Rocky
d656bac8c3
Unify Bailian/Volcengine/OpenAI realtime streaming, ABE polish routing with fun styles, and a shared card-page Settings hierarchy; bump to 1.1 (build 32).
773 lines
30 KiB
Swift
773 lines
30 KiB
Swift
// FlowContinuousCapture.swift
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// OSGKeyboard · Shared
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//
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// TypeWhisper-style continuous mic capture for Flow sessions: one
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// AVAudioEngine + input tap for the entire session. Utterances gate
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// whether buffers are forwarded to ASR; levels are always computed on
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// the audio thread and read from the main thread (never UserDefaults
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// from the realtime tap — that caused cross-process crashes).
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import Foundation
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import AVFoundation
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import os
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private enum FlowCaptureConstants {
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static let levelBarCount = 24
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static let targetSampleRate: Double = 16_000
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static let drainPollIntervalNs: UInt64 = 20_000_000
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}
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private enum UtteranceGatePhase: Equatable {
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case idle
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case recording
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case draining
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}
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/// Thread-safe relay for utterance-scoped ASR snapshots.
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private final class FlowCaptureStreamRelay: @unchecked Sendable {
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private let lock = OSAllocatedUnfairLock()
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private var continuation: AsyncStream<AudioBufferSnapshot>.Continuation?
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func bind(_ continuation: AsyncStream<AudioBufferSnapshot>.Continuation) {
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lock.withLock { self.continuation = continuation }
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}
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func replay(_ snapshots: [AudioBufferSnapshot]) {
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lock.withLock {
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for snapshot in snapshots {
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continuation?.yield(snapshot)
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}
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}
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}
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func yield(_ snapshot: AudioBufferSnapshot) {
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_ = lock.withLock { continuation?.yield(snapshot) }
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}
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func finish() {
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lock.withLock {
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continuation?.finish()
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continuation = nil
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}
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}
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}
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/// Rolling pre-roll while utterance gate is closed.
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///
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/// Sized by sample count (~3 s @ 16 kHz) so PiP mic spin-up between
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/// `capture.start()` and `beginUtterance` does not discard the user's
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/// opening words (the old 6-buffer cap was only ~400 ms).
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private final class FlowPrerollStore: @unchecked Sendable {
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private let lock = OSAllocatedUnfairLock()
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private var snapshots: [AudioBufferSnapshot] = []
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private let maxSamples: Int
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init(maxSamples: Int = 48_000) {
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self.maxSamples = maxSamples
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}
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func append(_ snapshot: AudioBufferSnapshot) {
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lock.withLock {
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snapshots.append(snapshot)
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var total = snapshots.reduce(0) { $0 + $1.samples.count }
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while total > maxSamples, !snapshots.isEmpty {
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let removed = snapshots.removeFirst()
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total -= removed.samples.count
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}
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}
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}
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func drain() -> [AudioBufferSnapshot] {
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lock.withLock {
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let drained = snapshots
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snapshots.removeAll()
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return drained
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}
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}
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}
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/// Rolling bar levels updated from the audio tap; read on the main actor.
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private final class FlowLevelStore: @unchecked Sendable {
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private let lock = OSAllocatedUnfairLock()
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private var levels: [Float]
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init(barCount: Int) {
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levels = Array(repeating: 0, count: barCount)
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}
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func update(from buffer: AVAudioPCMBuffer, barCount: Int) {
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let computed = Self.calculateLevels(from: buffer, barCount: barCount)
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lock.withLock { levels = computed }
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}
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func snapshot() -> [Float] {
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lock.withLock { levels }
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}
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private static func calculateLevels(from buffer: AVAudioPCMBuffer, barCount: Int) -> [Float] {
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guard let channelData = buffer.floatChannelData else {
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return Array(repeating: 0, count: barCount)
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}
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let frameLength = Int(buffer.frameLength)
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guard frameLength > 0 else {
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return Array(repeating: 0, count: barCount)
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}
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let samplesPerBar = max(frameLength / barCount, 1)
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var result = [Float]()
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result.reserveCapacity(barCount)
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for barIndex in 0..<barCount {
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let start = barIndex * samplesPerBar
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let end = min(start + samplesPerBar, frameLength)
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var sum: Float = 0
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for i in start..<end {
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sum += abs(channelData[0][i])
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}
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let avg = sum / Float(max(end - start, 1))
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result.append(min(avg * 50, 1))
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}
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return result
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}
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}
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/// Last observed audio tap timestamp. This lets the host publish "ready"
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/// only after the microphone pipeline has produced real frames.
