extract_transcript

Extracts text transcripts from YouTube videos to create LinkedIn post drafts, converting video content into editable written material.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`youtubeUrl`	Yes	YouTube video URL

Implementation Reference

src/modules/transcript-extractor.js:10-48 (handler)

Core handler function implementing the transcript extraction logic from YouTube videos using the 'youtube-transcript' library with API fallback.

export async function extractTranscript(youtubeUrl, youtubeApiKey = null) {
  try {
    console.log(`Extracting transcript from: ${youtubeUrl}`);
    
    // Extract video ID from URL
    const videoId = extractVideoId(youtubeUrl);
    if (!videoId) {
      throw new Error("Invalid YouTube URL. Could not extract video ID.");
    }
    
    // Try to get transcript using youtube-transcript package
    try {
      const transcriptItems = await YoutubeTranscript.fetchTranscript(videoId);
      if (!transcriptItems || transcriptItems.length === 0) {
        throw new Error("No transcript available");
      }
      
      // Combine transcript segments into a single text
      const fullTranscript = transcriptItems
        .map(item => item.text)
        .join(' ')
        .replace(/\s+/g, ' '); // Clean up extra spaces
      
      return fullTranscript;
    } catch (error) {
      console.error("Error with primary transcript method:", error);
      
      // Fallback to YouTube API if available
      if (youtubeApiKey) {
        return await fetchTranscriptWithYouTubeAPI(videoId, youtubeApiKey);
      } else {
        throw new Error("Failed to extract transcript: " + error.message);
      }
    }
  } catch (error) {
    console.error("Transcript extraction error:", error);
    throw new Error(`Failed to extract transcript: ${error.message}`);
  }
}

src/server.js:74-110 (registration)

MCP server tool registration for 'extract_transcript', including input schema, execution handler wrapper, and description.

server.tool(
  "extract_transcript",
  { 
    youtubeUrl: z.string().url().describe("YouTube video URL")
  },
  async ({ youtubeUrl }) => {
    try {
      // Check if YouTube API key is set (if needed)
      if (!apiKeyManager.hasYouTubeKey()) {
        console.log("No YouTube API key set, will try without it");
      }
      
      const transcript = await extractTranscript(youtubeUrl, apiKeyManager.getYouTubeKey());
      return {
        content: [{ 
          type: "text", 
          text: JSON.stringify({
            success: true,
            transcript
          }, null, 2)
        }]
      };
    } catch (error) {
      return {
        content: [{ 
          type: "text", 
          text: JSON.stringify({
            success: false,
            error: error.message
          }, null, 2)
        }],
        isError: true
      };
    }
  },
  { description: "Extract transcript from a YouTube video" }
);

src/server.js:76-78 (schema)
Zod schema defining the input parameter 'youtubeUrl' as a required URL string.
```
{ 
  youtubeUrl: z.string().url().describe("YouTube video URL")
},
```

src/modules/transcript-extractor.js:54-74 (helper)

Helper function to parse YouTube video ID from various URL formats.

 */
function extractVideoId(url) {
  try {
    const urlObj = new URL(url);
    
    // Standard YouTube URL (youtube.com/watch?v=VIDEO_ID)
    if (urlObj.hostname.includes('youtube.com')) {
      return urlObj.searchParams.get('v');
    }
    
    // Short YouTube URL (youtu.be/VIDEO_ID)
    if (urlObj.hostname === 'youtu.be') {
      return urlObj.pathname.substring(1);
    }
    
    return null;
  } catch (error) {
    console.error("Error extracting video ID:", error);
    return null;
  }
}

src/modules/transcript-extractor.js:81-104 (helper)

Fallback helper for fetching transcript via YouTube Data API v3 (incomplete, notes OAuth2 needed).

 */
async function fetchTranscriptWithYouTubeAPI(videoId, apiKey) {
  if (!apiKey) {
    throw new Error("YouTube API key not provided");
  }
  
  // First, get the caption track
  const captionUrl = `https://www.googleapis.com/youtube/v3/captions?part=snippet&videoId=${videoId}&key=${apiKey}`;
  
  const response = await fetch(captionUrl);
  if (!response.ok) {
    throw new Error(`YouTube API error: ${response.statusText}`);
  }
  
  const data = await response.json();
  
  if (!data.items || data.items.length === 0) {
    throw new Error("No captions available for this video");
  }
  
  // Note: Actually downloading the caption track requires OAuth2 authentication
  // which is beyond the scope of this example
  throw new Error("YouTube API fallback requires OAuth2 authentication");
}

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