Revert of Simplify and extend RtpHeaderExtensionMap (patchset #12 id:260001 of https://codereview.webrtc.org/2452293004/ )

Reason for revert:
breaks downstream project

Original issue's description:
> Simplify and extend RtpHeaderExtensionMap
> Add register functions for various codepaths.
> Add initialize-list constructor to create usable const RtpHeaderExtensionMap
> Optimize implementation for GetId/GetType.
>
> BUG=webrtc:1994
>
> Committed: https://crrev.com/d1d26fbeb37a69471a34004c6ac2d3fafde5d404
> Cr-Commit-Position: refs/heads/master@{#14986}

TBR=sprang@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:1994

Review-Url: https://codereview.webrtc.org/2484863007
Cr-Commit-Position: refs/heads/master@{#14988}

webrtc/modules/rtp_rtcp/source/rtp_header_extension.cc

@@ -8,143 +8,148 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#include "webrtc/modules/rtp_rtcp/source/rtp_header_extension.h"
+#include <assert.h>
 
-#include "webrtc/base/arraysize.h"
 #include "webrtc/base/checks.h"
-#include "webrtc/base/logging.h"
+#include "webrtc/common_types.h"
-#include "webrtc/modules/rtp_rtcp/source/rtp_header_extensions.h"
+#include "webrtc/modules/rtp_rtcp/source/rtp_header_extension.h"
 #include "webrtc/modules/rtp_rtcp/source/rtp_utility.h"
 
 namespace webrtc {
-namespace {
 
-using RtpUtility::Word32Align;
+constexpr uint8_t RtpHeaderExtensionMap::kInvalidId;
 
-struct ExtensionInfo {
+RtpHeaderExtensionMap::RtpHeaderExtensionMap() {
-  RTPExtensionType type;
-  size_t value_size;
-  const char* uri;
-};
-
-template <typename Extension>
-constexpr ExtensionInfo CreateExtensionInfo() {
-  return {Extension::kId, Extension::kValueSizeBytes, Extension::kUri};
 }
 
-constexpr ExtensionInfo kExtensions[] = {
+RtpHeaderExtensionMap::~RtpHeaderExtensionMap() {
-    CreateExtensionInfo<TransmissionOffset>(),
+  Erase();
-    CreateExtensionInfo<AudioLevel>(),
+}
-    CreateExtensionInfo<AbsoluteSendTime>(),
-    CreateExtensionInfo<VideoOrientation>(),
-    CreateExtensionInfo<TransportSequenceNumber>(),
-    CreateExtensionInfo<PlayoutDelayLimits>(),
-};
 
-// Because of kRtpExtensionNone, NumberOfExtension is 1 bigger than the actual
+void RtpHeaderExtensionMap::Erase() {
-// number of known extensions.
+  while (!extensionMap_.empty()) {
-static_assert(arraysize(kExtensions) ==
+    std::map<uint8_t, HeaderExtension*>::iterator it =
-                  static_cast<int>(kRtpExtensionNumberOfExtensions) - 1,
+        extensionMap_.begin();
-              "kExtensions expect to list all known extensions");
+    delete it->second;
+    extensionMap_.erase(it);
+  }
+}
 
-size_t ValueSize(RTPExtensionType type) {
+int32_t RtpHeaderExtensionMap::Register(RTPExtensionType type, uint8_t id) {
-  for (const ExtensionInfo& extension : kExtensions)
+  if (id < 1 || id > 14) {
-    if (type == extension.type)
+    return -1;
-      return extension.value_size;
+  }
-
+  std::map<uint8_t, HeaderExtension*>::iterator it =
-  RTC_NOTREACHED();
+      extensionMap_.find(id);
+  if (it != extensionMap_.end()) {
+    if (it->second->type != type) {
+      // An extension is already registered with the same id
+      // but a different type, so return failure.
+      return -1;
+    }
+    // This extension type is already registered with this id,
+    // so return success.
+    return 0;
+  }
+  RTC_DCHECK_EQ(kInvalidId, GetId(type));
+  extensionMap_[id] = new HeaderExtension(type);
   return 0;
 }
 