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private final class FlowAudioProofStore: @unchecked Sendable {
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private let lock = OSAllocatedUnfairLock(initialState: TimeInterval(0))
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func markFrameReceived() {
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lock.withLock { $0 = Date().timeIntervalSince1970 }
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}
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func reset() {
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lock.withLock { $0 = 0 }
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}
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func hasRecentFrame(maxAge: TimeInterval) -> Bool {
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let timestamp = lock.withLock { $0 }
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guard timestamp > 0 else { return false }
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return Date().timeIntervalSince1970 - timestamp <= maxAge
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}
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}
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/// Route-adaptive downsampling converter, safe to call from the realtime tap.
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///
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/// `AVAudioEngine.installTap(format:)` traps with an **uncatchable** NSException
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/// when the format passed to it does not match the input node's *live* format.
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/// After an audio-route change — which the on-device `SpeechAnalyzer` triggers
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/// during warmup by reconfiguring the shared `AVAudioSession` — the value
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/// returned by `inputNode.outputFormat(forBus:)` can lag behind the real
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/// hardware rate (e.g. it reports 48 kHz while the node has already switched to
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/// 24 kHz). Installing a tap with that stale explicit format crashes the whole
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/// app (`Failed to create tap due to format mismatch`).
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///
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/// We therefore install the tap with `format: nil` (which always uses the
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/// node's live format) and rebuild the sample-rate converter *here* whenever the
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/// incoming buffer's format actually changes, so downsampling to the ASR target
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/// rate is always valid regardless of route churn.
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private final class AdaptiveDownsampler: @unchecked Sendable {
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// `AVAudioConverter` / `AVAudioFormat` / `AVAudioPCMBuffer` are not
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// `Sendable`, so the state is guarded manually via the unchecked lock
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// APIs. The scratch output buffer is REUSED across tap callbacks —
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// allocating on the realtime audio thread risks priority inversion, and
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// taps on one bus are serialized, so a single scratch is safe as long as
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// callers copy its contents out before returning (AudioBufferSnapshot
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// does exactly that).
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private struct State {
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var converter: AVAudioConverter
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var source: AVAudioFormat
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var scratch: AVAudioPCMBuffer
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}
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private let lock = OSAllocatedUnfairLock<State?>(uncheckedState: nil)
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let targetFormat: AVAudioFormat
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/// Frame headroom for the reusable output buffer. Taps deliver ≤4096
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/// input frames; output frames = input × (16k / hardwareRate), which
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/// exceeds input only for sub-16 kHz hardware (rare telephony routes),
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/// so 2× the tap size covers every realistic ratio.
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private static let scratchCapacity: AVAudioFrameCount = 8_192
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init(targetFormat: AVAudioFormat) {
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self.targetFormat = targetFormat
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}
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/// Downsamples `buffer` into the reusable scratch buffer and returns it,
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/// rebuilding the converter lazily when the hardware route (and thus the
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/// source format) changes. The returned buffer is only valid until the
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/// next call — copy its samples out synchronously.
