diff --git a/api/video/hdr_metadata.h b/api/video/hdr_metadata.h
index 676a900..3be1d59 100644
--- a/api/video/hdr_metadata.h
+++ b/api/video/hdr_metadata.h
@@ -21,14 +21,19 @@
   struct Chromaticity {
     // xy chromaticity coordinates must be calculated as specified in ISO
     // 11664-3:2012 Section 7, and must be specified with four decimal places.
-    // The x coordinate must be in the range [0.0001, 0.7400] and the y
-    // coordinate must be in the range [0.0001, 0.8400].
+    // The x coordinate should be in the range [0.0001, 0.7400] and the y
+    // coordinate should be in the range [0.0001, 0.8400]. Valid range [0.0000,
+    // 1.0000].
     float x = 0.0f;
     float y = 0.0f;
     bool operator==(const Chromaticity& rhs) const {
       return x == rhs.x && y == rhs.y;
     }
 
+    bool Validate() const {
+      return x >= 0.0 && x <= 1.0 && y >= 0.0 && y <= 1.0;
+    }
+
     Chromaticity();
   };
 
@@ -41,13 +46,13 @@
   Chromaticity white_point;
 
   // The nominal maximum display luminance of the mastering display. Specified
-  // in the unit candela/m2. The value must be in the range [5, 10000] with zero
-  // decimal places.
+  // in the unit candela/m2. The value should be in the range [5, 10000] with
+  // zero decimal places. Valid range [0, 20000].
   float luminance_max = 0.0f;
 
   // The nominal minimum display luminance of the mastering display. Specified
-  // in the unit candela/m2. The value must be in the range [0.0001, 5.0000]
-  // with four decimal places.
+  // in the unit candela/m2. The value should be in the range [0.0001, 5.0000]
+  // with four decimal places. Valid range [0.0000, 5.0000].
   float luminance_min = 0.0f;
 
   HdrMasteringMetadata();
@@ -58,6 +63,13 @@
             (luminance_max == rhs.luminance_max) &&
             (luminance_min == rhs.luminance_min));
   }
+
+  bool Validate() const {
+    return luminance_max >= 0.0 && luminance_max <= 20000.0 &&
+           luminance_min >= 0.0 && luminance_min <= 5.0 &&
+           primary_r.Validate() && primary_g.Validate() &&
+           primary_b.Validate() && white_point.Validate();
+  }
 };
 
 // High dynamic range (HDR) metadata common for HDR10 and WebM/VP9-based HDR
@@ -66,11 +78,11 @@
 struct HdrMetadata {
   HdrMasteringMetadata mastering_metadata;
   // Max content light level (CLL), i.e. maximum brightness level present in the
-  // stream, in nits. 1 nit = 1 candela/m2.
-  uint32_t max_content_light_level = 0;
+  // stream, in nits. 1 nit = 1 candela/m2. Valid range [0, 20000].
+  int max_content_light_level = 0;
   // Max frame-average light level (FALL), i.e. maximum average brightness of
-  // the brightest frame in the stream, in nits.
-  uint32_t max_frame_average_light_level = 0;
+  // the brightest frame in the stream, in nits. Valid range [0, 20000].
+  int max_frame_average_light_level = 0;
 
   HdrMetadata();
 
@@ -80,6 +92,13 @@
         (max_frame_average_light_level == rhs.max_frame_average_light_level) &&
         (mastering_metadata == rhs.mastering_metadata));
   }
+
+  bool Validate() const {
+    return max_content_light_level >= 0 && max_content_light_level <= 20000 &&
+           max_frame_average_light_level >= 0 &&
+           max_frame_average_light_level <= 20000 &&
+           mastering_metadata.Validate();
+  }
 };
 
 }  // namespace webrtc
diff --git a/modules/rtp_rtcp/source/rtp_header_extensions.cc b/modules/rtp_rtcp/source/rtp_header_extensions.cc
index 1711092..38c2d5a 100644
--- a/modules/rtp_rtcp/source/rtp_header_extensions.cc
+++ b/modules/rtp_rtcp/source/rtp_header_extensions.cc
@@ -12,6 +12,7 @@
 
