media Player, VLC and legacy Windows tools | ffmpeg, x264, x265, aomenc, VLC and other video tools |
| Best for | legacy Windows streaming; old media servers | benchmarking codecs; feeding raw video to encoders |
Steps to convert ASF to Y4M
- Drop your ASF video file onto the converter, or click to choose it.
- Check that Y4M is selected as the target and adjust the options if you want.
- Press Convert, then download your new Y4M 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 ASF to Y4M?
Upload your ASF file, make sure Y4M is the selected target and press Convert. When the progress bar finishes, download the Y4M file. No account or software is needed.
Is the ASF to Y4M 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 ASF to Y4M?
Not necessarily. If the video and audio streams already fit inside Y4M, 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 Y4M file larger than the ASF original?
Expect a larger file than the ASF original, because Y4M is a less efficient format for the same quality. Choosing a lower quality or resolution reduces the size further.
Which devices can play Y4M files?
Y4M files play on ffmpeg, x264, x265, aomenc, VLC and other video 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.