Crate flexaudio_core 

flexaudio-core — OS-independent core.

The OS-independent part of the desktop audio capture abstraction library flexaudio. Provides ring buffers, sample-rate conversion, channel mixing, 20 ms chunking, clock normalization, events, and type definitions. OS-specific capture is implemented by separate flexaudio-os-* crates that implement backend::CaptureBackend, which the facade layer wires to the core.

Fixed contract

All internal processing uses interleaved f32 / 48000 Hz / stereo 2ch / 20 ms = 960 frames/chunk. OutputFormat can change the external rate/channels (the Normalizer’s second stage resamples; e.g. 16k/1ch gives 320 frames/chunk). Output chunks remain 20 ms regardless of rate.

The public API has no callbacks. RT threads only push; consumers poll. The RT path never blocks (DROP_OLDEST / overflow drop when full). PTS comes from the device and gaps are detected.

Two-stage ring-buffer layout

[RT cb] --push--> RawRing (rtrb, RT-safe) --pop--> [ingest/process thread]
                                                      |
                                         Normalizer (mix + rubato SRC + 960-frame slicing)
                                                      |
                                                      v
                                      ChunkRing (ringbuf, DROP_OLDEST) --try_pop--> [poll]

Re-exports

pub use backend::CaptureBackend;

pub use backend::RawSink;

pub use chunk_ring::chunk_ring;

pub use chunk_ring::ChunkConsumer;

pub use chunk_ring::ChunkProducer;

pub use clock::monotonic_now_ns;

pub use clock::ClockNormalizer;

pub use normalizer::InnerProcessor;

pub use normalizer::NormalizedChunk;

pub use normalizer::Normalizer;

pub use normalizer::CHUNK_FRAMES;

pub use quant::quantize_i16;

pub use raw_ring::raw_ring;

pub use raw_ring::RawConsumer;

pub use raw_ring::RawProducer;

pub use secondary_ring::secondary_chunk_ring;

pub use secondary_ring::SecondaryChunkConsumer;

pub use secondary_ring::SecondaryChunkProducer;

pub use types::AudioChunk;

pub use types::AudioLoss;

pub use types::AudioPath;

pub use types::ChunkFlags;

pub use types::DefaultDeviceKind;

pub use types::DeviceEvent;

pub use types::DeviceInfo;

pub use types::Error;

pub use types::ErrorContext;

pub use types::ErrorGroup;

pub use types::ErrorKind;

pub use types::Event;

pub use types::LossReason;

pub use types::MixLane;

pub use types::NativeStatus;

pub use types::Operation;

pub use types::OutputFormat;

pub use types::OutputTap;

pub use types::Permission;

pub use types::ProcessInfo;

pub use types::Result;

pub use types::SecondaryChunk;

pub use types::ShutdownReport;

pub use types::SourceKind;

pub use types::StreamConfig;

pub use types::CHANNELS;

pub use types::SAMPLE_RATE;

pub use diagnostics::CaptureDiagnostics;

Modules

backend

The CaptureBackend trait implemented by OS backends, and the RawSink handle used by backends to pass raw frames to the core.

chunk_ring

SPSC ring for completed AudioChunk values, backed by ringbuf.

clock

Helpers for normalizing device PTS and monotonic clocks to shared i64 nanoseconds.

diagnostics

Allocation-free realtime rejection summaries, materialized off callback.

error_context

Typed failure context and retained shutdown outcomes.

normalizer

Normalize arbitrary device frames (any sample rate/channel count, interleaved f32) in two stages, then convert them back to the requested output format.

process_list

OS-independent post-processing for process enumeration results (ProcessInfo).

quant

Signed 16-bit PCM quantization, shared by every output path.

raw_ring

SPSC, real-time-safe ring for raw interleaved f32 device frames, backed by rtrb.

secondary_ring

SPSC ring of finished SecondaryChunks (ringbuf-backed, DROP_OLDEST).

types

Shared types: internal canonical-form constants / AudioChunk / ChunkFlags / SourceKind / OutputFormat / StreamConfig / Event / Error.