 #include <string.h>
 #include <cmath>
+#include <limits>
 
 #include "modules/rtp_rtcp/include/rtp_cvo.h"
 #include "modules/rtp_rtcp/source/byte_io.h"
@@ -444,30 +445,30 @@
 //    0                   1                   2                   3
 //    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-//   |       ID      |   length=30   |   Primaries   |    Transfer   |
+//   |      ID       |   length=28   |   primaries   |   transfer    |
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-//   |    Matrix     |     Range     |                luminance_max  |
+//   |    matrix     |range+chr.sit. |         luminance_max         |
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-//   |               |                 luminance_min                 |
+//   |         luminance_min         |            mastering_metadata.|
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-//   |             mastering_metadata.primary_r.x and .y             |
+//   |primary_r.x and .y             |            mastering_metadata.|
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-//   |             mastering_metadata.primary_g.x and .y             |
+//   |primary_g.x and .y             |            mastering_metadata.|
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-//   |             mastering_metadata.primary_b.x and .y             |
+//   |primary_b.x and .y             |            mastering_metadata.|
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-//   |               mastering_metadata.white.x and .y               |
+//   |white.x and .y                 |    max_content_light_level    |
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-//   |    max_content_light_level    | max_frame_average_light_level |
-//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//   | max_frame_average_light_level |
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 //
 // Data layout of color space w/o HDR metadata (one-byte RTP header extension)
 //    0                   1                   2                   3
 //    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-//   |  ID   | L = 3 |   Primaries   |   Transfer    |    Matrix     |
+//   |  ID   | L = 3 |   primaries   |   transfer    |    matrix     |
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-//   |     Range     |
+//   |range+chr.sit. |
 //   +-+-+-+-+-+-+-+-+
 
 constexpr RTPExtensionType ColorSpaceExtension::kId;
@@ -483,13 +484,21 @@
 
   size_t offset = 0;
   // Read color space information.
-  if (!color_space->set_primaries_from_uint8(data.data()[offset++]))
+  if (!color_space->set_primaries_from_uint8(data[offset++]))
     return false;
-  if (!color_space->set_transfer_from_uint8(data.data()[offset++]))
+  if (!color_space->set_transfer_from_uint8(data[offset++]))
     return false;
-  if (!color_space->set_matrix_from_uint8(data.data()[offset++]))
+  if (!color_space->set_matrix_from_uint8(data[offset++]))
     return false;
-  if (!color_space->set_range_from_uint8(data.data()[offset++]))
+
+  uint8_t range_and_chroma_siting = data[offset++];
+  if (!color_space->set_range_from_uint8((range_and_chroma_siting >> 4) & 0x03))
+    return false;
+  if (!color_space->set_chroma_siting_horizontal_from_uint8(
+          (range_and_chroma_siting >> 2) & 0x03))
+    return false;
+  if (!color_space->set_chroma_siting_vertical_from_uint8(
+          range_and_chroma_siting & 0x03))
     return false;
 
   // Read HDR metadata if it exists, otherwise clear it.
@@ -497,26 +506,9 @@
     color_space->set_hdr_metadata(nullptr);
   } else {
     HdrMetadata hdr_metadata;
-    offset += ParseLuminance(data.data() + offset,
-                             &hdr_metadata.mastering_metadata.luminance_max,
-                             kLuminanceMaxDenominator);
-    offset += ParseLuminance(data.data() + offset,
-                             &hdr_metadata.mastering_metadata.luminance_min,
-                             kLuminanceMinDenominator);
-    offset += ParseChromaticity(data.data() + offset,
-                                &hdr_metadata.mastering_metadata.primary_r);
-    offset += ParseChromaticity(data.data() + offset,
-                                &hdr_metadata.mastering_metadata.primary_g);
-    offset += ParseChromaticity(data.data() + offset,
-                                &hdr_metadata.mastering_metadata.primary_b);
-    offset += ParseChromaticity(data.data() + offset,
-                                &hdr_metadata.mastering_metadata.white_point);
-    hdr_metadata.max_content_light_level =
-        ByteReader<uint16_t>::ReadBigEndian(data.data() + offset);
-    offset += 2;
-    hdr_metadata.max_frame_average_light_level =
-        ByteReader<uint16_t>::ReadBigEndian(data.data() + offset);
-    offset += 2;
+    offset += ParseHdrMetadata(data.subview(offset), &hdr_metadata);
+    if (!hdr_metadata.Validate())
+      return false;
     color_space->set_hdr_metadata(&hdr_metadata);
   }
   RTC_DCHECK_EQ(ValueSize(*color_space), offset);
@@ -528,40 +520,67 @@
   RTC_DCHECK_EQ(data.size(), ValueSize(color_space));
   size_t offset = 0;
   // Write color space information.
-  data.data()[offset++] = static_cast<uint8_t>(color_space.primaries());
-  data.data()[offset++] = static_cast<uint8_t>(color_space.transfer());
-  data.data()[offset++] = static_cast<uint8_t>(color_space.matrix());
-  data.data()[offset++] = static_cast<uint8_t>(color_space.range());
+  data[offset++] = static_cast<uint8_t>(color_space.primaries());
+  data[offset++] = static_cast<uint8_t>(color_space.transfer());
+  data[offset++] = static_cast<uint8_t>(color_space.matrix());
+  data[offset++] = CombineRangeAndChromaSiting(
+      color_space.range(), color_space.chroma_siting_horizontal(),
+      color_space.chroma_siting_vertical());
 