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func convertReusingScratch(_ buffer: AVAudioPCMBuffer) -> AVAudioPCMBuffer? {
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let sourceFormat = buffer.format
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guard sourceFormat.sampleRate > 0 else { return nil }
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return lock.withLockUnchecked { state -> AVAudioPCMBuffer? in
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if state == nil || state!.source != sourceFormat {
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guard let converter = AVAudioConverter(from: sourceFormat, to: targetFormat),
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let scratch = AVAudioPCMBuffer(
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pcmFormat: targetFormat,
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frameCapacity: Self.scratchCapacity
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) else {
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state = nil
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return nil
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}
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state = State(converter: converter, source: sourceFormat, scratch: scratch)
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}
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guard let current = state else { return nil }
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let wanted = AVAudioFrameCount(
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Double(buffer.frameLength) * targetFormat.sampleRate / sourceFormat.sampleRate
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)
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guard wanted > 0, wanted <= current.scratch.frameCapacity else { return nil }
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current.scratch.frameLength = 0
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// ONE-SHOT input: the converter keeps pulling until the output
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// buffer's frameCapacity is full, and the scratch is deliberately
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// oversized — feeding the same tap buffer on every pull would
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// duplicate the audio ~6× (stuttering ASR input). After the
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// single feed we report "ran dry", so the expected status is
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// `.inputRanDry` (output not full), not `.haveData`.
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let provided = OSAllocatedUnfairLock(initialState: false)
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var error: NSError?
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let status = current.converter.convert(to: current.scratch, error: &error) { _, outStatus in
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if provided.withLock({ $0 }) {
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outStatus.pointee = .noDataNow
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return nil
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}
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provided.withLock { $0 = true }
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outStatus.pointee = .haveData
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return buffer
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}
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guard status != .error, error == nil, current.scratch.frameLength > 0 else { return nil }
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return current.scratch
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}
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}
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}
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@MainActor
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public final class FlowContinuousCapture {
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public enum StartError: LocalizedError {
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case invalidHardwareFormat(sampleRate: Double, channels: Int)
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case formatCreateFailed
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case converterCreateFailed
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case engineStartFailed(String)
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case audioSessionFailed(String)
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public var errorDescription: String? {
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switch self {
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case .invalidHardwareFormat(let sr, let ch):
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return String.localizedStringWithFormat(
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NSLocalizedString("preview.error.micUnavailable", comment: ""),
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sr,
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ch
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)
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case .formatCreateFailed:
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return NSLocalizedString("preview.error.formatCreate", comment: "")
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case .converterCreateFailed:
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return NSLocalizedString("preview.error.converterCreate", comment: "")
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case .engineStartFailed(let detail):
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return String.localizedStringWithFormat(
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NSLocalizedString("preview.error.engineStart", comment: ""),
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detail
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)
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case .audioSessionFailed(let detail):
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return String.localizedStringWithFormat(
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NSLocalizedString("preview.error.audioSession", comment: ""),
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detail
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)
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}
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}
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}
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public static let levelBarCount = FlowCaptureConstants.levelBarCount
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private let audioEngine = AVAudioEngine()
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private let streamRelay = FlowCaptureStreamRelay()
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private let prerollStore = FlowPrerollStore()
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private let levelStore = FlowLevelStore(barCount: FlowCaptureConstants.levelBarCount)
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private let audioProofStore = FlowAudioProofStore()
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private let gate = OSAllocatedUnfairLock(initialState: UtteranceGatePhase.idle)
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private let drainTracker = FlowCaptureDrainTracker()
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private let tailSampleCounter = OSAllocatedUnfairLock(initialState: 0)
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private let utterancePCMStore = FlowUtterancePCMStore(
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maxSampleCount: Int(FlowSessionKeys.maxUtteranceDuration) * 16_000
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)
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private var downsampler: AdaptiveDownsampler?
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private var targetFormat: AVAudioFormat?
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private var hwFormat: AVAudioFormat?
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private var drainPolicy = FlowCaptureTailDrainPolicy.flowDefault
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private var didInstallTap = false
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private var isRunning = false
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private var isRebuilding = false
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private var interrupted = false
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/// When the engine last (re)activated — a freshly started engine has
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/// produced no frames yet and must not be misclassified as a zombie.
