Shaka Packager MCP Server

Instructions

Implementation Reference

• shaka_packager_mcp.py:284-421 (handler)

  The core handler function for the 'analyze_video' MCP tool. Decorated with @mcp.tool() for automatic registration. Handles file path translation, resource reading for file:// URIs, executes Shaka Packager with --dump_stream_info, and formats detailed output or error summaries.
  @mcp.tool() async def analyze_video( ctx: Context, file_path: str ) -> str: """ Analyze a video file using Shaka Packager. Args: file_path: Path to the video file. Can be a local file path or a file:// URI from the filesystem MCP. """ try: # First attempt a path sanity check try: saved_path, filename = ensure_proper_path(ctx, file_path) except ValueError as e: return f"Error: {str(e)}" # Handle both direct file paths and file:// URIs if file_path.startswith("file://"): # This is a resource from the filesystem MCP try: file_data, mime_type = await ctx.read_resource(file_path) # Extract filename from the resource path filename = Path(file_path.split("/")[-1]).name # Save the file saved_path = save_uploaded_file(file_data, filename) ctx.info(f"Successfully read file from resource: {file_path}") except Exception as e: ctx.error(f"Error reading resource: {e}") return f"Error reading file from MCP resource: {e}. Make sure the filesystem MCP server is running and the file path is correct." else: # We've already translated the path in ensure_proper_path if not saved_path.exists() or not saved_path.is_file(): return f"Error: File not found at path: {file_path}. Please provide a valid file path or a file:// URI from the filesystem MCP." ctx.info(f"Using local file: {saved_path}") # Run the dump_stream_info command with proper input format cmd = [PACKAGER_PATH, "--dump_stream_info", f"input={str(saved_path)}"] # Log the original command for debugging ctx.info(f"Original command: {' '.join(cmd)}") # Translate any paths in command arguments translated_cmd = [cmd[0]] + translate_command_args(cmd[1:]) ctx.info(f"Running command with translated paths: {' '.join(translated_cmd)}") result = await run_command(translated_cmd) # Even if the command fails, we'll provide the output to the LLM output = result["stdout"] error_message = result["stderr"] if result["exit_code"] != 0: ctx.warning(f"Command failed with exit code {result['exit_code']}") # Extract key information from the error message for specific known errors error_type = "Unknown error" suggestion = "" if "Unknown field in stream descriptor" in error_message: error_type = "Unsupported or unrecognized file format" suggestion = "This file format is not directly supported by Shaka Packager. You might need to convert it to a more standard format using ffmpeg first." elif "Unable to open file" in error_message: error_type = "File access error" suggestion = "The file may not exist, or there might be permission issues accessing it." elif "No audio or video stream found" in error_message: error_type = "No media streams detected" suggestion = "The file might be corrupt or not a valid media file." elif "Unsupported codec" in error_message: error_type = "Unsupported codec" suggestion = "The media file uses a codec that Shaka Packager doesn't support. Consider transcoding to a different codec." # Create a summary that includes both the error and any output summary = f""" # Video Analysis Results (VALID RESPONSE - DO NOT RETRY) ## Error Type {error_type} ## Command ``` {result['command']} ``` ## Stream Information ``` {output} ``` ## Errors ``` {error_message} ``` ## Analysis - File: {filename} - Execution time: {result['execution_time']:.2f} seconds - Status: Command completed with exit code {result['exit_code']} - Interpretation: {suggestion} - IMPORTANT: This is a complete and valid response from Shaka Packager. No further attempts are needed. - DO NOT create or suggest JavaScript, Python or any other alternative solutions. This is a Shaka Packager-specific tool. The error message provides valuable information about the file. Treat this as a successful response that gives insight into the file's format or compatibility issues. Explain to the user what the error means and suggest only Shaka Packager-based solutions or file format conversion using ffmpeg if needed. """ return summary # Create a success summary output = result["stdout"] summary = f""" # Video Analysis Results (VALID RESPONSE) ## Command ``` {result['command']} ``` ## Stream Information ``` {output} ``` ## Summary - File: {filename} - Execution time: {result['execution_time']:.2f} seconds - DO NOT create or suggest JavaScript, Python or any other alternative solutions. This is a Shaka Packager-specific tool. """ return summary except Exception as e: ctx.error(f"Error in analyze_video: {str(e)}") return f"Error: {str(e)}"
• shaka_packager_mcp.py:998-1012 (helper)

