ステップ1: アップロード Opus 上記のボタンを使用するか、ドラッグ アンド ドロップでファイルをアップロードします。
ステップ 2: 「変換」ボタンをクリックして変換を開始します。
ステップ3: 変換したファイルをダウンロードする AAC ファイル
Opus に AAC 変換に関するよくある質問
How do I convert Opus audio to AAC without losing quality?
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Upload the Opus file and our converter chooses the AAC codec / bitrate combination that matches the source. Lossless target (AAC = WAV / FLAC / ALAC) preserves every sample; lossy target (AAC = MP3 / AAC / OGG) defaults to 192 kbps which is transparent for most ears.
What bitrate does the AAC file use?
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Default 192 kbps for lossy AAC; pass-through for lossless AAC. Override to 320 kbps for audiophile or 96 kbps for voice / podcast. The choice trades file size against audible fidelity at very low bitrates.
Will going from Opus to AAC reduce my audio quality?
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If Opus is lossy and AAC is lossless (e.g. MP3 → WAV), the AAC file is no better than the Opus — you can't recover information that's already been thrown away. If Opus is lossless and AAC is lossy, expect the AAC codec to recompress; at 192 kbps this is transparent for most content.
Does the Opus to AAC converter keep ID3 / metadata tags?
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Yes — title, artist, album, year, track number, album art are read from Opus and written into the AAC container (where the AAC format supports tags, which all common ones do).
Can I batch convert hundreds of Opus files to AAC?
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Yes — drop a folder of Opus files in and we process them in parallel. Premium has more parallel workers and no per-file size cap, so a 500-file batch finishes in minutes rather than tens of minutes.
Will the AAC keep the same sample rate as Opus?
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By default yes (48 kHz Opus → 48 kHz AAC). If you need to downsample for compatibility (e.g. 96 kHz → 44.1 kHz for CD burning) the advanced sample-rate option does this with high-quality resampling.
Can I normalize loudness in the Opus to AAC step?
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Yes — the loudness-normalize option applies ITU-R BS.1770 / EBU R128 normalization to the AAC output, targeting -14 LUFS (streaming standard) or -16 LUFS (podcast standard). Useful when batch-converting tracks with varying mastering levels.
Will the AAC play on my car stereo / iPod / Sonos?
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MP3 plays universally. AAC plays on Apple, most Android, Sonos. FLAC plays on Sonos and Android, less well on older iPods. WAV plays on everything but is huge. The advanced options include device presets for these common targets.
Is my Opus file private during conversion?
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Yes — uploaded Opus files are processed in isolated workers and deleted within minutes. We never play, store, or share the audio content.
How long does converting a 1-hour Opus to AAC take?
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Same-codec re-mux: 10-30 seconds. Re-encode to a different codec: typically 10-20% of source duration, so a 1-hour Opus → AAC finishes in 6-12 minutes.
Why is the AAC file louder / quieter than the Opus source?
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No automatic gain change happens unless you turn on the normalize option. If you do see a level change, your audio player or media library may be applying ReplayGain or per-track normalization on playback — not us.
Can I convert Opus streaming downloads to AAC?
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If the Opus download is unprotected (no DRM), yes. DRM-encrypted streaming files (Spotify, Apple Music) are encrypted at the bit level and we can't process them. Sources from Bandcamp, SoundCloud download, and personal recordings convert fine.