• Assembling a sequence or cutting footage to a music track.
• Pacing drags or feels choppy; transitions feel arbitrary.
• Building speed ramps, match cuts, or tension/release structure.
• Converting an edit plan into a frame-accurate timeline (Remotion, AE, NLE).

What's the editing problem?
├─ Cuts feel off the music
│   └─ get BPM + offset → frames_per_beat = (60/BPM)*fps
│      → cut on PHRASES (2/4/8 beats), biggest visual on the drop
├─ A cut feels jarring / visible
│   └─ cut on action (mid-motion), match direction + velocity
│      → still rough? motivate a transition (match / J / L), else hard cut
├─ Pacing drags or feels flat
│   └─ shape an arc: Establish → Develop → Climax → Resolve
│      → shorten avg shot length toward climax, hold after it
├─ A hit needs impact
│   └─ speed ramp INTO it (slow-mo), snap back; land slowest frame on the beat
└─ Need to hand it to code
    └─ express every cut as a frame number, clip as from/duration,
       transition as overlap, retime as eased time-remap (Remotion/AE)

• Motion Personality (

  motion-art-direction

  ) sets cut rhythm: the chosen energy maps straight to phrase length and transition family. Pick one and commit (see the table below).
• Three Pillars + beat-sync (

  animation-principles

  ): settle emotional intent first (hype vs. calm) — it decides whether you cut every bar or hold for four.

  animation-principles

  defines the BPM→beat relationship; this skill turns it into frame-accurate cut points and the transition/retime craft on top.

• Match cut — outgoing and incoming frames share a shape, position, or motion vector, so the cut reads as a transformation (a circle becomes the moon; a wipe of an arm reveals the next scene). The strongest transition in motion design.
• J-cut — audio of the next shot starts before its picture (sound leads). Pulls the viewer forward; great for dialogue and reveals.
• L-cut — audio of the current shot continues under the next picture (sound trails). Smooths scene changes.
• Whip / motion blur transition — fast pan blends two shots; needs matched blur direction.
• Luma/wipe/dissolve — signals time passing or a softer mood; overuse reads as amateur.

Brief: hype sneaker drop, Energetic personality, drop at beat 32.

• Grid: 14.06 f/beat. Drop = beat 32 ≈ frame 450 (rounded cumulatively to avoid drift).
• Arc: Establish 0–120 (two 2s holds). Develop 120–450 (cuts shortening 8→4→2 beats, rising energy — matches Energetic). Climax at 450 (the drop). Resolve 700–900 (one long CTA hold).
• Cuts: structural cuts on the bar; two accent flash-cuts snapped to the eighth-grid in Develop.
• Craft: f112 is a match cut (shared circular logo → wheel). The drop at 450 carries the biggest visual and a speed ramp 100%→25%→100% landing the slowest frame on the downbeat. CTA enters under an L-cut (audio trails ~18f).
• To code: each cut a frame number, each clip

  <Sequence from/durationInFrames>

  , ramp = eased time-remap, beats verified

  frame/fps

  against detected beat seconds.

Why it works: phrase-based grid, an arc, one big moment on the drop, motivated transitions, frame-accurate and portable.

• A hard cut on all 32 beats → relentless, no focal moment, viewer fatigues by beat 8.
• A 12-frame crossfade on every cut to "smooth it" → mushy, amateur, and now nothing is on the beat because the dissolve midpoint drifts off-grid.
• Uniform 15-frame shots start to finish → flat; no establish, no climax, the drop lands on nothing.
• BPM math done from frame 0 ignoring the track's offset → every cut sits a few frames early, feels "almost right" but wrong.

Fix: cut on 4/8-beat phrases, hard cut by default, build an arc, anchor the grid to beat-1 offset, and put the one biggest visual on the drop.

remotion-video

after-effects

• Track spec: BPM, fps, beat-1 offset, drop frame(s), frames_per_beat.
• Arc: the four phases with frame ranges and target average shot length per phase.
• Cut list: every cut as an absolute frame number (from the BPM math), the clip at that cut, and the cut type.
• Transitions: type (hard/match/J/L/whip), and for J/L the audio offset in frames.
• Retimes: each speed ramp as eased time-remap keyframes (from→to %, frames, optical-flow on).
• Beat markers: the on-beat/eighth-grid frame array for verification.
• Cross-refs: the Motion Personality that set the rhythm.

For Remotion/AE this plan IS the frame timing: cuts →

from

/

durationInFrames

(or layer in/out), ramps → eased

interpolate

/time-remap, J/L → offset

<Audio from>

/ audio layer. See

references/editing-techniques.md

for the NLE↔code mapping table.

• BPM + fps + beat-1 offset captured; frames_per_beat computed and cumulatively rounded.
• Cuts on phrases (2/4/8 beats), not every beat; accents on the eighth-grid only.
• The single biggest visual lands on the drop.
• An arc exists (Establish→Develop→Climax→Resolve); avg shot length shortens toward the climax, then a hold.
• Hard cut is the default; every other transition is motivated; J/L audio offsets specified in frames.
• Speed ramps land the slowest frame on the beat; optical-flow/frame-blending enabled.
• Cut rhythm matches the chosen Motion Personality.
• Every cut, transition, and retime expressed as a frame number / from-duration so it ports to Remotion/AE/NLE.
• Audio sync verified:

  frame/fps

  against detected beat seconds.

• Cutting on every beat is busy; cut on 2/4/8-beat phrases and accent sparingly.
• Speed ramps without consistent motion blur look strobed; enable optical-flow/frame-blending for slow-mo.
• Crossfades/dissolves are not a fix for a bad cut — fix the timing first.
• Audio sync drift: in code timelines verify

  frame/fps

  against detected beat seconds; in NLEs lock audio to a frame-accurate guide track.
• One pacing throughout = flat. Always shape an arc.

• references/editing-techniques.md

  — BPM→frame math with phrase tables, cut-on-action breakdowns, building a match cut step by step, J-cut/L-cut audio-lead/trail diagrams with frame offsets, full speed-ramp recipe with motion-blur/optical-flow settings, sequence-arc templates with shot-length curves, and mapping an edit plan between an NLE timeline and a code timeline (Remotion

  <Sequence>

  / AE time-remap).