Free online OPUS to SPX converter

Source format: Opus

Opus is a modern, highly efficient audio codec and file format commonly stored in .opus files. It is widely used for voice chat, streaming, podcasts, and internet audio because it delivers very good sound quality at low bitrates. Opus is supported by many apps and platforms, including browsers, messaging tools, and media players that rely on FFmpeg or similar libraries.

In practice, an Opus file is usually a compressed audio recording that may contain speech, music, or mixed content. It is often chosen when small file size and low latency matter more than maximum archival compatibility.

Target format: Speex

Speex is an older speech-oriented audio codec, typically stored in .spx files. It was designed mainly for voice and telephony, with an emphasis on low bitrate speech compression rather than music quality. Speex is less common today than Opus, but it is still found in some legacy VoIP systems, embedded devices, and older voice applications.

The main advantage of Speex is its focus on speech compression and its historical use in voice communication systems. However, compared with Opus, it is generally less efficient and has broader compatibility only in older software.

How to perform the conversion

The most reliable way to convert .opus to .spx is with FFmpeg. This works on Windows, macOS, and Linux and gives you direct control over the audio codec.

1. Install FFmpeg if it is not already available on your system.
2. Open a terminal or command prompt in the folder containing your Opus file.
3. Run a command such as ffmpeg -i input.opus -c:a speex output.spx.
4. If needed, adjust the audio bitrate for speech-focused output, for example with -b:a 16k or -b:a 32k.
5. Play the resulting output.spx in a compatible player or test it in the target application.

If you prefer a graphical workflow, some audio editors or converters that support FFmpeg-based export may let you open the Opus file and then use File → Export or Save as to choose Speex as the output codec. Availability depends on the software version and installed codecs.

You can also convert the file on 101convert.com for free, without installing any software.

Notes on quality, compatibility, or limitations

Opus to Speex is a lossy-to-lossy conversion, so some audio quality is lost during the process. This is especially important if the source contains music or mixed audio, because Speex is optimized for speech and may sound worse than Opus for non-voice content.

Because Speex is a legacy format, the resulting .spx file may not play in many modern media players without codec support. For best compatibility, confirm that the destination system specifically requires Speex before converting. If your goal is general playback or archiving, keeping the original Opus file is usually the better choice.