remotion-composition

Remotion Composition

生成用于定义 Remotion 视频中场景排序、计时和转场方式的合成结构文档。本技能仅专注于 Sequence 布局和计时编排。

本技能的功能

生成合成结构，包括：

1. Sequence 布局 — 场景 Sequence 的排序和定位
2. 计时计算 — 每个场景的起始帧、结束帧和时长
3. 场景转场 — 场景之间的重叠和交叉淡化时长
4. 时长映射 — 将所有场景的秒数转换为帧数
5. 计时常量 — 用于 constants.ts 的结构化计时对象

范围边界

范围内：

• Sequence 组件组织
• 场景计时的帧数计算
• 场景重叠和转场计时
• 时长常量生成
• 场景排序逻辑

范围外：

• 场景组件实现（使用 /remotion-component-gen）
• 动画参数（使用 /remotion-animation）
• 视觉样式（颜色、布局）
• 资源管理（使用 /remotion-asset-coordinator）

输入/输出格式

输入格式：带时长的场景列表

接受场景计时规格：

自然语言：

Scene 1 (Intro): 0-5 seconds
Scene 2 (Features): 5-15 seconds
Scene 3 (Demo): 15-25 seconds
Scene 4 (CTA): 25-30 seconds

结构化格式：

## Scene Timing

**Total Duration:** 30 seconds
**Frame Rate:** 30 fps
**Total Frames:** 900

**Scenes:**
1. Scene 1 - Intro: 5 seconds (0s - 5s)
2. Scene 2 - Features: 10 seconds (5s - 15s)
3. Scene 3 - Demo: 10 seconds (15s - 25s)
4. Scene 4 - CTA: 5 seconds (25s - 30s)

**Transitions:**
- Fade transition between scenes: 0.5 seconds (15 frames)

输出格式：COMPOSITION_STRUCTURE.md

生成合成结构文档：

# Composition Structure: ProductDemo

## Status
✅ Sequence layout defined
✅ Timing calculations complete
⏳ Ready for scene implementation

## Composition Overview

**Total Duration:** 30 seconds (900 frames @ 30fps)
**Scenes:** 4
**Transitions:** Crossfade (15 frames)

## Scene Timing Constants

```typescript
const FPS = 30;

export const SCENE_TIMING = {
  intro: {
    start: 0,
    end: 150,
    duration: 150,
    // 0s - 5s
  },
  features: {
    start: 150,
    end: 450,
    duration: 300,
    // 5s - 15s
  },
  demo: {
    start: 450,
    end: 750,
    duration: 300,
    // 15s - 25s
  },
  cta: {
    start: 750,
    end: 900,
    duration: 150,
    // 25s - 30s
  },
} as const;

// Transition timing
export const TRANSITIONS = {
  crossfadeDuration: 15, // frames (0.5 seconds)
} as const;

合成布局

使用 Sequence 结构的主合成：

import { AbsoluteFill, Sequence } from "remotion";
import { SCENE_TIMING } from "./constants";
import { Scene1Intro } from "./scenes/Scene1Intro";
import { Scene2Features } from "./scenes/Scene2Features";
import { Scene3Demo } from "./scenes/Scene3Demo";
import { Scene4CTA } from "./scenes/Scene4CTA";

export function ProductDemo() {
  return (
    <AbsoluteFill>
      {/* Scene 1: Intro (0s - 5s) */}
      <Sequence
        from={SCENE_TIMING.intro.start}
        durationInFrames={SCENE_TIMING.intro.duration}
      >
        <Scene1Intro />
      </Sequence>

      {/* Scene 2: Features (5s - 15s) */}
      <Sequence
        from={SCENE_TIMING.features.start}
        durationInFrames={SCENE_TIMING.features.duration}
      >
        <Scene2Features />
      </Sequence>

      {/* Scene 3: Demo (15s - 25s) */}
      <Sequence
        from={SCENE_TIMING.demo.start}
        durationInFrames={SCENE_TIMING.demo.duration}
      >
        <Scene3Demo />
      </Sequence>

      {/* Scene 4: CTA (25s - 30s) */}
      <Sequence
        from={SCENE_TIMING.cta.start}
        durationInFrames={SCENE_TIMING.cta.duration}
      >
        <Scene4CTA />
      </Sequence>
    </AbsoluteFill>
  );
}

场景计时明细

场景	名称	时长	帧数	起始帧	结束帧
1	开场	5s	150	0	150
2	功能	10s	300	150	450
3	演示	10s	300	450	750
4	行动号召	5s	150	750	900

总计： 30 秒（900 帧）

时间线可视化

Frame:     0        150       450       750       900
Time:      0s        5s        15s       25s       30s
           |---------|---------|---------|---------|
Scene:     |  Intro  | Features|   Demo  |   CTA   |
           |---------|---------|---------|---------|

后续步骤

1. 实现场景，使用 /remotion-component-gen
2. 按需添加转场（交叉淡化、擦除）
3. 将常量集成到合成 constants.ts 中
4. 在 Remotion 预览中测试计时
5. 调整时长，避免场景显得过快或过慢

检查清单

• 已计算场景计时
• 已定义 Sequence 布局
• 已生成常量
• 已构建计时常量
• 已实现场景组件（下一步）
• 已添加转场（如有需要）
• 已在预览中测试计时

## Composition Patterns

### Pattern 1: Sequential Scenes (No Overlap)

Standard sequential layout where scenes don't overlap:

