v1.2.0

Pure Go implementation of the Opus audio codec (RFC 6716 / RFC 8251). This is a
backward-compatible additive release over v1.1.1.

Public API expansion

• Multistream encoder/decoder APIs.
• Surround with standard channel mappings.
• Projection / Ambisonics (mapping families 2 and 3).
• Ogg Opus container (single logical stream).
• Packet extensions (RFC 8251 padding/extension parsing and generation).
• Repacketizer and packet padding helpers; packet-inspection helpers.
• 24-bit PCM (Encode24/Decode24) and float32 encode/decode.
• CELT phase-inversion controls; production codec controls, getters, and a
  libopus-defaults profile; automatic/maximum bitrate; broadened voice-mode rate
  policy.

In-band FEC (LBRR)

• SILK-only and hybrid in-band FEC encode and decode for mono and stereo
  (SetInbandFEC + non-zero packet-loss percentage). DecodeFEC reconstructs
  lost frames from the redundant copy; missing/inactive slots fall back to PLC.

SILK encoder quality

• Proper silk_find_LPC_FLP-path NLSF target (Burg LPC + A2NLSF), active NLSF
  interpolation, and voiced/unvoiced delayed-decision (trellis) NSQ.
• Fixed a low-F0 first-frame pitch misdetection (16 kHz speech-harmonic peak
  overshoot). On the AB scoreboard the encoder now matches or beats libopus on
  all 15 sampled cells (8/12/16 kHz × silence/unvoiced/steady/harmonic/onset).

Decoder

• RFC 8251 official vector suite at 12/12 PASS; verified against libopus 1.6.1
  via the opusref reference tests.

Hardening

• Expanded opusref interoperability CI, parser fuzz targets, PLC/FEC separation,
  and assorted defensive fixes (PLC pitch-history update at 16 kHz, packet
  padding overflow guard, content-hint reapply on encoder Reset).

Full changelog: v1.1.1...v1.2.0

v1.1.1

v1.1.1 — Codec correctness and API polish

What's fixed

• Fixed mono decoders handling stereo CELT/hybrid packets by decoding stereo payloads with stereo CELT state before downmixing.
• Enforced the Opus 120 ms packet-duration limit on encode and decode paths.
• Rejected unsupported encoder frame sizes instead of silently padding or trimming non-20 ms multiples.
• Returned ErrBufferTooSmall from Decode instead of silently truncating output after advancing decoder state.
• Made GetLastPacketDuration report the actual decoded packet duration.
• Fixed mono SILK multi-frame LBRR side-symbol consumption to keep the range decoder aligned.
• Reset CELT final-range folding seed and hardened low-budget transient fallback.
• Fixed raw-only entropy EncodeBits flush behavior.

API additions since v1.1.0

• Added Encoder getters for bitrate, complexity, VBR state, and application mode.
• Exposed SetSignalType / SignalType so callers can provide voice/music hints.

Validation

• go test ./...
• go vet ./...

Upgrade: go get github.com/darui3018823/opus@v1.1.1

v1.1.0

v1.1.0 — Full CELT Encoder Quality Pipeline

What's new

Encoder — full CELT quality pipeline (Phase 1+2)

v1.0.0 shipped a working but basic CELT encoder. v1.1.0 completes the quality
pipeline: the encoder now produces standard Opus packets that libopus 1.6.1
decodes correctly, with SNR competitive with a full-featured codec at 64 kbps.

Signal quality

Signal	SNR (64 kbps)
440 Hz sine	~48 dB
1 kHz sine	~47 dB
4 kHz sine	~39 dB
1 kHz stereo	~43 dB

New encoder features

• Signal-driven bandwidth detection — per-frame FFT power analysis selects NB/WB/SWB/FB automatically; asymmetric hysteresis prevents flapping. Manual override via SetBandwidth/SetMaxBandwidth.
• Application-coupled bandwidth — ApplicationVOIP prefers narrower tiers for voice; ApplicationAudio uses music defaults.
• Transient detection + short-block MDCT — time-domain HPF masking (transientAnalysis) switches to 8×120-sample short blocks to limit pre-echo. patchTransientDecision is a complementary band-energy fallback for onsets the time-domain detector misses.
• tf_analysis — per-band transform-resolution RDO via 2-pass Viterbi.
• dynalloc / alloc_trim / spread — masking-follower dynamic allocation boost, spectral-tilt trim, spreading decision with recursive hysteresis.
• Stereo decisions — stereoAnalysis (dual vs joint M/S), intensity stereo with hysteresis.
• Anti-collapse — consecutive-transient bit prevents spectral collapse.
• VBR / CVBR rate control — SetVBR(true) / SetVBRConstraint(true).
• Multi-frame packetization — 20/40/60 ms packets (RFC 6716 §3.2 codes 0–3) including code-3 padding. SetPacketPadding for explicit padding.
• Silence detection + DTX — near-silent frames emit 2–3 byte packets; SetDTX enables discontinuous transmission.

New public API

func (e *Encoder) SetVBRConstraint(constrained bool)  // true = CVBR
func (e *Encoder) SetBandwidth(bw Bandwidth)           // Auto/NB/WB/SWB/FB
func (e *Encoder) SetMaxBandwidth(bw Bandwidth)
func (e *Encoder) Bandwidth() Bandwidth
func (e *Encoder) SetDTX(dtx bool)
func (e *Encoder) SetPacketPadding(n int)

const BandwidthAuto Bandwidth = ...   // plus BandwidthNB/WB/SWB/FB

Decoder — unchanged

The decoder continues to pass all 12 official RFC 8251 test vectors (RMSE < 0.001) and matches the libopus 1.6.1 reference.

---

Not yet implemented: SILK encoder, hybrid (SILK+CELT) encoder, FEC/PLC encode. The encoder is not bit-exact with libopus.

Upgrade: go get github.com/darui3018823/opus@v1.1.0

v1.0.0

v1.0.0 — Initial Release

Pure Go implementation of the Opus audio codec (RFC 6716), with no runtime CGO dependency.

Features

• Encoder: Accepts 8/12/16/24/48 kHz mono/stereo input; resamples to 48 kHz; emits CELT-only fullband 20 ms packets
• Decoder: Full CELT, SILK, and hybrid (SILK+CELT) packet decoding
  • Hybrid SILK+CELT reconstruction (time-domain sum)
  • Hybrid SILK→CELT redundancy / crossfade
  • RFC 6716 §3.2.5 code-3 multi-byte padding support
• RFC 8251 official test vectors: 12/12 PASS (all RMSE < 0.001)
• Entropy coder: Range encoder/decoder (internal/entcode)
• DSP utilities: FFT, MDCT/IMDCT, windowing (internal/dsp)
• Resampler: Opus-rate sample rate conversion (internal/resampler)
• CI: GitHub Actions matrix (amd64 + arm64), race detector, benchmarks, fuzz targets

Package

go get github.com/darui3018823/opus@v1.0.0