Plan 9 Rap Battle: A Bunny, a Beat, and 40 Bars of Machine Spit

128 seconds. One bunny. 40 bars. Harpsichord trap.

The Plan 9 bunny, Glenda from Bell Labs, steps into a dark alley at 3AM. Red bandana. 40oz in one hand, mini Uzi in the other. The brick wall behind scrolls with terminal commands and 80s Easter eggs. A Tesla coil pulses on the left. Paint splats explode on the hard consonants. The beat is a synthesized piano playing sparse Am-to-F stabs over a half-time 808 sub at 150 BPM. The bunny raps about code, the grind, and the machine frontier.

The rap is not good. The attempt is real, and the distance between those two is where the engineering got interesting.

TTS cannot rap. What it can do, with enough autotune and compression, is deliver short punchy lines with rhythmic aggression over a beat. The result sounds like a very confident robot who wandered into a cypher and refused to leave. Listen expecting Kendrick and you will be concerned. Listen for the engineering underneath and there is a lot here.

The Film

Three verses, three hooks, a bridge, a golden drop, and an outro. 1536 frames at 12fps. 128 seconds.

INTRO (0-12s). Dark alley fades in. Cricket ambient synthesized inline via ffmpeg, high sine tones with rapid tremolo plus a low frog drone, the Stranger Things vibe. The bunny steps out of the shadows. Beat drops at frame 96.

PRE-VERSE. Four quick opener bars: "Yeah. Plan Nine on the mic." / "3AM crew. Coming out the pen." / "Ears up. Eyes red. Check the stack." / "Bunny back. Tell the whole block." Establishes the voice and the cadence of the character.

VERSE 1. Eight bars at 26-frame spacing, Ice Cube-style short pockets. Bell Labs blood, Glenda in the veins, Tesla coil buzz, Feynman flow, vi and grep. The bars reference the hacker-scientist lineage without naming anyone real. "Plan Nine from Bell Labs. Take my lane."

HOOK 1. "Plan Nine. Built it from the block. / Plan Nine. Keyboard tick tick tock. / Plan Nine. Terminal loaded up. / Plan Nine. Whole world shut up." Wider spacing, 28 frames, for emphasis. Camera shake on each punch.

VERSE 2. The origin story verse. Wall came down, Berlin brown, moms worked doubles, stole a BASIC book. "Eight bit scars. I still got the pain." / "They said get a job. I said I made mine." The autobiographical material goes through the bunny, universal themes and no real names.

HOOK 2 + GOLDEN DROP. The beat's golden ratio moment, pattern 7 of 10 in the ChipForge score at 0.618 of the runtime, hits with a heavy sub drop. Four punch bars ride it: "Plan Nine in the drop. / Bunny on the top. / Hand on the keyboard. / Watch the whole system stop."

OUTRO. "Don't sleep. / Bunny up." Then two yelled deliberates at full intensity, "PLAN NINE!" and "CERTIFIED!" Credits roll over the beat's fade, the title card lingers.

The Autotune Pipeline

This is the third Napkin Films production to use autotune_voice.py, and the first to push the spit-rap mode to its limit.

1. Raw TTS. ElevenLabs villain_shadow persona, the Josh voice with the menacing emotion. Each bar is a 6-9 word line ending on a hard consonant. The persona delivers with weight and zero rhythm.

2. Autotune. rubberband, the pitch-shift library, chops the voice WAV on silence gaps, assigns each chunk to a note from an Em pentatonic scale (E3, G3, A3, B3, D3, E4, G4, B2), and pitch-corrects with --spit 0.80 for heavy T-Pain depth and --blend 0.70, mostly autotuned. --max-shift 8 semitones locks each chunk hard to its target note. --spit-gap-ms 8 catches very tight word boundaries.

3. Vocal polish. The finalmix chain runs loudnorm to -14 LUFS, a louder target for rap vocals, then acompressor at 6:1 with a -18dB threshold and slow attack, then parametric EQ cutting 250Hz mud and boosting 3kHz presence.

The rule from Stars Press Start holds. 6-12 words per bar, hard consonant clusters (crack, stack, drop, form, drive, step), hard-stop punctuation every 2-4 beats. Lines that "smear" under speed-up (serene, aura, flowing) are replaced with lines that "hold" (Bell Labs blood, vi and grep, Tesla coil buzz).

The Score: Harpsichord Trap

Two ChipForge WAVs layered.

The primary score, harpsichord_trap_score.wav. A minor at 150 BPM, a half-time feel so the vocal pocket sits at 75. Sparse 4-note piano motif (E5-D5-C5-A4, pentatonic descent) over deep 808 sub bass. Am | F chord vamp (i | bVI). Half-time snare on beat 3 only. Trap hi-hats in 16ths with velocity dynamics plus occasional rolls. 10 patterns, 128 seconds. The golden ratio falls at pattern 7, the heavy drop. The score carries the harpsichord name, but the instrument in it is ChipForge's additive grand piano.

The secondary score, circuit_glitch_score.wav. Dark electro-glitch texture, mixed underneath the primary at lower volume. Adds atmosphere and fills the spectral gaps the sparse trap beat leaves open.

Cricket ambient. Synthesized inline by the finalmix script via ffmpeg, two sine tones (4800Hz and 6000Hz) with rapid tremolo plus a 90Hz frog drone. It appears during the intro (0-10s) and outro (116-128s) only. The Stranger Things vibe.

