diff --git a/include/media/AudioRecord.h b/include/media/AudioRecord.h
index 5bfb65b..80d2d72 100644
--- a/include/media/AudioRecord.h
+++ b/include/media/AudioRecord.h
@@ -30,6 +30,7 @@
 #include <utils/threads.h>
 
 #include <system/audio.h>
+#include <media/AudioSystem.h>
 
 namespace android {
 
@@ -215,8 +216,11 @@
 
     /* After it's created the track is not active. Call start() to
      * make it active. If set, the callback will start being called.
+     * if event is not AudioSystem::SYNC_EVENT_NONE, the capture start will be delayed until
+     * the specified event occurs on the specified trigger session.
      */
-            status_t    start();
+            status_t    start(AudioSystem::sync_event_t event = AudioSystem::SYNC_EVENT_NONE,
+                              int triggerSession = 0);
 
     /* Stop a track. If set, the callback will cease being called and
      * obtainBuffer returns STOPPED. Note that obtainBuffer() still works
diff --git a/include/media/AudioSystem.h b/include/media/AudioSystem.h
index cc0a594..e64bc3f 100644
--- a/include/media/AudioSystem.h
+++ b/include/media/AudioSystem.h
@@ -145,6 +145,21 @@
         uint32_t latency;
     };
 
+    // Events used to synchronize actions between audio sessions.
+    // For instance SYNC_EVENT_PRESENTATION_COMPLETE can be used to delay recording start until playback
+    // is complete on another audio session.
+    // See definitions in MediaSyncEvent.java
+    enum sync_event_t {
+        SYNC_EVENT_SAME = -1,             // used internally to indicate restart with same event
+        SYNC_EVENT_NONE = 0,
+        SYNC_EVENT_PRESENTATION_COMPLETE,
+
+        //
+        // Define new events here: SYNC_EVENT_START, SYNC_EVENT_STOP, SYNC_EVENT_TIME ...
+        //
+        SYNC_EVENT_CNT,
+    };
+
     //
     // IAudioPolicyService interface (see AudioPolicyInterface for method descriptions)
     //
diff --git a/include/media/IAudioRecord.h b/include/media/IAudioRecord.h
index 089be3b..c486c6b 100644
--- a/include/media/IAudioRecord.h
+++ b/include/media/IAudioRecord.h
@@ -25,7 +25,6 @@
 #include <binder/IInterface.h>
 #include <binder/IMemory.h>
 
-
 namespace android {
 
 // ----------------------------------------------------------------------------
@@ -39,7 +38,7 @@
      * make it active. If set, the callback will start being called.
      * tid identifies the client callback thread, or 0 if not needed.
      */
-    virtual status_t    start(pid_t tid) = 0;
+    virtual status_t    start(pid_t tid, int event, int triggerSession) = 0;
 
     /* Stop a track. If set, the callback will cease being called and
      * obtainBuffer will return an error. Buffers that are already released
diff --git a/include/media/ToneGenerator.h b/include/media/ToneGenerator.h
index df0c97e..29c8fd9 100644
--- a/include/media/ToneGenerator.h
+++ b/include/media/ToneGenerator.h
@@ -159,6 +159,9 @@
 
     bool isInited() { return (mState == TONE_IDLE)?false:true;}
 
+    // returns the audio session this ToneGenerator belongs to or 0 if an error occured.
+    int getSessionId() { return (mpAudioTrack == NULL) ? 0 : mpAudioTrack->getSessionId(); }
+
 private:
 
     enum tone_state {