Added flags to the mp3 extractor to control behavior of the extractor. Added…

Added flags to the mp3 extractor to control behavior of the extractor. Added FLAG_ENABLE_CONSTANT_BITRATE_SEEKING to let the extractor know that the CBR seeker is desired in the case where the seeker has determine the track is not seekable For example, in the case where the track has a Xing Header but no content table.

library/src/main/java/com/google/android/exoplayer2/extractor/mp3/Mp3Extractor.java

@@ -31,8 +31,13 @@ import com.google.android.exoplayer2.metadata.Metadata;
 import com.google.android.exoplayer2.metadata.id3.Id3Decoder;
 import com.google.android.exoplayer2.util.ParsableByteArray;
 import com.google.android.exoplayer2.util.Util;
+
+import android.support.annotation.IntDef;
+
 import java.io.EOFException;
 import java.io.IOException;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
 
 /**
  * Extracts data from an MP3 file.
@@ -52,6 +57,19 @@ public final class Mp3Extractor implements Extractor {
   };
 
   /**
+   * Flags controlling the behavior of the extractor.
+   */
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef(flag = true, value = {FLAG_ENABLE_CONSTANT_BITRATE_SEEKING})
+  public @interface Flags {}
+
+  /**
+   * Flag to force enable seeking using a constant bitrate assumption in cases where seeking would
+   * otherwise not be possible.
+   */
+  public static final int FLAG_ENABLE_CONSTANT_BITRATE_SEEKING = 1;
+
+  /**
    * The maximum number of bytes to search when synchronizing, before giving up.
    */
   private static final int MAX_SYNC_BYTES = 128 * 1024;
@@ -72,6 +90,9 @@ public final class Mp3Extractor implements Extractor {
   private static final int INFO_HEADER = Util.getIntegerCodeForString("Info");
   private static final int VBRI_HEADER = Util.getIntegerCodeForString("VBRI");
 
+  @Flags
+  private final int flags;
+
   private final long forcedFirstSampleTimestampUs;
   private final ParsableByteArray scratch;
   private final MpegAudioHeader synchronizedHeader;
@@ -93,16 +114,27 @@ public final class Mp3Extractor implements Extractor {
    * Constructs a new {@link Mp3Extractor}.
    */
   public Mp3Extractor() {
-    this(C.TIME_UNSET);
+    this(0);
+  }
+
+  /**
+   * Constructs a new {@link Mp3Extractor}.
+   *
+   * @param flags Flags that control the extractor's behavior.
+   */
+  public Mp3Extractor(@Flags int flags) {
+    this(flags, C.TIME_UNSET);
   }
 
   /**
    * Constructs a new {@link Mp3Extractor}.
    *
+   * @param flags Flags that control the extractor's behavior.
    * @param forcedFirstSampleTimestampUs A timestamp to force for the first sample, or
    *     {@link C#TIME_UNSET} if forcing is not required.
    */
-  public Mp3Extractor(long forcedFirstSampleTimestampUs) {
+  public Mp3Extractor(@Flags int flags, long forcedFirstSampleTimestampUs) {
+    this.flags = flags;
     this.forcedFirstSampleTimestampUs = forcedFirstSampleTimestampUs;
     scratch = new ParsableByteArray(SCRATCH_LENGTH);
     synchronizedHeader = new MpegAudioHeader();
@@ -350,7 +382,8 @@ public final class Mp3Extractor implements Extractor {
       }
     }
 
-    if (seeker == null) {
+    if (seeker == null || (!seeker.isSeekable()
+        && (flags & FLAG_ENABLE_CONSTANT_BITRATE_SEEKING) != 0)) {
       // Repopulate the synchronized header in case we had to skip an invalid seeking header, which
       // would give an invalid CBR bitrate.
       input.resetPeekPosition();

library/src/main/java/com/google/android/exoplayer2/source/hls/HlsMediaChunk.java

@@ -379,7 +379,7 @@ import java.util.concurrent.atomic.AtomicInteger;
         || lastPathSegment.endsWith(EC3_FILE_EXTENSION)) {
       extractor = new Ac3Extractor(startTimeUs);
     } else if (lastPathSegment.endsWith(MP3_FILE_EXTENSION)) {
-      extractor = new Mp3Extractor(startTimeUs);
+      extractor = new Mp3Extractor(0, startTimeUs);
     } else {
       throw new IllegalArgumentException("Unkown extension for audio file: " + lastPathSegment);
     }