Sound source music is also called objective music. It is also called music in a painting, such as the characters in the painting singing or playing the piano. Refers to the music that should appear under specified circumstances in the movie screen, such as characters singing, playing musical instruments, broadcasting, etc. At this point, the presence of music is essential (but special arrangements can also be made).

Audio source music refers to the music that should appear under the circumstances specified in the movie screen, such as characters singing, playing musical instruments, broadcasting, etc. At this time, the appearance of music is indispensable; the picture does not provide a basis for the appearance of music, but music specially created by the composer to shape the character's personality, express the character's inner emotions, or enhance the environmental atmosphere. It is a supplement, explanation or evaluation of the picture. It expresses the composer's subjective attitude towards the events shown in the film. It can deepen the content of the picture and enhance the artistic appeal of the film.

As far as the film itself is concerned, the integration of music has significantly improved the overall artistic level of the film. The original movie only contains simple dialogues and characters' voices, leaving an extremely monotonous impression on the audience, and it seems to be just a two-dimensional effect. And when music penetrates into movies, a comprehensive stage that integrates literature, art and other artistic styles, the three-dimensional effect immediately appears.

The use of music in movies did not exist from the beginning, but movies have changed since music was incorporated into movies. In general, it plays an indispensable role in enhancing the emotion of the film, highlighting the drama of the plot, and exaggerating the atmosphere.