[WVDRM] Fix for stuttering on low bandwidth

Reintroduces the play/pause rebuffering logic we eliminated
in JB zero day to fix double spins and slow startup - but
activates that logic only based on a comparison of the
current bandwidth measurement and the lowest bitrate track
in the movie.

Needs to be submitted with related changes in /frameworks/av

bug: 7230071
Change-Id: Ib3859a961bd3901a9c4df01eeab2b8b75f49aefe

proprietary/wvm/WVMExtractorImpl.cpp

@@ -524,19 +524,26 @@ int64_t WVMExtractorImpl::getCachedDurationUs(status_t *finalStatus) {
     const size_t kMaxEncodedRates = 32;
     unsigned long encodedRates[kMaxEncodedRates];
     size_t ratesReturned, currentTrack;
+    unsigned long minRate = ULONG_MAX;
+    unsigned long bandwidth = ULONG_MAX;
 
     WVStatus status = WV_Info_GetAdaptiveBitrates(mSession, encodedRates, kMaxEncodedRates,
                                                   &ratesReturned, &currentTrack);
     if (status == WV_Status_OK) {
         if (currentTrack != kMaxEncodedRates && ratesReturned != 0) {
+            for (size_t i = 0; i < ratesReturned; i++) {
+                if (encodedRates[i] < minRate) {
+                    minRate = encodedRates[i];
+                }
+            }
+
+            WV_Info_CurrentBandwidth(mSession, &bandwidth);
+
             // Log the current adaptive rate every 5 seconds
             time_t now = time(0);
             static time_t lastLogTime = now;
             if (now > lastLogTime + 5) {
                 lastLogTime = now;
-                unsigned long bandwidth = -1;
-                WV_Info_CurrentBandwidth(mSession, &bandwidth);
-
                 ALOGI("using adaptive track #%d, rate=%ld, bandwidth=%ld\n",
                       currentTrack, encodedRates[currentTrack], bandwidth);
             }
@@ -544,12 +551,22 @@ int64_t WVMExtractorImpl::getCachedDurationUs(status_t *finalStatus) {
     }
 
     uint64_t durationUs = 0;
+    float secondsBuffered;
+    status = WV_Info_TimeBuffered(mSession, &secondsBuffered);
 
-    if (!mVideoSource->isStalled() && !mAudioSource->isStalled()) {
-        // Data is buffered as long as the pull isn't stalled.
-        // The amount indicated doesn't matter as long as it
-        // is more than the high water mark.
+    //
+    // As long as the bandwidth is greater than the min bitrate, don't
+    // need to consider rebuffering so return a buffered time greater
+    // than the low water mark.  This provides fast startup when the
+    // network speed is good and rebuffering when it is not.
+    //
+    if (bandwidth != ULONG_MAX && minRate != ULONG_MAX && bandwidth >= minRate) {
+        //ALOGD("Bandwidth %ld is sufficient for lowest rate %ld, override buffered time", bandwidth, minRate);
         durationUs = 10000000LL;
+    } else {
+        unsigned long kScaleFactor = 2; // scale to cached duration to tune watermark levels
+        durationUs = (uint64_t)(secondsBuffered * 1000000LL * kScaleFactor);
+        //ALOGD("Bandwidth %ld is too low for lowest rate %ld, use buffered time %lld", bandwidth, minRate, durationUs);
     }
 
     if (status == WV_Status_End_Of_Media) {

proprietary/wvm/WVMMediaSource.cpp

@@ -37,7 +37,6 @@ WVMMediaSource::WVMMediaSource(WVSession *session, WVEsSelector esSelector,
       mIsLiveStream(isLive),
       mNewSegment(false),
       mCryptoInitialized(false),
-      mIsStalled(false),
       mStripADTS(false),
       mGroup(NULL),
       mKeyTime(0),
@@ -214,8 +213,6 @@ status_t WVMMediaSource::read(MediaBuffer **buffer, const ReadOptions *options)
 {
     Mutex::Autolock autoLock(mLock);
 
-    mIsStalled = false;
-
     CHECK(mStarted);
 
     *buffer = NULL;
@@ -351,8 +348,6 @@ status_t WVMMediaSource::read(MediaBuffer **buffer, const ReadOptions *options)
                 return ERROR_IO;
             } else {
                 // Didn't get anything, sleep a bit so we don't hog the CPU then try again
-                if (retryCount > 10)
-                    mIsStalled = true;
                 usleep(10000);
                 continue;
             }
@@ -364,15 +359,12 @@ status_t WVMMediaSource::read(MediaBuffer **buffer, const ReadOptions *options)
 
         if (seekNextSync && ((mKeyTime < seekTimeUs) || !syncFrame)) {
             // drop frames up to next sync if requested
-            mIsStalled = true;
             usleep(10000);
             mDecryptContext.Initialize(mediaBuf);
             mEncryptedSizes.clear();
             continue;
         }
 
-        mIsStalled = false;
-
         if (offset + bytesRead < mediaBuf->size())
             break;
 

proprietary/wvm/include/WVMMediaSource.h

@@ -41,7 +41,6 @@ public:
     virtual status_t read(MediaBuffer **buffer, const ReadOptions *options = NULL);
 
     void addEncryptedSize(size_t size) { mEncryptedSizes.push_back(size); }
-    bool isStalled() const { return mIsStalled; }
 
     static int sLastError;
 
@@ -87,7 +86,6 @@ private:
     bool mIsLiveStream;
     bool mNewSegment;
     bool mCryptoInitialized;
-    bool mIsStalled;
     bool mStripADTS;
 
     MediaBufferGroup *mGroup;