Googleの メディア生成 API（Nano Banana / Veo3 / Lyria）と FFmpeg.wasmで動画つくる

			
			# Google Cloudプロジェクトの作成
gcloud projects create <YOUR_PROJECT_ID> --name="AI Media Project"

		

			
			# Vertex AI APIを有効化
gcloud services enable aiplatform.googleapis.com

# gcloud services enable compute.googleapis.com
# gcloud services enable storage.googleapis.com

		

			
			
# ログイン
gcloud auth login

		

			
			npm init -y

# 必要なパッケージのインストール
npm install express cors dotenv
npm install @google/generative-ai  # Gemini SDK
npm install @ffmpeg/ffmpeg @ffmpeg/core


		

			
			# Google Cloud設定
GOOGLE_CLOUD_PROJECT=YOUR_PROJECT_ID
GOOGLE_CLOUD_LOCATION=us-central1

# Google AI Studio APIキー（Gemini用）
GOOGLE_AI_STUDIO_API_KEY=your_gemini_api_key_here

		

			
			// Google AI Studio SDKを使用
const { GoogleGenerativeAI } = require('@google/generative-ai');

async function generateImage(prompt) {
  const API_KEY = process.env.GOOGLE_AI_STUDIO_API_KEY;

  const genAI = new GoogleGenerativeAI(API_KEY);
  const model = genAI.getGenerativeModel({ 
    model: 'gemini-2.5-flash-image-preview',
    generationConfig: {
      temperature: 0.4,
      topK: 32,
      topP: 1,
      maxOutputTokens: 8192
    }
  });

  // 画像生成
  const result = await model.generateContent(prompt);
  const response = result.response;

  const imageData = response.candidates[0].content.parts.find(
    part => part.inlineData
  )?.inlineData.data;

  return `data:image/png;base64,${imageData}`;
}

		

			
			const { execSync } = require('child_process');

function getAccessToken() {
  return execSync('gcloud auth print-access-token', { encoding: 'utf8' }).trim();
}

// 音楽生成
async function generateMusic(prompt) {
  const PROJECT_ID = 'your-project-id';
  const LOCATION = 'us-central1';
  const endpoint = `https://${LOCATION}-aiplatform.googleapis.com/v1/projects/${PROJECT_ID}/locations/${LOCATION}/publishers/google/models/lyria-002:predict`;

  const response = await fetch(endpoint, {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${getAccessToken()}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      instances: [{
        prompt: prompt  // ex. "slow jazz piano"
      }],
      parameters: {
        sample_count: 1
      }
    })
  });

  const result = await response.json();
  const audioContent = result.predictions[0].bytesBase64Encoded;

  // WAVファイルとして保存
  const audioBuffer = Buffer.from(audioContent, 'base64');
  return audioBuffer;
}

		

			
			// テキストから動画生成
async function generateVideo(prompt, params = {}) {
  const PROJECT_ID = 'your-project-id';
  const LOCATION = 'us-central1';
  const endpoint = `https://${LOCATION}-aiplatform.googleapis.com/v1/projects/${PROJECT_ID}/locations/${LOCATION}/publishers/google/models/veo-3.0-generate-001:predictLongRunning`;

  const response = await fetch(endpoint, {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${getAccessToken()}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      instances: [{
        prompt: prompt
      }],
      parameters: {
        aspectRatio: params.aspectRatio,
        durationSeconds: params.duration,
        resolution: params.resolution ,
        sampleCount: 1,
        generateAudio: false,
        seed: params.seed
    })
  });

  const operation = await response.json();
  return operation.name;
}

// 画像から動画生成
async function generateVideoFromImage(imageBase64, prompt) {
  const requestBody = {
    instances: [{
      prompt: prompt || '',
      image: {
        bytesBase64Encoded: imageBase64,
        mimeType: 'image/jpeg'
      }
    }],
    parameters: {
      aspectRatio: '16:9',
      durationSeconds: 8,
      resolution: '720p'
    }
  };

}

		

			
			// FFmpeg.wasmの読み込みと初期化
const { FFmpeg } = FFmpeg;
const ffmpeg = new FFmpeg();

async function initFFmpeg() {
  await ffmpeg.load({
    coreURL: 'https://unpkg.com/@ffmpeg/core@0.11.0/dist/ffmpeg-core.js',
    wasmURL: 'https://unpkg.com/@ffmpeg/core@0.11.0/dist/ffmpeg-core.wasm'
  });

  // SharedArrayBufferのサポート確認
  if (!crossOriginIsolated) {
    console.warn('SharedArrayBuffer is not available');
  }
}

		

			
			async function trimVideo(videoBlob, startTime, endTime) {
  // 動画データをFFmpegに書き込み
  const videoData = new Uint8Array(await videoBlob.arrayBuffer());
  await ffmpeg.writeFile('input.mp4', videoData);

  // トリミング実行
  const duration = endTime - startTime;
  await ffmpeg.exec([
    '-i', 'input.mp4',
    '-ss', startTime.toString(),
    '-t', duration.toString(),
    '-c', 'copy',  // 再エンコードなし
    'output.mp4'
  ]);

  // 結果を取得
  const data = await ffmpeg.readFile('output.mp4');
  return new Blob([data.buffer], { type: 'video/mp4' });
}