Fixes for correctly supporting UTF-16 and UTF-16BE charsets

For fields encoded using UTF-16 or UTF-16BE charsets when looking for
termination character we have to look for two zero consecutive bytes.

Otherwise, as many characters encoded with UTF-16 or UTF-16BE has one
of their 2 bytes set with the value zero, we will be truncating text
fields.

library/src/main/java/com/google/android/exoplayer/metadata/Id3Parser.java

@@ -29,6 +29,11 @@ import java.util.Map;
  */
 public class Id3Parser implements MetadataParser<Map<String, Object>> {
 
+  private static final int ID3_TEXT_ENCODING_ISO_8859_1 = 0;
+  private static final int ID3_TEXT_ENCODING_UTF_16 = 1;
+  private static final int ID3_TEXT_ENCODING_UTF_16BE = 2;
+  private static final int ID3_TEXT_ENCODING_UTF_8 = 3;
+
   @Override
   public boolean canParse(String mimeType) {
     return mimeType.equals(MimeTypes.APPLICATION_ID3);
@@ -60,10 +65,10 @@ public class Id3Parser implements MetadataParser<Map<String, Object>> {
         byte[] frame = new byte[frameSize - 1];
         id3Data.readBytes(frame, 0, frameSize - 1);
 
-        int firstZeroIndex = indexOf(frame, 0, (byte) 0);
+        int firstZeroIndex = indexOfEOS(frame, 0, encoding);
         String description = new String(frame, 0, firstZeroIndex, charset);
-        int valueStartIndex = indexOfNot(frame, firstZeroIndex, (byte) 0);
+        int valueStartIndex = firstZeroIndex + 1;
-        int valueEndIndex = indexOf(frame, valueStartIndex, (byte) 0);
+        int valueEndIndex = indexOfEOS(frame, valueStartIndex, encoding);
         String value = new String(frame, valueStartIndex, valueEndIndex - valueStartIndex,
             charset);
         metadata.put(TxxxMetadata.TYPE, new TxxxMetadata(description, value));
@@ -73,7 +78,7 @@ public class Id3Parser implements MetadataParser<Map<String, Object>> {
         id3Data.readBytes(frame, 0, frameSize);
 
         int firstZeroIndex = indexOf(frame, 0, (byte) 0);
-        String owner = new String(frame, 0, firstZeroIndex);
+        String owner = new String(frame, 0, firstZeroIndex, "ISO-8859-1");
         byte[] privateData = new byte[frameSize - firstZeroIndex - 1];
         System.arraycopy(frame, firstZeroIndex + 1, privateData, 0, frameSize - firstZeroIndex - 1);
         metadata.put(PrivMetadata.TYPE, new PrivMetadata(owner, privateData));
@@ -85,13 +90,13 @@ public class Id3Parser implements MetadataParser<Map<String, Object>> {
         id3Data.readBytes(frame, 0, frameSize - 1);
 
         int firstZeroIndex = indexOf(frame, 0, (byte) 0);
-        String mimeType = new String(frame, 0, firstZeroIndex);
+        String mimeType = new String(frame, 0, firstZeroIndex, "ISO-8859-1");
         int filenameStartIndex = firstZeroIndex + 1;
-        int filenameEndIndex = indexOf(frame, filenameStartIndex, (byte) 0);
+        int filenameEndIndex = indexOfEOS(frame, filenameStartIndex, encoding);
         String filename = new String(frame, filenameStartIndex,
                                      filenameEndIndex - filenameStartIndex, charset);
         int descriptionStartIndex = filenameEndIndex + 1;
-        int descriptionEndIndex = indexOf(frame, descriptionStartIndex, (byte) 0);
+        int descriptionEndIndex = indexOfEOS(frame, descriptionStartIndex, encoding);
         String description = new String(frame, descriptionStartIndex,
                 descriptionEndIndex - descriptionStartIndex, charset);
 
@@ -131,6 +136,25 @@ public class Id3Parser implements MetadataParser<Map<String, Object>> {
     return data.length;
   }
 
+  private static int indexOfEOS(byte[] data, int fromIndex, int encodingByte) {
+    int terminationPos = indexOf(data, fromIndex, (byte) 0);
+
+    // For single byte encoding charsets, we are done
+    if(encodingByte == ID3_TEXT_ENCODING_ISO_8859_1 || encodingByte == ID3_TEXT_ENCODING_UTF_8) {
+      return terminationPos;
+    }
+
+    // Otherwise, look for a two zero bytes
+    while(terminationPos < data.length - 1) {
+      if(data[terminationPos + 1] == (byte) 0) {
+        return terminationPos + 1;
+      }
+      terminationPos = indexOf(data, terminationPos + 1, (byte) 0);
+    }
+
+    return data.length;
+  }
+
   /**
    * Parses an ID3 header.
    *
@@ -175,13 +199,13 @@ public class Id3Parser implements MetadataParser<Map<String, Object>> {
    */
   private static String getCharsetName(int encodingByte) {
     switch (encodingByte) {
-      case 0:
+      case ID3_TEXT_ENCODING_ISO_8859_1:
         return "ISO-8859-1";
-      case 1:
+      case ID3_TEXT_ENCODING_UTF_16:
         return "UTF-16";
-      case 2:
+      case ID3_TEXT_ENCODING_UTF_16BE:
         return "UTF-16BE";
-      case 3:
+      case ID3_TEXT_ENCODING_UTF_8:
         return "UTF-8";
       default:
         return "ISO-8859-1";

library/src/main/java/com/google/android/exoplayer/metadata/PrivMetadata.java

@@ -26,7 +26,7 @@ public class PrivMetadata {
   public final String owner;
   public final byte[] privateData;
 
-  public PrivMetadata(String owner, byte [] privateData) {
+  public PrivMetadata(String owner, byte[] privateData) {
     this.owner = owner;
     this.privateData = privateData;
   }