Convert Advanced Audio Coding (.aac) to Free Lossless Audio Codec (.flac) online for free. Fast, secure audio conversion with no watermarks or registration.
Conversion settings — add a file to adjust
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 .flac file when it's ready.
AAC delivers perceptually transparent audio through lossy compression, typically at 128-256 kbps. FLAC (Free Lossless Audio Codec) stores audio with perfect bit-for-bit accuracy while achieving 50-70% compression versus raw PCM. Converting AAC to FLAC decodes the lossy AAC data and re-encodes it losslessly, producing a file that preserves every sample the AAC decoder outputs. This is commonly done for archival purposes or to prepare files for workflows that require lossless input.
Lossless audio editors and mastering chains expect FLAC or WAV input. If you apply effects to an AAC file and re-export as AAC, you compound lossy artifacts with each generation. Converting to FLAC first gives you a lossless working copy that survives unlimited editing cycles without further degradation. FLAC is also the standard archival format on Linux and Android, supported natively without extra software.
FFmpeg decodes the AAC stream to PCM, then encodes using the FLAC encoder at a configurable compression level (0-12, default 5). Higher compression levels produce smaller files but take longer to encode — the decoded audio is identical regardless of compression level. Output sample rate and bit depth match the source. Metadata from the AAC container transfers to FLAC's Vorbis comment tags.
The conversion is lossless from the point of decoding. Every PCM sample decoded from AAC is preserved perfectly in FLAC. However, information discarded by the original AAC encoder cannot be recovered. The FLAC file sounds exactly like the AAC source — no better, no worse — but it will not degrade further during editing or future transcoding.
| Device | AAC | FLAC |
|---|---|---|
| Windows PC | Partial | Partial |
| macOS | Native | Partial |
| iPhone/iPad | Native | Partial |
| Android | Partial | Native |
| Linux | Partial | Native |
| 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
AAC to FLAC is the go-to conversion when you need a lossless, editable, archival copy of compressed audio. The file will be larger but immune to generation loss, making it ideal for long-term storage and professional workflows.
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| No |
| Χαρακτηριστικό | AAC | FLAC |
|---|---|---|
| Πλήρες όνομα | Advanced Audio Coding | Free Lossless Audio Codec |
| Επέκταση | .aac | .flac |
| Ιδανικό για | Superior to MP3 | Lossless compression |