-}  // namespace
+int32_t RtpHeaderExtensionMap::Deregister(const RTPExtensionType type) {
-
+  uint8_t id;
-constexpr RTPExtensionType RtpHeaderExtensionMap::kInvalidType;
+  if (GetId(type, &id) != 0) {
-constexpr uint8_t RtpHeaderExtensionMap::kInvalidId;
+    return 0;
-constexpr uint8_t RtpHeaderExtensionMap::kMinId;
+  }
-constexpr uint8_t RtpHeaderExtensionMap::kMaxId;
+  std::map<uint8_t, HeaderExtension*>::iterator it =
-
+      extensionMap_.find(id);
-RtpHeaderExtensionMap::RtpHeaderExtensionMap() {
+  assert(it != extensionMap_.end());
-  total_values_size_bytes_ = 0;
+  delete it->second;
-  for (auto& type : types_)
+  extensionMap_.erase(it);
-    type = kInvalidType;
+  return 0;
-  for (auto& id : ids_)
-    id = kInvalidId;
 }
 
-RtpHeaderExtensionMap::RtpHeaderExtensionMap(
+bool RtpHeaderExtensionMap::IsRegistered(RTPExtensionType type) const {
-    std::initializer_list<RtpExtension> extensions)
+  std::map<uint8_t, HeaderExtension*>::const_iterator it =
-    : RtpHeaderExtensionMap() {
+    extensionMap_.begin();
-  for (const RtpExtension& extension : extensions)
+  for (; it != extensionMap_.end(); ++it) {
-    RegisterByUri(extension.id, extension.uri);
+    if (it->second->type == type)
+      return true;
   }
-
-bool RtpHeaderExtensionMap::RegisterByType(uint8_t id, RTPExtensionType type) {
-  for (const ExtensionInfo& extension : kExtensions)
-    if (type == extension.type)
-      return Register(id, extension.type, extension.value_size, extension.uri);
-  RTC_NOTREACHED();
   return false;
 }
 
-bool RtpHeaderExtensionMap::RegisterByUri(uint8_t id, const std::string& uri) {
+int32_t RtpHeaderExtensionMap::GetType(const uint8_t id,
-  for (const ExtensionInfo& extension : kExtensions)
+                                       RTPExtensionType* type) const {
-    if (uri == extension.uri)
+  assert(type);
-      return Register(id, extension.type, extension.value_size, extension.uri);
+  std::map<uint8_t, HeaderExtension*>::const_iterator it =
-  LOG(LS_WARNING) << "Unknown extension uri:'" << uri
+      extensionMap_.find(id);
-                  << "', id: " << static_cast<int>(id) << '.';
+  if (it == extensionMap_.end()) {
-  return false;
+    return -1;
+  }
+  HeaderExtension* extension = it->second;
+  *type = extension->type;
+  return 0;
+}
+
+RTPExtensionType RtpHeaderExtensionMap::GetType(uint8_t id) const {
+  auto it = extensionMap_.find(id);
+  if (it == extensionMap_.end()) {
+    return kInvalidType;
+  }
+  return it->second->type;
+}
+
+int32_t RtpHeaderExtensionMap::GetId(const RTPExtensionType type,
+                                     uint8_t* id) const {
+  assert(id);
+  std::map<uint8_t, HeaderExtension*>::const_iterator it =
+      extensionMap_.begin();
+
+  while (it != extensionMap_.end()) {
+    HeaderExtension* extension = it->second;
+    if (extension->type == type) {
+      *id = it->first;
+      return 0;
+    }
+    it++;
+  }
+  return -1;
+}
+
+uint8_t RtpHeaderExtensionMap::GetId(RTPExtensionType type) const {
+  for (auto kv : extensionMap_) {
+    if (kv.second->type == type)
+      return kv.first;
+  }
+  return kInvalidId;
 }
 
