diff --git a/packager/media/codecs/h264_parser.cc b/packager/media/codecs/h264_parser.cc
index 5d3348ab73..f57361d8a9 100644
--- a/packager/media/codecs/h264_parser.cc
+++ b/packager/media/codecs/h264_parser.cc
@@ -985,8 +985,8 @@ H264Parser::Result H264Parser::ParseSliceHeader(const Nalu& nalu,
 
   shdr->idr_pic_flag = (nalu.type() == 5);
   shdr->nal_ref_idc = nalu.ref_idc();
-  shdr->nalu_data = nalu.data() + nalu.header_size();
-  shdr->nalu_size = nalu.payload_size();
+  shdr->nalu_data = nalu.data();
+  shdr->nalu_size = nalu.header_size() + nalu.payload_size();
 
   READ_UE_OR_RETURN(&shdr->first_mb_in_slice);
   READ_UE_OR_RETURN(&shdr->slice_type);
@@ -1116,9 +1116,7 @@ H264Parser::Result H264Parser::ParseSliceHeader(const Nalu& nalu,
     return kUnsupportedStream;
   }
 
-  size_t epb = br->NumEmulationPreventionBytesRead();
-  shdr->header_bit_size = (shdr->nalu_size - epb) * 8 - br->NumBitsLeft();
-
+  shdr->header_bit_size = nalu.payload_size() * 8 - br->NumBitsLeft();
   return kOk;
 }
 
diff --git a/packager/media/codecs/h264_parser.h b/packager/media/codecs/h264_parser.h
index 66717c62db..eb97f94ba8 100644
--- a/packager/media/codecs/h264_parser.h
+++ b/packager/media/codecs/h264_parser.h
@@ -165,9 +165,17 @@ struct H264SliceHeader {
 
   bool idr_pic_flag;       // from NAL header
   int nal_ref_idc;         // from NAL header
-  const uint8_t* nalu_data;  // from NAL header
-  off_t nalu_size;         // from NAL header
-  off_t header_bit_size;   // calculated
+  // Points to the beginning of the nal unit.
+  const uint8_t* nalu_data;
+
+  // Size of whole nalu unit.
+  off_t nalu_size;
+
+  // This is the size of the slice header not including the nalu header byte.
+  // Sturcture: |NALU Header|     Slice Header    |    Slice Data    |
+  // Size:      |<- 8bits ->|<- header_bit_size ->|<- Rest of nalu ->|
+  // Note that this is not a field in the H.264 spec.
+  off_t header_bit_size;
 
   int first_mb_in_slice;
   int slice_type;
diff --git a/packager/media/codecs/h264_parser_unittest.cc b/packager/media/codecs/h264_parser_unittest.cc
index 2a7329ff36..842ad38504 100644
--- a/packager/media/codecs/h264_parser_unittest.cc
+++ b/packager/media/codecs/h264_parser_unittest.cc
@@ -11,6 +11,22 @@
 namespace shaka {
 namespace media {
 
+namespace {
+// SPS, PPS (for first slice), slice header from test-25fps.h264 file.
+const uint8_t kSps[] = {
+    0x27, 0x4D, 0x40, 0x0D, 0xA9, 0x18, 0x28, 0x3E, 0x60, 0x0D,
+    0x41, 0x80, 0x41, 0xAD, 0xB0, 0xAD, 0x7B, 0xDF, 0x01,
+};
+const uint8_t kPps[] = {
+    0x28, 0xDE, 0x9, 0x88,
+};
+// This is the prefix of a video slice that only has the header.
+// The actual slice header size is 30 bits (not including the nalu header).
+const uint8_t kVideoSliceTrimmed[] = {
+    0x25, 0xB8, 0x20, 0x20, 0x63,
+};
+}  // namespace
+
 TEST(H264ParserTest, StreamFileParsing) {
   std::vector<uint8_t> buffer = ReadTestDataFile("test-25fps.h264");
 
@@ -65,6 +81,25 @@ TEST(H264ParserTest, StreamFileParsing) {
   }
 }
 
+// Verify that SliceHeader::nalu_data points to the beginning of nal unit.
+// Also verify that header_bit_size is set correctly.
+TEST(H264ParserTest, SliceHeaderSize) {
+  H264Parser parser;
+  int unused_id;
+  Nalu nalu;
+  ASSERT_TRUE(nalu.Initialize(Nalu::kH264, kSps, arraysize(kSps)));
+  ASSERT_EQ(H264Parser::kOk, parser.ParseSps(nalu, &unused_id));
+  ASSERT_TRUE(nalu.Initialize(Nalu::kH264, kPps, arraysize(kPps)));
+  ASSERT_EQ(H264Parser::kOk, parser.ParsePps(nalu, &unused_id));
+  ASSERT_TRUE(nalu.Initialize(Nalu::kH264, kVideoSliceTrimmed,
+                              arraysize(kVideoSliceTrimmed)));
+
+  H264SliceHeader slice_header;
+  ASSERT_EQ(H264Parser::kOk, parser.ParseSliceHeader(nalu, &slice_header));
+  EXPECT_EQ(nalu.data(), slice_header.nalu_data);
+  EXPECT_EQ(30u, slice_header.header_bit_size);
+}
+
 TEST(H264ParserTest, ExtractResolutionFromSpsData) {
   const uint8_t kSps[] = {0x67, 0x64, 0x00, 0x1E, 0xAC, 0xD9, 0x40, 0xB4,
                           0x2F, 0xF9, 0x7F, 0xF0, 0x00, 0x80, 0x00, 0x91,
diff --git a/packager/media/codecs/h265_parser.cc b/packager/media/codecs/h265_parser.cc
index 3909111ec4..7292c55a24 100644
--- a/packager/media/codecs/h265_parser.cc
+++ b/packager/media/codecs/h265_parser.cc
@@ -390,10 +390,7 @@ H265Parser::Result H265Parser::ParseSliceHeader(const Nalu& nalu,
     TRUE_OR_RETURN(br->SkipBits(extension_length * 8));
   }
 
-  size_t epb = br->NumEmulationPreventionBytesRead();
-  slice_header->header_bit_size =
-      (nalu.payload_size() - epb) * 8 - br->NumBitsLeft();
-
+  slice_header->header_bit_size = nalu.payload_size() * 8 - br->NumBitsLeft();
   return kOk;
 }
 
diff --git a/packager/media/codecs/h265_parser.h b/packager/media/codecs/h265_parser.h
index 5f535b1b4c..0c9b696449 100644
--- a/packager/media/codecs/h265_parser.h
+++ b/packager/media/codecs/h265_parser.h
@@ -218,6 +218,10 @@ struct H265SliceHeader {
   // Many of the fields here are required when parsing so the default here may
   // not be valid.
 
+  // This is the size of the slice header not including the nalu header byte.
+  // Sturcture: |NALU Header |     Slice Header    |    Slice Data    |
+  // Size:      |<- 16bits ->|<- header_bit_size ->|<- Rest of nalu ->|
+  // Note that this is not a field in the H.265 spec.
   int header_bit_size = 0;
 
   bool first_slice_segment_in_pic_flag = false;