From 0f665fbeb8fca52853ab5dd0a8030484e50402dd Mon Sep 17 00:00:00 2001
From: rohks <rohks@google.com>
Date: Tue, 12 Jul 2022 16:53:03 +0000
Subject: [PATCH] Ignore reserved bit in parsing NAL unit type

`HevcConfig.parse` misreads reserved bit to determine NAL unit type. This is currently meant to be always set to 0, but could be given some kind of meaning in a future revision.

Issue: google/ExoPlayer#10366
PiperOrigin-RevId: 460487613
---
 .../android/exoplayer2/video/HevcConfig.java  |  5 +-
 .../exoplayer2/video/HevcConfigTest.java      | 90 +++++++++++++++++++
 2 files changed, 93 insertions(+), 2 deletions(-)

diff --git a/library/extractor/src/main/java/com/google/android/exoplayer2/video/HevcConfig.java b/library/extractor/src/main/java/com/google/android/exoplayer2/video/HevcConfig.java
index 7e688b2e42..6b8e633555 100644
--- a/library/extractor/src/main/java/com/google/android/exoplayer2/video/HevcConfig.java
+++ b/library/extractor/src/main/java/com/google/android/exoplayer2/video/HevcConfig.java
@@ -45,7 +45,7 @@ public final class HevcConfig {
       int csdLength = 0;
       int csdStartPosition = data.getPosition();
       for (int i = 0; i < numberOfArrays; i++) {
-        data.skipBytes(1); // completeness (1), nal_unit_type (7)
+        data.skipBytes(1); // completeness (1), reserved (1), nal_unit_type (6)
         int numberOfNalUnits = data.readUnsignedShort();
         for (int j = 0; j < numberOfNalUnits; j++) {
           int nalUnitLength = data.readUnsignedShort();
@@ -63,7 +63,8 @@ public final class HevcConfig {
       float pixelWidthHeightRatio = 1;
       @Nullable String codecs = null;
       for (int i = 0; i < numberOfArrays; i++) {
-        int nalUnitType = data.readUnsignedByte() & 0x7F; // completeness (1), nal_unit_type (7)
+        int nalUnitType =
+            data.readUnsignedByte() & 0x3F; // completeness (1), reserved (1), nal_unit_type (6)
         int numberOfNalUnits = data.readUnsignedShort();
         for (int j = 0; j < numberOfNalUnits; j++) {
           int nalUnitLength = data.readUnsignedShort();
diff --git a/library/extractor/src/test/java/com/google/android/exoplayer2/video/HevcConfigTest.java b/library/extractor/src/test/java/com/google/android/exoplayer2/video/HevcConfigTest.java
index a4c312e8f7..d87948bb69 100644
--- a/library/extractor/src/test/java/com/google/android/exoplayer2/video/HevcConfigTest.java
+++ b/library/extractor/src/test/java/com/google/android/exoplayer2/video/HevcConfigTest.java
@@ -162,6 +162,86 @@ public final class HevcConfigTest {
         64
       };
 
+  private static final byte[] HVCC_BOX_PAYLOAD_WITH_SET_RESERVED_BIT =
+      new byte[] {
+        // Header
+        1,
+        1,
+        96,
+        0,
+        0,
+        0,
+        -80,
+        0,
+        0,
+        0,
+        0,
+        0,
+        -103,
+        -16,
+        0,
+        -4,
+        -4,
+        -8,
+        -8,
+        0,
+        0,
+        15,
+
+        // Number of arrays
+        1,
+
+        // NAL unit type = SPS (Ignoring reserved bit)
+        // completeness (1), reserved (1), nal_unit_type (6)
+        97,
+        // Number of NAL units
+        0,
+        1,
+        // NAL unit length
+        0,
+        39,
+        // NAL unit
+        66,
+        1,
+        1,
+        1,
+        96,
+        0,
+        0,
+        3,
+        0,
+        -80,
+        0,
+        0,
+        3,
+        0,
+        0,
+        3,
+        0,
+        -103,
+        -96,
+        1,
+        -32,
+        32,
+        2,
+        32,
+        124,
+        78,
+        90,
+        -18,
+        76,
+        -110,
+        -22,
+        86,
+        10,
+        12,
+        12,
+        5,
+        -38,
+        20,
+        37
+      };
+
   @Test
   public void parseHevcDecoderConfigurationRecord() throws Exception {
     ParsableByteArray data = new ParsableByteArray(HVCC_BOX_PAYLOAD);
@@ -170,4 +250,14 @@ public final class HevcConfigTest {
     assertThat(hevcConfig.codecs).isEqualTo("hvc1.1.6.L153.B0");
     assertThat(hevcConfig.nalUnitLengthFieldLength).isEqualTo(4);
   }
+
+  /** https://github.com/google/ExoPlayer/issues/10366 */
+  @Test
+  public void parseHevcDecoderConfigurationRecord_ignoresReservedBit() throws Exception {
+    ParsableByteArray data = new ParsableByteArray(HVCC_BOX_PAYLOAD_WITH_SET_RESERVED_BIT);
+    HevcConfig hevcConfig = HevcConfig.parse(data);
+
+    assertThat(hevcConfig.codecs).isEqualTo("hvc1.1.6.L153.B0");
+    assertThat(hevcConfig.nalUnitLengthFieldLength).isEqualTo(4);
+  }
 }