Convert Adaptive Multi-Rate Audio (.amr) to MPEG-4 Part 14 (.mp4) online for free. Fast, secure audio conversion with no watermarks or registration.
Upload your .amr 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 .mp4 file when it's ready.
MP4 (MPEG-4 Part 14) is the universal multimedia container, supported by every operating system, browser, and device manufactured in the last 15 years. While MP4 is commonly associated with video, it also serves as an audio container — in fact, M4A is simply an MP4 file with an audio-only extension. Converting AMR voice recordings to MP4 creates the single most compatible audio file possible.
MP4 is the format that everything understands. Every web browser can play it inline. Every phone previews it. Every social media platform accepts it. Every cloud storage service generates thumbnails and waveforms for it. If you need a voice recording to work everywhere without any friction, MP4 is the safest bet. The container also supports rich metadata, chapter markers, and multiple audio tracks.
FFmpeg decodes the AMR audio to PCM and re-encodes it using the AAC-LC codec at 64-128 kbps inside an MP4 container with the moov atom at the front (faststart). The output is recognized by every modern media framework as a valid MPEG-4 file. The audio codec, container structure, and metadata conform to ISO 14496-14.
AAC encoding at 64 kbps transparently preserves AMR voice content. MP4's container adds no quality overhead — it merely organizes the encoded audio data with timing, metadata, and seeking information.
| Device | AMR | MP4 |
|---|---|---|
| Windows PC | Partial | Native |
| macOS | Partial | Native |
| iPhone/iPad | Partial | Native |
| 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
AMR to MP4 gives you the most universally compatible audio format in existence. It works on every platform, every browser, and every device without exception.
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Funguje všude
Jakýkoli prohlížeč, jakékoli zařízení
| Native |
| Vlastnost | AMR | MP4 |
|---|---|---|
| Celý název | Adaptive Multi-Rate Audio | MPEG-4 Part 14 |
| Přípona | .amr | .mp4 |
| Nejlepší pro | Speech optimized | Universal compatibility |