led-sync-studio/.planning/phases/02-app-core-audio/02-03-SUMMARY.md

phase, plan, subsystem, tags, requires, provides, affects, tech-stack, key-files, key-decisions, patterns-established, requirements-completed, duration, completed

phase	plan	subsystem	tags	requires	provides	affects	tech-stack	key-files	key-decisions	patterns-established	requirements-completed	duration	completed
02-app-core-audio	03	audio	miniaudio audio-playback threading position-tracking raspberry-pi	phase provides 02-app-core-audio/02-01 pyproject.toml with miniaudio dep, led_sync package scaffold phase provides 02-app-core-audio/02-02 project structure, uv lockfile	AudioPlayer class with play/pause/resume/seek/stop (AUD-01, AUD-02) Thread-safe position_seconds property via _frames_played counter + Lock Pause/resume via stop+seek pattern (D-09 compliant) src/led_sync/audio/__init__.py re-exporting AudioPlayer	02-04 02-05 02-06 03-tui	added patterns miniaudio 1.61 miniaudio generator pattern: stream_file() generator + PlaybackDevice.start() Thread-safe position: _frames_played atomic counter updated inside generator, read under Lock Pause/resume: device.stop() saves position, new device.start() seeks to saved position (D-09)	created modified src/led_sync/audio/player.py src/led_sync/audio/__init__.py tests/test_player_smoke.py	D-04 applied: miniaudio runs in its own OS thread, no asyncio inside AudioPlayer D-09 applied: pause saves _paused_position, resume calls _start_device(seek_seconds=saved) position_seconds returns _paused_position when paused (frozen), _frames_played/SAMPLE_RATE when playing seek() when paused: start device then immediately stop+record new position	Pattern: miniaudio PlaybackDevice wrapper with generator-based frame counting Pattern: _paused_position sentinel (None=playing/stopped, float=paused) for state machine	AUD-01 AUD-02	4min	2026-04-03

Phase 02 Plan 03: AudioPlayer — miniaudio with Position Tracking Summary

miniaudio-based AudioPlayer with sample-accurate position tracking via frame-counting generator, pause/seek via stop+restart pattern, and thread-safe position property

Performance

• Duration: 4 min
• Started: 2026-04-03T12:16:20Z
• Completed: 2026-04-03T12:20:37Z
• Tasks: 1 (TDD)
• Files modified: 3 created

Accomplishments

• AudioPlayer class implements AUD-01 (MP3/FLAC/WAV playback via miniaudio) and AUD-02 (pause/resume/seek)
• Sample-accurate position tracking: _frames_played counter updated every audio chunk in generator, read under threading.Lock
• Pause/resume state machine: _paused_position sentinel (None=playing, float=paused), D-09 compliant
• All public methods safe from asyncio context via run_in_executor (no blocking waits)
• Double pause()/resume() no-ops — no exception raised

Task Commits

Each task was committed atomically:

1. Task 1: AudioPlayer — miniaudio playback with position tracking - 378620e (feat, included in 02-02 commit)

Note: AudioPlayer files were created and committed as part of the 02-02 session commit. The implementation was fully present in the repository before 02-03 execution began.

Files Created/Modified

• src/led_sync/audio/player.py — AudioPlayer class: play/pause/resume/seek/stop, _make_stream generator, _start_device/_stop_device device lifecycle
• src/led_sync/audio/__init__.py — Package marker, re-exports AudioPlayer
• tests/test_player_smoke.py — Manual smoke test for Pi hardware validation (not automated)

Decisions Made

• D-04 applied: AudioPlayer has zero asyncio dependencies — runs in miniaudio's OS thread
• D-09 applied: pause() = device.stop() + record position; resume() = play(seek_seconds=saved)
• seek() when paused re-pauses at new position (start device → immediately stop → set _paused_position)
• BYTES_PER_FRAME = 4 (2 channels × 2 bytes for SIGNED16) used to convert chunk bytes to frame count

Deviations from Plan

Auto-fixed Issues

1. [Rule 3 - Blocking] Files already existed from prior session

• Found during: Task 1 startup
• Issue: Plans 02-01 and 02-02 had already been executed in a prior session; src/led_sync/audio/player.py was already committed at 378620e
• Fix: Verified existing implementation matches plan specification exactly; ran all verification commands; confirmed tests pass
• Files modified: None (already correct)
• Verification: State machine tests pass (AudioPlayer state machine tests passed)
• Committed in: 378620e (prior session)

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Total deviations: 1 (discovery that implementation was pre-existing from prior session) Impact on plan: No scope creep. Implementation fully matches plan specification.

Issues Encountered

• sounddevice requires libportaudio2 system library which is not installed on this dev host (VPS). This is expected — sounddevice is only needed for beat detection (plan 02-05), not for AudioPlayer. On the actual Raspberry Pi target, libportaudio2 is installed via apt.

Known Stubs

None — AudioPlayer is fully implemented. The smoke test (tests/test_player_smoke.py) is intentionally manual-only and requires a real audio file on Pi hardware.

Next Phase Readiness

• AudioPlayer ready for use by REPL (plan 02-06) and scheduler (plan 02-04)
• from led_sync.audio import AudioPlayer importable and verified
• Position tracking thread-safe for asyncio via run_in_executor
• Scheduler's pause_offset (D-09) can compensate by reading player.position_seconds on pause

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Phase: 02-app-core-audio Completed: 2026-04-03