How do the AV-sync, Frame Dropping and No Sync options in Timeline work when working with audio and video?
They come in help when the animation is too heavy to handle realtime reproduction, affecting only the 3D viewport, not the renders.
No sync means that every frame in the viewport is showed as soon as possible, and a number in the upper left corner of the 3D view tells you the frame rate actually being reproduced: if white everything is OK (I.E. 24 FPS - default), if Red is slower (Maybe 4.67 FPS).
Frame Dropping means that the FPS is always the choosen one (24 - default), and blender jumps from a frame to another trying to remain in sync, actually not displaying (dropping) all the frames between.
AV Sync is used in combination with the VSE, assuring corrispondence between the 3D frame and the VSE frame.
$\begingroup$ Thanks a lot! That was really clarifying. Specially the "affecting only the 3D viewport, not the renders" part. $\endgroup$ Jun 13, 2015 at 18:38
1$\begingroup$ AV Sync is useful for Video Footage in the VSE. It assures, that your playback audio and video matches up. $\endgroup$– SamothJan 20, 2016 at 23:27
As far as I can see:
- No Sync just tries to play back every single Frame no matter if it causes lags or time shifting problems with the Audio or the actual physical time.
- Frame Dropping drops Frames from the ViewPort Animation Playback to match up with the actual Frame Rate being used
- AV Sync skips Frames from Video Footage in the VSE so that Audio and Video in the Image Preview Sequencer Mode stays in sync
The AV Sync mode has been greatly improved in the Gooseberry Branch as Mathieu Auvray explains in his second VSE Editing Tutorial. It works through the whole Blender interface, Sequencer, 3D View, etc and makes sure, that your Audio and Video are in sync and it mostly uses Frame Skipping for this.