> ## Documentation Index
> Fetch the complete documentation index at: https://hyperframes.heygen.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Beat Timeline

> A paused master-timeline orchestration spine that pins titled beat rows to evenly spaced named labels. Each row enters on its label, holds with the sequence, then exits with the group.

export const InstallCommand = ({command}) => {
  const [copied, setCopied] = React.useState(false);
  const copy = async () => {
    try {
      if (navigator.clipboard && window.isSecureContext) {
        await navigator.clipboard.writeText(command);
      } else {
        const previous = document.activeElement;
        const scratch = document.createElement("textarea");
        scratch.value = command;
        scratch.setAttribute("readonly", "");
        scratch.style.position = "fixed";
        scratch.style.opacity = "0";
        document.body.appendChild(scratch);
        scratch.select();
        document.execCommand("copy");
        document.body.removeChild(scratch);
        previous?.focus?.();
      }
      setCopied(true);
      setTimeout(() => setCopied(false), 2000);
    } catch {}
  };
  return <div className="hf-install-command not-prose my-4 flex items-stretch overflow-hidden rounded-xl border border-zinc-200 bg-zinc-50 dark:border-zinc-800 dark:bg-zinc-900">
      <code className="flex-1 overflow-x-auto whitespace-nowrap border-r border-zinc-200 px-4 py-3 font-mono text-sm text-zinc-800 dark:border-zinc-800 dark:text-zinc-100">
        {command}
      </code>
      <button type="button" onClick={copy} data-copied={copied ? "true" : "false"} aria-label={`Copy ${command} to the clipboard`} className="hf-install-copy">
        <svg className="hf-install-copy-clipboard" xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 18 18" fill="none" stroke="currentColor" strokeWidth="1.5" strokeLinecap="round" strokeLinejoin="round" aria-hidden="true">
          <path d="M14.25 5.25H7.25C6.14543 5.25 5.25 6.14543 5.25 7.25V14.25C5.25 15.3546 6.14543 16.25 7.25 16.25H14.25C15.3546 16.25 16.25 15.3546 16.25 14.25V7.25C16.25 6.14543 15.3546 5.25 14.25 5.25Z" />
          <path d="M2.80103 11.998L1.77203 5.07397C1.61003 3.98097 2.36403 2.96397 3.45603 2.80197L10.38 1.77297C11.313 1.63397 12.19 2.16297 12.528 3.00097" />
        </svg>
        <svg className="hf-install-copy-check" xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 18 18" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round" aria-hidden="true">
          <path d="M2.75 9.5L6.5 13.25L15.25 4.5" />
        </svg>
      </button>
      <span className="hf-install-copy-status" role="status" aria-live="polite">
        {copied ? "Copied" : ""}
      </span>
    </div>;
};

<iframe className="w-full aspect-video rounded-xl border-0 bg-zinc-100 dark:bg-zinc-800" title="beat-timeline preview" loading="lazy" srcDoc={`<!doctype html><html><head><meta charset="utf-8"><style>html,body{margin:0;height:100%;overflow:hidden;background:transparent}hyperframes-player{display:block;width:100%;height:100%}</style><script src="https://cdn.jsdelivr.net/npm/@hyperframes/player@0.7/dist/hyperframes-player.global.js"><\/script></head><body><script>fetch("/public/catalog/components/beat-timeline.json").then(function(r){return r.json()}).then(function(d){var p=document.createElement("hyperframes-player");p.setAttribute("srcdoc",d.html);p.setAttribute("controls","");p.setAttribute("autoplay","");p.setAttribute("loop","");p.setAttribute("muted","");p.setAttribute("poster","https://static.heygen.ai/hyperframes-oss/docs/images/catalog/components/beat-timeline.png");document.body.appendChild(p)});<\/script></body></html>`} />

## Install

<InstallCommand command="npx hyperframes add beat-timeline" />

That writes one file: `compositions/components/beat-timeline.html`.

## Paste it into your composition

Open `compositions/components/beat-timeline.html` and copy what is inside into your own composition.

A component has no size or duration of its own. It takes both from the composition
you paste it into.

