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MP4 to AAC Converter

Convert MP4 to AAC online for free. Fast, secure, and high-quality conversion with no sign-up or software required.

Free to useNo file stored beyond 1 hourEncrypted over TLS 1.2/1.3No watermarks

How it works

Three steps to your converted file

Everything happens in your browser tab - upload, pick a format, download. The heavy lifting runs on our servers.

01

Upload your file

Drag and drop, click to browse, or paste a URL. Batches take up to 20 files at once - 230+ input formats across video, audio, image, document, and archive types.

02

Choose an output format

Pick from over a hundred output formats. Filter by category or search by name - every option is open to everyone, no account needed.

03

Convert & download

Hit Convert and grab your download link moments later. Originals are erased when the job completes; results are cleared within about an hour.

What is an MP4 file?

MPEG-4 Part 14 (MP4) is a digital multimedia container format defined by ISO/IEC 14496-14. Based directly on the QuickTime File Format (QTFF), it allows for streaming over the Internet and is the global standard for video compatibility. An MP4 file can store video streams (encoded with H.264/AVC, H.265/HEVC, or MPEG-4 Visual), audio streams (typically AAC or MP3), subtitles, and still images. It utilizes object-oriented structures specifically designed to support initial object descriptors (IOD) and other MPEG features.

How to open an MP4 file

MP4 is the most widely supported video format in existence. It opens natively on virtually all modern operating systems including Windows (via Movies & TV or Windows Media Player), macOS (QuickTime), Android, and iOS. Web browsers (Chrome, Firefox, Safari) also support native MP4 playback via the HTML5 video tag. No external software is generally required, though VLC Media Player is useful for MP4 files containing obscure codecs.

MP4 Technical Info

Full Name
MPEG-4 Part 14
Developed By
ISO / IEC
Initial Release
2001
MIME Type
video/mp4

What is an AAC file?

Advanced Audio Coding (AAC) is a lossy digital audio compression standard defined by ISO/IEC 13818-7 (MPEG-2) and ISO/IEC 14496-3 (MPEG-4). Developed by a consortium including Bell Labs, Fraunhofer IIS, and Dolby Laboratories as the successor to MP3, AAC utilizes the Modified Discrete Cosine Transform (MDCT) algorithm and perceptual noise shaping to discard imperceptible signal components. It supports up to 48 audio channels, arbitrary sample rates, and utilizes extensions such as Spectral Band Replication (SBR) to achieve higher fidelity at lower bitrates than predecessor formats.

How to open an AAC file

AAC serves as the default audio container for Apple's iTunes and iOS devices, ensuring native support within the macOS Core Audio framework and Apple Music. Windows 10 and 11 provide native decoding support via the Groove Music and Windows Media Player applications. For cross-platform playback or advanced stream analysis, users should utilize VLC Media Player or FFmpeg, which contain the necessary libavcodec libraries to decode AAC streams without external codec packs.

AAC Technical Info

Full Name
Advanced Audio Coding
Developed By
Bell Labs, Fraunhofer IIS, Dolby, Sony, Nokia
Initial Release
1997
MIME Type
audio/aac

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Why RunConvert

The fastest way to convert any file

Purpose-built for speed, privacy, and breadth of format support.

Convert MP4 to AAC in seconds

Every MP4 to AAC conversion runs on our servers, so your device stays fast and the output quality stays intact.

Fast, cloud-powered

No queue, no waiting. Files are processed on high-performance servers and returned in seconds, even for large files.

Secure & private

Encrypted in transit and never shared with anyone. Uploads are erased the moment your job completes, and results shortly after.

Free - no account needed

Convert without creating an account - no credit card, no trial clock. Sign in only if you want history and higher daily limits.

Developer API

Convert MP4 to AAC via API

Automate MP4 to AAC conversions in three steps: create a job, upload your file, then poll for the result.

# 1. Create job
curl -X POST https://api.runconvert.com/v3/jobs \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "tag": "mp4-to-aac",
    "tasks": {
      "upload-file": {
        "operation": "import/upload"
      },
      "convert": {
        "operation": "convert",
        "input": "upload-file",
        "output_format": "aac"
      },
      "export-result": {
        "operation": "export/url",
        "input": "convert"
      }
    }
  }'

# 2. Upload your file (use upload_url from the response)
curl -X PUT "$UPLOAD_URL" --upload-file input.mp4

# 3. Poll for result
curl https://api.runconvert.com/v3/jobs/$JOB_ID?include=tasks \
  -H "Authorization: Bearer YOUR_API_KEY"

Replace YOUR_API_KEY with your RunConvert API key. Get your free API key at runconvert.com/api.