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private var lastActivationAt = Date.distantPast
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private var routeObserver: NSObjectProtocol?
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private var interruptionObserver: NSObjectProtocol?
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private var mediaResetObserver: NSObjectProtocol?
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private let log = Logger(subsystem: "com.osgkeyboard.shared", category: "FlowCapture")
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public init() {}
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public var running: Bool { isRunning }
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/// True between interruption `.began` and `.ended` (phone call, Siri).
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/// While set, `setActive(true)` is guaranteed to fail — owners should
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/// wait for `.ended` (which rebuilds the engine) instead of retrying.
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public var isInterrupted: Bool { interrupted }
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/// True when the capture session flag, tap, and audio engine are all live.
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public var engineIsLive: Bool {
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isRunning && didInstallTap && audioEngine.isRunning
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}
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/// True only when the engine is live and the input tap has recently
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/// delivered an actual audio frame.
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public func engineHasRecentAudio(maxAge: TimeInterval = 1) -> Bool {
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engineIsLive && audioProofStore.hasRecentFrame(maxAge: maxAge)
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}
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/// Called on the main actor when `engineIsLive` may have changed.
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public var onEngineLiveChanged: ((Bool) -> Void)?
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/// Called on the main actor when the system interrupted capture (phone
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/// call, Siri). The session owner should fail any mic-open utterance —
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/// audio frames stop arriving, so continuing to "record" only captures
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/// a silence gap the user cannot see.
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public var onInterruptionBegan: (() -> Void)?
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/// Configure `.playAndRecord`, install a permanent input tap, start the engine.
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///
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/// Idempotent: "already running and healthy" is a warm-start fast path,
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/// while "already running but producing no audio" is a zombie state
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/// (force-quit relaunch, failed cold start, mediaserverd reset) that is
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/// torn down and rebuilt in place. It must never be a silent no-op —
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/// a `guard !isRunning` early-return here turned every cold-start retry
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/// into a guaranteed audio-proof timeout.
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public func start() throws {
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if isRunning {
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let startedMomentsAgo = Date().timeIntervalSince(lastActivationAt) < 2
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if engineIsLive && (engineHasRecentAudio(maxAge: 2) || startedMomentsAgo) {
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// Healthy warm engine — or one so fresh it simply hasn't
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// produced its first frame yet (interleaved start attempts
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// land here; rebuilding a 100 ms-old engine only multiplies
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// audio-session churn in the fragile post-relaunch window).
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return
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}
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log.info("start(): zombie engine detected (running but no live audio) — forcing rebuild")
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stop()
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}
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audioProofStore.reset()
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try activateEngine()
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isRunning = true
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installSessionObservers()
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notifyEngineLiveChanged()
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}
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/// Bring up the audio session + engine for the *current* hardware route.
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/// Reused for route-change / interruption recovery, so it always rebuilds
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/// the tap against the live hardware format (which changes when the user
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/// plugs in AirPods or a wired headset mid-session).
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private func activateEngine() throws {
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let session = AVAudioSession.sharedInstance()
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do {
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try session.setCategory(
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.playAndRecord,
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mode: .measurement,
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options: [.defaultToSpeaker, .allowBluetoothHFP, .mixWithOthers]
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)
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try session.setActive(true, options: .notifyOthersOnDeactivation)
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} catch {
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throw StartError.audioSessionFailed(error.localizedDescription)
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}
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let inputNode = audioEngine.inputNode
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let hardwareFormat = inputNode.outputFormat(forBus: 0)
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guard hardwareFormat.sampleRate > 0, hardwareFormat.channelCount > 0 else {
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throw StartError.invalidHardwareFormat(
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sampleRate: hardwareFormat.sampleRate,
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channels: Int(hardwareFormat.channelCount)
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)
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}
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guard let resolvedTargetFormat = AVAudioFormat(
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commonFormat: .pcmFormatFloat32,
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sampleRate: FlowCaptureConstants.targetSampleRate,
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channels: 1,
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interleaved: false
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) else {
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throw StartError.formatCreateFailed
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}
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// Route-adaptive converter: it rebuilds itself from the live buffer
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// format inside the tap, so it never assumes a fixed hardware rate.
