Convert Opus Audio Codec (.opus) to Advanced Audio Coding (.aac) online for free. Fast, secure audio conversion with no watermarks or registration.
Conversion settings — add a file to adjust
Upload your .opus 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.
Opus and AAC are both modern lossy audio codecs, but they serve different ecosystems. Opus, standardized by the IETF in 2012, dominates real-time communication — it powers Discord voice chat, WhatsApp calls, and WebRTC audio in every browser. AAC (Advanced Audio Coding), developed by the MPEG group in 1997 and continuously refined, is the default audio format for Apple devices, YouTube, Spotify's internal encoding, and broadcast television worldwide.
Converting Opus to AAC moves your audio from the open-standard internet world into the Apple and broadcast ecosystem. While Opus technically achieves better quality at any given bitrate, AAC has vastly broader device support — every iPhone, iPad, Mac, Apple TV, game console, smart TV, and car infotainment system plays AAC natively without any third-party software.
Apple devices do not support Opus playback in their native music and media apps. If you have voice recordings, podcast captures, or audio from Discord and need to play them in Apple Music, import them into GarageBand, or share them with iPhone users, AAC is the required format. Apple's entire audio pipeline — from AirPlay to CarPlay to HomePod — is built around AAC.
Beyond Apple, AAC is required for uploading audio to platforms like iTunes Connect (for podcast distribution), certain online radio stations, and professional broadcast workflows that mandate MPEG standards. YouTube also re-encodes all uploaded audio to AAC, so providing AAC source material avoids a double-encode quality penalty. Converting Opus to AAC at 256 kbps produces transparent-quality audio indistinguishable from the Opus source for most listeners.
FFmpeg decodes the Opus stream (typically 48 kHz, up to 510 kbps, using the libopus decoder) and re-encodes it with the native AAC encoder at the specified bitrate (default 128 kbps) and 44.1 kHz sample rate. The AAC-LC (Low Complexity) profile is used for maximum compatibility. The output is wrapped in a raw ADTS container (.aac) or can be placed in an M4A container for better metadata support. Opus's internal 48 kHz rate is downsampled to 44.1 kHz to match the AAC standard.
At 128 kbps AAC, the output is transparent for speech and near-transparent for music relative to the Opus source. At 256 kbps AAC, the conversion is perceptually lossless — no human listener can distinguish it from the Opus original in blind tests. Since both Opus and AAC are lossy codecs, there is a theoretical generation loss from decoding one lossy format and re-encoding to another, but at adequate bitrates this is inaudible.
| Device | Opus | AAC |
|---|---|---|
| Windows PC | Partial | Partial |
| macOS | Partial | Native |
| iPhone/iPad | Partial | Native |
| Android | Partial | Partial |
| Linux | Partial | Partial |
| 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
Opus to AAC conversion is the standard bridge between the WebRTC/internet audio world and the Apple/broadcast ecosystem. At 192-256 kbps AAC, you get transparent quality that plays natively on billions of devices worldwide, making it the practical choice whenever Opus compatibility falls short.
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| No |
| 기능 | Opus | AAC |
|---|---|---|
| 전체 이름 | Opus Audio Codec | Advanced Audio Coding |
| 확장자 | .opus | .aac |
| 최적 용도 | Low latency | Superior to MP3 |