def initialize(self, start_time=0):
        """Opens the file, creates the pipe."""
        self.close()  # if any

        if start_time != 0:
            offset = min(1, start_time)
            i_arg = [
                "-ss",
                "%.05f" % (start_time - offset),
                "-i",
                ffmpeg_escape_filename(self.filename),
                "-vn",
                "-ss",
                "%.05f" % offset,
            ]
        else:
            i_arg = ["-i", ffmpeg_escape_filename(self.filename), "-vn"]

        cmd = (
            [FFMPEG_BINARY]
            + i_arg
            + [
                "-loglevel",
                "error",
                "-f",
                self.format,
                "-acodec",
                self.codec,
                "-ar",
                "%d" % self.fps,
                "-ac",
                "%d" % self.nchannels,
                "-",
            ]
        )

        popen_params = cross_platform_popen_params(
            {
                "bufsize": self.buffersize,
                "stdout": sp.PIPE,
                "stderr": sp.PIPE,
                "stdin": sp.DEVNULL,
            }
        )

        self.proc = sp.Popen(cmd, **popen_params)

        self.pos = np.round(self.fps * start_time)
Opens the file, creates the pipe.
moviepy/audio/io/readers.py