OPUS to AAC Converter

How to Convert OPUS to AAC Online

1. Upload Your OPUS Files: Drag and drop or click "Add Files" to select one or more .opus files. Batch conversion is supported, so a folder of WhatsApp or Discord voice messages can be processed in one pass.
2. Set the Bitrate under File Compression: File Compression opens on Quality Preset, the hands-off mode and the least predictable control on this page — see the section below. Switch it to Constant Bitrate (the dropdown runs from 8 kbps to 384 kbps and opens on 128 kbps) for a rate you can predict, or to Variable Bitrate and pick one of the five AAC bands (96k-112k down to 20k-32k) to let the encoder spend bits where the material needs them.
3. Adjust Audio Channel and Sample Rate (Optional): Set Audio Channel to Mono (smaller files, fine for voice) or Stereo, leave it on Original to inherit the source. Audio Sample Rate options are Original, 8000, 12000, 16000, 24000, 44100, and 48000 Hz — match 44100 Hz for iTunes libraries or 48000 Hz for video-track audio.
4. Trim and Convert: Use Audio Trim to set Start (seconds or HH:MM:SS.sss) and Duration if you only need a clip, then click Convert. Files are uploaded over an encrypted connection, processed on our servers, and deleted automatically after a few hours — no sign-up, no watermark, never shared.

Why Convert OPUS to AAC?

Opus is the codec behind most modern voice and low-latency streaming — Discord voice, Telegram and WhatsApp voice messages, Google Meet, WebRTC calls, and YouTube's audio streams since late 2014 all ship Opus. It excels at low bitrates because it merges Xiph's CELT (music) and Skype's SILK (speech) codecs into one switchable stream. AAC (Advanced Audio Coding), standardized as MPEG-2 Part 7 in 1997 and folded into MPEG-4 Part 3 in 1999, is the codec Apple's ecosystem speaks natively. The conversion is what bridges those two worlds when a .opus file refuses to play in iTunes, lands as a broken attachment in Mail, or stalls on an older car stereo.

• Apple ecosystem playback — iOS 17 added Opus decoding through AudioToolbox and the Files app can open .opus containers, but Apple Music, Music.app library, iTunes, CarPlay, and Apple TV still expect AAC or Apple Lossless. Convert before importing to a library.
• WhatsApp and Discord voice messages — WhatsApp has used Opus for voice notes since 2016; Discord recordings are typically Opus at 48–96 kbps. iPhone users who AirDrop those clips often hit "QuickTime Player can't open this file." AAC fixes that.
• Podcast and audiobook distribution — Apple Podcasts, Spotify for Podcasters, Amazon Music, and most podcast hosts require MP3 or AAC ingest; the RSS spec doesn't recognize audio/opus enclosures.
• Car audio and Bluetooth headsets — A2DP profiles on most car head units and older Bluetooth speakers advertise SBC and AAC, occasionally aptX, but rarely Opus. Converting before sideloading to a USB drive avoids "Unsupported format" on the dashboard.
• Embedding in MP4 video — AAC is the default audio track for MP4/M4V deliverables on YouTube, Vimeo, broadcast, and Final Cut Pro / Premiere timelines. Opus-in-MP4 is technically valid (ISOBMFF supports it) but many editors and CDNs still reject it.
• Email and document attachments — Outlook, Apple Mail, and Gmail all preview AAC inline; Opus attachments usually require recipients to download and find a player.

OPUS vs AAC — Format Comparison

Which Bitrate Control Gives a Predictable Result

The Quality Preset dropdown is the mode File Compression opens on, and it is the hands-off option: nothing is pre-selected in it, so leaving it untouched hands the decision to the server's own default rather than the "Highest" label showing on screen. It is also the least predictable control here, so when the output rate matters, name it yourself with one of the modes below. Treat the Variable Bitrate band labels as nominal too — a variable-rate encoder spends bits by content, so sparse speech lands under the label and dense material can run over it.

Frequently Asked Questions

Will I lose audio quality converting OPUS to AAC?

Some loss is unavoidable because both formats are lossy — encoding a decoded Opus stream into AAC is a second-generation transcode. In practice, if the source Opus is at typical voice-message bitrates (24–64 kbps) and you re-encode at AAC 128 kbps or higher, the audible difference is usually below the threshold most listeners can detect on phone speakers or earbuds. For music masters, set Constant Bitrate to 256 kbps or higher and keep a copy of the original Opus.

Why won't my Opus voice message play on my iPhone?

iOS 17 added Opus decoding through Apple's AudioToolbox framework and the Files app can play Ogg-Opus, but the Music app, Apple Music library, iTunes, CarPlay, and the standard QuickTime preview pane do not. Older iOS versions don't decode Opus at all. Converting to AAC (or M4A, which is AAC in an MP4 container) gets you native playback everywhere on iOS without third-party apps.

Should I pick AAC or M4A — what's the difference?

AAC is the codec; M4A is the most common file extension when AAC is wrapped in an MP4 container. iTunes and Music.app libraries prefer .m4a. Raw .aac (ADTS framing) is what this tool produces and works fine in players like VLC, ffplay, and most browsers. If you need a tagged file for a music library, use the OPUS to M4A tool instead.

What bitrate should I pick for a Discord voice clip?

Discord voice typically encodes Opus at 48–64 kbps mono; there's no benefit to encoding the AAC output above 96–128 kbps because the source already discarded that detail. A Variable Bitrate band of 64k-72k, or Constant Bitrate at 96 kbps, produces a file that plays everywhere without bloating the size.

Will the AAC file be larger than the original Opus?

Usually yes. Opus is more efficient bit-for-bit than AAC, especially below 128 kbps, so an Opus voice file at 32 kbps re-encoded to AAC at 96 kbps will be roughly 3× the size for similar perceived quality. If file size matters more than universal compatibility, consider OPUS to MP3 at the same bitrate or stay on Opus.

Can I convert WhatsApp voice notes (.opus) in batch?

Yes. Drop a folder of .opus files exported from WhatsApp's chat backup; each file converts independently. WhatsApp has used Opus for voice since 2016, so any voice note newer than that is Opus inside an Ogg container with a .opus extension.

Does the converter strip metadata or chapter markers?

Plain Opus voice messages from messaging apps don't carry chapter markers, so there's nothing to lose. Music Opus files in Vorbis-comment metadata (artist, album, title) are read from the source, but AAC stores tags differently and not every field maps cleanly. For full tag fidelity, output to M4A and check the tags in iTunes or Music.app afterward.

Are my files uploaded to a server?

Files are processed in a temporary session and removed automatically — no account, no signup, no permanent storage. For longer multi-track work or to extract a specific segment, see the audio cutter.

Why convert to AAC instead of MP3?

At the same bitrate, AAC produces noticeably better sound than MP3 — that is the whole reason MPEG designed it as MP3's successor. AAC is also the native format for YouTube uploads, broadcast TV, iTunes Store purchases, and most music streaming services. MP3 only wins on legacy hardware (very old MP3 players or car stereos from before ~2008). For broader compatibility on those devices, use OPUS to MP3 instead.