   // Write HDR metadata if it exists.
   if (color_space.hdr_metadata()) {
-    const HdrMetadata& hdr_metadata = *color_space.hdr_metadata();
-    offset += WriteLuminance(data.data() + offset,
-                             hdr_metadata.mastering_metadata.luminance_max,
-                             kLuminanceMaxDenominator);
-    offset += WriteLuminance(data.data() + offset,
-                             hdr_metadata.mastering_metadata.luminance_min,
-                             kLuminanceMinDenominator);
-    offset += WriteChromaticity(data.data() + offset,
-                                hdr_metadata.mastering_metadata.primary_r);
-    offset += WriteChromaticity(data.data() + offset,
-                                hdr_metadata.mastering_metadata.primary_g);
-    offset += WriteChromaticity(data.data() + offset,
-                                hdr_metadata.mastering_metadata.primary_b);
-    offset += WriteChromaticity(data.data() + offset,
-                                hdr_metadata.mastering_metadata.white_point);
-
-    ByteWriter<uint16_t>::WriteBigEndian(data.data() + offset,
-                                         hdr_metadata.max_content_light_level);
-    offset += 2;
-    ByteWriter<uint16_t>::WriteBigEndian(
-        data.data() + offset, hdr_metadata.max_frame_average_light_level);
-    offset += 2;
+    offset +=
+        WriteHdrMetadata(data.subview(offset), *color_space.hdr_metadata());
   }
   RTC_DCHECK_EQ(ValueSize(color_space), offset);
   return true;
 }
 
