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@darui3018823 darui3018823 released this 15 Jun 04:33
· 145 commits to main since this release
v1.1.0
8975b36

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

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