Convert Advanced Systems Format (.asf) to MPEG-4 Audio (.m4a) online for free. Fast, secure video conversion with no watermarks or registration.
Conversion settings — add a file to adjust
Upload your .asf file by dragging it into the upload area or clicking to browse.
Choose your output settings. The default settings work great for most files.
Click Convert and download your .m4a file when it's ready.
M4A is an MPEG-4 audio container that typically holds AAC-encoded audio, serving as the default format for iTunes Store purchases and Apple Music downloads. ASF files containing WMA audio can be converted to M4A for seamless integration with the Apple ecosystem. The conversion extracts the audio from the ASF container, transcodes it from WMA to AAC, and wraps it in the M4A container with iTunes-compatible metadata.
M4A is the native audio format for Apple's entire ecosystem — iTunes, Apple Music, iPhone, iPad, Mac, Apple Watch, and HomePod all handle M4A without any plugins. WMA audio inside ASF files is effectively invisible to Apple devices and software. M4A also supports gapless playback, chapter markers, and rich metadata that WMA/ASF does not portably expose on Apple platforms.
The WMA audio stream is decoded from the ASF container and re-encoded to AAC-LC at the specified bitrate (commonly 128-256 kbps). The output is packaged in an M4A (MPEG-4 Part 14 Audio) container. Metadata from the ASF file — title, artist, album, track number, genre — is mapped to the M4A's iTunes metadata atoms. Gapless playback info is encoded if applicable.
AAC at 256 kbps in M4A is considered transparent (indistinguishable from the original) for most listeners. At 128 kbps, quality matches the old iTunes Store standard. Going above the source WMA bitrate provides no benefit. For music, 192-256 kbps is the sweet spot; for speech, 96-128 kbps is sufficient.
| Device | ASF | M4A |
|---|---|---|
| Windows PC | Partial | Partial |
| macOS | Partial | Native |
| iPhone/iPad | Partial | Native |
| Android | Partial | Partial |
| Linux | Partial | Partial |
| Web Browser | No |
Resolution: 1920x1080
Bitrate: 8-12 Mbps
H.264 recommended for fast processing
Resolution: 1080x1080
Bitrate: 3.5 Mbps
Square or 9:16 for Reels
Resolution: 1080x1920
Bitrate: 4 Mbps
9:16 vertical, under 60s ideal
Resolution: 1280x720
Bitrate: 5 Mbps
Under 140s, 512MB max
Resolution: 960x540
Bitrate: 2 Mbps
16MB limit for standard, 64MB for document
Resolution: 1280x720
Bitrate: 4 Mbps
8MB free, 50MB Nitro
ASF to M4A conversion is the definitive step for bringing Windows Media audio into Apple's world, providing native playback, full metadata support, and seamless library integration.
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| No |
| 기능 | ASF | M4A |
|---|---|---|
| 전체 이름 | Advanced Systems Format | MPEG-4 Audio |
| 확장자 | .asf | .m4a |
| 최적 용도 | Streaming optimized | Better than MP3 |