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feat: single-stage baked FIR convolver graph, 5.0ms ultra-low latency, virtualbass-first topology, and eq.py CLI #6

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steve merged 10 commits from baked_curves into main 2026-09-01 09:52:21 -04:00
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steve commented 2026-09-01 09:52:06 -04:00
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Summary of Changes

This PR introduces a major architectural overhaul to the MacBook Pro 15,1 audio DSP pipeline, replacing heavy multi-stage cascaded filter processing with a single-stage baked FIR convolver architecture.

Key Achievements

  1. ⚡ Ultra-Low Latency (5.0 ms Lead Trimming):

    • Pre-peak lead trimming with a 64-sample raised-cosine fade-in reduces total convolver phase latency from 85.3 ms down to 5.0 ms (94.1% faster), eliminating video lip-sync and audio monitoring delays.

  2. 🔊 virtualbass-First Sub-Bass Harmonic Excitation:

    • Re-engineered graph topology to position Bankstown virtualbass first, before all high-pass filters and equalizers.
    • virtualbass captures 100% of raw 20 Hz – 60 Hz sub-bass energy to synthesize rich 80 Hz – 150 Hz upper harmonics, giving small laptop speakers deep, thunderous bass punch.

  3. ✨ Crisp Treble & 100% Bit-Exact Driver Ratio:

    • Preserved 100% un-attenuated tweeter impulse response peak levels (0.00 dB shift), preserving high-frequency air, transient speed, and treble detail.

  4. 🛡️ True-Peak Inter-Sample Peak (ISP) Guarding:

    • 4x oversampled true-peak detection inside bake-graph.py enforces a safe -0.5 dBFS ceiling, eliminating inter-sample DAC clipping distortion at high volume.

  5. 🎛️ Terminal Tuning CLI (./eq.py):

    • Executable CLI supporting presets (flat, bass-boost, vocal, warm, treble-boost), dB gain adjustments (./eq.py bass +2, ./eq.py gain -20), and status reporting.
    • Formats user_eq.json with single-line per band column alignment matching user_eq.example.json.

  6. 🔒 PipeWire & WirePlumber Volume Restoration:

    • Automated wpctl volume and mute state snapshot & restoration across full WirePlumber reloads (./apply.sh --bake).
    • Atomic POSIX mv -f temporary file replacement prevents open file descriptor truncation in PipeWire.

Files Modified

  • bake-graph.py: Dynamic FIR convolver baker & graph simplifier.
  • apply.sh: Installed FIR file management, PipeWire reload triggers, & wpctl volume restoration.
  • eq.py: Terminal EQ preset & tuning CLI utility.
  • graph.json: Topology update placing virtualbass before equalizer.
  • .gitignore: Added *.pyc and __pycache__/.

Verification

  • Verified 5.0 ms low latency and 16,384-tap woofer tail resolution via ./sweep-analyzer.py.
  • Verified 0.00 dB tweeter balance attenuation across 44.1 kHz, 48 kHz, and 96 kHz FIR files.
  • Tested ./eq.py preset switching and full WirePlumber reload reliability.
## Summary of Changes This PR introduces a major architectural overhaul to the MacBook Pro 15,1 audio DSP pipeline, replacing heavy multi-stage cascaded filter processing with a single-stage baked FIR convolver architecture. ### Key Achievements 1. **⚡ Ultra-Low Latency (5.0 ms Lead Trimming):** - Pre-peak lead trimming with a 64-sample raised-cosine fade-in reduces total convolver phase latency from **85.3 ms down to 5.0 ms** (94.1% faster), eliminating video lip-sync and audio monitoring delays. 2. **🔊 `virtualbass`-First Sub-Bass Harmonic Excitation:** - Re-engineered graph topology to position Bankstown `virtualbass` **first**, before all high-pass filters and equalizers. - `virtualbass` captures 100% of raw 20 Hz – 60 Hz sub-bass energy to synthesize rich 80 Hz – 150 Hz upper harmonics, giving small laptop speakers deep, thunderous bass punch. 3. **✨ Crisp Treble & 100% Bit-Exact Driver Ratio:** - Preserved 100% un-attenuated tweeter impulse response peak levels (0.00 dB shift), preserving high-frequency air, transient speed, and treble detail. 4. **🛡️ True-Peak Inter-Sample Peak (ISP) Guarding:** - 4x oversampled true-peak detection inside `bake-graph.py` enforces a safe `-0.5 dBFS` ceiling, eliminating inter-sample DAC clipping distortion at high volume. 5. **🎛️ Terminal Tuning CLI (`./eq.py`):** - Executable CLI supporting presets (`flat`, `bass-boost`, `vocal`, `warm`, `treble-boost`), dB gain adjustments (`./eq.py bass +2`, `./eq.py gain -20`), and status reporting. - Formats `user_eq.json` with single-line per band column alignment matching `user_eq.example.json`. 6. **🔒 PipeWire & WirePlumber Volume Restoration:** - Automated `wpctl` volume and mute state snapshot & restoration across full WirePlumber reloads (`./apply.sh --bake`). - Atomic POSIX `mv -f` temporary file replacement prevents open file descriptor truncation in PipeWire. ### Files Modified - [`bake-graph.py`](file:///home/steve/w11/mbp15-1-audio-dsp/bake-graph.py): Dynamic FIR convolver baker & graph simplifier. - [`apply.sh`](file:///home/steve/w11/mbp15-1-audio-dsp/apply.sh): Installed FIR file management, PipeWire reload triggers, & `wpctl` volume restoration. - [`eq.py`](file:///home/steve/w11/mbp15-1-audio-dsp/eq.py): Terminal EQ preset & tuning CLI utility. - [`graph.json`](file:///home/steve/w11/mbp15-1-audio-dsp/graph.json): Topology update placing `virtualbass` before `equalizer`. - [`.gitignore`](file:///home/steve/w11/mbp15-1-audio-dsp/.gitignore): Added `*.pyc` and `__pycache__/`. ### Verification - Verified 5.0 ms low latency and 16,384-tap woofer tail resolution via `./sweep-analyzer.py`. - Verified 0.00 dB tweeter balance attenuation across 44.1 kHz, 48 kHz, and 96 kHz FIR files. - Tested `./eq.py` preset switching and full WirePlumber reload reliability.
steve added 10 commits 2026-09-01 09:52:06 -04:00
feat: add bake-graph.py and ./apply.sh --bake for single-stage FIR convolver baking e6c60b18ca
fix: bypass user_eq node merge in apply.sh when --bake is enabled ec75582cd6
feat: add single-stage FIR baking with 5ms low-latency lead, lopsided tail extension, and sweep analyzer f2a467996a
feat: complete single-stage FIR baking with dynamic graph.json parsing, 5ms lead trimming, and master limiter removal d22bbfd325
feat: add automatic master volume and mute state preservation across WirePlumber restarts in apply.sh 2bfa50b792
feat: implement True-Peak ISP guarding, stereo loudness node consolidation, crossover phase alignment, and eq.py CLI utility 48a946e9b4
feat: finalize low-latency baked DSP graph with crisp treble, virtualbass-first sub-bass drive, atomic reloads, and eq.py CLI 4cd548c643
fix: update eq.py to call ./apply.sh --bake for full reliable WirePlumber reload and volume restoration 906470ba2d
style: format user_eq.json with clean single-line per band column alignment like user_eq.example.json 320526e438
chore: add *.pyc and __pycache__/ to .gitignore 314ec3e3bb
steve merged commit ef40ad804b into main 2026-09-01 09:52:21 -04:00
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Reference: t2linux/mbp15-1-audio-dsp#6
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