Even though Opus is now standardized by the IETF, this Opus implementation will keep improving in the future. Of course, all future versions will still be fully compliant with the Opus IETF specification. See the development page for the latest development information.

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Development binary builds

In addition to support in Firefox, Mozilla provides binary builds of Opus utilities.
Package Version Platform Download link Size
opus-tools 0.1.9 Windows 403KiB
Mac OS X opus-tools-0.1.9-macos.tar.gz 399KiB
Source opus-tools-0.1.9.tar.gz 376KiB
Opus-tools provides command-line utilities to encode, inspect, and decode .opus files.
opusfile 0.6 Windows 1.5MiB
Source opusfile-0.6.tar.gz 428KiB
Opusfile provides application developers with a high-level API for decoding and seeking in .opus files. DLLs for the required libraries libogg 1.3.2, libopus 1.1 and openssl, are also included in the binary package.

Source code

Latest stable release

libopus 1.1.1

Opus 1.1.1 includes:

  • x86 SSE, SSE2 and SSE4.1 intrinsics optimizations with run-time CPU detection contributed by Cisco Systems,
  • MIPS intrinsics optimizations contributed by Imagination Technologies,
  • ARM Neon optimizations contributed by Linaro and ARM,
  • many architecture-independent optimizations and memory footprint reductions that should improve performance on all platforms, and
  • several minor bug fixes.
The quality of the encoder should be mostly unchanged compared to version 1.1.

Latest development releases

opusfile 0.6

The opusfile library provides seeking, decode, and playback of Opus streams in the Ogg container (.opus files) including over http(s) on posix and windows systems.

Changes since the v0.5 release:

  • Fix bugs with comment handling
  • Fix build for BSD
  • Fix bugs handling invalid and non-opus streams

Some of these bugs kept basic functionality of the APIs from working at all, so we recommend all users upgrade.

Older/Historic Releases