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let downsampler = AdaptiveDownsampler(targetFormat: resolvedTargetFormat)
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self.downsampler = downsampler
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targetFormat = resolvedTargetFormat
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hwFormat = hardwareFormat
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// Rebuild the tap so its bound hardware format matches the new route.
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if didInstallTap {
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inputNode.removeTap(onBus: 0)
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didInstallTap = false
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}
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let gateLock = gate
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let relay = streamRelay
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let preroll = prerollStore
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let levels = levelStore
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let proof = audioProofStore
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let tracker = drainTracker
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let tailCounter = tailSampleCounter
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let pcmStore = utterancePCMStore
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let policy = drainPolicy
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let tap = Self.makeAudioTapBlock(
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downsampler: downsampler,
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gate: gateLock,
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levelStore: levels,
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audioProofStore: proof,
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prerollStore: preroll,
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streamRelay: relay,
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drainTracker: tracker,
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tailSampleCounter: tailCounter,
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utterancePCMStore: pcmStore,
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drainPolicy: policy
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)
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// `format: nil` binds the tap to the input node's *live* format. Passing
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// an explicit (possibly stale) format here is what crashed the app on a
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// route change (48 kHz client vs 24 kHz hardware); nil can never mismatch.
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inputNode.installTap(onBus: 0, bufferSize: 4096, format: nil, block: tap)
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didInstallTap = true
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audioEngine.prepare()
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do {
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try audioEngine.start()
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} catch {
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throw StartError.engineStartFailed(error.localizedDescription)
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}
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lastActivationAt = Date()
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}
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/// Tear down the engine and release the audio session.
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public func stop() {
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removeSessionObservers()
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gate.withLock { $0 = .idle }
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drainTracker.reset()
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tailSampleCounter.withLock { $0 = 0 }
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streamRelay.finish()
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if didInstallTap {
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audioEngine.inputNode.removeTap(onBus: 0)
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didInstallTap = false
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}
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if audioEngine.isRunning {
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audioEngine.stop()
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}
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isRunning = false
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interrupted = false
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audioProofStore.reset()
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downsampler = nil
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targetFormat = nil
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hwFormat = nil
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try? AVAudioSession.sharedInstance().setActive(
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false,
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options: .notifyOthersOnDeactivation
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)
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notifyEngineLiveChanged()
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}
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/// Re-activate capture after returning from background without
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/// reinstalling the tap (iOS may deactivate the audio session).
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///
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/// Doubles as the interruption-recovery probe: `setActive(true)` FAILS
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/// while a call/Siri interruption is live and succeeds once it ends, so a
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/// successful reassert proves the interruption is over. iOS does not
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/// guarantee delivery of `.ended` (commonly dropped when the app was
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/// suspended during the call), so this is the only reliable way to clear
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/// the `interrupted` latch in that case.
