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.

Mozilla logo

Development binary builds

In addition to support in Firefox, Mozilla provides binary builds of Opus utilities.
Package Version Platform Download link Size
opus-tools 0.1.8 Windows 411KiB
Mac OS X opus-tools-0.1.8-macos.tar.gz 399KiB
Opus-tools provides command-line utilities to encode, inspect, and decode .opus files.
opusfile 0.5 Windows 2.6MiB
Source opusfile-0.5.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 1.3.1, 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

opusfile 0.5

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 v0.4 release:

  • Report HTTP (ICY) headers to client
  • New tag comparison and copy functions
  • New application decoding callback API for advanced clients
  • New dither disable function for advanced clients
  • constify API
  • Avoid clipping downmixing from a fixed-point decoder
  • Better practices for dual stack IPv6
  • Documentation improvements
  • Fix a unicode bug on Windows
  • Fix proxy user/password macros
  • Fix HTTP pipelining support detection

opus-tools 0.1.8

This release fixes a memory corruption bug with FLAC album art handling.

libopus 1.1-rc3

This third release candidate fixes some issues with the fixed-point build. Floating-point is unaffected.

libopus 1.1-rc2

This second release candidate fixes an alignment issue on ARMv5E and improves the Neon optimizations. Other platforms are unaffected.

libopus 1.1-rc

Compared to 1.1-beta, this new release further improves surround encoding quality. It also includes better tuning of surround and stereo for lower bitrates. The complexity has been reduced on all CPUs, but especially ARM, which now has Neon assembly for the encoder. At last, there are a few bugfixes.

opus-tools 0.1.7

This release has numerious build fixes, including updated Visual Studio project files to match similar changes in the opus package. Support encoding from FLAC files. Metadata tag support, including album art. Use the new surround encoder API in opus 1.0.3. The opusenc --uncoupled switch no longer works.

opusfile 0.4

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

This release includes Microsoft Visual Studio project files, supports HTTPS urls on Windows, and includes new API calls for gain control and picture metadata as well as numerous bug fixes.

Older/Historic Releases