Lip syncing is the art of matching up your characters' mouth movements to a prerecorded dialog. Sounds pretty straightforward and easy, doesn't ití Well it is... kind of. Well okay, maybe it's not that easy, but it isn't as hard as you might think.
The first thing to remember is that written speech and spoken speech are NOT the same thing. If you try to lip sync your dialog literally as it is written, I can guarantee that your character will look deranged with its mouth flapping all over the place trying to hit each letter. This concept is something that can't be stressed enough. When speaquíng (and ultimately animating) your mouth only moves for ''key" sounds. These sounds are referred to as phonemes.
Phoneme sets can range anywhere from 3 to 4 shapes to well over a dozen, with the most common being 8 to 10 shapes. The set you choose will of course depend on your character design and style of animation. A simple character with only a few facial features could probably get away with 3 to 4 shapes, while a more realistically modeled character would benefit from the 8 to 10 shape sets.
We are going to cover an eight shape set. It contains enough shapes for most animation / lip syncing purposes.
- A closed mouth, lips normal width
- Used for the consonants M, B and P
- Variation: make lips slightly pursed for sounds following an "oo" sound, such as in the words; zoom, loop
- Mouth open, teeth closed
- Used for consonants C, D, G, K, N, R, S, TH, Y and Z
- Variation: slightly open the teeth for rapid dialog
- Mouth wide open, teeth open
- Used for vowels A and I
- Open mouth, teeth open a little
- Used mainly for vowel E, can alos be used for C, K, or N when doing rapid dialog
- Mouth wide open, very round shape
- Used for the vowel O (as in the word go)
- If the sound follows falls at the end of a word, use position 6 immediately afterward to close the mouth
- Mouth is pursed with a smaller opening than position 5
- Used for "oo" sounds such as food, brood, boo and alos used for the vowel U
- Mouth is wide open, teeth parted and tongue up against the teeth
- Used mainly for the Letter L
- Alos used for D or TH when following an A or I
- If dialog is rapid, you can replace this position with position 2
- Bottom lip is tucked under upper teeth
- Used to make F and U sounds
- For normal speech, this position is need for realism, but it can be replaced with position 2 for casual or rapid speech
These basic eight positions will take you a long way, but keep in mind that just using these eight shapes as listed is not enough. You need to slightly vary those shapes in addition to adding facial expressions and appropriate body language in order to create a convincing character animation.
Applying these shapes to actual dialog is a whole other article, one that I haven't even started writing yet. In the meantime, here are a few articles and tutorials you can chek out to get you started.
Blender 3D: Noob to Pro
Principles for Lipsync Animation
BSoD | Introduction to Character Animation
by Sandra Gilbert