Website: https://g729.huny.dev/. The site includes listening samples and a browser-side WebAssembly encoder/decoder demo built from the same pure-Go code.

github.com/hunydev/g729 is a clean-room, pure-Go, MIT-licensed G.729A-compatible codec for G729/8000 annexb=no RTP send paths.

• Encoder: independent, quality-gated, and not byte-exact to the ITU reference encoder or bcg729.
• Decoder: the strict path matches private ITU Annex A reference PCM sample-for-sample in the current verifier run (740800/740800).
• Scope: G.729 Annex A, RTP payload type 18, ptime=10, and ptime=20.
• Not supported: Annex B SID/CNG/DTX, G.729.1, G.729D, and G.729E.
• Certification: no ITU certification, endorsement, or encoder byte-exact conformance claim is made.

No cgo, native codec dependency, or vendored codec source is required. The intended deployment targets are SIP/RTP, MRCP, TTS, IVR, and server-side media applications that need G729/8000 with annexb=no. This package targets the common RTP profile G729/8000 with annexb=no. It is not a full implementation of every G.729 family variant. See docs/annex-b.md for the Annex B / annexb=yes policy.

github.com/hunydev/g729 is an independent, clean-room, pure-Go implementation compatible with the ITU-T G.729 Annex A 8 kbps CS-ACELP speech codec, intended primarily as a server-side encoder/decoder for RTP payload type 18 (G729/8000) inside MRCP / TTS / VoIP deployments.

The codec was implemented from public ITU-T specifications and public textbooks only. No ITU reference C source, bcg729, Sipro Lab implementation, FFmpeg libavcodec/g729dec.c, or any other extant G.729 implementation source was consulted at any point. See the Clean-room statement below.

This module is the G.729 piece of a multi-codec deployment. G.711 (µ-law / A-law) and G.722 are intentionally out of scope for this module and should live in separate codec packages in a deployment stack.

Many practical G.729 deployments still rely on native C libraries, GPL/commercial licensing, or platform-specific codec modules. This package aims to provide a small, dependency-free, MIT-licensed Go codec for server-side RTP media paths where cgo and native codec packaging are undesirable.

The Annex B boundary is documented in docs/annex-b.md.

go get github.com/hunydev/g729

Module is pure Go (stdlib only). Go 1.22 or newer.

Minimal frame-at-a-time encode + decode:

package main

import (
    "github.com/hunydev/g729"
)

func main() {
    enc := g729.NewEncoder()
    dec := g729.NewDecoder()

    pcmIn := make([]int16, g729.FrameSamples) // 80 samples = 10 ms @ 8 kHz
    bits := make([]byte, g729.FrameBytes)     // 10 bytes
    pcmOut := make([]int16, g729.FrameSamples)

    // Fill pcmIn from your audio source (8 kHz mono int16) ...

    if err := enc.EncodeFrame(pcmIn, bits); err != nil {
        panic(err)
    }
    if err := dec.DecodeFrame(bits, pcmOut); err != nil {
        panic(err)
    }
}

See examples/ for fuller programs:

• examples/encode_pcm — raw PCM int16 LE 8 kHz mono → G.729 frames
• examples/decode_g729 — G.729 frames → raw PCM int16 LE 8 kHz mono
• examples/streaming_encode — NewStreamingEncoder + Write + Flush
• examples/rtp_packetize — illustrative RTP payload packetization
• examples/rtp_pion_packetize — full RTP packet marshal example using Pion RTP
• cmd/g729rtpfixture — Pion RTP pcap fixture generator for integration tests
• cmd/g729rtpcheck — raw payload / Ethernet IPv4 UDP RTP pcap validator
• cmd/g729rtpreport — optional SIP/RTP black-box pcap evidence JSON reporter
• cmd/g729rtpreportcheck — optional SIP/RTP evidence report acceptance checker
• cmd/g729wasm — Go WebAssembly wrapper used by the project website demo

cmd/g729rtpcheck test fixtures include Pion RTP generated packets so the pcap path is checked against a generic Go RTP packet library. Pion is used only in tests/examples/tools and is not part of the codec runtime.

Each Encoder and each Decoder is single-threaded. Concurrent calls on the same instance are a data race; one instance per stream.

