Convert OPUS to MP3

What Opus voice notes are

Opus is an open codec from 2012, designed to sound good at very low bit rates. That makes it ideal for voice messages, and WhatsApp and Telegram both use it. Depending on the app and how you saved a note, the file ends in .opus, .ogg or .oga; inside, it is the same Opus sound.

Chrome, Edge, Firefox and VLC play these files. Many other programs don't: older media players, some video editors, older phones, and transcription services that list only MP3, WAV or M4A. An MP3 copy fixes all of that. It is also a sensible way to keep a recording that matters to you, like a message from a grandparent, in the most widely supported sound format there is.

Getting voice notes onto the PC

Most chat apps let you share or export a voice note from the chat itself, to email, a cloud drive or another app; save what arrives into one folder. On many Android phones you can also copy them over a USB cable from WhatsApp's media folder, where received notes sit in “WhatsApp Voice Notes” as .opus files, usually with names that start with PTT and a date.

Octoolo keeps each file's name for its MP3, so dates in the names survive the conversion. Only the ending changes, from .opus or .ogg to .mp3, which makes it easy to match a converted note with its original.

If the notes arrive packed in a .zip file, for example from an exported chat, unzip it first: Octoolo reads the sound files, not the archive around them. Photos and text files in the same folder are skipped, since a dropped folder brings in only sound and video files; if videos come along, take them out of the list or let their sound be converted too.

Private messages should stay private

An online converter needs you to upload the file to its server, which means a stranger's computer holds a copy of your conversation for a while. In Octoolo, FFmpeg does the converting right here on the PC and nothing is sent anywhere; once FFmpeg is set up, it works the same with the internet switched off.

That matters most for exactly the notes people tend to convert: a doctor's instructions, a family message, a voice note kept as a record of what was agreed. They go from your phone to your PC and nowhere else, and the MP3s are saved next to the originals, in a folder you already know, rather than in a downloads list on some website.

Size, sound and clean-up

Opus squeezes speech very hard, so the MP3 will be bigger than the note, but still small: at Small, a three-minute mono note becomes about 1.4 MB, easy to email or keep by the hundred. Voice notes are mono and stay mono, and since Opus always plays back at 48 kHz, the MP3 is written at 48 kHz too.

Converting can't make a muffled recording clearer. The Audio Editor can help, though: open the MP3, switch on noise reduction or level the loudness, and export it again. To put several notes into one file, for instance a long story told in ten messages, see the audio joiner. And if a note is headed for a video project, pick WAV instead of MP3 in the same window: it skips another round of compression.