AMR (Adaptive Multi-Rate) は、音声コーディングに最適化されたオーディオ圧縮形式です。携帯電話の音声録音やオーディオ再生によく使用されます。
一般的な用途
Voice recordings
Mobile audio
Telephony
AMR 変換に関するよくある質問
What is a AMR audio file?
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AMR is a narrow-band speech codec originally used by 2G/3G mobile networks. AMR captures intelligible voice at very low bitrates and is common in voicemail exports, push-to-talk recordings, and older feature-phone voice memos.
Is AMR lossy or lossless?
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AMR is lossy — the encoder removes data the encoder judges to be inaudible to reach a small file size.
What should I convert AMR to for sharing?
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For email and social-media sharing, convert AMR to MP3 — universal playback and small file size. For high-fidelity sharing with audiophiles, convert to FLAC or WAV to preserve the original quality.
How much will conversion change the file size?
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Converting AMR to a lossless format like WAV or FLAC keeps the size large; converting to MP3 or AAC at common bitrates (192-320 kbps) shrinks the file by roughly 5-10x with minimal perceptible quality change.
Will my AMR ringtone work on iPhone?
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iPhone ringtones need to be in M4R format (Apple's ringtone container). Convert AMR to M4R using MOV.to, then transfer the M4R file to your device through Finder or Apple Devices.
How long can a AMR file be before MOV.to refuses it?
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There is no hard time limit — the cap is on file size. Free users get 100 MB per upload (often an hour or more of AMR audio at common bitrates). Pro users go up to multiple GB.
Does MOV.to preserve metadata (tags, album art) from AMR?
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Yes — ID3 tags, artist/album/title, and embedded artwork in your AMR file are preserved in the output where the destination format supports them. WAV strips most metadata by design, so converting to WAV will drop tags.
Can I extract audio from a video as AMR?
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Yes. Upload an MP4, MOV, MKV or any supported video and pick AMR as the output. MOV.to demuxes the audio track and re-encodes only if needed.
Does MOV.to delete my AMR files after conversion?
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Yes. Your AMR upload and the converted output are deleted automatically after a short window. We do not retain, listen to, or share your audio.
What bitrate should I pick when converting from AMR?
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For music, 256-320 kbps is the sweet spot — transparent to most listeners. For voice and podcasts, 96-128 kbps is plenty. Going higher than the source bitrate cannot recover quality the source already lost.