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@discardableResult
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public func reassertIfRunning() -> Bool {
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guard isRunning else { return false }
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let session = AVAudioSession.sharedInstance()
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do {
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try session.setCategory(
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.playAndRecord,
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mode: .measurement,
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options: [.defaultToSpeaker, .allowBluetoothHFP, .mixWithOthers]
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)
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try session.setActive(true, options: .notifyOthersOnDeactivation)
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interrupted = false
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if !audioEngine.isRunning {
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try audioEngine.start()
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}
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notifyEngineLiveChanged()
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return engineIsLive
|
||
} catch {
|
||
notifyEngineLiveChanged()
|
||
return false
|
||
}
|
||
}
|
||
|
||
public func awaitAudioFlowing(
|
||
timeout: TimeInterval,
|
||
recentFrameMaxAge: TimeInterval = 1
|
||
) async -> Bool {
|
||
let deadline = Date().addingTimeInterval(timeout)
|
||
while Date() < deadline {
|
||
if engineHasRecentAudio(maxAge: recentFrameMaxAge) {
|
||
return true
|
||
}
|
||
do {
|
||
try await Task.sleep(nanoseconds: 50_000_000)
|
||
} catch {
|
||
// Cancelled — bail out instead of busy-spinning the main
|
||
// actor for the rest of the window (a cancelled Task.sleep
|
||
// returns immediately, starving concurrent start attempts).
|
||
return false
|
||
}
|
||
}
|
||
return engineHasRecentAudio(maxAge: recentFrameMaxAge)
|
||
}
|
||
|
||
// MARK: - Route / interruption recovery
|
||
|
||
private func installSessionObservers() {
|
||
let center = NotificationCenter.default
|
||
if routeObserver == nil {
|
||
routeObserver = center.addObserver(
|
||
forName: AVAudioSession.routeChangeNotification,
|
||
object: nil,
|
||
queue: .main
|
||
) { [weak self] note in
|
||
let reasonRaw = note.userInfo?[AVAudioSessionRouteChangeReasonKey] as? UInt
|
||
MainActor.assumeIsolated { self?.handleRouteChange(reasonRaw: reasonRaw) }
|
||
}
|
||
}
|
||
if interruptionObserver == nil {
|
||
interruptionObserver = center.addObserver(
|
||
forName: AVAudioSession.interruptionNotification,
|
||
object: nil,
|
||
queue: .main
|
||
) { [weak self] note in
|
||
let typeRaw = note.userInfo?[AVAudioSessionInterruptionTypeKey] as? UInt
|
||
let optionsRaw = note.userInfo?[AVAudioSessionInterruptionOptionKey] as? UInt
|
||
MainActor.assumeIsolated {
|
||
self?.handleInterruption(typeRaw: typeRaw, optionsRaw: optionsRaw)
|
||
}
|
||
}
|
||
}
|
||
// Apple QA1749: when the system media server resets, the engine,
|
||
// converter and audio session all become orphaned and must be
|
||
// rebuilt from scratch — otherwise capture silently produces no
|
||
// audio (another cause of "waveform moves but ASR is empty").
|
||
if mediaResetObserver == nil {
|
||
mediaResetObserver = center.addObserver(
|
||
forName: AVAudioSession.mediaServicesWereResetNotification,
|
||
object: nil,
|
||
queue: .main
|
||
) { [weak self] _ in
|
||
MainActor.assumeIsolated { self?.handleMediaServicesReset() }
|
||
}
|
||
}
|
||
}
|
||
|
||
private func removeSessionObservers() {
|
||
let center = NotificationCenter.default
|
||
if let routeObserver { center.removeObserver(routeObserver) }
|
||
if let interruptionObserver { center.removeObserver(interruptionObserver) }
|
||
if let mediaResetObserver { center.removeObserver(mediaResetObserver) }
|
||
routeObserver = nil
|