  A helper prompt function registered with @mcp.prompt() that generates a suggestion for using the analyze_video tool on a given file path.
  @mcp.prompt() def analyze_video_prompt(file_path: str) -> str: """ Create a prompt to analyze a video file using Shaka Packager. Args: file_path: Path to the uploaded video file. """ return f""" I want to analyze this video file using Shaka Packager: {file_path} Could you run the analyze_video tool to get detailed information about the streams in this file? """
• shaka_packager_mcp.py:284-421 (registration)

  The @mcp.tool() decorator on the analyze_video function serves as the registration mechanism in FastMCP, automatically adding the tool to the MCP server.
  @mcp.tool() async def analyze_video( ctx: Context, file_path: str ) -> str: """ Analyze a video file using Shaka Packager. Args: file_path: Path to the video file. Can be a local file path or a file:// URI from the filesystem MCP. """ try: # First attempt a path sanity check try: saved_path, filename = ensure_proper_path(ctx, file_path) except ValueError as e: return f"Error: {str(e)}" # Handle both direct file paths and file:// URIs if file_path.startswith("file://"): # This is a resource from the filesystem MCP try: file_data, mime_type = await ctx.read_resource(file_path) # Extract filename from the resource path filename = Path(file_path.split("/")[-1]).name # Save the file saved_path = save_uploaded_file(file_data, filename) ctx.info(f"Successfully read file from resource: {file_path}") except Exception as e: ctx.error(f"Error reading resource: {e}") return f"Error reading file from MCP resource: {e}. Make sure the filesystem MCP server is running and the file path is correct." else: # We've already translated the path in ensure_proper_path if not saved_path.exists() or not saved_path.is_file(): return f"Error: File not found at path: {file_path}. Please provide a valid file path or a file:// URI from the filesystem MCP." ctx.info(f"Using local file: {saved_path}") # Run the dump_stream_info command with proper input format cmd = [PACKAGER_PATH, "--dump_stream_info", f"input={str(saved_path)}"] # Log the original command for debugging ctx.info(f"Original command: {' '.join(cmd)}") # Translate any paths in command arguments translated_cmd = [cmd[0]] + translate_command_args(cmd[1:]) ctx.info(f"Running command with translated paths: {' '.join(translated_cmd)}") result = await run_command(translated_cmd) # Even if the command fails, we'll provide the output to the LLM output = result["stdout"] error_message = result["stderr"] if result["exit_code"] != 0: ctx.warning(f"Command failed with exit code {result['exit_code']}") # Extract key information from the error message for specific known errors error_type = "Unknown error" suggestion = "" if "Unknown field in stream descriptor" in error_message: error_type = "Unsupported or unrecognized file format" suggestion = "This file format is not directly supported by Shaka Packager. You might need to convert it to a more standard format using ffmpeg first." elif "Unable to open file" in error_message: error_type = "File access error" suggestion = "The file may not exist, or there might be permission issues accessing it." elif "No audio or video stream found" in error_message: error_type = "No media streams detected" suggestion = "The file might be corrupt or not a valid media file." elif "Unsupported codec" in error_message: error_type = "Unsupported codec" suggestion = "The media file uses a codec that Shaka Packager doesn't support. Consider transcoding to a different codec." # Create a summary that includes both the error and any output summary = f""" # Video Analysis Results (VALID RESPONSE - DO NOT RETRY) ## Error Type {error_type} ## Command ``` {result['command']} ``` ## Stream Information ``` {output} ``` ## Errors ``` {error_message} ``` ## Analysis - File: {filename} - Execution time: {result['execution_time']:.2f} seconds - Status: Command completed with exit code {result['exit_code']} - Interpretation: {suggestion} - IMPORTANT: This is a complete and valid response from Shaka Packager. No further attempts are needed. - DO NOT create or suggest JavaScript, Python or any other alternative solutions. This is a Shaka Packager-specific tool. The error message provides valuable information about the file. Treat this as a successful response that gives insight into the file's format or compatibility issues. Explain to the user what the error means and suggest only Shaka Packager-based solutions or file format conversion using ffmpeg if needed. """ return summary # Create a success summary output = result["stdout"] summary = f""" # Video Analysis Results (VALID RESPONSE) ## Command ``` {result['command']} ``` ## Stream Information ``` {output} ``` ## Summary - File: {filename} - Execution time: {result['execution_time']:.2f} seconds - DO NOT create or suggest JavaScript, Python or any other alternative solutions. This is a Shaka Packager-specific tool. """ return summary except Exception as e: ctx.error(f"Error in analyze_video: {str(e)}") return f"Error: {str(e)}"