When WMA is the answer
Opus is one of the newest audio codecs, and WMA belongs to an earlier generation. You convert Opus to WMA when you have to work with older Windows software: Windows Media Player on Windows 7, old versions of PowerPoint and Movie Maker, school or office computers with locked-down software, or a portable player or car stereo that reads WMA and MP3 only. In those environments, an .opus file is simply unknown.
If your device or program also supports MP3, prefer Opus to MP3. MP3 is understood by more software and is just as easy to make.
Bitrate and sample rate
The converter creates standard WMA (version 2), which old players understand. It is less efficient than Opus, especially for speech, so the bitrate needs to be higher than the source:
- Voice notes and lectures: 64 kbps mono, about 0.5 MB per minute.
- Music: 128–192 kbps stereo, about 1–1.4 MB per minute.
Decoded Opus audio is always 48 kHz. Many older WMA players, especially portable ones, were built around 44.1 kHz, so choose 44.1 kHz for hardware. For Windows software, 48 kHz is fine.
Using the file in a presentation
A frequent case is adding a voice message or a short sound to an old PowerPoint file on a Windows computer. Older versions handled WMA better than most other formats. Keep the clip short, and trim it beforehand with Cut so the presentation stays small. Newer PowerPoint versions prefer M4A, which you can make with Opus to M4A.
Quality expectations
The conversion decodes the Opus stream and encodes it again, so the result cannot be better than the source and will be slightly larger. For a voice message, the difference in sound is negligible at 64 kbps. Basic tags such as title and artist are carried into the WMA file where they exist.