HDMI 1.4b standard defines how 3D is packaged in one frame. The AVI infoframe contains the packing information that is sent to the sink. The sink, of which the 7619 is only a receiver, must then interpret the infoframe data and unpack the left/right images from the frame.
The ADV7619 only converts serial to parallel data. It does not unpack the images. That is the responsibility of the devices connected to the pixel bus.
The LM1881 is meant to do CVBS sync separation, nothing to do with 3D.