Convert MPEG-4 Part 14 (.mp4) 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 .mp4 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.
MP4 to AAC conversion extracts the audio track from an MPEG-4 video and saves it as a standalone Advanced Audio Coding file. AAC is the audio codec used by Apple Music, YouTube, and most streaming services — it delivers better sound quality than MP3 at equivalent bitrates. Since MP4 containers almost always carry AAC audio internally, this conversion is often a simple demux operation that copies the existing audio stream without re-encoding.
Our converter detects the audio codec inside your MP4 file. When it finds AAC audio, it performs a direct stream copy in milliseconds with zero quality loss. When the source contains a different codec (AC3, DTS, PCM), it transcodes to AAC using the high-quality native FFmpeg encoder.
You want the sound from a video without the video. Extracting audio as AAC gives you a high-quality audio file at roughly one-tenth the size of the original MP4. Podcasters pull interview audio from video recordings. Musicians isolate backing tracks from concert footage. Language learners extract dialogue for listening practice. AAC is preferred over MP3 because it preserves higher frequencies at the same bitrate — 128 kbps AAC sounds comparable to 192 kbps MP3.
FFmpeg reads the MP4 container and inspects the audio stream codec. If the stream is already AAC (codec_name: aac), the converter uses -c:a copy to extract the raw AAC stream without decoding or re-encoding. The output is wrapped in an ADTS container with the .aac extension. If the source audio is not AAC, FFmpeg decodes it and re-encodes using the native AAC encoder at 256 kbps stereo by default, with VBR mode available for variable bitrate output.
When the MP4 already contains AAC audio (the majority of MP4 files), extraction is bit-perfect — the output is identical to the original audio stream. No generation loss occurs. If transcoding from another codec is necessary, the high bitrate (256 kbps) ensures transparent quality that is indistinguishable from the source in blind listening tests. Lossy-to-lossy transcoding (e.g., MP3 inside MP4 to AAC) should be avoided when possible as it compounds compression artifacts.
| Device | MP4 | AAC |
|---|---|---|
| Windows PC | Native | Partial |
| macOS | Native | Native |
| iPhone/iPad | Native | Native |
| Android | Native | Partial |
| Linux | Partial | Partial |
| Web Browser | Native |
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 from MP4 is fast, lossless in most cases, and produces a universally compatible audio file. Whether you are building a podcast feed, archiving audio, or creating a playlist from video content, AAC delivers excellent quality at compact file sizes.
Безопасная передача
Загрузки зашифрованы по HTTPS
Конфиденциальность прежде всего
Файлы автоматически удаляются после обработки
Без регистрации
Начните конвертировать мгновенно
Работает везде
| No |
8MB free, 50MB Nitro
Любой браузер, любое устройство
| Характеристика | MP4 | AAC |
|---|---|---|
| Полное название | MPEG-4 Part 14 | Advanced Audio Coding |
| Расширение | .mp4 | .aac |
| Лучше всего подходит для | Universal compatibility | Superior to MP3 |