Music sits at 0.55 volume during verses, voice forward, ducks to 0.35 during the golden drop so the spit cuts through, returns to 0.72 at the outro, and fades out over the last 8 seconds.

The Visual Stack

Every frame drawn in PIL, 854x480 at 12fps.

The bunny. draw_plan9() from characters/plan9_bunny.py, with three custom prop drawers. draw_40oz() is a brown-green bottle with amber liquid visible in the neck, draw_bandana() a Tupac-style forehead wrap with paisley dots, side knot, and two hanging tails, and draw_uzi() a stylized micro-Uzi with muzzle flash.

The wall. Brick texture with 24 scrolling Easter-egg text lines referencing Bell Labs, Tesla, WarGames, Tron, Commodore 64, Run-DMC, Grandmaster Flash, Eric B & Rakim, Neuromancer, Dennis Ritchie, Ken Thompson, and the Glenda bunny. Each line drifts left-to-right over 150 frames, fading in and out. Terminal green and amber against dark brick.

Lip sync. Phoneme-based draw_mouth() with key_beats per line, explicit mouth shapes (closed, small, mid, open, wide) at set frame offsets so the strongest syllables snap open even without audio-driven sync. 40 lines, each with 4-6 key-beat anchors.

Camera work. cinematography.py provides crop_to_shot() and ease_shot() for animated pushes from wide to close-up, plus dutch_angle() for tilted aggression shots during the hooks. camera_shake fires on every hook and drop impact.

Paint splats. Particle system that fires colored paint explosions on hook impacts and bar transitions. Red, blue, green, yellow against the dark brick.

The Easter Eggs

The scrolling wall text is half the fun. A selection.

• $ awk -f beats.awk | grep -E '^\$'
• tesla coil ok. 3.6.9 ok.
• wargames: shall we play a game?
• neuromancer, case still dreams
• tron → end of line.
• COMMODORE BASIC V2 followed by READY.
• paid in full, eric b & rakim
• wardenclyffe.sh --broadcast all
• // plan9 bunny, certified
• // signal --> noise --> truth

Each line is color-coded, green for Bell Labs/UNIX, amber for Tesla, blue for 80s movies, warm gold for hip-hop.

The Lyrics

40 bars total. Every line 6-9 words, ending on a hard consonant. The privacy contract from the scene file says "lyrics draw on universal inner-life themes (identity, the grind, reinvention, the human-machine frontier). No real names, places, family, or biographical specifics."

The voice is the bunny's. The autobiographical material goes through the character and comes out general. "Came up hard. Wall came down." could be anyone. "Stole a BASIC book. Never looked back." could be any 80s kid, which is the point. The bunny is an archetype, the builder in the void, the 3AM crew, the one who coded through the night and came back changed.

What This Proves

Stars Press Start proved TTS could be pushed toward musical performance over 21 passes. Deduct Yourself proved double-time rap delivery worked with 10 passes. Plan 9 Rap Battle tests whether the autotune pipeline, applied to short aggressive bars over a trap beat, can produce something that sounds like it belongs over the music.

Almost. The autotune locks each word-chunk to a pitch in Em pentatonic, which gives the vocal a melodic contour it never earned by performing. The compression and EQ chain gives it presence and the key_beats lip sync gives it a visual rhythm. Over a beat left deliberately sparse, two chords, a half-time snare, lots of space, the voice sits in the pocket without fighting the music. What comes out is an engineer's approximation of a rap, and at 128 seconds it does not overstay.

The Stack

Same as every Napkin Films production.

• Animation: Python + PIL, Plan 9 bunny drawn frame by frame, 854x480 at 12fps
• Music: ChipForge, two layered scores (harpsichord trap + circuit glitch), plus ffmpeg-synthesized cricket ambient
• Voice: ElevenLabs v3, villain_shadow persona, rubberband autotune (Em pentatonic, spit 0.80, blend 0.70)
• Assembly: FFmpeg, stem-preserving finalmix with vocal compression, EQ, and per-section ducking
• Direction: Claude Code, Opus 4.6, agent mode

No GPU. No subscriptions beyond ElevenLabs. No animation software.

Watch Plan 9 Rap Battle on YouTube. The film is Creative Commons (CC BY-NC 4.0).

License. This film is licensed under Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0). Share and adapt with attribution to "Organic Arts LLC" and a link to the original, non-commercial use only. ElevenLabs voice audio is licensed content and is not redistributed. Contact: j@organicartsllc.com

The full origin story of the Napkin Films stack is in Four Films From Code, how the architecture works and why constraint is the feature. For the autotune pipeline's first outing, Stars Press Start walks through 21 passes of TTS voice engineering. The ten-minute theological tribunal is The Reckoning. The Agentic Development post explains the agent mode workflow underneath all of it. I Want to Be Martian is a Bradbury tribute with three voices, a Holst-Mars ostinato, and a rover on Mars in 2035. And the companion to this one, released the same day: Arp Cathedral. Plan 9 returns in Agent Mode: Plan 9 x OG Bobby Johnson with a russet potato, five real voice memos chopped into DJ loops, and a 15-channel festival-trap beat.

---

Produced with Napkin Films and ChipForge, custom tools built by Joshua Ayson and AI agents at Organic Arts LLC.