 size_t RtpHeaderExtensionMap::GetTotalLengthInBytes() const {
-  if (total_values_size_bytes_ == 0)
+  // Get length for each extension block.
-    return 0;
+  size_t length = 0;
-  return Word32Align(kRtpOneByteHeaderLength + total_values_size_bytes_);
+  for (const auto& kv : extensionMap_)
+    length += kv.second->length;
+  // Add RTP extension header length.
+  if (length > 0)
+    length += kRtpOneByteHeaderLength;
+  // Pad up to nearest 32bit word.
+  length = RtpUtility::Word32Align(length);
+  return length;
 }
 
-int32_t RtpHeaderExtensionMap::Deregister(RTPExtensionType type) {
+int32_t RtpHeaderExtensionMap::Size() const {
-  if (IsRegistered(type)) {
+  return extensionMap_.size();
-    uint8_t id = GetId(type);
-    total_values_size_bytes_ -= (ValueSize(type) + 1);
-    types_[id] = kInvalidType;
-    ids_[type] = kInvalidId;
-  }
-  return 0;
 }
 
-bool RtpHeaderExtensionMap::Register(uint8_t id,
+void RtpHeaderExtensionMap::GetCopy(RtpHeaderExtensionMap* map) const {
-                                     RTPExtensionType type,
+  assert(map);
-                                     size_t value_size,
+  std::map<uint8_t, HeaderExtension*>::const_iterator it =
-                                     const char* uri) {
+      extensionMap_.begin();
-  RTC_DCHECK_GT(type, kRtpExtensionNone);
+  while (it != extensionMap_.end()) {
-  RTC_DCHECK_LT(type, kRtpExtensionNumberOfExtensions);
+    HeaderExtension* extension = it->second;
-  RTC_DCHECK_GE(value_size, 1U);
+    map->Register(extension->type, it->first);
-  RTC_DCHECK_LE(value_size, 16U);
+    it++;
-
-  if (id < kMinId || id > kMaxId) {
-    LOG(LS_WARNING) << "Failed to register extension uri:'" << uri
-                    << "' with invalid id:" << static_cast<int>(id) << ".";
-    return false;
   }
-
-  if (GetType(id) == type) {  // Same type/id pair already registered.
-    LOG(LS_VERBOSE) << "Reregistering extension uri:'" << uri
-                    << "', id:" << static_cast<int>(id);
-    return true;
 }
-
-  if (GetType(id) != kInvalidType) {  // |id| used by another extension type.
-    LOG(LS_WARNING) << "Failed to register extension uri:'" << uri
-                    << "', id:" << static_cast<int>(id)
-                    << ". Id already in use by extension type "
-                    << static_cast<int>(GetType(id));
-    return false;
-  }
-  RTC_DCHECK(!IsRegistered(type));
-
-  types_[id] = type;
-  ids_[type] = id;
-  total_values_size_bytes_ += (value_size + 1);
-  return true;
-}
-
 }  // namespace webrtc

webrtc/modules/rtp_rtcp/source/rtp_header_extension.h

@@ -11,13 +11,10 @@
 #ifndef WEBRTC_MODULES_RTP_RTCP_SOURCE_RTP_HEADER_EXTENSION_H_
 #define WEBRTC_MODULES_RTP_RTCP_SOURCE_RTP_HEADER_EXTENSION_H_
 
-#include <initializer_list>
+#include <map>
-#include <string>
 
-#include "webrtc/base/basictypes.h"
-#include "webrtc/base/checks.h"
-#include "webrtc/config.h"
 #include "webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h"
+#include "webrtc/typedefs.h"
 
 namespace webrtc {
 
@@ -38,63 +35,74 @@ const int kPlayoutDelayGranularityMs = 10;
 // Maximum playout delay value in milliseconds.
 const int kPlayoutDelayMaxMs = 40950;
 