||
interruptionObserver = nil
|
||
mediaResetObserver = nil
|
||
}
|
||
|
||
private func handleMediaServicesReset() {
|
||
guard isRunning else { return }
|
||
log.info("Media services were reset — rebuilding engine and converter")
|
||
rebuildEngine()
|
||
}
|
||
|
||
private func handleRouteChange(reasonRaw: UInt?) {
|
||
guard isRunning else { return }
|
||
guard let reasonRaw,
|
||
let reason = AVAudioSession.RouteChangeReason(rawValue: reasonRaw) else { return }
|
||
switch reason {
|
||
case .oldDeviceUnavailable, .newDeviceAvailable:
|
||
log.info("Audio route changed (\(reasonRaw, privacy: .public)) — rebuilding engine")
|
||
rebuildEngine()
|
||
default:
|
||
break
|
||
}
|
||
}
|
||
|
||
private func handleInterruption(typeRaw: UInt?, optionsRaw: UInt?) {
|
||
guard let typeRaw,
|
||
let type = AVAudioSession.InterruptionType(rawValue: typeRaw) else { return }
|
||
switch type {
|
||
case .began:
|
||
log.info("Audio interruption began")
|
||
interrupted = true
|
||
notifyEngineLiveChanged()
|
||
onInterruptionBegan?()
|
||
case .ended:
|
||
interrupted = false
|
||
guard isRunning else { return }
|
||
let shouldResume: Bool
|
||
if let optionsRaw {
|
||
shouldResume = AVAudioSession.InterruptionOptions(rawValue: optionsRaw).contains(.shouldResume)
|
||
} else {
|
||
shouldResume = true
|
||
}
|
||
if shouldResume {
|
||
log.info("Audio interruption ended — resuming capture")
|
||
rebuildEngine()
|
||
}
|
||
@unknown default:
|
||
break
|
||
}
|
||
}
|
||
|
||
/// Stop and rebuild the engine against the current route, keeping
|
||
/// `isRunning` intact so the session survives the swap transparently.
|
||
private func rebuildEngine() {
|
||
guard isRunning, !isRebuilding else { return }
|
||
isRebuilding = true
|
||
defer { isRebuilding = false }
|
||
if audioEngine.isRunning {
|
||
audioEngine.stop()
|
||
}
|
||
do {
|
||
try activateEngine()
|
||
notifyEngineLiveChanged()
|
||
} catch {
|
||
log.error("Engine rebuild failed: \(error.localizedDescription, privacy: .public)")
|
||
notifyEngineLiveChanged()
|
||
}
|
||
}
|
||
|
||
private func notifyEngineLiveChanged() {
|
||
onEngineLiveChanged?(engineIsLive)
|
||
}
|
||
|
||
/// Begin forwarding downsampled buffers to ASR for one utterance.
|
||
public func beginUtterance() -> AsyncStream<AudioBufferSnapshot> {
|
||
let (stream, continuation) = AsyncStream<AudioBufferSnapshot>.makeStream()
|
||
drainTracker.reset()
|
||
tailSampleCounter.withLock { $0 = 0 }
|
||
utterancePCMStore.reset()
|
||
// Bind the consumer before opening the gate so early tap frames
|
||
// are not dropped on the floor.
|
||
streamRelay.bind(continuation)
|
||
streamRelay.replay(prerollStore.drain())
|
||
gate.withLock { $0 = .recording }
|
||
return stream
|
||
}
|
||
|
||
/// Drain trailing PCM after the user stops, then finish the ASR stream.
|
||
public func endUtteranceAndDrain(
|
||
policy: FlowCaptureTailDrainPolicy = .flowDefault
|
||
) async -> FlowCaptureDrainReport {
|
||
let currentPhase = gate.withLock { $0 }
|
||
guard currentPhase == .recording else {
|
||
return .skipped
|
||
}
|
||
|
||
drainPolicy = policy
|
||
gate.withLock { $0 = .draining }
|
||
drainTracker.beginDrain()
|
||
|
||
let timing = await FlowUtteranceEndCoordinator.awaitTailCapture(
|
||
tracker: drainTracker,
|
||
policy: policy,
|
||
pollIntervalNs: FlowCaptureConstants.drainPollIntervalNs
|
||
)
|
||
|
||
// NOTE: We intentionally do NOT signal `.endOfStream` to the shared
|
||
// downsampling converter here. `AVAudioConverter` is stateful: once its
|
||
// input block returns `.endOfStream`, the converter is permanently
|
||
// finished and every subsequent `.haveData` conversion (from the live
|
||
// tap) returns no data — which silently starved every utterance after
|
||
// the first (Apple docs + AVAudioConverter reuse guidance). Trailing
|
||
// speech is already preserved by the live `.draining` forwarding loop
|
||
// above; the converter's sub-millisecond internal filter tail is not
|
||
// worth poisoning a session-long converter for.
