pagecast

Instructions

Implementation Reference

• src/converter.js:27-64 (handler)

  The actual implementation of the tool logic, using ffmpeg to convert a .webm file to an optimized GIF.

  export async function convertToGif(webmPath, options = {}) {
    await checkFfmpeg();
    await access(webmPath); // throws if file doesn't exist
  
    const fps = options.fps || 10;
    const width = options.width || 640;
    const startTime = options.startTime || 0; // skip blank loading frames
    const gifPath = options.outputPath || webmPath.replace(/\.webm$/, '.gif');
    const palettePath = webmPath.replace(/\.webm$/, '-palette.png');
  
    const scaleFilter = `fps=${fps},scale=${width}:-1:flags=lanczos`;
    const inputArgs = startTime > 0 ? ['-ss', String(startTime), '-i', webmPath] : ['-i', webmPath];
  
    // Pass 1: generate palette
    await run('ffmpeg', [
      ...inputArgs,
      '-vf', `${scaleFilter},palettegen=stats_mode=diff`,
      '-y', palettePath
    ]);
  
    // Pass 2: encode GIF with palette
    await run('ffmpeg', [
      ...inputArgs,
      '-i', palettePath,
      '-lavfi', `${scaleFilter}[x];[x][1:v]paletteuse=dither=bayer:bayer_scale=5:diff_mode=rectangle`,
      '-y', gifPath
    ]);
  
    // Clean up palette
    await unlink(palettePath).catch(() => {});
  
    const gifStat = await stat(gifPath);
    return {
      gifPath,
      sizeBytes: gifStat.size,
      sizeMB: (gifStat.size / 1024 / 1024).toFixed(2)
    };
  }

• src/index.js:99-121 (registration)

  Registration of the 'convert_to_gif' MCP tool.

  mcp.tool(
    'convert_to_gif',
    'Convert a .webm video to an optimized GIF using ffmpeg two-pass palette method.',
    {
      webmPath: z.string().describe('Path to the .webm file'),
      fps: z.number().optional().default(10).describe('GIF frame rate (default 10)'),
      width: z.number().optional().default(640).describe('GIF width in pixels (default 640, height auto-scaled)'),
      startTime: z.number().optional().default(0).describe('Skip first N seconds (useful to trim blank loading frames)')
    },
    async ({ webmPath, fps, width, startTime }) => {
      try {
        const result = await convertToGif(webmPath, { fps, width, startTime });
        return {
          content: [{
            type: 'text',
            text: `GIF created!\n\nFile: ${result.gifPath}\nSize: ${result.sizeMB} MB`
          }]
        };
      } catch (err) {
        return { content: [{ type: 'text', text: `Error: ${err.message}` }], isError: true };
      }
    }
  );