1 files changed, 131 insertions, 0 deletions
diff --git a/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/GaplessInfoHolder.java b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/GaplessInfoHolder.java
new file mode 100644
index 0000000000..11893d6136
--- /dev/null
+++ b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/GaplessInfoHolder.java
@@ -0,0 +1,131 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.mozilla.thirdparty.com.google.android.exoplayer2.extractor;
+
+import org.mozilla.thirdparty.com.google.android.exoplayer2.Format;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.metadata.Metadata;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.metadata.id3.CommentFrame;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.metadata.id3.InternalFrame;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+ * Holder for gapless playback information.
+ */
+public final class GaplessInfoHolder {
+
+  private static final String GAPLESS_DOMAIN = "com.apple.iTunes";
+  private static final String GAPLESS_DESCRIPTION = "iTunSMPB";
+  private static final Pattern GAPLESS_COMMENT_PATTERN =
+      Pattern.compile("^ [0-9a-fA-F]{8} ([0-9a-fA-F]{8}) ([0-9a-fA-F]{8})");
+
+  /**
+   * The number of samples to trim from the start of the decoded audio stream, or
+   * {@link Format#NO_VALUE} if not set.
+   */
+  public int encoderDelay;
+
+  /**
+   * The number of samples to trim from the end of the decoded audio stream, or
+   * {@link Format#NO_VALUE} if not set.
+   */
+  public int encoderPadding;
+
+  /**
+   * Creates a new holder for gapless playback information.
+   */
+  public GaplessInfoHolder() {
+    encoderDelay = Format.NO_VALUE;
+    encoderPadding = Format.NO_VALUE;
+  }
+
+  /**
+   * Populates the holder with data from an MP3 Xing header, if valid and non-zero.
+   *
+   * @param value The 24-bit value to decode.
+   * @return Whether the holder was populated.
+   */
+  public boolean setFromXingHeaderValue(int value) {
+    int encoderDelay = value >> 12;
+    int encoderPadding = value & 0x0FFF;
+    if (encoderDelay > 0 || encoderPadding > 0) {
+      this.encoderDelay = encoderDelay;
+      this.encoderPadding = encoderPadding;
+      return true;
+    }
+    return false;
+  }
+
+  /**
+   * Populates the holder with data parsed from ID3 {@link Metadata}.
+   *
+   * @param metadata The metadata from which to parse the gapless information.
+   * @return Whether the holder was populated.
+   */
+  public boolean setFromMetadata(Metadata metadata) {
+    for (int i = 0; i < metadata.length(); i++) {
+      Metadata.Entry entry = metadata.get(i);
+      if (entry instanceof CommentFrame) {
+        CommentFrame commentFrame = (CommentFrame) entry;
+        if (GAPLESS_DESCRIPTION.equals(commentFrame.description)
+            && setFromComment(commentFrame.text)) {
+          return true;
+        }
+      } else if (entry instanceof InternalFrame) {
+        InternalFrame internalFrame = (InternalFrame) entry;
+        if (GAPLESS_DOMAIN.equals(internalFrame.domain)
+            && GAPLESS_DESCRIPTION.equals(internalFrame.description)
+            && setFromComment(internalFrame.text)) {
+          return true;
+        }
+      }
+    }
+    return false;
+  }
+
+  /**
+   * Populates the holder with data parsed from a gapless playback comment (stored in an ID3 header
+   * or MPEG 4 user data), if valid and non-zero.
+   *
+   * @param data The comment's payload data.
+   * @return Whether the holder was populated.
+   */
+  private boolean setFromComment(String data) {
+    Matcher matcher = GAPLESS_COMMENT_PATTERN.matcher(data);
+    if (matcher.find()) {
+      try {
+        int encoderDelay = Integer.parseInt(matcher.group(1), 16);
+        int encoderPadding = Integer.parseInt(matcher.group(2), 16);
+        if (encoderDelay > 0 || encoderPadding > 0) {
+          this.encoderDelay = encoderDelay;
+          this.encoderPadding = encoderPadding;
+          return true;
+        }
+      } catch (NumberFormatException e) {
+        // Ignore incorrectly formatted comments.
+      }
+    }
+    return false;
+  }
+
+  /**
+   * Returns whether {@link #encoderDelay} and {@link #encoderPadding} have been set.
+   */
+  public boolean hasGaplessInfo() {
+    return encoderDelay != Format.NO_VALUE && encoderPadding != Format.NO_VALUE;
+  }
+
+}