1 files changed, 238 insertions, 0 deletions
diff --git a/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/video/spherical/ProjectionDecoder.java b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/video/spherical/ProjectionDecoder.java
new file mode 100644
index 0000000000..cff4b2845d
--- /dev/null
+++ b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/video/spherical/ProjectionDecoder.java
@@ -0,0 +1,238 @@
+/*
+ * 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.video.spherical;
+
+import androidx.annotation.Nullable;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.C;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.ParsableBitArray;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.ParsableByteArray;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Util;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.video.spherical.Projection.Mesh;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.video.spherical.Projection.SubMesh;
+import java.util.ArrayList;
+import java.util.zip.Inflater;
+
+/**
+ * A decoder for the projection mesh.
+ *
+ * <p>The mesh boxes parsed are described at <a
+ * href="https://github.com/google/spatial-media/blob/master/docs/spherical-video-v2-rfc.md">
+ * Spherical Video V2 RFC</a>.
+ *
+ * <p>The decoder does not perform CRC checks at the moment.
+ */
+public final class ProjectionDecoder {
+
+  private static final int TYPE_YTMP = 0x79746d70;
+  private static final int TYPE_MSHP = 0x6d736870;
+  private static final int TYPE_RAW = 0x72617720;
+  private static final int TYPE_DFL8 = 0x64666c38;
+  private static final int TYPE_MESH = 0x6d657368;
+  private static final int TYPE_PROJ = 0x70726f6a;
+
+  // Sanity limits to prevent a bad file from creating an OOM situation. We don't expect a mesh to
+  // exceed these limits.
+  private static final int MAX_COORDINATE_COUNT = 10000;
+  private static final int MAX_VERTEX_COUNT = 32 * 1000;
+  private static final int MAX_TRIANGLE_INDICES = 128 * 1000;
+
+  private ProjectionDecoder() {}
+
+  /*
+   * Decodes the projection data.
+   *
+   * @param projectionData The projection data.
+   * @param stereoMode A {@link C.StereoMode} value.
+   * @return The projection or null if the data can't be decoded.
+   */
+  public static @Nullable Projection decode(byte[] projectionData, @C.StereoMode int stereoMode) {
+    ParsableByteArray input = new ParsableByteArray(projectionData);
+    // MP4 containers include the proj box but webm containers do not.
+    // Both containers use mshp.
+    ArrayList<Mesh> meshes = null;
+    try {
+      meshes = isProj(input) ? parseProj(input) : parseMshp(input);
+    } catch (ArrayIndexOutOfBoundsException ignored) {
+      // Do nothing.
+    }
+    if (meshes == null) {
+      return null;
+    } else {
+      switch (meshes.size()) {
+        case 1:
+          return new Projection(meshes.get(0), stereoMode);
+        case 2:
+          return new Projection(meshes.get(0), meshes.get(1), stereoMode);
+        case 0:
+        default:
+          return null;
+      }
+    }
+  }
+
+  /** Returns true if the input contains a proj box. Indicates MP4 container. */
+  private static boolean isProj(ParsableByteArray input) {
+    input.skipBytes(4); // size
+    int type = input.readInt();
+    input.setPosition(0);
+    return type == TYPE_PROJ;
+  }
+
+  private static @Nullable ArrayList<Mesh> parseProj(ParsableByteArray input) {
+    input.skipBytes(8); // size and type.
+    int position = input.getPosition();
+    int limit = input.limit();
+    while (position < limit) {
+      int childEnd = position + input.readInt();
+      if (childEnd <= position || childEnd > limit) {
+        return null;
+      }
+      int childAtomType = input.readInt();
+      // Some early files named the atom ytmp rather than mshp.
+      if (childAtomType == TYPE_YTMP || childAtomType == TYPE_MSHP) {
+        input.setLimit(childEnd);
+        return parseMshp(input);
+      }
+      position = childEnd;
+      input.setPosition(position);
+    }
+    return null;
+  }
+
+  private static @Nullable ArrayList<Mesh> parseMshp(ParsableByteArray input) {
+    int version = input.readUnsignedByte();
+    if (version != 0) {
+      return null;
+    }
+    input.skipBytes(7); // flags + crc.
