Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 883 insertions, 0 deletions

diff --git a/third_party/libwebrtc/modules/rtp_rtcp/source/rtp_header_extensions.cc b/third_party/libwebrtc/modules/rtp_rtcp/source/rtp_header_extensions.cc
new file mode 100644
index 0000000000..ea41226abf
--- /dev/null
+++ b/third_party/libwebrtc/modules/rtp_rtcp/source/rtp_header_extensions.cc
@@ -0,0 +1,883 @@
+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "modules/rtp_rtcp/source/rtp_header_extensions.h"
+
+#include <string.h>
+
+#include <cmath>
+#include <cstddef>
+#include <cstdint>
+#include <limits>
+#include <string>
+#include <vector>
+
+#include "absl/strings/string_view.h"
+#include "absl/types/optional.h"
+#include "api/array_view.h"
+#include "api/rtp_headers.h"
+#include "api/video/color_space.h"
+#include "api/video/hdr_metadata.h"
+#include "api/video/video_content_type.h"
+#include "api/video/video_rotation.h"
+#include "api/video/video_timing.h"
+#include "modules/rtp_rtcp/include/rtp_cvo.h"
+#include "modules/rtp_rtcp/source/byte_io.h"
+#include "rtc_base/checks.h"
+
+namespace webrtc {
+// Absolute send time in RTP streams.
+//
+// The absolute send time is signaled to the receiver in-band using the
+// general mechanism for RTP header extensions [RFC8285]. The payload
+// of this extension (the transmitted value) is a 24-bit unsigned integer
+// containing the sender's current time in seconds as a fixed point number
+// with 18 bits fractional part.
+//
+// The form of the absolute send time extension block:
+//
+//    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   | len=2 |              absolute send time               |
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+bool AbsoluteSendTime::Parse(rtc::ArrayView<const uint8_t> data,
+                             uint32_t* time_24bits) {
+  if (data.size() != 3)
+    return false;
+  *time_24bits = ByteReader<uint32_t, 3>::ReadBigEndian(data.data());
+  return true;
+}
+
+bool AbsoluteSendTime::Write(rtc::ArrayView<uint8_t> data,
+                             uint32_t time_24bits) {
+  RTC_DCHECK_EQ(data.size(), 3);
+  RTC_DCHECK_LE(time_24bits, 0x00FFFFFF);
+  ByteWriter<uint32_t, 3>::WriteBigEndian(data.data(), time_24bits);
+  return true;
+}
+
+// Absolute Capture Time
+//
+// The Absolute Capture Time extension is used to stamp RTP packets with a NTP
+// timestamp showing when the first audio or video frame in a packet was
+// originally captured. The intent of this extension is to provide a way to
+// accomplish audio-to-video synchronization when RTCP-terminating intermediate
+// systems (e.g. mixers) are involved.
+//
+// Data layout of the shortened version of abs-capture-time:
+//
+//    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   | len=7 |     absolute capture timestamp (bit 0-23)     |
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//   |             absolute capture timestamp (bit 24-55)            |
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//   |  ... (56-63)  |
+//   +-+-+-+-+-+-+-+-+
+//
+// Data layout of the extended version of abs-capture-time:
+//
+//    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   | len=15|     absolute capture timestamp (bit 0-23)     |
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//   |             absolute capture timestamp (bit 24-55)            |
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//   |  ... (56-63)  |   estimated capture clock offset (bit 0-23)   |
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//   |           estimated capture clock offset (bit 24-55)          |
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//   |  ... (56-63)  |
+//   +-+-+-+-+-+-+-+-+
+bool AbsoluteCaptureTimeExtension::Parse(rtc::ArrayView<const uint8_t> data,
+                                         AbsoluteCaptureTime* extension) {
+  if (data.size() != kValueSizeBytes &&
+      data.size() != kValueSizeBytesWithoutEstimatedCaptureClockOffset) {
+    return false;
+  }
+
+  extension->absolute_capture_timestamp =
+      ByteReader<uint64_t>::ReadBigEndian(data.data());
+
+  if (data.size() != kValueSizeBytesWithoutEstimatedCaptureClockOffset) {
+    extension->estimated_capture_clock_offset =
+        ByteReader<int64_t>::ReadBigEndian(data.data() + 8);
+  }
+
+  return true;
+}
+
+size_t AbsoluteCaptureTimeExtension::ValueSize(
+    const AbsoluteCaptureTime& extension) {
+  if (extension.estimated_capture_clock_offset != absl::nullopt) {
+    return kValueSizeBytes;
+  } else {
+    return kValueSizeBytesWithoutEstimatedCaptureClockOffset;
+  }
+}
+
+bool AbsoluteCaptureTimeExtension::Write(rtc::ArrayView<uint8_t> data,
+                                         const AbsoluteCaptureTime& extension) {
+  RTC_DCHECK_EQ(data.size(), ValueSize(extension));
+
+  ByteWriter<uint64_t>::WriteBigEndian(data.data(),
+                                       extension.absolute_capture_timestamp);
+
+  if (data.size() != kValueSizeBytesWithoutEstimatedCaptureClockOffset) {
+    ByteWriter<int64_t>::WriteBigEndian(
+        data.data() + 8, extension.estimated_capture_clock_offset.value());
+  }
+
+  return true;
+}
+
+// An RTP Header Extension for Client-to-Mixer Audio Level Indication
+//
+// https://tools.ietf.org/html/rfc6464
+//
+// The form of the audio level extension block:
+//
+//  0                   1
+//  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// |  ID   | len=0 |V| level       |
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// Sample Audio Level Encoding Using the One-Byte Header Format
+//
+//  0                   1                   2
+//  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// |      ID       |     len=1     |V|    level    |
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// Sample Audio Level Encoding Using the Two-Byte Header Format
+bool AudioLevel::Parse(rtc::ArrayView<const uint8_t> data,
+                       bool* voice_activity,
+                       uint8_t* audio_level) {
+  // One-byte and two-byte format share the same data definition.
