Opus

Opus is an open source, royalty-free, highly versatile and cross-platform audio codec that is fully compliant with the Opus specification (RFC 6716) and runs on GNU/Linux, Microsoft Windows and Mac OS X operating systems.

Features at a glance

Key features include support for bit-rates from 6 kb/s to 510 kb/s, support for frame sizes from 2.5 ms to 60 ms, support for sampling rates from 8 kHz (narrowband) to 48 kHz (full-band), audio bandwidth support from full-band to narrowband, frame size and bitrate support, as well as dynamically adjustable audio bandwidth.

In addition, the Opus audio codec comes with packet loss concealment and good loss robustness, fixed-point and floating point implementation, support for both variable bit-rate (VBR) and constant bit-rate (CBR), music and speech support, stereo and mono support, and supports up to 255 channels (multi-stream frames).

Getting started with the Opus

Installing the Opus audio codec on a GNU/Linux operating system is done the same way you install any other open source software, either by using the binary packages from the main software repositories of your distribution or by compiling the source package.

After installation, the codec will be automatically detected by the applications that need it. In addition, two command-line programs will be available after installation, opus_demo and opus_compare. Run them in a terminal emulator to view available options and usage examples.

Installing Opus from sources

If you decide to install the Opus codec using the latest source package, which is distributed for free as a TAR archive right here on Softoware, download it and save it on your Home directory, open a terminal emulator and go to the location where the archive was extracted (e.g. cd /home/softoware/opus-1.1).

Run the ‘./configure && make’ command to configure and compile the program, and then run the ‘sudo make install’ command to install it system and make it available to all users on your GNU/Linux operating system. With this method, you can install Opus on both 32-bit and 64-bit computer platforms.

What is new in this release:

• Making it possible to use SILK down to bitrates around 5 kb/s
• Using wideband encoding down to 9 kb/s
• Improving security (including a new -enable-hardening option)
• Minor quality improvement on tones
• Improving Ambisonics support (still experimental)
• Minor bug fixes

What is new in version :

• This Opus 1.2.1 minor release fixes a relatively rare issue where the 1.2 encoder would wrongly assume a signal to be bandlimited to 12 kHz and not encode frequencies between 12 and 20 kHz. This only happens on a few clips, but it is good to update to avoid a potential loss of quality.

What is new in version 1.2:

• Speech quality improvements especially in the 12-20 kbit/s range
• Improved VBR encoding for hybrid mode
• More aggressive use of wider speech bandwidth, including fullband speech starting at 14 kbit/s
• Music quality improvements in the 32-48 kb/s range
• Generic and SSE CELT optimizations
• Support for directly encoding packets up to 120 ms
• DTX support for CELT mode
• SILK CBR improvements
• Support for all of the fixes in draft-ietf-codec-opus-update-06 (the mono downmix and the folding fixes need --enable-update-draft)
• Many bug fixes, including integer wrap-arounds discovered through fuzzing (no security implications)

What is new in version 1.1 / 1.1.1 Beta:

• This release focuses on code optimizations, especially on x86, MIPS and ARM.

What is new in version 1.1:

• 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.