Handle cenc:pssh elements in DASH manifests.

Issue: #407

library/src/main/java/com/google/android/exoplayer/dash/DashChunkSource.java

@@ -419,7 +419,9 @@ public class DashChunkSource implements ChunkSource {
             (ChunkIndex) initializationChunk.getSeekMap(),
             initializationChunk.dataSpec.uri.toString());
       }
-      if (initializationChunk.hasDrmInitData()) {
+      // The null check avoids overwriting drmInitData obtained from the manifest with drmInitData
+      // obtained from the stream, as per DASH IF Interoperability Recommendations V3.0, 7.5.3.
+      if (drmInitData == null && initializationChunk.hasDrmInitData()) {
         drmInitData = initializationChunk.getDrmInitData();
       }
     }

library/src/main/java/com/google/android/exoplayer/dash/mpd/MediaPresentationDescriptionParser.java

@@ -24,10 +24,12 @@ import com.google.android.exoplayer.dash.mpd.SegmentBase.SingleSegmentBase;
 import com.google.android.exoplayer.upstream.UriLoadable;
 import com.google.android.exoplayer.util.Assertions;
 import com.google.android.exoplayer.util.MimeTypes;
+import com.google.android.exoplayer.util.ParsableByteArray;
 import com.google.android.exoplayer.util.UriUtil;
 import com.google.android.exoplayer.util.Util;
 
 import android.text.TextUtils;
+import android.util.Base64;
 
 import org.xml.sax.helpers.DefaultHandler;
 import org.xmlpull.v1.XmlPullParser;
@@ -41,6 +43,7 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
+import java.util.UUID;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -270,11 +273,27 @@ public class MediaPresentationDescriptionParser extends DefaultHandler
   protected ContentProtection parseContentProtection(XmlPullParser xpp)
       throws XmlPullParserException, IOException {
     String schemeIdUri = xpp.getAttributeValue(null, "schemeIdUri");
-    return buildContentProtection(schemeIdUri);
+    UUID uuid = null;
+    byte[] data = null;
+    do {
+      xpp.next();
+      // The cenc:pssh element is defined in 23001-7:2015
+      if (isStartTag(xpp, "cenc:pssh") && xpp.next() == XmlPullParser.TEXT) {
+        byte[] decodedData = Base64.decode(xpp.getText(), Base64.DEFAULT);
+        ParsableByteArray psshAtom = new ParsableByteArray(decodedData);
+        psshAtom.skipBytes(12);
+        uuid = new UUID(psshAtom.readLong(), psshAtom.readLong());
+        int dataSize = psshAtom.readInt();
+        data = new byte[dataSize];
+        psshAtom.readBytes(data, 0, dataSize);
+      }
+    } while (!isEndTag(xpp, "ContentProtection"));
+
+    return buildContentProtection(schemeIdUri, uuid, data);
   }
 
-  protected ContentProtection buildContentProtection(String schemeIdUri) {
-    return new ContentProtection(schemeIdUri, null, null);
+  protected ContentProtection buildContentProtection(String schemeIdUri, UUID uuid, byte[] data) {
+    return new ContentProtection(schemeIdUri, uuid, data);
   }
 
   /**