+struct HeaderExtension {
+  explicit HeaderExtension(RTPExtensionType extension_type)
+      : type(extension_type), length(0) {
+    Init();
+  }
+
+  void Init() {
+    // TODO(solenberg): Create handler classes for header extensions so we can
+    // get rid of switches like these as well as handling code spread out all
+    // over.
+    switch (type) {
+      case kRtpExtensionTransmissionTimeOffset:
+        length = kTransmissionTimeOffsetLength;
+        break;
+      case kRtpExtensionAudioLevel:
+        length = kAudioLevelLength;
+        break;
+      case kRtpExtensionAbsoluteSendTime:
+        length = kAbsoluteSendTimeLength;
+        break;
+      case kRtpExtensionVideoRotation:
+        length = kVideoRotationLength;
+        break;
+      case kRtpExtensionTransportSequenceNumber:
+        length = kTransportSequenceNumberLength;
+        break;
+      case kRtpExtensionPlayoutDelay:
+        length = kPlayoutDelayLength;
+        break;
+      default:
+        assert(false);
+    }
+  }
+
+  const RTPExtensionType type;
+  uint8_t length;
+};
+
 class RtpHeaderExtensionMap {
  public:
   static constexpr RTPExtensionType kInvalidType = kRtpExtensionNone;
   static constexpr uint8_t kInvalidId = 0;
-
   RtpHeaderExtensionMap();
-  RtpHeaderExtensionMap(std::initializer_list<RtpExtension>);
+  ~RtpHeaderExtensionMap();
 
-  template <typename Extension>
+  void Erase();
-  bool Register(uint8_t id) {
-    return Register(id, Extension::kId, Extension::kValueSizeBytes,
-                    Extension::kUri);
-  }
-  bool RegisterByType(uint8_t id, RTPExtensionType type);
-  bool RegisterByUri(uint8_t id, const std::string& uri);
 
-  bool IsRegistered(RTPExtensionType type) const {
+  int32_t Register(RTPExtensionType type, uint8_t id);
-    return GetId(type) != kInvalidId;
+
-  }
+  int32_t Deregister(RTPExtensionType type);
+
+  bool IsRegistered(RTPExtensionType type) const;
+
+  int32_t GetType(uint8_t id, RTPExtensionType* type) const;
   // Return kInvalidType if not found.
-  RTPExtensionType GetType(uint8_t id) const {
+  RTPExtensionType GetType(uint8_t id) const;
-    RTC_DCHECK_GE(id, kMinId);
-    RTC_DCHECK_LE(id, kMaxId);
-    return types_[id];
-  }
-  // Return kInvalidId if not found.
-  uint8_t GetId(RTPExtensionType type) const {
-    RTC_DCHECK_GT(type, kRtpExtensionNone);
-    RTC_DCHECK_LT(type, kRtpExtensionNumberOfExtensions);
-    return ids_[type];
-  }
 
+  int32_t GetId(const RTPExtensionType type, uint8_t* id) const;
+  // Return kInvalidId if not found.
+  uint8_t GetId(RTPExtensionType type) const;
   size_t GetTotalLengthInBytes() const;
 
-  // TODO(danilchap): Remove use of the functions below.
+  void GetCopy(RtpHeaderExtensionMap* map) const;
-  void Erase() { *this = RtpHeaderExtensionMap(); }
+
-  int32_t Register(RTPExtensionType type, uint8_t id) {
+  int32_t Size() const;
-    return RegisterByType(id, type) ? 0 : -1;
-  }
-  int32_t Deregister(RTPExtensionType type);
-  int32_t GetType(uint8_t id, RTPExtensionType* type) const {
-    *type = GetType(id);
-    return *type == kInvalidType ? -1 : 0;
-  }
-  void GetCopy(RtpHeaderExtensionMap* copy) const { *copy = *this; }
 
  private:
-  static constexpr uint8_t kMinId = 1;
+  std::map<uint8_t, HeaderExtension*> extensionMap_;
-  static constexpr uint8_t kMaxId = 14;
-  bool Register(uint8_t id,
-                RTPExtensionType type,
-                size_t value_size,
-                const char* uri);
-
-  size_t total_values_size_bytes_ = 0;
-  RTPExtensionType types_[kMaxId + 1];
-  uint8_t ids_[kRtpExtensionNumberOfExtensions];
 };
 }  // namespace webrtc
 

