[android JB audioflinger] SyncEvent

 

1. SyncEvent can be used to delayapp receiving data   until playback is complete onanother audio seasion (trigger session).

 

2. mFramestoDrop:numberof captured frames to drop after the start sync event has been received. when< 0, maximum frames to drop before starting capture even if sync eventis not received, which is used to control whether callmActiveTrack->releaseBuffer(&buffer); because, record client  has no space to get the data unless release the buffer;

 

3.  Playback thread callPlaybackThread::Track::triggerEvents to trigger the event callback;