INTRODUCTION
In almost all source engine games, a lip sync or sound to motion sync system in the nature of Half-Life 1 exists. This primarily allows simple models to be created with the ability to lip sync any given WAV file.
The interesting thing about this system is the design that enables more than just mouth movement to fit under this controller. For the mouth parameter of a qc in a model, a series of blend animations are required rather than the specification of an individual bone. This allows for a wide variety of motion sync to sound volume. Also, when using this system, no facial animation or phoneme editing is required, any WAV file can be synced instantly.
METHOD
To use the Half-Life 1 Mouth system on new models, you will obviously require tools to create the models. (I think I have a few links to trial and free resources in my other posts).
A model using the Half-Life Mouth system must initially have a mesh and the ability to animate. The final animation is usually done with an NPC entity, so rigging and bone structures would be beneficial.
First you require a reference .SMD for your model, this is obvious to create the model and will be used as an animation layers comparison for animating the mouth parameter.
Then two or more sequence .SMDs are required as components of the blend sequence animation, one being the animation played when there is no sound passing through or being spoken by the model and the other being when the model has sound passing or being spoken through it.
CLASSIC HL1 MOUTH PROCEDURE
While the animation of a mouth is not the maximum potential of this parameter, the requirements to create a mouth animation for any custom model are:
A bone or bones skinned to mouth components (or mesh that can be animated and compiled correctly)
A reference .SMD file for the model
A mouth open sequence, usually two frames, only have animation on the mouth components, the rest of the body should remain in its reference position so the layer remover can have something to compare to.
A mouth close sequence, two frames, same as above.
These should all naturally be exported to one work folder, where the QC file to compile your model with the new mouth parameter should be. (see below)
QC MOUTH PARAMETER LAYOUT
The mouth system is basically a blend sequence with a tag Source recognises as a set of animations to raise and lower depending on the volume of sound passing through the model ingame.
A basic layout for a mouth controller in a QC file is as shown:
$animation Referencefile.smd "Referencefile.smd" fps 30
$animation lowsoundsequence "lowsoundsequence" fps 30.000000 subtract Referencefile.smd 0
$animation highsoundsequence "highsoundsequence" fps 30.000000 subtract Referencefile.smd 0
$sequence model_mouth "lowsoundsequence" fps 30.00 {
blendwidth 2
blend mouth 0.000000 90.000000
delta
autoplay
highsoundsequence
}
LINE 1
The first line creates an animation to compare the 'open' and 'close' sequences to so the rest of the body can remain in a blank layer that can be filled by other animations, as seen in Half-Life: Source. The Referencefile.smd will be the file name of your reference SMD for your model, this is a simple way to achieve a motion comparison to a reference pose, however, if you want, you can create another reference pose .SMD to use for this parameter.
LINE 2
The second line creates the animation that will be the 'mouth close' sequence, this will usually be looped as an animation layer on the model when there is no sound playing through the model.
The lowsoundsequence will be replaced by the name of your 'mouth closed' sequence .SMD, alongside the choice of speed in framerate for the animation and the subtraction of the reference file, as mentioned in the paragraph above this. The reference file subtract must be the reference file sequence for it to subtract layers of animation correctly.
LINE 3
The third line is as above, creating a 'mouth open' animation for when there is sound passing through the model, these two animations will be blended together and move between each other gradually depending on the sound volume. Again this will use your 'mouth open' animation in place of the highsoundsequence, you can choose the fps and the reference.SMD mentioned two paragraphs above this one.
LINE 4
The fourth component brings it all together in a standard blend sequence. The most important part of this is the blend mouth 0 - 90 component, that registers this as the sequence to play for mouth movement.
Model_mouth is the optional title for this animation, call it what you like.
the following "lowsoundsequence" will be the low sound point sequence using the 'mouth closed' sequence mentioned in above paragraphs.
Then there is the play speed for the whole sequence in frames per second.
Blendwidth 2 indicates or records the number of animations to blend between, this one uses two, an open and a close animation, you could experiment by adding more animations and keeping this number equil to the number of animations included in the blend.
The Blend Mouth parameter registers the sequence as the Mouth sequence to be used to vary depending on volume, the 0.00 to 90.00 is the distance the blend has to go from completely open to completely closed, reducing or increasing this will create a larger distance.
Delta is the key parameter with no arguements that intialises the animation layers, so the mouth sequence plays over the top of other animations, rather than replacing them.
Autoplay triggers this sequence automatically when the model is created, so the mouth sequence is always active, ready to animate when sound passes through the model.
Under autoplay is the list of animations to blend between, in this case there is one, because the other is placed at the top of this section, making two. As mentioned before, you can play with adding more animations while changing Blendwidth to get different effects.
Hopefully this post helps, I'd be interested to see what you can manage with this.