+// Combines range and chroma siting into one byte with the following bit layout:
+// bits 0-1 Chroma siting vertical.
+//      2-3 Chroma siting horizontal.
+//      4-5 Range.
+//      6-7 Unused.
+uint8_t ColorSpaceExtension::CombineRangeAndChromaSiting(
+    ColorSpace::RangeID range,
+    ColorSpace::ChromaSiting chroma_siting_horizontal,
+    ColorSpace::ChromaSiting chroma_siting_vertical) {
+  RTC_DCHECK_LE(static_cast<uint8_t>(range), 3);
+  RTC_DCHECK_LE(static_cast<uint8_t>(chroma_siting_horizontal), 3);
+  RTC_DCHECK_LE(static_cast<uint8_t>(chroma_siting_vertical), 3);
+  return (static_cast<uint8_t>(range) << 4) |
+         (static_cast<uint8_t>(chroma_siting_horizontal) << 2) |
+         static_cast<uint8_t>(chroma_siting_vertical);
+}
+
+size_t ColorSpaceExtension::ParseHdrMetadata(rtc::ArrayView<const uint8_t> data,
+                                             HdrMetadata* hdr_metadata) {
+  RTC_DCHECK_EQ(data.size(),
+                kValueSizeBytes - kValueSizeBytesWithoutHdrMetadata);
+  size_t offset = 0;
+  offset += ParseLuminance(data.data() + offset,
+                           &hdr_metadata->mastering_metadata.luminance_max,
+                           kLuminanceMaxDenominator);
+  offset += ParseLuminance(data.data() + offset,
+                           &hdr_metadata->mastering_metadata.luminance_min,
+                           kLuminanceMinDenominator);
+  offset += ParseChromaticity(data.data() + offset,
+                              &hdr_metadata->mastering_metadata.primary_r);
+  offset += ParseChromaticity(data.data() + offset,
+                              &hdr_metadata->mastering_metadata.primary_g);
+  offset += ParseChromaticity(data.data() + offset,
+                              &hdr_metadata->mastering_metadata.primary_b);
+  offset += ParseChromaticity(data.data() + offset,
+                              &hdr_metadata->mastering_metadata.white_point);
+  hdr_metadata->max_content_light_level =
+      ByteReader<uint16_t>::ReadBigEndian(data.data() + offset);
+  offset += 2;
+  hdr_metadata->max_frame_average_light_level =
+      ByteReader<uint16_t>::ReadBigEndian(data.data() + offset);
+  offset += 2;
+  return offset;
+}
+
 size_t ColorSpaceExtension::ParseChromaticity(
     const uint8_t* data,
     HdrMasteringMetadata::Chromaticity* p) {
@@ -576,16 +595,48 @@
 size_t ColorSpaceExtension::ParseLuminance(const uint8_t* data,
                                            float* f,
                                            int denominator) {
-  uint32_t luminance_scaled = ByteReader<uint32_t, 3>::ReadBigEndian(data);
+  uint16_t luminance_scaled = ByteReader<uint16_t>::ReadBigEndian(data);
   *f = static_cast<float>(luminance_scaled) / denominator;
-  return 3;  // Return number of bytes read.
+  return 2;  // Return number of bytes read.
+}
+
+size_t ColorSpaceExtension::WriteHdrMetadata(rtc::ArrayView<uint8_t> data,
+                                             const HdrMetadata& hdr_metadata) {
+  RTC_DCHECK_EQ(data.size(),
+                kValueSizeBytes - kValueSizeBytesWithoutHdrMetadata);
+  RTC_DCHECK(hdr_metadata.Validate());
+  size_t offset = 0;
+  offset += WriteLuminance(data.data() + offset,
+                           hdr_metadata.mastering_metadata.luminance_max,
+                           kLuminanceMaxDenominator);
+  offset += WriteLuminance(data.data() + offset,
+                           hdr_metadata.mastering_metadata.luminance_min,
+                           kLuminanceMinDenominator);
+  offset += WriteChromaticity(data.data() + offset,
+                              hdr_metadata.mastering_metadata.primary_r);
+  offset += WriteChromaticity(data.data() + offset,
+                              hdr_metadata.mastering_metadata.primary_g);
+  offset += WriteChromaticity(data.data() + offset,
+                              hdr_metadata.mastering_metadata.primary_b);
+  offset += WriteChromaticity(data.data() + offset,
+                              hdr_metadata.mastering_metadata.white_point);
+
+  ByteWriter<uint16_t>::WriteBigEndian(data.data() + offset,
+                                       hdr_metadata.max_content_light_level);
+  offset += 2;
+  ByteWriter<uint16_t>::WriteBigEndian(
+      data.data() + offset, hdr_metadata.max_frame_average_light_level);
+  offset += 2;
+  return offset;
 }
 
 size_t ColorSpaceExtension::WriteChromaticity(
     uint8_t* data,
     const HdrMasteringMetadata::Chromaticity& p) {
   RTC_DCHECK_GE(p.x, 0.0f);
+  RTC_DCHECK_LE(p.x, 1.0f);
   RTC_DCHECK_GE(p.y, 0.0f);
+  RTC_DCHECK_LE(p.y, 1.0f);
   ByteWriter<uint16_t>::WriteBigEndian(
       data, std::round(p.x * kChromaticityDenominator));
   ByteWriter<uint16_t>::WriteBigEndian(
@@ -597,8 +648,10 @@
                                            float f,
                                            int denominator) {
   RTC_DCHECK_GE(f, 0.0f);
-  ByteWriter<uint32_t, 3>::WriteBigEndian(data, std::round(f * denominator));
-  return 3;  // Return number of bytes written.
+  float upscaled_value = f * denominator;
+  RTC_DCHECK_LE(upscaled_value, std::numeric_limits<uint16_t>::max());
+  ByteWriter<uint16_t>::WriteBigEndian(data, std::round(upscaled_value));
+  return 2;  // Return number of bytes written.
 }
 
