Schmelzer was born in Scheibbs, Lower Austria. Nothing is known about his early years, and most of the surviving information about his background was recounted by the composer himself in his petition for ennoblement of 1673. He described his father as a soldier, but in another document, the 1645 marriage certificate of Schmelzer's sister Eva Rosina, he is listed as a baker. Schmelzer does not mention his father's name, but Eva Rosina's marriage certificate does: Daniel Schmelzer. At any rate, it remains unclear where and from whom Schmelzer received primary music education. His activities before 1643 are similarly unknown–the composer is first mentioned in a document dated 28 June 1643, relating to his first marriage. He is referred to as a cornettist at St. Stephen's Cathedral ("Stephansdom"), Vienna. The date of his arrival to Vienna is unknown, but he probably worked at the court chapel in the late 1630s, in the employ of Ferdinand II and, after 1637, Ferdinand III. Schmelzer's colleagues at the chapel included such distinguished composers as Johann Jakob Froberger, Giovanni Valentini, and Antonio Bertali.