EncodeFrame and DecodeFrame are zero-allocation in steady state. DecodeFrameEnhanced is available as an opt-in, non-strict local listening aid. It is not used by the default decoder and is not an ITU conformance claim.

The repository includes single-thread benchmarks for real-time streaming capacity planning. They pin the benchmark to one OS thread, report real-time factor (rtf), codec-only streams/core, and per-frame processing-time jitter against the 10 ms G.729 deadline.

GOMAXPROCS=1 go test -run=^$ \
  -bench='BenchmarkThroughput_|BenchmarkRealtimeJitter_' \
  -benchmem -count=5

rtf < 1.0 means the measured codec path is faster than real time. The streams/core metric is a codec-only upper bound; production sizing should apply safety margin for RTP, scheduling, jitter buffers, and co-hosted work.

See docs/performance.md for metric definitions and interpretation.

NewEncoder() and NewStreamingEncoder() use EncoderProfileCore, the product default.

EncoderProfileCoreFast is available as an explicit opt-in performance trade-off for high-density deployments. Diagnostic profiles are available for PESQ experiments, A/B listening, and regression analysis. All profiles emit normal 10-byte G.729 frames, but non-default profiles are not conformance claims and are not recommended as the default send path.

See docs/encoder-profiles.md for details.

G.729 frames are 10 ms each (80 samples / 10 bytes). RFC 3551 assigns static payload type 18 to G729/8000.

For ptime=10, one G.729 frame is the RTP payload (10 bytes).

For ptime=20, the sender concatenates two consecutive 10-byte encoder outputs into a single 20-byte RTP payload; the receiver hands them to two consecutive DecodeFrame calls.

This module does not implement RTP framing itself — the caller owns RTP header / sequence-number / timestamp generation. See examples/rtp_packetize/main.go for an illustrative payload builder and cmd/g729rtpcheck for black-box validation of raw payload streams or Ethernet/IPv4/UDP/RTP pcap captures.

# Validate raw one-frame-per-packet payload bytes.
go run ./cmd/g729rtpcheck -mode=payload -ptime=10 -in output.g729

# Validate payload type 18 packets in a pcap and check RTP continuity.
go run ./cmd/g729rtpcheck -mode=pcap -pt=18 -ptime=20 -strict-ts -in capture.pcap

# Add -json when the result should be archived by CI or release tooling.
go run ./cmd/g729rtpcheck -mode=pcap -pt=18 -ptime=20 -strict-ts -json -in capture.pcap

# Write a private SIP/RTP integration evidence report from a captured call.
go run ./cmd/g729rtpreport -in capture.pcap -pt=18 -ptime=20 -out report.json

# Check that a private evidence report satisfies release-local thresholds.
go run ./cmd/g729rtpreportcheck -in report.json -pt=18 -ptime=20

ptime=10, single G.729 frame per RTP packet:

m=audio 49170 RTP/AVP 18
a=rtpmap:18 G729/8000
a=fmtp:18 annexb=no
a=ptime:10
a=maxptime:10

ptime=20, two G.729 frames bundled per RTP packet (20 bytes payload):

m=audio 49170 RTP/AVP 18
a=rtpmap:18 G729/8000
a=fmtp:18 annexb=no
a=ptime:20
a=maxptime:20

annexb=no MUST be advertised — this codec does not implement Annex B SID / CNG / DTX. RTP Annex B SID/CNG frames are rejected with ErrUnsupportedAnnexB rather than decoded as speech. See docs/annex-b.md for the current policy and future implementation requirements.

The codec's intended deployment target is the server-side audio egress path of MRCP-driven TTS and IVR systems: the TTS engine produces 8 kHz int16 PCM; this module produces RTP-shaped 10-byte G.729 frames; the MRCP/SIP framework wraps them in RTP packets and sends them to the SIP endpoint.

Decoder side is provided for inbound audio (e.g. ASR ingress), loopback testing, and tooling.

Validation evidence is summarized below and detailed in docs/validation.md.

An experimental DecodeFrameEnhanced path remains available for listening diagnostics. It is non-strict and is not used as evidence for the G729/8000 annexb=no product claim.

