Opus release 1.3

Opus 1.3 is the latest major release of Opus and brings many improvements,
including:
- The spec fixes in RFC 8251 are now enabled by default
- Improvements to the VAD and speech/music classification using an RNN
- Improvements to stereo speech coding at low bitrate
- Support for ambisonics coding using mappings 2 and 3
- Making it possible to use SILK down to bitrates around 5 kb/s
- Using wideband encoding down to 9 kb/s
- Minor quality improvement on tones
- Security improvements

Notable bug fixes include:
- Fixes to the CELT PLC
- Bandwidth detection fixes

Opus release 1.3-rc2

This is a second release candidate for the upcoming 1.3 release and includes:
- Fixing an issue with bandwidth detection
- Ambisonics support now exabled by default
- Ambisonics now uses families 2 and 3 (instead of experimental 253 and 254)
- Hardening is now enabled by default

Opus release 1.3-rc

This is a release candidate for the upcoming 1.3 release and includes:
- 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

Opus release 1.3-beta

This is a beta release towards the upcoming 1.3 release. Changes include:
- The spec fixes in RFC 8251 are now enabled by default
- Improvements to the VAD and speech/music classification using an RNN
- Improvements to stereo speech coding at low bitrate
- Added support for ambisonics projection using mapping 3 (disabled by default)
- Fixes to the CELT PLC

Opus 1.2.1 release

This fixes an issue where the encoder can misdetect that the signal is SWB
instead of FB, lowpassing the signal. This patch makes the encoder much more
careful about doing that.

Opus release 1.2

Opus 1.2 is the latest major release of Opus and brings many improvements,
including:
- Speech quality improvements especially in the 12-24 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
- More optimizations for x86 (SSEx) and ARM Neon
- 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-04 (the mono
    downmix and the folding fixes need --enable-update-draft)
- Many bug fixes, including integer overflows discovered through fuzzing
    (no security implications)

Opus release 1.2-rc1

This is the first release candidate for the upcoming Opus 1.2 release. If no
issues are found with it, it will soon become 1.2-final, so I encourage
everyone to give it a try. Changes compared to 1.2beta include:
- Improves quality on files with powerful tones that cause MDCT leakage
- Improves bit allocation on mode transitions (CELT to/from SILK/hybrid)
- More ARM Neon optimizations
- Fixes to the speech/music detection at the very beginning of files
- Fixes to the unit tests (fixes illegal instructions and --disable-static)

Opus release 1.2-beta

This release fixes a bug in surround encoding causing very bad quality
on signals beyond a certain amplitude. Also included are a few ARM Neon
optimizations and some low-bitrate quality tuning.

Opus release 1.1.5

This release fixes a bug in surround encoding causing very bad quality
on signals beyond a certain amplitude.

Opus release 1.1.4

This release fixes a single bug. A specially-crafted Opus packet could cause
an integer wrap-around in the SILK LSF stabilization code. This would cause
an out-of-bounds read 256 bytes before a constant table. In most circumstances,
the consequences are harmless and the result is simply noise in the audio.

This was reported as CVE-2017-0381. Contrary to that report, we do not believe
that any remote code execution is possible. However, we are making this release
as a precaution.