webrtc/modules/rtp_rtcp/source/rtp_header_extension_unittest.cc

@@ -10,99 +10,87 @@
 
 #include "webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h"
 #include "webrtc/modules/rtp_rtcp/source/rtp_header_extension.h"
-#include "webrtc/modules/rtp_rtcp/source/rtp_header_extensions.h"
 #include "webrtc/test/gtest.h"
 #include "webrtc/typedefs.h"
 
 namespace webrtc {
 
-TEST(RtpHeaderExtensionTest, RegisterByType) {
+class RtpHeaderExtensionTest : public ::testing::Test {
-  RtpHeaderExtensionMap map;
+ protected:
-  EXPECT_FALSE(map.IsRegistered(TransmissionOffset::kId));
+  RtpHeaderExtensionTest() {}
+  ~RtpHeaderExtensionTest() {}
 
-  EXPECT_TRUE(map.RegisterByType(3, TransmissionOffset::kId));
+  RtpHeaderExtensionMap map_;
+  static const uint8_t kId;
+};
 
-  EXPECT_TRUE(map.IsRegistered(TransmissionOffset::kId));
+const uint8_t RtpHeaderExtensionTest::kId = 3;
-  EXPECT_EQ(3, map.GetId(TransmissionOffset::kId));
+
-  EXPECT_EQ(TransmissionOffset::kId, map.GetType(3));
+TEST_F(RtpHeaderExtensionTest, Register) {
+  EXPECT_EQ(0, map_.Size());
+  EXPECT_EQ(0, map_.Register(kRtpExtensionTransmissionTimeOffset, kId));
+  EXPECT_TRUE(map_.IsRegistered(kRtpExtensionTransmissionTimeOffset));
+  EXPECT_EQ(1, map_.Size());
+  EXPECT_EQ(0, map_.Deregister(kRtpExtensionTransmissionTimeOffset));
+  EXPECT_EQ(0, map_.Size());
 }
 
-TEST(RtpHeaderExtensionTest, RegisterByUri) {
+TEST_F(RtpHeaderExtensionTest, RegisterIllegalArg) {
-  RtpHeaderExtensionMap map;
-
-  EXPECT_TRUE(map.RegisterByUri(3, TransmissionOffset::kUri));
-
-  EXPECT_TRUE(map.IsRegistered(TransmissionOffset::kId));
-  EXPECT_EQ(3, map.GetId(TransmissionOffset::kId));
-  EXPECT_EQ(TransmissionOffset::kId, map.GetType(3));
-}
-
-TEST(RtpHeaderExtensionTest, RegisterWithTrait) {
-  RtpHeaderExtensionMap map;
-
-  EXPECT_TRUE(map.Register<TransmissionOffset>(3));
-
-  EXPECT_TRUE(map.IsRegistered(TransmissionOffset::kId));
-  EXPECT_EQ(3, map.GetId(TransmissionOffset::kId));
-  EXPECT_EQ(TransmissionOffset::kId, map.GetType(3));
-}
-
-TEST(RtpHeaderExtensionTest, RegisterDuringContruction) {
-  const RtpHeaderExtensionMap map = {{TransmissionOffset::kUri, 1},
-                                     {AbsoluteSendTime::kUri, 3}};
-
-  EXPECT_EQ(1, map.GetId(TransmissionOffset::kId));
-  EXPECT_EQ(3, map.GetId(AbsoluteSendTime::kId));
-}
-
-TEST(RtpHeaderExtensionTest, RegisterIllegalArg) {
-  RtpHeaderExtensionMap map;
   // Valid range for id: [1-14].
-  EXPECT_FALSE(map.Register<TransmissionOffset>(0));
+  EXPECT_EQ(-1, map_.Register(kRtpExtensionTransmissionTimeOffset, 0));
-  EXPECT_FALSE(map.Register<TransmissionOffset>(15));
+  EXPECT_EQ(-1, map_.Register(kRtpExtensionTransmissionTimeOffset, 15));
 }
 