## Variables

Every one of these has a default, so the piece works untouched. Set the ones you
want to change on the element:

| Variable    | Default              | Accepts                | What it does                                                                                                  |
| ----------- | -------------------- | ---------------------- | ------------------------------------------------------------------------------------------------------------- |
| `beatCount` | `4`                  | 2 to 6, step 1         | Number of beat rows in the sequence.                                                                          |
| `interval`  | `0.6`                | 0.2s to 2s, step 0.05s | Base time between consecutive beat markers.                                                                   |
| `labels`    | `One,Two,Three,Four` | string                 | Comma-separated beat titles, one per beat. Extra entries are ignored and missing entries fall back to Beat N. |

Set them with `data-variable-values` on the element that mounts it. These are the
defaults, so this behaves exactly like the preview above until you change one:

```html wrap theme={null}
<div
  data-composition-id="beat-timeline"
  data-composition-src="compositions/components/beat-timeline.html"
  data-variable-values='{"beatCount":4,"interval":0.6,"labels":"One,Two,Three,Four"}'
></div>
```

## Source

<Accordion title={`beat-timeline.html`}>
  ```html theme={null}
  <!doctype html>
  <!--
    beat-timeline -- HyperFrames video primitive (transitions / sequencing / bridge)

    Concept: a visible orchestration spine made from a paused master GSAP
    timeline. Each beat row is pinned to an evenly spaced named label, then
    enters exactly on that mark. One mechanic, one job: bridge a sequence by
    making its deterministic beat grid readable and copy-and-own-able.

    Compiled-from evidence: launches-motion-vocabulary.md, "Paused, seeked
    timeline orchestration" census entry (15/18 projects, 134/159 files).

    Use when: a scene needs several titled beats to land in a clear order, or
    when a copied composition needs a legible master-timeline sequencing spine.

    Variables (declared in data-composition-variables below):
      - beatCount (number, default 4): integer row count, clamped to 2..6.
      - interval (number, default 0.6s): base spacing between named beat labels,
        clamped to 0.2..2s before any short-duration compression.
      - labels (string): comma-separated row titles. Missing entries fall back
        to "Beat N" and extra entries are ignored.

    Envelope (holdable orchestration adaptation, never gsap.timeScale()):
      ENTRANCE_SPAN = (beatCount - 1) * interval + ROW_IN_DURATION.
      HOLD = max(0, D - (ENTRANCE_SPAN + OUT_BASE)); every landed row remains
             fully visible and deliberately still during this elastic phase.
      OUT_BASE = 0.40s; all rows fade together with power2.in at D - OUT_BASE.
      If D is shorter than ENTRANCE_SPAN + OUT_BASE, interval and each row's
      entrance duration scale down together so the final row still lands before
      OUT. Only a host duration at or below OUT_BASE also compresses OUT, which
      keeps the full lifecycle inside an otherwise impossible time box.

    Sync points: beat labels are fixed offsets inside IN. Every label owns one
    declared SFX cue at the same offset, never inside elastic HOLD. Beats use
    "beat-tick" and the last beat uses "beat-tick-final". The primitive only
    dispatches bubbling hf:sfx events; scene-level audio mixing owns playback.

    Mount contract: this file is a mountable sub-composition. The runtime clones
    only <template> contents, so all live styles, markup, and scripts are inside
    the template. #root fills the host-owned box with no data-width/data-height,
    and all internal geometry is based on its own cqw/cqh container. Variables
    come from window.__hyperframes.getVariables(), because document.documentElement
    belongs to the host after mounting.
  -->
  <html
    lang="en"
    data-composition-variables='[
      { "id": "beatCount", "type": "number", "role": "content", "label": "Beat count", "description": "Number of beat rows in the sequence.", "default": 4, "min": 2, "max": 6, "step": 1 },
      { "id": "interval", "type": "number", "role": "layout", "label": "Interval", "description": "Base time between consecutive beat markers.", "default": 0.6, "min": 0.2, "max": 2, "step": 0.05, "unit": "s" },
      { "id": "labels", "type": "string", "role": "content", "label": "Labels", "description": "Comma-separated beat titles, one per beat. Extra entries are ignored and missing entries fall back to Beat N.", "default": "One,Two,Three,Four" }
    ]'
  >
    <head>
      <meta charset="UTF-8" />
      <title>Beat Timeline</title>
      <!-- Metadata only. The loader reads variable declarations from <html>,
