Convert Advanced Audio Coding (.aac) to iPhone Audio (.iphone-audio) online for free. Fast, secure audio conversion with no watermarks or registration.
Upload your .aac 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.
The iPhone has used AAC as its primary audio codec since the original 2007 model. The iPhone Audio preset ensures your AAC files are encoded with parameters that match the iPhone's hardware audio decoder exactly — AAC-LC profile at 44.1 kHz in an M4A container. This eliminates edge-case playback failures and maximizes battery efficiency during audio playback.
Some AAC files encoded with HE-AACv2, unusual sample rates, or non-M4A containers (like raw ADTS streams or MKV) can cause stuttering, metadata display issues, or software-fallback decoding on iPhone. The iPhone Audio preset normalizes everything to the codec profile Apple optimized the A-series chip's audio DSP for, ensuring native hardware decoding on every iPhone model from the 3G onwards.
FFmpeg re-encodes to AAC-LC at 44.1 kHz, 2 channels, with a target bitrate of 256 kbps. The M4A container includes proper moov atom placement for instant playback start (no buffering delay). The encoder avoids SBR (Spectral Band Replication) and PS (Parametric Stereo) tools, relying purely on AAC-LC which iPhone's hardware decoder handles most efficiently.
AAC-LC at 256 kbps is considered transparent — listeners cannot distinguish it from CD audio in controlled tests. Re-encoding an already-AAC source adds one generation of lossy compression, but at 256 kbps the artifacts are below the threshold of human perception. For sources below 128 kbps, the re-encode preserves existing quality without improvement.
| Device | AAC | iPhone Audio |
|---|---|---|
| Windows PC | Partial | Partial |
| macOS | Native | Partial |
| iPhone/iPad | Native | Partial |
| Android | Partial | Partial |
| Linux | Partial | Partial |
| Web Browser | No |
Resolution: N/A
Bitrate: 320 kbps
OGG Vorbis preferred
Resolution: N/A
Bitrate: 256 kbps
AAC format required
Resolution: N/A
Bitrate: 128 kbps
Lossless FLAC/WAV for best quality
Resolution: N/A
Bitrate: 128 kbps
MP3 mono for spoken word
The iPhone Audio preset is the safest choice for audio that must play perfectly on every iPhone. It normalizes codec profiles, containers, and metadata for Apple's hardware decoder path.
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| No |
| Egenskap | AAC | iPhone Audio |
|---|---|---|
| Fullt navn | Advanced Audio Coding | iPhone Compatible Audio |
| Filendelse | .aac | .m4a |
| Best egnet for | Superior to MP3 | iPhone optimized |