-TEST(RtpHeaderExtensionTest, Idempotent) {
+TEST_F(RtpHeaderExtensionTest, Idempotent) {
-  RtpHeaderExtensionMap map;
+  EXPECT_EQ(0, map_.Register(kRtpExtensionTransmissionTimeOffset, kId));
-
+  EXPECT_EQ(0, map_.Register(kRtpExtensionTransmissionTimeOffset, kId));
-  EXPECT_TRUE(map.Register<TransmissionOffset>(3));
+  EXPECT_EQ(0, map_.Deregister(kRtpExtensionTransmissionTimeOffset));
-  EXPECT_TRUE(map.Register<TransmissionOffset>(3));
+  EXPECT_EQ(0, map_.Deregister(kRtpExtensionTransmissionTimeOffset));
-
-  map.Deregister(TransmissionOffset::kId);
-  map.Deregister(TransmissionOffset::kId);
 }
 
-TEST(RtpHeaderExtensionTest, NonUniqueId) {
+TEST_F(RtpHeaderExtensionTest, NonUniqueId) {
-  RtpHeaderExtensionMap map;
+  EXPECT_EQ(0, map_.Register(kRtpExtensionTransmissionTimeOffset, kId));
-  EXPECT_TRUE(map.Register<TransmissionOffset>(3));
+  EXPECT_EQ(-1, map_.Register(kRtpExtensionAudioLevel, kId));
-
-  EXPECT_FALSE(map.Register<AudioLevel>(3));
-  EXPECT_TRUE(map.Register<AudioLevel>(4));
 }
 
-TEST(RtpHeaderExtensionTest, GetTotalLength) {
+TEST_F(RtpHeaderExtensionTest, GetTotalLength) {
-  RtpHeaderExtensionMap map;
+  EXPECT_EQ(0u, map_.GetTotalLengthInBytes());
-  EXPECT_EQ(0u, map.GetTotalLengthInBytes());
+  EXPECT_EQ(0, map_.Register(kRtpExtensionTransmissionTimeOffset, kId));
-  EXPECT_TRUE(map.Register<TransmissionOffset>(3));
+  EXPECT_EQ(kRtpOneByteHeaderLength + kTransmissionTimeOffsetLength,
-  EXPECT_EQ(kRtpOneByteHeaderLength + (TransmissionOffset::kValueSizeBytes + 1),
+            map_.GetTotalLengthInBytes());
-            map.GetTotalLengthInBytes());
 }
 
-TEST(RtpHeaderExtensionTest, GetType) {
+TEST_F(RtpHeaderExtensionTest, GetType) {
-  RtpHeaderExtensionMap map;
+  RTPExtensionType typeOut;
-  EXPECT_EQ(RtpHeaderExtensionMap::kInvalidType, map.GetType(3));
+  EXPECT_EQ(-1, map_.GetType(kId, &typeOut));
-  EXPECT_TRUE(map.Register<TransmissionOffset>(3));
 
-  EXPECT_EQ(TransmissionOffset::kId, map.GetType(3));
+  EXPECT_EQ(0, map_.Register(kRtpExtensionTransmissionTimeOffset, kId));
+  EXPECT_EQ(0, map_.GetType(kId, &typeOut));
+  EXPECT_EQ(kRtpExtensionTransmissionTimeOffset, typeOut);
 }
 
-TEST(RtpHeaderExtensionTest, GetId) {
+TEST_F(RtpHeaderExtensionTest, GetId) {
-  RtpHeaderExtensionMap map;
+  uint8_t idOut;
-  EXPECT_EQ(RtpHeaderExtensionMap::kInvalidId,
+  EXPECT_EQ(-1, map_.GetId(kRtpExtensionTransmissionTimeOffset, &idOut));
-            map.GetId(TransmissionOffset::kId));
-  EXPECT_TRUE(map.Register<TransmissionOffset>(3));
 
