diff --git a/media/libmedia/AudioTrack.cpp b/media/libmedia/AudioTrack.cpp
index 02e1570..fb2ee0f 100644
--- a/media/libmedia/AudioTrack.cpp
+++ b/media/libmedia/AudioTrack.cpp
@@ -546,12 +546,13 @@
     }
 
     if (loopStart >= loopEnd ||
-        loopEnd - loopStart > cblk->frameCount) {
+        loopEnd - loopStart > cblk->frameCount ||
+        cblk->server > loopStart) {
         LOGE("setLoop invalid value: loopStart %d, loopEnd %d, loopCount %d, framecount %d, user %d", loopStart, loopEnd, loopCount, cblk->frameCount, cblk->user);
         return BAD_VALUE;
     }
 
-    if ((mSharedBuffer != 0) && (loopEnd   > cblk->frameCount)) {
+    if ((mSharedBuffer != 0) && (loopEnd > cblk->frameCount)) {
         LOGE("setLoop invalid value: loop markers beyond data: loopStart %d, loopEnd %d, framecount %d",
             loopStart, loopEnd, cblk->frameCount);
         return BAD_VALUE;
@@ -825,6 +826,12 @@
 
     uint32_t framesAvail = cblk->framesAvailable();
 
+    cblk->lock.lock();
+    if (cblk->flags & CBLK_INVALID_MSK) {
+        goto create_new_track;
+    }
+    cblk->lock.unlock();
+
     if (framesAvail == 0) {
         cblk->lock.lock();
         goto start_loop_here;
@@ -1148,6 +1155,7 @@
              fromStart ? "start()" : "obtainBuffer()");
 
         cblk->flags |= CBLK_RESTORING_ON;
+
         // signal old cblk condition so that other threads waiting for available buffers stop
         // waiting now
         cblk->cv.broadcast();
@@ -1167,10 +1175,20 @@
                                false);
 
         if (result == NO_ERROR) {
+            // restore write index and set other indexes to reflect empty buffer status
+            mCblk->user = cblk->user;
+            mCblk->server = cblk->user;
+            mCblk->userBase = cblk->user;
+            mCblk->serverBase = cblk->user;
+            // restore loop: this is not guaranteed to succeed if new frame count is not
+            // compatible with loop length
+            setLoop_l(cblk->loopStart, cblk->loopEnd, cblk->loopCount);
             if (!fromStart) {
                 mCblk->bufferTimeoutMs = MAX_RUN_TIMEOUT_MS;
             }
-            result = mAudioTrack->start();
+            if (mActive) {
+                result = mAudioTrack->start();
+            }
             if (fromStart && result == NO_ERROR) {
                 mNewPosition = mCblk->server + mUpdatePeriod;
             }