+  if (data.size() != 1)
+    return false;
+  *voice_activity = (data[0] & 0x80) != 0;
+  *audio_level = data[0] & 0x7F;
+  return true;
+}
+
+bool AudioLevel::Write(rtc::ArrayView<uint8_t> data,
+                       bool voice_activity,
+                       uint8_t audio_level) {
+  // One-byte and two-byte format share the same data definition.
+  RTC_DCHECK_EQ(data.size(), 1);
+  RTC_CHECK_LE(audio_level, 0x7f);
+  data[0] = (voice_activity ? 0x80 : 0x00) | audio_level;
+  return true;
+}
+
+#if !defined(WEBRTC_MOZILLA_BUILD)
+// An RTP Header Extension for Mixer-to-Client Audio Level Indication
+//
+// https://tools.ietf.org/html/rfc6465
+//
+// The form of the audio level extension block:
+//
+//  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   | len=2 |0|   level 1   |0|   level 2   |0|   level 3   |
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// Sample Audio Level Encoding Using the One-Byte Header Format
+//
+//  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       |     len=3     |0|   level 1   |0|   level 2   |
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// |0|   level 3   |    0 (pad)    |               ...             |
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// Sample Audio Level Encoding Using the Two-Byte Header Format
+bool CsrcAudioLevel::Parse(rtc::ArrayView<const uint8_t> data,
+                           std::vector<uint8_t>* csrc_audio_levels) {
+  if (data.size() > kRtpCsrcSize) {
+    return false;
+  }
+  csrc_audio_levels->resize(data.size());
+  for (size_t i = 0; i < data.size(); i++) {
+    (*csrc_audio_levels)[i] = data[i] & 0x7F;
+  }
+  return true;
+}
+
+size_t CsrcAudioLevel::ValueSize(
+    rtc::ArrayView<const uint8_t> csrc_audio_levels) {
+  return csrc_audio_levels.size();
+}
+
+bool CsrcAudioLevel::Write(rtc::ArrayView<uint8_t> data,
+                           rtc::ArrayView<const uint8_t> csrc_audio_levels) {
+  RTC_CHECK_LE(csrc_audio_levels.size(), kRtpCsrcSize);
+  if (csrc_audio_levels.size() != data.size()) {
+    return false;
+  }
+  for (size_t i = 0; i < csrc_audio_levels.size(); i++) {
+    data[i] = csrc_audio_levels[i] & 0x7F;
+  }
+  return true;
+}
+#endif
+
+// From RFC 5450: Transmission Time Offsets in RTP Streams.
+//
+// The transmission time is signaled to the receiver in-band using the
+// general mechanism for RTP header extensions [RFC8285]. The payload
+// of this extension (the transmitted value) is a 24-bit signed integer.
+// When added to the RTP timestamp of the packet, it represents the
+// "effective" RTP transmission time of the packet, on the RTP
+// timescale.
