From f2963ac821a3af1c54002ba13944552166956d04 Mon Sep 17 00:00:00 2001 From: skal Date: Sat, 7 Feb 2026 16:41:30 +0100 Subject: fix(audio): Synchronize audio-visual timing with playback time MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Problem: test_demo was "flashing a lot" - visual effects triggered ~400ms before audio was heard, causing poor synchronization. Root Causes: 1. Beat calculation used physical time (platform_state.time), but audio peak measured at playback time (400ms behind due to ring buffer) 2. Peak decay too slow (0.7 per callback = 800ms fade) relative to beat interval (500ms at 120 BPM) Solution: 1. Use audio_get_playback_time() for beat calculation - Automatically accounts for ring buffer latency - No hardcoded constants (was considering hardcoding 400ms offset) - System queries its own state 2. Faster decay rate (0.5 vs 0.7) to match beat interval 3. Added inline PeakMeterEffect for visual debugging Changes: - src/test_demo.cc: - Added inline PeakMeterEffect class (red bar visualization) - Use audio_get_playback_time() instead of physical time for beat calc - Updated logging to show audio time - src/audio/backend/miniaudio_backend.cc: - Changed decay rate from 0.7 to 0.5 (500ms fade time) - src/gpu/gpu.{h,cc}: - Added gpu_add_custom_effect() API for runtime effect injection - Exposed g_device, g_queue, g_format as non-static globals - doc/PEAK_METER_DEBUG.md: - Initial analysis of timing issues - doc/AUDIO_TIMING_ARCHITECTURE.md: - Comprehensive architecture documentation - Time source hierarchy (physical → audio playback → music) - Future work: TimeProvider class, tracker_get_bpm() API Architectural Principle: Single source of truth - platform_get_time() is the only physical clock. Everything else derives from it. No hardcoded latency constants. Result: Visual effects now sync perfectly with heard audio. --- src/gpu/gpu.cc | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) (limited to 'src/gpu/gpu.cc') diff --git a/src/gpu/gpu.cc b/src/gpu/gpu.cc index 45f0f34..63a30ff 100644 --- a/src/gpu/gpu.cc +++ b/src/gpu/gpu.cc @@ -21,10 +21,11 @@ static WGPUInstance g_instance = nullptr; static WGPUAdapter g_adapter = nullptr; -static WGPUDevice g_device = nullptr; -static WGPUQueue g_queue = nullptr; +WGPUDevice g_device = nullptr; // Non-static for external access (debug builds) +WGPUQueue g_queue = nullptr; // Non-static for external access (debug builds) static WGPUSurface g_surface = nullptr; static WGPUSurfaceConfiguration g_config = {}; +WGPUTextureFormat g_format = WGPUTextureFormat_BGRA8Unorm; // Exposed for custom effects static MainSequence g_main_sequence; @@ -354,6 +355,7 @@ void gpu_init(PlatformState* platform_state) { g_config.device = g_device; g_config.format = swap_chain_format; + g_format = swap_chain_format; // Update global format for external access g_config.usage = WGPUTextureUsage_RenderAttachment; g_config.width = platform_state->width; g_config.height = platform_state->height; @@ -386,6 +388,13 @@ void gpu_resize(int width, int height) { void gpu_simulate_until(float time) { g_main_sequence.simulate_until(time, 1.0f / 60.0f); } + +void gpu_add_custom_effect(Effect* effect, float start_time, float end_time, int priority) { + auto seq = std::make_shared(); + seq->add_effect(std::shared_ptr(effect), start_time, end_time, priority); + seq->init(&g_main_sequence); + g_main_sequence.add_sequence(seq, 0.0f, priority); +} #endif /* !defined(STRIP_ALL) */ void gpu_shutdown() { -- cgit v1.2.3