```typescript
<Sequence from={0} durationInFrames={150}>
  <Scene1 />
</Sequence>

<Sequence from={150} durationInFrames={300}>
  <Scene2 />
</Sequence>

<Sequence from={450} durationInFrames={300}>
  <Scene3 />
</Sequence>

模式 2：场景重叠（交叉淡化）

场景重叠，实现平滑转场：

const CROSSFADE = 15; // frames

// Scene 1: Full duration
<Sequence from={0} durationInFrames={150}>
  <Scene1 />
</Sequence>

// Scene 2: Starts before Scene 1 ends
<Sequence from={150 - CROSSFADE} durationInFrames={300 + CROSSFADE}>
  <Scene2 />
</Sequence>

// Scene 3: Starts before Scene 2 ends
<Sequence from={450 - CROSSFADE} durationInFrames={300 + CROSSFADE}>
  <Scene3 />
</Sequence>

模式 3：分层合成

背景和前景场景同时运行：

{/* Background layer - runs full duration */}
<Sequence from={0} durationInFrames={900}>
  <BackgroundScene />
</Sequence>

{/* Foreground scenes - sequential */}
<Sequence from={0} durationInFrames={150}>
  <Scene1 />
</Sequence>

<Sequence from={150} durationInFrames={300}>
  <Scene2 />
</Sequence>

模式 4：嵌套 Sequence

主场景内的子场景：

<Sequence from={0} durationInFrames={300}>
  <AbsoluteFill>
    {/* Sub-scene 1 */}
    <Sequence from={0} durationInFrames={100}>
      <Intro />
    </Sequence>

    {/* Sub-scene 2 */}
    <Sequence from={100} durationInFrames={200}>
      <MainContent />
    </Sequence>
  </AbsoluteFill>
</Sequence>

计时计算辅助工具

常见的帧数计算：

// Convert seconds to frames
const secondsToFrames = (seconds: number, fps: number = 30): number =>
  Math.round(seconds * fps);

// Calculate scene timing
interface SceneTiming {
  start: number;
  end: number;
  duration: number;
}

const calculateSceneTiming = (
  startSeconds: number,
  durationSeconds: number,
  fps: number = 30
): SceneTiming => {
  const start = secondsToFrames(startSeconds, fps);
  const duration = secondsToFrames(durationSeconds, fps);
  const end = start + duration;

  return { start, end, duration };
};

