Video & Audio Editing MCP Server

Instructions

Implementation Reference

• server.py:427-439 (handler)

  The handler function for the 'set_video_audio_track_codec' MCP tool. It uses FFmpeg to change the audio codec of the video's audio track, first trying to copy the video stream, falling back to re-encoding the video if necessary. The schema (input parameters and description) is defined in the function signature and docstring.

  @mcp.tool()
  def set_video_audio_track_codec(input_video_path: str, output_video_path: str, audio_codec: str) -> str:
      """Sets the audio codec of a video's audio track, attempting to copy the video stream.
      Args:
          input_video_path: Path to the source video file.
          output_video_path: Path to save the video with the new audio codec.
          audio_codec: Target audio codec (e.g., 'aac', 'mp3').
      Returns:
          A status message indicating success or failure.
      """
      primary_kwargs = {'acodec': audio_codec, 'vcodec': 'copy'}
      fallback_kwargs = {'acodec': audio_codec} # Re-encode video
      return _run_ffmpeg_with_fallback(input_video_path, output_video_path, primary_kwargs, fallback_kwargs)

• server.py:332-349 (helper)

  Supporting helper function called by set_video_audio_track_codec (and similar tools) to execute the FFmpeg command with a primary set of parameters (e.g., copying the video stream) and a fallback (full re-encode). Handles errors and provides status messages.

  def _run_ffmpeg_with_fallback(input_path: str, output_path: str, primary_kwargs: dict, fallback_kwargs: dict) -> str:
      """Helper to run ffmpeg command with primary kwargs, falling back to other kwargs on ffmpeg.Error."""
      try:
          ffmpeg.input(input_path).output(output_path, **primary_kwargs).run(capture_stdout=True, capture_stderr=True)
          return f"Operation successful (primary method) and saved to {output_path}"
      except ffmpeg.Error as e_primary:
          try:
              ffmpeg.input(input_path).output(output_path, **fallback_kwargs).run(capture_stdout=True, capture_stderr=True)
              return f"Operation successful (fallback method) and saved to {output_path}"
          except ffmpeg.Error as e_fallback:
              err_primary_msg = e_primary.stderr.decode('utf8') if e_primary.stderr else str(e_primary)
              err_fallback_msg = e_fallback.stderr.decode('utf8') if e_fallback.stderr else str(e_fallback)
              return f"Error. Primary method failed: {err_primary_msg}. Fallback method also failed: {err_fallback_msg}"
      except FileNotFoundError:
          return f"Error: Input file not found at {input_path}"
      except Exception as e:
          return f"An unexpected error occurred: {str(e)}"

• server.py:10-10 (registration)

  Initialization of the FastMCP server instance where tools like set_video_audio_track_codec are registered via the @mcp.tool() decorator.

  mcp = FastMCP("VideoAudioServer")