           then discards everything outside <template> during mounting. -->
    </head>
    <body>
      <template>
        <div
          id="root"
          data-composition-id="beat-timeline"
          data-start="0"
          data-duration="5.5"
          data-fps="30"
        >
          <style>
            *,
            *::before,
            *::after {
              box-sizing: border-box;
            }

            /* Root is styled by ID for mounted CSS scoping. It owns no stage
               dimensions, only the host box and the container-unit basis. */
            #root {
              --ease-standard: cubic-bezier(0.215, 0.61, 0.355, 1);
              --ease-exit: cubic-bezier(0.55, 0.055, 0.675, 0.19);
              position: absolute;
              inset: 0;
              container-type: size;
              isolation: isolate;
              overflow: hidden;
              background: var(--bg, Canvas);
              color: var(--fg, CanvasText);
              font-family: var(--font-body, system-ui, sans-serif);
            }

            .bt-clip {
              width: 100%;
              height: 100%;
              display: grid;
              place-items: center;
            }

            .bt-stack {
              width: 84cqw;
              display: flex;
              flex-direction: column;
              gap: 1.4cqh;
            }

            /* EDIT ZONE: row geometry only. Motion timing is owned by the script's
               RETIME RANGE below, and theme paint remains token-driven here. */
            .bt-row {
              min-height: 10cqh;
              display: grid;
              grid-template-columns: 6cqw 1fr;
              align-items: center;
              column-gap: 2.6cqw;
              padding: 1.4cqh 2.4cqw;
              border: 0.12cqw solid var(--border, currentColor);
              border-radius: var(--radius, 2cqh);
              background: var(--surface, Canvas);
              box-shadow: 0 1.2cqh 4cqh color-mix(in srgb, var(--bg, Canvas) 52%, transparent);
            }

            .bt-index {
              width: 6cqw;
              height: 6cqw;
              display: grid;
              place-items: center;
              border-radius: 50%;
              background: var(--brand, currentColor);
              color: var(--bg, Canvas);
              font-family: var(--font-display, system-ui, sans-serif);
              font-size: 1.8cqw;
              font-weight: 750;
              line-height: 1;
            }

            .bt-copy {
              min-width: 0;
            }

            .bt-title {
              overflow: hidden;
              color: var(--fg, CanvasText);
              font-family: var(--font-display, system-ui, sans-serif);
              font-size: min(4.4cqw, 5.2cqh);
              font-weight: 700;
              line-height: 1.04;
              letter-spacing: -0.08cqw;
              text-overflow: ellipsis;
              white-space: nowrap;
            }

            .bt-subtitle {
              margin-top: 0.7cqh;
              color: var(--muted, currentColor);
              font-size: min(1.8cqw, 2.2cqh);
              font-weight: 550;
              line-height: 1.15;
              letter-spacing: 0.04cqw;
            }
          </style>

          <div
            id="beat-timeline-clip"
            class="bt-clip clip"
            data-start="0"
            data-duration="5.5"
            data-track-index="0"
          >
            <div class="bt-stack" aria-label="Beat timeline"></div>
          </div>

          <script src="https://cdn.jsdelivr.net/npm/gsap@3.14.2/dist/gsap.min.js"></script>
          <script>
            (function () {
              "use strict";

              var root = document.getElementById("root");
              // Literal by contract: mounting strips data-composition-id from the
              // flattened inner root, so reading the attribute post-mount would
              // register under null and fail the timeline lookup.
              var compositionId = "beat-timeline";
              var stack = root.querySelector(".bt-stack");

              // EDIT ZONE: declarations live on <html>; this runtime call is the
              // single owner of declared defaults plus per-instance overrides.
              var vars =
                window.__hyperframes && window.__hyperframes.getVariables
                  ? window.__hyperframes.getVariables()
                  : {};

              var parsedBeatCount = Number(vars.beatCount);
              // INVARIANT: exactly 2..6 integer rows reach the DOM and timeline.
              var beatCount = Math.max(
                2,
                Math.min(6, Math.round(Number.isFinite(parsedBeatCount) ? parsedBeatCount : 4)),
              );
              var parsedInterval = Number(vars.interval);
              // INVARIANT: invalid timing falls back once, valid timing clamps to
              // the declared range before duration elasticity is calculated.
