Song of the Flame (1930)
Song of the Flame (1930) is an all-talking pre-code musical operetta film photographed entirely in Technicolor. It was produced and distributed by First National Pictures, a subsidiary of Warner Brothers. It was the first color film to feature a widescreen sequence, using a process called Vitascope, the trademark name for Warner Bros.' widescreen process. The film, based on the 1925 Broadway musical of the same name, was nominated for an Academy Award for Sound Recording (George Groves).
More at Wikipedia.