-  EXPECT_EQ(3, map.GetId(TransmissionOffset::kId));
+  EXPECT_EQ(0, map_.Register(kRtpExtensionTransmissionTimeOffset, kId));
+  EXPECT_EQ(0, map_.GetId(kRtpExtensionTransmissionTimeOffset, &idOut));
+  EXPECT_EQ(kId, idOut);
 }
 
+TEST_F(RtpHeaderExtensionTest, GetCopy) {
+  EXPECT_EQ(0, map_.Register(kRtpExtensionTransmissionTimeOffset, kId));
+
+  RtpHeaderExtensionMap mapOut;
+  map_.GetCopy(&mapOut);
+  EXPECT_EQ(1, mapOut.Size());
+  EXPECT_EQ(kId, mapOut.GetId(kRtpExtensionTransmissionTimeOffset));
+}
+
+TEST_F(RtpHeaderExtensionTest, Erase) {
+  EXPECT_EQ(0, map_.Register(kRtpExtensionTransmissionTimeOffset, kId));
+  EXPECT_EQ(1, map_.Size());
+  map_.Erase();
+  EXPECT_EQ(0, map_.Size());
+}
 }  // namespace webrtc

webrtc/modules/rtp_rtcp/source/rtp_header_extensions.cc

@@ -33,7 +33,8 @@ namespace webrtc {
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 constexpr RTPExtensionType AbsoluteSendTime::kId;
 constexpr uint8_t AbsoluteSendTime::kValueSizeBytes;
-constexpr const char* AbsoluteSendTime::kUri;
+const char* const AbsoluteSendTime::kUri =
+    "http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time";
 
 bool AbsoluteSendTime::Parse(const uint8_t* data, uint32_t* time_24bits) {
   *time_24bits = ByteReader<uint32_t, 3>::ReadBigEndian(data);
@@ -59,7 +60,8 @@ bool AbsoluteSendTime::Write(uint8_t* data, int64_t time_ms) {
 //
 constexpr RTPExtensionType AudioLevel::kId;
 constexpr uint8_t AudioLevel::kValueSizeBytes;
-constexpr const char* AudioLevel::kUri;
+const char* const AudioLevel::kUri =
+    "urn:ietf:params:rtp-hdrext:ssrc-audio-level";
 
 bool AudioLevel::Parse(const uint8_t* data,
                        bool* voice_activity,
@@ -95,7 +97,8 @@ bool AudioLevel::Write(uint8_t* data,
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 constexpr RTPExtensionType TransmissionOffset::kId;
 constexpr uint8_t TransmissionOffset::kValueSizeBytes;
-constexpr const char* TransmissionOffset::kUri;
+const char* const TransmissionOffset::kUri =
+    "urn:ietf:params:rtp-hdrext:toffset";
 
 bool TransmissionOffset::Parse(const uint8_t* data, int32_t* rtp_time) {
   *rtp_time = ByteReader<int32_t, 3>::ReadBigEndian(data);
@@ -115,7 +118,8 @@ bool TransmissionOffset::Write(uint8_t* data, int32_t rtp_time) {
 //  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 constexpr RTPExtensionType TransportSequenceNumber::kId;
 constexpr uint8_t TransportSequenceNumber::kValueSizeBytes;
-constexpr const char* TransportSequenceNumber::kUri;
+const char* const TransportSequenceNumber::kUri =
+    "http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions";
 
 bool TransportSequenceNumber::Parse(const uint8_t* data, uint16_t* value) {
   *value = ByteReader<uint16_t>::ReadBigEndian(data);
@@ -140,7 +144,7 @@ bool TransportSequenceNumber::Write(uint8_t* data, uint16_t value) {
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 constexpr RTPExtensionType VideoOrientation::kId;
 constexpr uint8_t VideoOrientation::kValueSizeBytes;
-constexpr const char* VideoOrientation::kUri;
+const char* const VideoOrientation::kUri = "urn:3gpp:video-orientation";
 
