Convert Flash Video (.flv) to Advanced Audio Coding (.aac) online for free. Fast, secure video conversion with no watermarks or registration.
Conversion settings — add a file to adjust
Upload your .flv 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 .aac file when it's ready.
FLV files from the Flash Video era frequently contain audio encoded as MP3 at 44.1 kHz or AAC-LC within Adobe's proprietary container. AAC (Advanced Audio Coding) is the successor to MP3, delivering superior sound quality at equivalent bitrates thanks to its modified discrete cosine transform and temporal noise shaping. Converting FLV to AAC extracts the audio layer and outputs it in a widely compatible format recognized by iOS, Android, iTunes, and every major streaming platform.
You may have FLV recordings — lectures, music performances, podcasts — where only the audio matters. Extracting to AAC gives you a compact, high-fidelity audio file without the video overhead. AAC at 128 kbps matches or exceeds MP3 at 192 kbps in perceptual listening tests. Since Apple adopted AAC as the default iTunes format in 2003, compatibility is universal across modern devices.
FFmpeg demuxes the FLV container, isolates the audio elementary stream, and either copies the AAC bitstream directly (when the FLV already contains AAC-LC audio) or transcodes MP3/Nellymoser/Speex audio to AAC-LC using the libfdk_aac or native aac encoder. The output is wrapped in an ADTS or MP4 container with .aac extension. Sample rates up to 96 kHz and channel counts up to 7.1 surround are supported.
If the source FLV contains AAC audio, conversion is lossless — the bitstream is copied without re-encoding. If the source uses MP3, transcoding from one lossy codec to another introduces a small generation loss. Using a higher output bitrate (192-256 kbps) minimizes audible degradation. The resulting AAC file will typically sound transparent to the original at 128+ kbps.
| Device | FLV | AAC |
|---|---|---|
| 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
Extracting AAC audio from FLV files rescues valuable audio content trapped in an obsolete video container. Whether you are archiving lectures or building a music library, the AAC output delivers excellent quality with universal device support.
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8MB free, 50MB Nitro
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| Funktion | FLV | AAC |
|---|---|---|
| Fulde navn | Flash Video | Advanced Audio Coding |
| Filendelse | .flv | .aac |
| Bedst til | Small file size | Superior to MP3 |