6 min read
5.1 surround mixing for film, and the stereo fold down nobody checks
Most viewers will hear your 5.1 mix folded to two channels. If you never check the fold down, you never heard what the audience hears.
A 5.1 mix gives you a centre channel for dialogue, two fronts for music and effects, two surrounds for space and an LFE channel for weight. Used well it separates the elements that fight each other in stereo.
What goes where
- Centre: dialogue, almost always, and the anchor of the whole mix.
- Left and right: music, hard effects and anything panned to picture.
- Surrounds: ambience, reverb returns, occasional flybys. Not dialogue.
- LFE: low frequency reinforcement, not a bass channel for the whole mix.
Channel order matters
Film convention is L, R, C, LFE, Ls, Rs. Consumer and some broadcast tools use L, R, Ls, Rs, C, LFE. Deliver a file with the wrong order and dialogue comes out of a surround speaker. Always confirm the order in the delivery spec, and verify the file itself.
The fold down is the real deliverable
Laptops, phones and most home setups play a two channel fold down. A mix that leans on the centre channel can arrive with dialogue too loud or too quiet once folded, and dialogue buried under music is a note you get after delivery.
Check it with a standard LoRo fold down, where the centre is added to both sides at around minus three dB and surrounds are folded in at a lower level. Listen for dialogue intelligibility and phase cancellation in the music.
Doing the check quickly
Our surround to stereo tool takes a 5.1 file, lets you set the level of each channel before the fold, and exports a LoRo stereo file. It runs locally, so a confidential mix never leaves your machine.