 bool VideoOrientation::Parse(const uint8_t* data, VideoRotation* rotation) {
   *rotation = ConvertCVOByteToVideoRotation(data[0]);
@@ -169,7 +173,8 @@ bool VideoOrientation::Write(uint8_t* data, uint8_t value) {
 //  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 constexpr RTPExtensionType PlayoutDelayLimits::kId;
 constexpr uint8_t PlayoutDelayLimits::kValueSizeBytes;
-constexpr const char* PlayoutDelayLimits::kUri;
+const char* const PlayoutDelayLimits::kUri =
+    "http://www.webrtc.org/experiments/rtp-hdrext/playout-delay";
 
 bool PlayoutDelayLimits::Parse(const uint8_t* data,
                                PlayoutDelay* playout_delay) {

webrtc/modules/rtp_rtcp/source/rtp_header_extensions.h

@@ -20,8 +20,7 @@ class AbsoluteSendTime {
  public:
   static constexpr RTPExtensionType kId = kRtpExtensionAbsoluteSendTime;
   static constexpr uint8_t kValueSizeBytes = 3;
-  static constexpr const char* kUri =
+  static const char* const kUri;
-      "http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time";
 
   static bool Parse(const uint8_t* data, uint32_t* time_24bits);
   static bool Write(uint8_t* data, int64_t time_ms);
@@ -35,8 +34,7 @@ class AudioLevel {
  public:
   static constexpr RTPExtensionType kId = kRtpExtensionAudioLevel;
   static constexpr uint8_t kValueSizeBytes = 1;
-  static constexpr const char* kUri =
+  static const char* const kUri;
-      "urn:ietf:params:rtp-hdrext:ssrc-audio-level";
 
   static bool Parse(const uint8_t* data,
                     bool* voice_activity,
@@ -48,7 +46,7 @@ class TransmissionOffset {
  public:
   static constexpr RTPExtensionType kId = kRtpExtensionTransmissionTimeOffset;
   static constexpr uint8_t kValueSizeBytes = 3;
-  static constexpr const char* kUri = "urn:ietf:params:rtp-hdrext:toffset";
+  static const char* const kUri;
 
   static bool Parse(const uint8_t* data, int32_t* rtp_time);
   static bool Write(uint8_t* data, int32_t rtp_time);
@@ -58,9 +56,8 @@ class TransportSequenceNumber {
  public:
   static constexpr RTPExtensionType kId = kRtpExtensionTransportSequenceNumber;
   static constexpr uint8_t kValueSizeBytes = 2;
-  static constexpr const char* kUri =
+  static const char* const kUri;
-      "http://www.ietf.org/id/"
+
-      "draft-holmer-rmcat-transport-wide-cc-extensions-01";
   static bool Parse(const uint8_t* data, uint16_t* value);
   static bool Write(uint8_t* data, uint16_t value);
 };
@@ -69,7 +66,7 @@ class VideoOrientation {
  public:
   static constexpr RTPExtensionType kId = kRtpExtensionVideoRotation;
   static constexpr uint8_t kValueSizeBytes = 1;
-  static constexpr const char* kUri = "urn:3gpp:video-orientation";
+  static const char* const kUri;
 
   static bool Parse(const uint8_t* data, VideoRotation* value);
   static bool Write(uint8_t* data, VideoRotation value);
@@ -81,8 +78,7 @@ class PlayoutDelayLimits {
  public:
   static constexpr RTPExtensionType kId = kRtpExtensionPlayoutDelay;
   static constexpr uint8_t kValueSizeBytes = 3;
-  static constexpr const char* kUri =
+  static const char* const kUri;
-      "http://www.webrtc.org/experiments/rtp-hdrext/playout-delay";
 
   // Playout delay in milliseconds. A playout delay limit (min or max)
   // has 12 bits allocated. This allows a range of 0-4095 values which