diff --git a/modules/rtp_rtcp/source/rtp_packet.cc b/modules/rtp_rtcp/source/rtp_packet.cc
index 9b5bc8671b..4387fe74c3 100644
--- a/modules/rtp_rtcp/source/rtp_packet.cc
+++ b/modules/rtp_rtcp/source/rtp_packet.cc
@@ -107,32 +107,6 @@ bool RtpPacket::Parse(rtc::CopyOnWriteBuffer buffer) {
   return true;
 }
 
-bool RtpPacket::Marker() const {
-  RTC_DCHECK_EQ(marker_, (data()[1] & 0x80) != 0);
-  return marker_;
-}
-
-uint8_t RtpPacket::PayloadType() const {
-  RTC_DCHECK_EQ(payload_type_, data()[1] & 0x7f);
-  return payload_type_;
-}
-
-uint16_t RtpPacket::SequenceNumber() const {
-  RTC_DCHECK_EQ(sequence_number_,
-                ByteReader<uint16_t>::ReadBigEndian(data() + 2));
-  return sequence_number_;
-}
-
-uint32_t RtpPacket::Timestamp() const {
-  RTC_DCHECK_EQ(timestamp_, ByteReader<uint32_t>::ReadBigEndian(data() + 4));
-  return timestamp_;
-}
-
-uint32_t RtpPacket::Ssrc() const {
-  RTC_DCHECK_EQ(ssrc_, ByteReader<uint32_t>::ReadBigEndian(data() + 8));
-  return ssrc_;
-}
-
 std::vector<uint32_t> RtpPacket::Csrcs() const {
   size_t num_csrc = data()[0] & 0x0F;
   RTC_DCHECK_GE(capacity(), kFixedHeaderSize + num_csrc * 4);
@@ -144,48 +118,6 @@ std::vector<uint32_t> RtpPacket::Csrcs() const {
   return csrcs;
 }
 
-size_t RtpPacket::headers_size() const {
-  return payload_offset_;
-}
-
-size_t RtpPacket::payload_size() const {
-  return payload_size_;
-}
-
-size_t RtpPacket::padding_size() const {
-  return padding_size_;
-}
-
-rtc::ArrayView<const uint8_t> RtpPacket::payload() const {
-  return rtc::MakeArrayView(data() + payload_offset_, payload_size_);
-}
-
-rtc::CopyOnWriteBuffer RtpPacket::Buffer() const {
-  return buffer_;
-}
-
-size_t RtpPacket::capacity() const {
-  return buffer_.capacity();
-}
-
-size_t RtpPacket::size() const {
-  size_t ret = payload_offset_ + payload_size_ + padding_size_;
-  RTC_DCHECK_EQ(buffer_.size(), ret);
-  return ret;
-}
-
-const uint8_t* RtpPacket::data() const {
-  return buffer_.cdata();
-}
-
-size_t RtpPacket::FreeCapacity() const {
-  return capacity() - size();
-}
-
-size_t RtpPacket::MaxPayloadSize() const {
-  return capacity() - payload_offset_;
-}
-
 void RtpPacket::CopyHeaderFrom(const RtpPacket& packet) {
   RTC_DCHECK_GE(capacity(), packet.headers_size());
 
@@ -235,7 +167,7 @@ void RtpPacket::SetSsrc(uint32_t ssrc) {
   ByteWriter<uint32_t>::WriteBigEndian(WriteAt(8), ssrc);
 }
 
-void RtpPacket::SetCsrcs(const std::vector<uint32_t>& csrcs) {
+void RtpPacket::SetCsrcs(rtc::ArrayView<const uint32_t> csrcs) {
   RTC_DCHECK_EQ(extensions_size_, 0);
   RTC_DCHECK_EQ(payload_size_, 0);
   RTC_DCHECK_EQ(padding_size_, 0);
@@ -517,12 +449,4 @@ rtc::ArrayView<uint8_t> RtpPacket::AllocateExtension(ExtensionType type,
   return nullptr;
 }
 
-uint8_t* RtpPacket::WriteAt(size_t offset) {
-  return buffer_.data() + offset;
-}
-
-void RtpPacket::WriteAt(size_t offset, uint8_t byte) {
-  buffer_.data()[offset] = byte;
-}
-
 }  // namespace webrtc
diff --git a/modules/rtp_rtcp/source/rtp_packet.h b/modules/rtp_rtcp/source/rtp_packet.h
index 64a4bcb0ae..21adf6229b 100644
--- a/modules/rtp_rtcp/source/rtp_packet.h
+++ b/modules/rtp_rtcp/source/rtp_packet.h
@@ -51,27 +51,31 @@ class RtpPacket {
   void IdentifyExtensions(const ExtensionManager& extensions);
 
   // Header.
-  bool Marker() const;
-  uint8_t PayloadType() const;
-  uint16_t SequenceNumber() const;
-  uint32_t Timestamp() const;
-  uint32_t Ssrc() const;
+  bool Marker() const { return marker_; }
+  uint8_t PayloadType() const { return payload_type_; }
+  uint16_t SequenceNumber() const { return sequence_number_; }
+  uint32_t Timestamp() const { return timestamp_; }
+  uint32_t Ssrc() const { return ssrc_; }
   std::vector<uint32_t> Csrcs() const;
 
-  size_t headers_size() const;
+  size_t headers_size() const { return payload_offset_; }
 
   // Payload.
-  size_t payload_size() const;
-  size_t padding_size() const;
-  rtc::ArrayView<const uint8_t> payload() const;
+  size_t payload_size() const { return payload_size_; }
+  size_t padding_size() const { return padding_size_; }
+  rtc::ArrayView<const uint8_t> payload() const {
+    return rtc::MakeArrayView(data() + payload_offset_, payload_size_);
+  }
 
   // Buffer.
-  rtc::CopyOnWriteBuffer Buffer() const;
-  size_t capacity() const;
-  size_t size() const;
-  const uint8_t* data() const;
-  size_t FreeCapacity() const;
-  size_t MaxPayloadSize() const;
+  rtc::CopyOnWriteBuffer Buffer() const { return buffer_; }
+  size_t capacity() const { return buffer_.capacity(); }
+  size_t size() const {
+    return payload_offset_ + payload_size_ + padding_size_;
+  }
+  const uint8_t* data() const { return buffer_.cdata(); }
+  size_t FreeCapacity() const { return capacity() - size(); }
+  size_t MaxPayloadSize() const { return capacity() - headers_size(); }
 
   // Reset fields and buffer.
   void Clear();
@@ -87,7 +91,7 @@ class RtpPacket {
   // Writes csrc list. Assumes:
   // a) There is enough room left in buffer.
   // b) Extension headers, payload or padding data has not already been added.
-  void SetCsrcs(const std::vector<uint32_t>& csrcs);
+  void SetCsrcs(rtc::ArrayView<const uint32_t> csrcs);
 
   // Header extensions.
   template <typename Extension>
@@ -131,8 +135,8 @@ class RtpPacket {
   // to write raw extension to or an empty view on failure.
   rtc::ArrayView<uint8_t> AllocateExtension(ExtensionType type, size_t length);
 
-  uint8_t* WriteAt(size_t offset);
-  void WriteAt(size_t offset, uint8_t byte);
+  uint8_t* WriteAt(size_t offset) { return buffer_.data() + offset; }
+  void WriteAt(size_t offset, uint8_t byte) { buffer_.data()[offset] = byte; }
 
   // Header.
   bool marker_;