              var interval = Math.max(
                0.2,
                Math.min(2, Number.isFinite(parsedInterval) ? parsedInterval : 0.6),
              );
              // INVARIANT: labels is always a string; blank or missing entries
              // fall back per row, while authored extra entries stay unused.
              var labelsValue = vars.labels == null ? "One,Two,Three,Four" : String(vars.labels);
              var suppliedLabels = labelsValue.split(",").map(function (label) {
                return label.trim();
              });

              var parsedDuration = parseFloat(root.dataset.duration || "5.5");
              // INVARIANT: the lifecycle remains finite even under a malformed
              // host duration. The authored and demo durations are both 5.5s.
              var duration = Math.max(0.001, Number.isFinite(parsedDuration) ? parsedDuration : 5.5);

              // RETIME RANGE: these values own the whole pacing decision. The
              // interval and row entrance compress together, never via timeScale.
              var ROW_IN_BASE = 0.4;
              var OUT_BASE = 0.4;
              var baseEntranceSpan = (beatCount - 1) * interval + ROW_IN_BASE;
              var OUT = duration <= OUT_BASE ? duration / 2 : OUT_BASE;
              var entranceBudget = duration - OUT;
              var scale = baseEntranceSpan > entranceBudget ? entranceBudget / baseEntranceSpan : 1;
              var timedInterval = interval * scale;
              var ROW_IN = ROW_IN_BASE * scale;
              var ENTRANCE_SPAN = (beatCount - 1) * timedInterval + ROW_IN;
              var HOLD = Math.max(0, duration - (ENTRANCE_SPAN + OUT));
              var OUT_START = ENTRANCE_SPAN + HOLD;

              function fireSfx(id, t) {
                root.dispatchEvent(
                  new CustomEvent("hf:sfx", { detail: { id: id, t: t }, bubbles: true }),
                );
              }

              var rows = [];
              for (var i = 0; i < beatCount; i += 1) {
                var title = suppliedLabels[i] || "Beat " + (i + 1);
                var row = document.createElement("div");
                row.className = "bt-row";
                row.innerHTML =
                  '<div class="bt-index" aria-hidden="true"></div>' +
                  '<div class="bt-copy"><div class="bt-title"></div><div class="bt-subtitle"></div></div>';
                row.querySelector(".bt-index").textContent = String(i + 1).padStart(2, "0");
                row.querySelector(".bt-title").textContent = title;
                row.querySelector(".bt-subtitle").textContent =
                  "Cue " +
                  String(i + 1).padStart(2, "0") +
                  "  ·  " +
                  (i * timedInterval).toFixed(2) +
                  "s";
                stack.appendChild(row);
                rows.push(row);
              }

              // Explicit entrance and exit endpoints make a direct seek to t=0
              // correct without ever playing the timeline.
              gsap.set(rows, { opacity: 0, y: "2cqh", scale: 0.98 });

              var tl = gsap.timeline({ paused: true });

              // ORCHESTRATION SPINE: every row tween and its declared cue are
              // pinned to the named label, never to a duplicated numeric offset.
              for (var beatIndex = 0; beatIndex < beatCount; beatIndex += 1) {
                var labelName = "beat" + beatIndex;
                var cueTime = beatIndex * timedInterval;
                var cueId = beatIndex === beatCount - 1 ? "beat-tick-final" : "beat-tick";
                tl.addLabel(labelName, cueTime);
                tl.to(
                  rows[beatIndex],
                  { opacity: 1, y: "0cqh", scale: 1, duration: ROW_IN, ease: "power2.out" },
                  labelName,
                );
                // SFX CUE (IN, beat N): one scene-mixed cue at this beat label.
                tl.call(fireSfx, [cueId, cueTime], labelName);
              }

              // HOLD is deliberately still. OUT accelerates every landed row away
              // together, asymmetrically paired with the power2.out entrances.
              tl.to(rows, { opacity: 0, duration: OUT, ease: "power2.in" }, OUT_START);

              tl.seek(0);

              window.__timelines = window.__timelines || {};
              window.__timelines[compositionId] = tl;
            })();
          </script>
        </div>
      </template>
    </body>
  </html>
  ```
</Accordion>

Tagged `orchestration` `transitions` `sequencing` `bridge` `timeline`.

## Related topics

* [Browse the complete Catalog](/catalog)
* [Add assets and Catalog items in Studio](/studio/assets-and-blocks)
* [Build a richer composition](/go-further)


## Related topics

- [Beat Accent](/catalog/components/beat-accent.md)
- [Beat Freeze Cut](/catalog/blocks/beat-freeze-cut.md)
- [Beat Pulse Background](/catalog/components/beat-pulse-background.md)
