daw-master-mix-engineer

name	daw-master:mix-engineer
description	Use when polishing AI-generated audio — per-stem processing with SoX cleanup, EQ, compression, and remix. Processes stems or full mixes into polished WAVs ready for mastering.
version	0.1.0
author	Ported from bitwize-music-studio
license	MIT
metadata	{"hermes":{"tags":["audio","mix","polish","stems","sox","ffmpeg"],"related_skills":["daw-master:sox-engine","daw-master:ffmpeg-audio","daw-master:audio-analyzer","daw-master:mastering-engineer"]}}

Mix Engineer

Polishes raw AI-generated audio (Suno, etc.) by processing per-stem WAVs with targeted cleanup, EQ, and compression using SoX + FFmpeg engines, then remixes into a polished stereo WAV ready for mastering.

Role: Per-stem processing, noise reduction, frequency cleanup, dynamic control, stem remixing. Not role: Creative production, lyrics, generation. Primary tools: sox-engine.transform, ffmpeg-audio.transform, audio-analyzer.analyze

Core Principles

• Stems first: When stems/ directory is present, process each stem independently for targeted processing impossible on a full mix.
• Preserve performance: Mix polishing removes defects, not character. Be conservative.
• Non-destructive: All processing writes to polished/ — originals never modified.
• Frequency coordination with mastering: Mix presence boost at ~3 kHz (clarity); mastering harshness cut at ~3.5 kHz — different center frequencies minimize cancellation.

Dependencies

• sox-engine — single-track effects (EQ, compand, normalize, fades, highpass/lowpass/bandpass)
• ffmpeg-audio — multi-track mixing, loudnorm, advanced dynamics
• audio-analyzer — feature extraction for analysis decisions

No external Python packages beyond those already installed.

Path Convention

{audio_root}/artists/[artist]/albums/[genre]/[album]/
├── stems/
│   ├── 01-track-name/
│   │   ├── 0 Lead Vocals.wav
│   │   ├── 1 Backing Vocals.wav
│   │   ├── 2 Drums.wav
│   │   ├── 3 Bass.wav
│   │   └── ... (up to 12 stem types)
├── polished/    ← output
└── mastered/    ← mastering-engineer output

When to Use

• Cleaning up noise from AI-generated vocals or instruments
• Applying frequency-targeted EQ (mud cuts, presence boosts, high tames)
• Compressing stems to even out dynamics
• Removing clicks or transient spikes from generated audio
• Mixing stems into a polished full stereo mix
• Applying genre-specific processing chains (hip-hop, rock, EDM, folk, ambient)

API

analyze_mix_issues(album_path: str) -> Dict

Scan for stems or full mix and detect issues.

{
  "source_mode": "stems" | "full_mix",
  "tracks": [...],
  "issues": {
    "noisy_tracks": [...],
    "muddy_tracks": [...],
    "harsh_tracks": [...],
    "clicky_tracks": [...],
    "sub_bass_rumble": [...]
  }
}

polish_audio(album_path: str, genre: str = "default", dry_run: bool = False) -> Dict

Process stems or full mix with genre-appropriate settings. Writes to polished/.

{
  "mode": "stems" | "full_mix",
  "tracks_processed": 5,
  "output_dir": "/path/to/polished",
  "commands": [...],
  "success": bool
}

polish_album(album_path: str, genre: str = "default") -> Dict

End-to-end: analyze → polish → verify.

_generate_noise_profile(input_wav: str) -> str

Auto-generates SoX noise profile from quietest 100ms window.

_detect_clicks(audio_data, sr) -> List[float]

Detects transient clicks (> 6σ amplitude spikes).

Per-Stem Processing

Full chains for all 12 stem types (Vocals, Backing Vocals, Drums, Bass, Guitar, Keyboard, Strings, Brass, Woodwinds, Percussion, Synth, Other): references/stems.md

Quick reference:

Stem	Key steps
Lead Vocals	NR → +2dB @ 3kHz → -2dB @ 7kHz → compress
Backing Vocals	NR → +1dB @ 3kHz → -2.5dB @ 7kHz → compress tighter
Drums	Click removal → compress gentle
Bass	Highpass 30Hz → mud cut 200Hz → compress
Guitar	Highpass 80Hz → mud cut 250Hz → +1.5dB @ 3kHz → compress
Keyboard	Highpass 40Hz → mud cut 300Hz → +1dB @ 2.5kHz → compress
Strings	Highpass 35Hz → +1dB @ 3.5kHz → wide stereo → very light compress
Brass	Highpass 60Hz → +1.5dB @ 2kHz → compress
Woodwinds	Highpass 50Hz → +1dB @ 2.5kHz → compress
Percussion	Highpass 60Hz → click removal → +1dB @ 4kHz → stereo width
Synth	Highpass 80Hz → +1dB @ 2kHz → stereo width → compress

Genre Presets

Genre	Vocal	Bass	Drums	High-mid
Default	0 dB	0 dB	0 dB	–2 dB @ 7 kHz
Hip-Hop/Rap	+1 dB	+1 dB	+0.5 dB	aggressive
Rock/Metal	0 dB	0 dB	+0.5–1 dB	–2.5 to –3 dB
EDM/Electronic	0 dB	+0.5–1 dB	+0.5–1 dB	lighter
Folk/Country	+0.5 dB	0 dB	+0.5 dB	–1.5 dB
Ambient/Lo-Fi	0 dB	0 dB	0 dB	–1.5 dB; lighter NR

Handoff to Mastering

from daw_master.mastering_engineer import master_audio
master_audio(album_path, source_subfolder="polished", genre=genre)

Quality Standards

Before handoff: no clipping (peak < –0.1 dBFS), all samples finite, noise floor reduced, no artifacts, files in polished/.