I'm using Blender 2.8 Alpha and I was wondering if in Grease Pencil there's a way that you can use a link instead of coping drawings (shift+d) for mouth shapes in the dope sheet. So if I have 10 mouth shapes that cover the basic phonemes and I do an animation that uses those shapes I have to copy each shape in the GP dope sheet to the place I would like to use it. if I finish my animation and find I want to change one of the phonemes shapes I could change the original but I would have to find each occurrence of that shape in the dope sheet and replace it. It would be great if there was a way to only have to update the original. I didn't know if this is already in GP or not.
maybe you've already found the way, but just in case: If I understood it well, yes. You have to create the phonemes as a grease pencil object whit all shapes as a frames in a separate blend file. Link the mouth object via "file> link>object" in the destination file. place your instance and edit frame phoneme order as you want. Go back to the original file whenever you want to edit one of the phonemes. Save and the edited shapes would update.
I found the answer to this problem in this video.
To summarize, create your mouth shapes on a separate layer, one shape per frame.
Then add a Time Offset modifier, set the mode to Fixed Frame and under Layer select your mouths layer.
To lipsync, you now can move around the timeline, select the appropriate mouth shape by changing the frame number in the Time Offset modifier and add a keyframe by pressing
I over it.
And when you change a mouthshape it will update for the whole animation!
Also, changing the dope sheet from Grease Pencil to general will let you adjust the timing of the keyframes easily.