Crate blip25_mbe 

blip25-mbe

A clean-room implementation of the MBE vocoder family.

Quick start

Most consumers should use the chip-shaped vocoder::Vocoder façade:

use blip25_mbe::vocoder::{Rate, Vocoder};

// Open a P25 Phase 1 (full-rate IMBE) channel.
let mut tx = Vocoder::new(Rate::Imbe7200x4400);
let pcm: [i16; 160] = [0; 160];
let bits = tx.encode_pcm(&pcm).unwrap();
assert_eq!(bits.len(), 18);

let mut rx = Vocoder::new(Rate::Imbe7200x4400);
let out = rx.decode_bits(&bits).unwrap();
assert_eq!(out.len(), 160);

Three streaming variants on top of the per-frame primitive:

• vocoder::Vocoder::encode_stream / vocoder::Vocoder::decode_stream — slice → Iterator<Item = Result<…>>, drops trailing partial frames.
• vocoder::LiveEncoder / vocoder::LiveDecoder — chunk-driven with internal residue buffer for audio-callback / socket use.
• vocoder::VocoderBuilder — fluent configuration of optional knobs (tone detection, beyond-spec repeat reset).

See vocoder for the full API and INTEGRATION.md for the AMBE-3000R protocol → Vocoder operation correspondence.

Module organization

See DESIGN.md at the repository root for the architectural model. The public API is organized around four orthogonal axes joined at a common parameter type:

• vocoder — chip-shaped façade. Recommended entry point.
• mbe_params — the parameter model. The interchange type and the center of gravity of the crate.
• codecs — analysis and synthesis algorithms, one submodule per codec generation (mbe_baseline, ambe, ambe_plus, ambe_plus2).
• Wire formats, one module per protocol-rate combination: imbe_wire (P25 Phase 1 IMBE, 144-bit), ambe_plus2_wire (P25 Phase 2 AMBE+2, 72-bit), and dvsi_3000 (DVSI chip protocol, r0..r63). Future protocols (DMR, D-STAR, NXDN, …) become sibling modules.
• rate_conversion — parameter-domain bits-to-bits conversion, a peer of the codec and wire layers, not a sub-concern of either.

Primitives shared across layers live in fec and bits.

Cargo features

• serde (off by default) — derive Serialize / Deserialize on the diagnostic types in vocoder (Rate, FrameStats, AnalysisStats, AnalysisOutputKind, DecodeStats) plus mbe_params::MbeParams and codecs::mbe_baseline::FrameDisposition. Useful for shipping stats / params over a future RPC layer (gRPC / protobuf / WS) without hand-rolled converters.

Modules

ambe_plus2_wire

P25 Phase 2 TDMA half-rate vocoder wire format.

bits

Bit-packing and bit-slicing primitives shared across wire formats.

codecs

Codec generations: analysis (PCM → MbeParams) and synthesis (MbeParams → PCM).

dvsi_3000

DVSI AMBE-3000 chip protocol — 64 rate configurations (r0..r63).

enhancement

Post-decoder PCM enhancement — optional classical DSP filter chain applied to decoded PCM before it leaves the crate::vocoder::Vocoder.

fec

Forward-error-correction primitives shared across wire formats.

imbe_wire

P25 Phase 1 FDMA full-rate vocoder wire format.

mbe_params

The MBE parameter model — the crate’s interchange type.

rate_conversion

Parametric rate conversion — the bits-to-bits operation in parameter space.

vocoder

Unified Vocoder handle — chip-shaped façade over the rate-specific pipelines.