+    int encoding = input.readInt();
+    if (encoding == TYPE_DFL8) {
+      ParsableByteArray output = new ParsableByteArray();
+      Inflater inflater = new Inflater(true);
+      try {
+        if (!Util.inflate(input, output, inflater)) {
+          return null;
+        }
+      } finally {
+        inflater.end();
+      }
+      input = output;
+    } else if (encoding != TYPE_RAW) {
+      return null;
+    }
+    return parseRawMshpData(input);
+  }
+
+  /** Parses MSHP data after the encoding_four_cc field. */
+  private static @Nullable ArrayList<Mesh> parseRawMshpData(ParsableByteArray input) {
+    ArrayList<Mesh> meshes = new ArrayList<>();
+    int position = input.getPosition();
+    int limit = input.limit();
+    while (position < limit) {
+      int childEnd = position + input.readInt();
+      if (childEnd <= position || childEnd > limit) {
+        return null;
+      }
+      int childAtomType = input.readInt();
+      if (childAtomType == TYPE_MESH) {
+        Mesh mesh = parseMesh(input);
+        if (mesh == null) {
+          return null;
+        }
+        meshes.add(mesh);
+      }
+      position = childEnd;
+      input.setPosition(position);
+    }
+    return meshes;
+  }
+
+  private static @Nullable Mesh parseMesh(ParsableByteArray input) {
+    // Read the coordinates.
+    int coordinateCount = input.readInt();
+    if (coordinateCount > MAX_COORDINATE_COUNT) {
+      return null;
+    }
+    float[] coordinates = new float[coordinateCount];
+    for (int coordinate = 0; coordinate < coordinateCount; coordinate++) {
+      coordinates[coordinate] = input.readFloat();
+    }
+    // Read the vertices.
+    int vertexCount = input.readInt();
+    if (vertexCount > MAX_VERTEX_COUNT) {
+      return null;
+    }
+
+    final double log2 = Math.log(2.0);
+    int coordinateCountSizeBits = (int) Math.ceil(Math.log(2.0 * coordinateCount) / log2);
+
+    ParsableBitArray bitInput = new ParsableBitArray(input.data);
+    bitInput.setPosition(input.getPosition() * 8);
+    float[] vertices = new float[vertexCount * 5];
+    int[] coordinateIndices = new int[5];
+    int vertexIndex = 0;
+    for (int vertex = 0; vertex < vertexCount; vertex++) {
+      for (int i = 0; i < 5; i++) {
+        int coordinateIndex =
+            coordinateIndices[i] + decodeZigZag(bitInput.readBits(coordinateCountSizeBits));
+        if (coordinateIndex >= coordinateCount || coordinateIndex < 0) {
+          return null;
+        }
+        vertices[vertexIndex++] = coordinates[coordinateIndex];
+        coordinateIndices[i] = coordinateIndex;
+      }
+    }
+
+    // Pad to next byte boundary
+    bitInput.setPosition(((bitInput.getPosition() + 7) & ~7));
+
+    int subMeshCount = bitInput.readBits(32);
+    SubMesh[] subMeshes = new SubMesh[subMeshCount];
+    for (int i = 0; i < subMeshCount; i++) {
+      int textureId = bitInput.readBits(8);
+      int drawMode = bitInput.readBits(8);
+      int triangleIndexCount = bitInput.readBits(32);
+      if (triangleIndexCount > MAX_TRIANGLE_INDICES) {
+        return null;
+      }
+      int vertexCountSizeBits = (int) Math.ceil(Math.log(2.0 * vertexCount) / log2);
+      int index = 0;
+      float[] triangleVertices = new float[triangleIndexCount * 3];
+      float[] textureCoords = new float[triangleIndexCount * 2];
+      for (int counter = 0; counter < triangleIndexCount; counter++) {
+        index += decodeZigZag(bitInput.readBits(vertexCountSizeBits));
+        if (index < 0 || index >= vertexCount) {
+          return null;
+        }
+        triangleVertices[counter * 3] = vertices[index * 5];
+        triangleVertices[counter * 3 + 1] = vertices[index * 5 + 1];
+        triangleVertices[counter * 3 + 2] = vertices[index * 5 + 2];
+        textureCoords[counter * 2] = vertices[index * 5 + 3];
+        textureCoords[counter * 2 + 1] = vertices[index * 5 + 4];
+      }
+      subMeshes[i] = new SubMesh(textureId, triangleVertices, textureCoords, drawMode);
+    }
+    return new Mesh(subMeshes);
+  }
+
+  /**
+   * Decodes Zigzag encoding as described in
+   * https://developers.google.com/protocol-buffers/docs/encoding#signed-integers
+   */
+  private static int decodeZigZag(int n) {
+    return (n >> 1) ^ -(n & 1);
+  }
+}