Split AudioEngine::start_with_gate into two backends:
* start_with_gate_cpal — non-iOS path, the existing cpal + (SDL on
Linux) flow, renamed verbatim, no
behavioural change.
* start_with_gate_ios — iOS path, constructs a single
IosVoiceUnit (VoiceProcessingIO via
coreaudio-rs) for combined mic + speaker.
Spawns the same inbound forwarder task
that pumps Opus packets into AudioHandler.
The public entry point start_with_gate dispatches at the top via
cfg(target_os = "ios") so callers stay backend-agnostic.
Struct field changes:
* _input_stream : cfg-gated to not(ios)
* _output_stream : cfg-gated to not(ios), keeps the
Linux=SdlOutput / else=cpal::Stream split
* _ios_voice_unit: new field, cfg-gated to ios, owns the VPIO
AudioUnit for the engine's lifetime.
Module-level cfg-gating:
* All cpal-only helpers (try_open_capture, build_input_stream,
build_output_stream, CaptureState + impl, ToF32 / FromF32 traits
and impls, PlaybackResampleState) are now wrapped with
#[cfg(not(target_os = "ios"))]. Same for the audiopus
encoder + cpal trait imports — iOS doesn't pull libopus into the
engine yet (commit 3 will, once the VPIO input callback wires
into CaptureState).
Behaviour on iOS for THIS commit:
* AudioEngine starts cleanly, IosVoiceUnit::start succeeds (VPIO
unit allocates + initialises + starts).
* Mic capture is dropped (the input callback is a no-op stub).
* Output emits silence (the render callback fills the buffer with
zeros).
* Inbound forwarder still runs and pushes Opus packets into
AudioHandler — they accumulate in the jitter buffer but no
fill_buffer drain happens (commit 4 fixes that), so the buffer
will grow up to MAX_BUFFER_TIME (~0.5 s) and then tsclientlib
starts dropping the oldest frames. This is fine for now — the
point of this commit is verifying the AudioUnit constructs +
starts cleanly on the device. Audible silence is the expected
state until commits 3/4 land.
Build verify (Linux host): cargo check -p chanora_audio clean in
0.53s. iOS-side compile happens on the Mac via the Xcode build
the user will trigger next.
EdisonJwa
3b1724e970