// Calculate crossfade overlap
const calculateCrossfade = (
  scene1Start: number,
  scene1Duration: number,
  crossfadeDuration: number
) => ({
  scene1: {
    from: scene1Start,
    durationInFrames: scene1Duration,
  },
  scene2: {
    from: scene1Start + scene1Duration - crossfadeDuration,
    durationInFrames: crossfadeDuration, // or more if scene is longer
  },
});

// Validate total duration
const validateDuration = (
  scenes: SceneTiming[],
  expectedTotal: number
): boolean => {
  const lastScene = scenes[scenes.length - 1];
  return lastScene.end === expectedTotal;
};

场景计时生成

根据场景列表自动生成计时：

interface SceneSpec {
  name: string;
  durationSeconds: number;
}

const generateSceneTiming = (
  scenes: SceneSpec[],
  fps: number = 30
) => {
  let currentFrame = 0;
  const timing: Record<string, SceneTiming> = {};

  for (const scene of scenes) {
    const duration = secondsToFrames(scene.durationSeconds, fps);

    timing[scene.name] = {
      start: currentFrame,
      end: currentFrame + duration,
      duration,
    };

    currentFrame += duration;
  }

  return {
    timing,
    totalFrames: currentFrame,
    totalSeconds: currentFrame / fps,
  };
};

// Usage:
const scenes = [
  { name: 'intro', durationSeconds: 5 },
  { name: 'features', durationSeconds: 10 },
  { name: 'demo', durationSeconds: 10 },
  { name: 'cta', durationSeconds: 5 },
];

const result = generateSceneTiming(scenes, 30);
// Result:
// {
//   timing: {
//     intro: { start: 0, end: 150, duration: 150 },
//     features: { start: 150, end: 450, duration: 300 },
//     ...
//   },
//   totalFrames: 900,
//   totalSeconds: 30,
// }

转场模式

交叉淡化转场

场景之间平滑地交叉淡化不透明度：

const CROSSFADE = 15;

// Scene 1 - fades out at end
<Sequence from={0} durationInFrames={150}>
  <Scene1 crossfadeOut={CROSSFADE} />
</Sequence>

// Scene 2 - fades in at start
<Sequence from={150 - CROSSFADE} durationInFrames={300}>
  <Scene2 crossfadeIn={CROSSFADE} />
</Sequence>

// In Scene component:
function Scene1({ crossfadeOut = 0 }) {
  const frame = useCurrentFrame();
  const { durationInFrames } = useVideoConfig();

  const opacity = crossfadeOut > 0
    ? interpolate(
        frame,
        [durationInFrames - crossfadeOut, durationInFrames],
        [1, 0],
        { extrapolateRight: 'clamp' }
      )
    : 1;

  return <AbsoluteFill style={{ opacity }}>...</AbsoluteFill>;
}

硬切转场

无转场，场景即时切换：

<Sequence from={0} durationInFrames={150}>
  <Scene1 />
</Sequence>

<Sequence from={150} durationInFrames={300}>
  <Scene2 />
</Sequence>

滑动转场

一个场景滑出，同时下一个场景滑入：

const TRANSITION_DURATION = 20;

<Sequence from={0} durationInFrames={150}>
  <Scene1 slideOut={TRANSITION_DURATION} />
</Sequence>

<Sequence from={150 - TRANSITION_DURATION} durationInFrames={300}>
  <Scene2 slideIn={TRANSITION_DURATION} />
</Sequence>

时长验证

确保计时总和正确：

// Validation helper
const validateCompositionTiming = (
  scenes: Record<string, SceneTiming>,
  expectedDuration: number,
  fps: number
): { valid: boolean; issues: string[] } => {
  const issues: string[] = [];

