About the Opus format
Opus is an open audio codec standardised by the IETF in 2012. It combines two techniques, one tuned for speech and one for music, and switches between them as needed. That makes it very efficient: speech is clear at 16–32 kbps, and music sounds good at 96–128 kbps. Opus always runs at a 48 kHz sample rate internally and supports bitrates from 6 to 510 kbps.
You meet Opus in more places than you might think. WhatsApp voice notes are .opus files, Telegram voice messages are Opus inside .ogg, Discord and browser video calls use it, and many web videos carry Opus audio. A .opus file is technically an Ogg container with Opus inside.
The problem is support outside browsers and chat apps. Older iPhones and Macs, many car stereos, Windows Media Player, some video editors and transcription services do not open Opus files. Converting them to a common format solves that. It is also the easiest way to keep voice notes from a phone that you are about to replace: an archive of MP3 or M4A files will still open in many years, on any system.
Which target to choose
- MP3 – plays everywhere; the usual choice for voice notes you want to keep or share: Opus to MP3.
- WAV – for editing, transcription software and video projects: Opus to WAV. On a Mac, Opus to AIFF works the same way.
- M4A or AAC – for iPhone, iMessage and the Apple Music app: Opus to M4A, Opus to AAC.
- FLAC – a lossless working copy: Opus to FLAC.
- OGG Vorbis – for games and older software that read Vorbis but not Opus: Opus to OGG.
- WMA – for old Windows tools: Opus to WMA.
- M4R – an iPhone ringtone from a voice note: Opus to M4R.
- MMF – old feature phones: Opus to MMF.
- MIDI – turn a hummed melody into notes: Opus to MIDI.
- MP4 – a video with a picture for social media: Opus to MP4.
Batch conversion and settings
Exported chats often contain dozens of voice notes. Add them all at once and they are converted in order with the same settings. Most voice notes are mono and low bitrate, so there is no reason to make them stereo or use high bitrates: 64 kbps mono MP3 keeps a voice note clear at about 0.5 MB per minute.
For sample rate, you can keep 48 kHz or switch to 44.1 kHz for older players. For lossless targets, 16-bit is enough for voice; choose 24-bit for music you will process further. Tags stored in the Opus file are copied when the target format supports them.
Everything runs in your browser, which matters for private voice messages: nothing is sent to a server. If the recordings are noisy, Noise Reduction can clean them after conversion.