17 Film Mixing

Film mixing is an entirely different process than stereo music mixing, primarily due to the use of surround sound, with six or more channels of audio in the final mix. But even beyond that fundamental difference, the process of creating audio and then mixing it all together is more complex, with music being only one component of the sonic landscape.

A single, mono audio track can be routed through one or more 5.1 group channels, FX channels, stem channels, and then a final mix channel, all while maintaining perspective among the six channels of the mix path. Beyond that, a two-channel version of the mix for stereo presentation is almost always needed in the final deliverables.

Even before the mix that will be heard by the end viewer of a film, an intermediate mixing step creates “stems,” or groups of sounds each in their own mix, that are then used to create mixes for each delivery format, from theatrical presentation to DVD release, and also stereo broadcast. Each final mix for a specific delivery format is known as a print master.

There can be so many source tracks that a film uses, running into the hundreds of tracks, that it is often necessary to first pare these down into sets of tracks known as pre-dubs. Each pre-dub contains a set of related sounds (dialogue, sound FX, etc.) that have been prepared for mixdown. If a single element (such as the growl of a monster) is made up of several tracks, the pre-dub process will mix those elemental tracks down to a single growl sound that is ready to be part of the final mix.

You can think of a complete film production process in four basic stages:

Assembly. In this first stage, all the elements are edited together to the picture. Often this is such a large task that teams will handle each group of sounds: dialogue to one team, foley to another, sound effects to a third, and of course, music to the film composer and music editor.

Pre-Dubs. In this stage, each team will prepare its tracks for the mixing process, combining elements into complete sounds.

Stems. This is the main mixing stage, often called the dub, and it is where all the sounds are combined into subgroups for each type of sound: dialogue, foley, SFX, etc. Each group is mixed to a stem. Think of a stem as a submix.

Print Mastering. All the stems are combined together to create a final mix for each specific delivery format: 5.1, 7.1, stereo, foreign language, etc.

For this chapter, we will be looking at primarily the third stage, the dubbing process. It is here that all the creative mix decisions are made between the sound team and the director of the film.