docs(02): capture phase context

2026-03-26 11:19:39 +01:00
parent b1fbae0a23
commit 339c03c4eb
2 changed files with 305 additions and 0 deletions
@@ -0,0 +1,192 @@
+# Phase 2: Audio Synthesis Engine - Discussion Log
+
+> **Audit trail only.** Do not use as input to planning, research, or execution agents.
+> Decisions are captured in CONTEXT.md — this log preserves the alternatives considered.
+
+**Date:** 2026-03-26
+**Phase:** 02-audio-synthesis-engine
+**Areas discussed:** Tone mapping, Waveform texture, Amplitude dynamics, Mixing & headroom
+
+---
+
+## Tone Mapping
+
+### Frequency range
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Narrow ambient (80-400 Hz) | Deep, bass-heavy drones — everything in warm low register | |
+| Wide ambient (60-800 Hz) | Spread across bass to mid range — rich, layered soundscape | ✓ |
+| Full spectrum (50-2000 Hz) | Bass through high-mid — maximum separation | |
+
+**User's choice:** Wide ambient (60-800 Hz)
+**Notes:** None
+
+### Register assignment
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Keep as shown | HTTPS at ~175 Hz is low enough for bulk drone feel | ✓ |
+| Swap to match prior rule | Strictly follow bulk=low, control=mid, interactive=high | |
+| You decide | Let Claude optimize Hz values | |
+
+**User's choice:** Keep as shown
+**Notes:** None
+
+### Tuning approach
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Musical intervals | Harmonic/musical relationships so layers blend pleasantly | ✓ |
+| Arbitrary spacing | Spread evenly, simpler but may clash | |
+| You decide | Claude picks | |
+
+**User's choice:** Musical intervals
+**Notes:** None
+
+### Unknown traffic tone
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Single fixed tone at top of range | Always ~800 Hz | |
+| Dissonant/detuned tone | Off-key or beating frequency signals unclassified traffic | ✓ |
+| You decide | Claude picks | |
+
+**User's choice:** Dissonant/detuned tone
+**Notes:** None
+
+---
+
+## Waveform Texture
+
+### Richness
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Pure sine waves | Clean, minimal, ethereal — single frequency per class | |
+| Sine + 2-3 harmonics | Fundamental + overtones — warm, pad-like, textured | ✓ |
+| Unique waveform per class | Different harmonic profiles per traffic type | |
+
+**User's choice:** Sine + 2-3 harmonics
+**Notes:** None
+
+### Harmonic ratios
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Same ratios everywhere | All classes use identical harmonic recipe | |
+| Vary per class | Each class gets different harmonic weights for timbral distinction | ✓ |
+| You decide | Claude picks | |
+
+**User's choice:** Vary per class
+**Notes:** None
+
+---
+
+## Amplitude Dynamics
+
+### Responsiveness
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Slow, glacial (2-4 sec) | Layers swell and fade gradually like weather | |
+| Medium (1-2 sec) | Noticeable response, still smooth | ✓ |
+| Snappy (0.5-1 sec) | Layers track traffic closely, more reactive | |
+
+**User's choice:** Medium (1-2 sec)
+**Notes:** None
+
+### Zero-traffic behavior
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Fade to full silence | Only active traffic produces sound | |
+| Fade to a whisper | Barely-audible trace remains for any seen protocol | ✓ |
+| You decide | Claude picks | |
+
+**User's choice:** Fade to a whisper
+**Notes:** None
+
+### Whisper floor type
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Fixed floor | Once seen, stays at fixed very-low amplitude (2-5%) | ✓ |
+| Recency-based decay | Whisper fades further over time based on recency | |
+| You decide | Claude picks | |
+
+**User's choice:** Fixed floor
+**Notes:** None
+
+---
+
+## Mixing & Headroom
+
+### Mix strategy
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Fixed equal gain | Each layer gets 1/N headroom (~0.09 max) | ✓ |
+| Weighted gain by priority | Bulk traffic gets more headroom | |
+| Dynamic limiter | No fixed gain, soft-clip if exceeds headroom | |
+
+**User's choice:** Fixed equal gain
+**Notes:** None
+
+### Sample rate
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| 44100 Hz (CD quality) | Standard, LAME native | ✓ |
+| 22050 Hz (half rate) | Smaller files, still fine for <800 Hz | |
+| You decide | Claude picks | |
+
+**User's choice:** 44100 Hz
+**Notes:** None
+
+### MP3 bitrate
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| 128 kbps | Good quality, ~1 MB/min | ✓ |
+| 192 kbps | Higher quality, ~1.5 MB/min | |
+| You decide | Claude picks | |
+
+**User's choice:** 128 kbps
+**Notes:** None
+
+### Channel mode
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Mono | Single channel, simpler | |
+| Stereo with panning | Each class panned for spatial separation | ✓ |
+
+**User's choice:** Stereo with panning
+**Notes:** None
+
+### Panning approach
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Fixed positions by register | Bass center, mid spread, high wider | ✓ |
+| Even spread | All 11 evenly from hard L to hard R | |
+| You decide | Claude picks | |
+
+**User's choice:** Fixed positions by register
+**Notes:** ICMP center, DNS slight-L, HTTPS slight-R, etc.
+
+---
+
+## Claude's Discretion
+
+- Exact Hz values per class (within 60-800 Hz, musical intervals)
+- Specific harmonic ratios per traffic class
+- Exact EMA alpha/decay constants for 1-2 sec feel
+- Exact whisper floor percentage (2-5%)
+- WAV intermediate format usage
+- Stereo panning implementation method
+
+## Deferred Ideas
+
+None — discussion stayed within phase scope