1 files changed, 87 insertions, 0 deletions
diff --git a/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/Id3Peeker.java b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/Id3Peeker.java
new file mode 100644
index 0000000000..a0a26c76d8
--- /dev/null
+++ b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/Id3Peeker.java
@@ -0,0 +1,87 @@
+/*
+ * Copyright (C) 2018 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 androidx.annotation.Nullable;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.metadata.Metadata;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.metadata.id3.Id3Decoder;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.ParsableByteArray;
+import java.io.EOFException;
+import java.io.IOException;
+
+/**
+ * Peeks data from the beginning of an {@link ExtractorInput} to determine if there is any ID3 tag.
+ */
+public final class Id3Peeker {
+
+  private final ParsableByteArray scratch;
+
+  public Id3Peeker() {
+    scratch = new ParsableByteArray(Id3Decoder.ID3_HEADER_LENGTH);
+  }
+
+  /**
+   * Peeks ID3 data from the input and parses the first ID3 tag.
+   *
+   * @param input The {@link ExtractorInput} from which data should be peeked.
+   * @param id3FramePredicate Determines which ID3 frames are decoded. May be null to decode all
+   *     frames.
+   * @return The first ID3 tag decoded into a {@link Metadata} object. May be null if ID3 tag is not
+   *     present in the input.
+   * @throws IOException If an error occurred peeking from the input.
+   * @throws InterruptedException If the thread was interrupted.
+   */
+  @Nullable
+  public Metadata peekId3Data(
+      ExtractorInput input, @Nullable Id3Decoder.FramePredicate id3FramePredicate)
+      throws IOException, InterruptedException {
+    int peekedId3Bytes = 0;
+    Metadata metadata = null;
+    while (true) {
+      try {
+        input.peekFully(scratch.data, /* offset= */ 0, Id3Decoder.ID3_HEADER_LENGTH);
+      } catch (EOFException e) {
+        // If input has less than ID3_HEADER_LENGTH, ignore the rest.
+        break;
+      }
+      scratch.setPosition(0);
+      if (scratch.readUnsignedInt24() != Id3Decoder.ID3_TAG) {
+        // Not an ID3 tag.
+        break;
+      }
+      scratch.skipBytes(3); // Skip major version, minor version and flags.
+      int framesLength = scratch.readSynchSafeInt();
+      int tagLength = Id3Decoder.ID3_HEADER_LENGTH + framesLength;
+
+      if (metadata == null) {
+        byte[] id3Data = new byte[tagLength];
+        System.arraycopy(scratch.data, 0, id3Data, 0, Id3Decoder.ID3_HEADER_LENGTH);
+        input.peekFully(id3Data, Id3Decoder.ID3_HEADER_LENGTH, framesLength);
+
+        metadata = new Id3Decoder(id3FramePredicate).decode(id3Data, tagLength);
+      } else {
+        input.advancePeekPosition(framesLength);
+      }
+
+      peekedId3Bytes += tagLength;
+    }
+
+    input.resetPeekPosition();
+    input.advancePeekPosition(peekedId3Bytes);
+    return metadata;
+  }
+}