  // Check for gaps
  const sceneList = Object.entries(scenes).sort((a, b) => a[1].start - b[1].start);

  for (let i = 0; i < sceneList.length - 1; i++) {
    const currentEnd = sceneList[i][1].end;
    const nextStart = sceneList[i + 1][1].start;

    if (nextStart > currentEnd) {
      issues.push(`Gap detected: ${currentEnd} to ${nextStart} (${(nextStart - currentEnd) / fps}s)`);
    }
    if (nextStart < currentEnd) {
      issues.push(`Overlap detected: ${sceneList[i][0]} and ${sceneList[i + 1][0]}`);
    }
  }

  // Check total duration
  const lastScene = sceneList[sceneList.length - 1][1];
  if (lastScene.end !== expectedDuration) {
    issues.push(
      `Total duration mismatch: expected ${expectedDuration}, got ${lastScene.end} (${lastScene.end / fps}s)`
    );
  }

  return {
    valid: issues.length === 0,
    issues,
  };
};

时间线可视化辅助工具

生成 ASCII 时间线：

const generateTimeline = (
  scenes: Record<string, SceneTiming>,
  fps: number,
  width: number = 60
) => {
  const lastScene = Object.values(scenes).reduce((max, scene) =>
    scene.end > max ? scene.end : max, 0
  );

  const timeline: string[] = [];

  // Frame markers
  const frameMarkers = Array.from({ length: width + 1 }, (_, i) => {
    const frame = Math.round((i / width) * lastScene);
    return frame.toString().padStart(4);
  }).join('');
  timeline.push('Frame: ' + frameMarkers);

  // Time markers
  const timeMarkers = Array.from({ length: width + 1 }, (_, i) => {
    const time = ((i / width) * lastScene) / fps;
    return time.toFixed(1) + 's';
  }).join(' ');
  timeline.push('Time:  ' + timeMarkers);

  // Scene bars
  for (const [name, timing] of Object.entries(scenes)) {
    const startPos = Math.round((timing.start / lastScene) * width);
    const endPos = Math.round((timing.end / lastScene) * width);
    const bar = ' '.repeat(startPos) + '|' + '='.repeat(endPos - startPos - 1) + '|';
    timeline.push(`${name.padEnd(8)}: ${bar}`);
  }

  return timeline.join('\n');
};

最佳实践

计时指南

// Minimum scene duration for readability
const MIN_SCENE_DURATION = 30; // 1 second at 30fps

// Standard transition duration
const STANDARD_TRANSITION = 15; // 0.5 seconds

// Maximum scene duration before pacing feels slow
const MAX_SCENE_DURATION = 600; // 20 seconds

// Recommended scene duration range
const IDEAL_SCENE_DURATION = {
  min: 60,   // 2 seconds
  max: 300,  // 10 seconds
};

合成组织

// Group related Sequences
// Good:
<>
  {/* Background layer */}
  <Sequence from={0} durationInFrames={900}>
    <Background />
  </Sequence>

  {/* Content scenes */}
  <Sequence from={0} durationInFrames={150}>
    <Scene1 />
  </Sequence>
  <Sequence from={150} durationInFrames={300}>
    <Scene2 />
  </Sequence>
</>

// Bad: Mixed layers without organization

集成工作流

1. 定义场景时长 → 输入到本技能
2. 生成合成结构 → COMPOSITION_STRUCTURE.md
3. 添加到合成文件（index.tsx）
4. 将计时添加到常量（constants.ts）
5. 实现场景，使用 /remotion-component-gen
6. 在预览中测试计时
7. 按需调整并重新生成

与其他技能集成

此技能会与以下技能协同：

remotion-composition (this skill)
    ↓ outputs: COMPOSITION_STRUCTURE.md
remotion-component-gen
    ↓ implements scenes with timing awareness
remotion-animation
    ↓ animation timing works within scene durations

协同使用：

• /motion-designer — 根据设计规范确定场景时长
• /remotion-scaffold — 将结构添加到合成文件中
• /remotion-animation — 时序与动画配置相协调
• /remotion-component-gen — 场景时长符合计算结果
• /remotion-spec-translator — 在工作流中协调此技能

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此技能提供精确的合成结构和时长计算，确保 Remotion 视频流畅且节奏得当。