|
||
streamRelay.finish()
|
||
gate.withLock { $0 = .idle }
|
||
|
||
let tailSamples = tailSampleCounter.withLock { $0 }
|
||
let report = FlowCaptureDrainReport(
|
||
drainDurationSeconds: drainTracker.elapsedSeconds(),
|
||
endedBySilence: timing.endedBySilence,
|
||
tailSampleCount: tailSamples,
|
||
postRollDurationSeconds: timing.postRollDurationSeconds
|
||
)
|
||
drainTracker.reset()
|
||
tailSampleCounter.withLock { $0 = 0 }
|
||
FlowPipelineDiagnostics.logDrain(report)
|
||
return report
|
||
}
|
||
|
||
/// Returns the utterance PCM accumulated during the last recording cycle.
|
||
public func consumeUtteranceSamples() -> [Float] {
|
||
utterancePCMStore.consume()
|
||
}
|
||
|
||
/// Immediate stop without tail drain (abort / session teardown).
|
||
public func cancelUtterance() {
|
||
gate.withLock { $0 = .idle }
|
||
drainTracker.reset()
|
||
tailSampleCounter.withLock { $0 = 0 }
|
||
utterancePCMStore.reset()
|
||
streamRelay.finish()
|
||
}
|
||
|
||
public func currentAudioLevels() -> [Float] {
|
||
levelStore.snapshot()
|
||
}
|
||
|
||
// MARK: - Audio tap (nonisolated — runs on realtime thread)
|
||
|
||
private nonisolated static func makeAudioTapBlock(
|
||
downsampler: AdaptiveDownsampler,
|
||
gate: OSAllocatedUnfairLock<UtteranceGatePhase>,
|
||
levelStore: FlowLevelStore,
|
||
audioProofStore: FlowAudioProofStore,
|
||
prerollStore: FlowPrerollStore,
|
||
streamRelay: FlowCaptureStreamRelay,
|
||
drainTracker: FlowCaptureDrainTracker,
|
||
tailSampleCounter: OSAllocatedUnfairLock<Int>,
|
||
utterancePCMStore: FlowUtterancePCMStore,
|
||
drainPolicy: FlowCaptureTailDrainPolicy
|
||
) -> @Sendable (AVAudioPCMBuffer, AVAudioTime) -> Void {
|
||
return { buffer, _ in
|
||
audioProofStore.markFrameReceived()
|
||
levelStore.update(from: buffer, barCount: FlowCaptureConstants.levelBarCount)
|
||
|
||
// The downsampler derives its converter from the *live* buffer
|
||
// format (mid-session route changes handled transparently) and
|
||
// returns a REUSED scratch buffer — no per-callback allocation
|
||
// on the realtime thread. The snapshot below copies the samples
|
||
// out before the next tap callback can overwrite the scratch.
|
||
guard let outBuffer = downsampler.convertReusingScratch(buffer) else { return }
|
||
|
||
let snapshot = AudioBufferSnapshot(buffer: outBuffer)
|
||
guard !snapshot.samples.isEmpty else { return }
|
||
|
||
let phase = gate.withLock { $0 }
|
||
switch phase {
|
||
case .recording, .draining:
|
||
utterancePCMStore.append(snapshot.samples)
|
||
streamRelay.yield(snapshot)
|
||
if phase == .draining {
|
||
drainTracker.noteAudio(samples: snapshot.samples, policy: drainPolicy)
|
||
tailSampleCounter.withLock { $0 += snapshot.samples.count }
|
||
}
|
||
case .idle:
|
||
prerollStore.append(snapshot)
|
||
}
|
||
}
|
||
}
|
||
}
|