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

Opus 1.1 includes:

  • new analysis code and tuning that significantly improves encoding quality, especially for variable-bitrate (VBR),
  • automatic detection of speech or music to decide which encoding mode to use,
  • surround with good quality at 128 kbps for 5.1 and usable down to 48 kbps, and
  • speed improvements on all architectures, especially ARM, where decoding uses around 40% less CPU and encoding uses around 30% less CPU.
These improvements are explained in more details in Monty's demo (updated from the 1.1 beta demo).

libopus 1.0.3

Opus 1.0.3 includes a backport of the new 1.1 surround API. Aside from that, it includes fixes for a few minor glitches during mode switching, some minor fixed-point fixes, and fixes a regression in the FEC code introduced in 1.0.2.

Latest development releases

libopus 1.1.1-rc

This is a release candidate for the upcoming 1.1.1 version. This release includes further ARM optimizations.

opus-tools 0.1.9

This release adds support for 32-bit floating point WAV output and fixes a number of minor issues.

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