For the full test matrix, opt-in commands, PESQ notes, and private oracle workflow, see docs/validation.md. For operational hardening, see docs/operational-hardening.md. For optional real SIP/RTP peer validation, see docs/sip-rtp-blackbox-integration.md. For release wording boundaries, see docs/claims-and-nonclaims.md. For Annex B scope, see docs/annex-b.md.

This release distinguishes decoder conformance evidence, encoder quality evidence, and standards certification:

1. Decoder final PCM exact gate passes. Fixed ITU Annex A bitstreams decoded by this package match the official reference PCM sample-for-sample in the current private verifier run. See the validation summary for the current aggregate count.
2. The decoder claim is not an ITU certification claim. ITU has not certified this implementation, and no endorsement is implied.
3. The encoder is quality-gated, not byte-exact-gated. EncoderProfileCore emits standard 10-byte G.729 frames and passes the project FFmpeg black-box outbound quality gate, but it is an independent encoder implementation and is not expected to match the ITU reference encoder or bcg729 bit-for-bit.
4. Verifier data is not redistributed. Private oracle files and reference execution CSVs are not part of the MIT-licensed source distribution and are not relicensed as MIT.
5. Annex B and other G.729 variants remain out of scope. SID/CNG/DTX (annexb=yes), G.729.1, G.729D, and G.729E are not implemented. See docs/annex-b.md.
6. DecodeFrameEnhanced is diagnostic-only. It is useful for listening experiments but is not the strict decoder path and is not used as conformance evidence.

This project maintains a clean-room constraint. No ITU reference C, bcg729, FFmpeg, Sipro, or other G.729 implementation source was used. Public specifications, black-box executable behavior, private numeric oracle outputs, and independently written tests were used. Current release claims strict decoder final-PCM sample equality against the current private ITU Annex A oracle gate; it does not claim ITU certification, ITU endorsement, or encoder byte-exact conformance. See CLEANROOM_AUDIT.md for the engineering clean-room audit record, docs/similarity-review.md for similarity claim triage, IP_PROVENANCE.md for the distribution provenance record, and THIRD_PARTY_NOTICES.md for the redistribution notice inventory.

Permitted reference materials, used during development:

• ITU-T Recommendation G.729 (06/2012), main body PDF
• ITU-T Recommendation G.729 Annex A (06/2012), PDF
• Salami, Laflamme, Adoul, Massaloux (1998), Description of ITU-T Recommendation G.729 Annex A, IEEE Transactions on Speech and Audio Processing, §V.B
• Kondoz (2004), Digital Speech, §6 (CS-ACELP)
• Chu (2003), Speech Coding Algorithms, LP analysis chapter
• Goldberg & Riek (2000), A Practical Handbook of Speech Coders
• Quackenbush, Barnwell, Clements (1988), Objective Measures of Speech Quality
• Oppenheim & Schafer, Discrete-Time Signal Processing (3rd ed.)

Forbidden sources, never consulted at any point:

• ITU C reference source files (g729a.c, cb_search.c, dec_gain.c, any other reference distribution file)
• bcg729 (Belledonne Communications)
• Sipro Lab implementations
• FFmpeg G.729 decoder (libavcodec/g729dec.c)
• Any other extant G.729 implementation

Each diagnostic and design note in docs/superpowers/diagnostics/ and docs/superpowers/plans/ carries its own per-document I1 declaration with citation list.

MIT. See LICENSE. The repository includes an engineering clean-room audit record in CLEANROOM_AUDIT.md, a provenance record in IP_PROVENANCE.md, claims guidance in docs/claims-and-nonclaims.md, and a third-party notice inventory in THIRD_PARTY_NOTICES.md.

This is the v0.2.x release line. The encoder/decoder core, RTP send-path tooling, decoder oracle workflow, WebAssembly demo assets, operational hardening checks, and release packaging pass the current project gates.

The public API (Encoder, Decoder, EncoderProfile, NewEncoder, NewEncoderWithProfile, NewDecoder, NewStreamingEncoder, NewStreamingEncoderWithProfile, EncodeFrame, DecodeFrame, Reset, Write, Flush, sentinel errors, and frame-shape constants) is intended to be stable across the v0.2.x line.

Detailed engineering plans and historical diagnostics remain in docs/superpowers/ for auditability, but they are not required reading for normal use.