 bool BaseRtpStringExtension::Parse(rtc::ArrayView<const uint8_t> data,
diff --git a/modules/rtp_rtcp/source/rtp_header_extensions.h b/modules/rtp_rtcp/source/rtp_header_extensions.h
index c1eaf8c..9f4a28b 100644
--- a/modules/rtp_rtcp/source/rtp_header_extensions.h
+++ b/modules/rtp_rtcp/source/rtp_header_extensions.h
@@ -186,7 +186,7 @@
  public:
   using value_type = ColorSpace;
   static constexpr RTPExtensionType kId = kRtpExtensionColorSpace;
-  static constexpr uint8_t kValueSizeBytes = 30;
+  static constexpr uint8_t kValueSizeBytes = 28;
   static constexpr uint8_t kValueSizeBytesWithoutHdrMetadata = 4;
   static constexpr const char kUri[] =
       "http://www.webrtc.org/experiments/rtp-hdrext/color-space";
@@ -201,12 +201,21 @@
                     const ColorSpace& color_space);
 
  private:
-  static constexpr int kChromaticityDenominator = 10000;  // 0.0001 resolution.
-  static constexpr int kLuminanceMaxDenominator = 100;    // 0.01 resolution.
+  static constexpr int kChromaticityDenominator = 50000;  // 0.00002 resolution.
+  static constexpr int kLuminanceMaxDenominator = 1;      // 1 resolution.
   static constexpr int kLuminanceMinDenominator = 10000;  // 0.0001 resolution.
+
+  static uint8_t CombineRangeAndChromaSiting(
+      ColorSpace::RangeID range,
+      ColorSpace::ChromaSiting chroma_siting_horizontal,
+      ColorSpace::ChromaSiting chroma_siting_vertical);
+  static size_t ParseHdrMetadata(rtc::ArrayView<const uint8_t> data,
+                                 HdrMetadata* hdr_metadata);
   static size_t ParseChromaticity(const uint8_t* data,
                                   HdrMasteringMetadata::Chromaticity* p);
   static size_t ParseLuminance(const uint8_t* data, float* f, int denominator);
+  static size_t WriteHdrMetadata(rtc::ArrayView<uint8_t> data,
+                                 const HdrMetadata& hdr_metadata);
   static size_t WriteChromaticity(uint8_t* data,
                                   const HdrMasteringMetadata::Chromaticity& p);
   static size_t WriteLuminance(uint8_t* data, float f, int denominator);
diff --git a/modules/rtp_rtcp/source/rtp_packet_unittest.cc b/modules/rtp_rtcp/source/rtp_packet_unittest.cc
index b1c0e42..e53125b 100644
--- a/modules/rtp_rtcp/source/rtp_packet_unittest.cc
+++ b/modules/rtp_rtcp/source/rtp_packet_unittest.cc
@@ -205,14 +205,13 @@
 }
 
 ColorSpace CreateTestColorSpace(bool with_hdr_metadata) {
-  ColorSpace color_space(
+  HdrMetadata hdr_metadata = CreateTestHdrMetadata();
+  return ColorSpace(
       ColorSpace::PrimaryID::kBT709, ColorSpace::TransferID::kGAMMA22,
-      ColorSpace::MatrixID::kSMPTE2085, ColorSpace::RangeID::kFull);
-  if (with_hdr_metadata) {
-    HdrMetadata hdr_metadata = CreateTestHdrMetadata();
-    color_space.set_hdr_metadata(&hdr_metadata);
-  }
-  return color_space;
+      ColorSpace::MatrixID::kSMPTE2085, ColorSpace::RangeID::kFull,
+      ColorSpace::ChromaSiting::kCollocated,
+      ColorSpace::ChromaSiting::kCollocated,
+      with_hdr_metadata ? &hdr_metadata : nullptr);
 }
 
 void TestCreateAndParseColorSpaceExtension(bool with_hdr_metadata) {