or informational signals to the audio system 120 to assist the audio system to maintain synchronization typically a v systems provide some user adjustment to the synching in the event that the synching done by the system does not yield a desired result normally processing and rendering of video signals takes longer than processing and rendering of audio signals a typical processing and rendering time for video signals is 150 ms while a typical processing and rendering time for audio signals is 30 ms synching usually involves applying a delay indicated by delay 216 to the audio signals of for example about 120 ms one factor that can dramatically affect the processing and rendering time for video signals is whether the video signals are two dimensional 2d or three dimensional 3d the processing and rendering of 3d video signals may take as long as 400 ms compared with a typical processing and rendering time of 150 ms for non 3d video signals digital audio and digital video signals are transmitted in discrete units as indicated by blocks 240 a and 242 a each unit of audio and video signal may include two types of information the audio signal data or video signal data 248 a and 244 a respectively and metadata i e information about the audio signal.