+//
+// The form of the transmission offset extension block:
+//
+//    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   | len=2 |              transmission offset              |
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+bool TransmissionOffset::Parse(rtc::ArrayView<const uint8_t> data,
+                               int32_t* rtp_time) {
+  if (data.size() != 3)
+    return false;
+  *rtp_time = ByteReader<int32_t, 3>::ReadBigEndian(data.data());
+  return true;
+}
+
+bool TransmissionOffset::Write(rtc::ArrayView<uint8_t> data, int32_t rtp_time) {
+  RTC_DCHECK_EQ(data.size(), 3);
+  RTC_DCHECK_LE(rtp_time, 0x00ffffff);
+  ByteWriter<int32_t, 3>::WriteBigEndian(data.data(), rtp_time);
+  return true;
+}
+
+// TransportSequenceNumber
+//
+//   0                   1                   2
+//   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//  |  ID   | L=1   |transport-wide sequence number |
+//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+bool TransportSequenceNumber::Parse(rtc::ArrayView<const uint8_t> data,
+                                    uint16_t* transport_sequence_number) {
+  if (data.size() != kValueSizeBytes)
+    return false;
+  *transport_sequence_number = ByteReader<uint16_t>::ReadBigEndian(data.data());
+  return true;
+}
+
+bool TransportSequenceNumber::Write(rtc::ArrayView<uint8_t> data,
+                                    uint16_t transport_sequence_number) {
+  RTC_DCHECK_EQ(data.size(), ValueSize(transport_sequence_number));
+  ByteWriter<uint16_t>::WriteBigEndian(data.data(), transport_sequence_number);
+  return true;
+}
+
+// TransportSequenceNumberV2
+//
+// In addition to the format used for TransportSequencNumber, V2 also supports
+// the following packet format where two extra bytes are used to specify that
+// the sender requests immediate feedback.
+//   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   |transport-wide sequence number |T|  seq count  |
+//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//  |seq count cont.|
+//  +-+-+-+-+-+-+-+-+
+//
+// The bit `T` determines whether the feedback should include timing information
+// or not and `seq_count` determines how many packets the feedback packet should
+// cover including the current packet. If `seq_count` is zero no feedback is
+// requested.
+bool TransportSequenceNumberV2::Parse(
+    rtc::ArrayView<const uint8_t> data,
+    uint16_t* transport_sequence_number,
+    absl::optional<FeedbackRequest>* feedback_request) {
+  if (data.size() != kValueSizeBytes &&
+      data.size() != kValueSizeBytesWithoutFeedbackRequest)
+    return false;
+
+  *transport_sequence_number = ByteReader<uint16_t>::ReadBigEndian(data.data());
+
+  *feedback_request = absl::nullopt;
+  if (data.size() == kValueSizeBytes) {
+    uint16_t feedback_request_raw =
+        ByteReader<uint16_t>::ReadBigEndian(data.data() + 2);
+    bool include_timestamps =
+        (feedback_request_raw & kIncludeTimestampsBit) != 0;
+    uint16_t sequence_count = feedback_request_raw & ~kIncludeTimestampsBit;
+
+    // If `sequence_count` is zero no feedback is requested.
+    if (sequence_count != 0) {
+      *feedback_request = {include_timestamps, sequence_count};
+    }
+  }
+  return true;
+}
+
+bool TransportSequenceNumberV2::Write(
+    rtc::ArrayView<uint8_t> data,
+    uint16_t transport_sequence_number,
+    const absl::optional<FeedbackRequest>& feedback_request) {
+  RTC_DCHECK_EQ(data.size(),
+                ValueSize(transport_sequence_number, feedback_request));
+
+  ByteWriter<uint16_t>::WriteBigEndian(data.data(), transport_sequence_number);
+
+  if (feedback_request) {
+    RTC_DCHECK_GE(feedback_request->sequence_count, 0);
+    RTC_DCHECK_LT(feedback_request->sequence_count, kIncludeTimestampsBit);
+    uint16_t feedback_request_raw =
+        feedback_request->sequence_count |
+        (feedback_request->include_timestamps ? kIncludeTimestampsBit : 0);
+    ByteWriter<uint16_t>::WriteBigEndian(data.data() + 2, feedback_request_raw);
+  }
+  return true;
+}
+
+// Coordination of Video Orientation in RTP streams.
+//
+// Coordination of Video Orientation consists in signaling of the current
+// orientation of the image captured on the sender side to the receiver for
+// appropriate rendering and displaying.
+//
+//    0                   1
+//    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//   |  ID   | len=0 |0 0 0 0 C F R R|
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+bool VideoOrientation::Parse(rtc::ArrayView<const uint8_t> data,
+                             VideoRotation* rotation) {
+  if (data.size() != 1)
+    return false;
+  *rotation = ConvertCVOByteToVideoRotation(data[0]);
+  return true;
+}
+
+bool VideoOrientation::Write(rtc::ArrayView<uint8_t> data,
+                             VideoRotation rotation) {
+  RTC_DCHECK_EQ(data.size(), 1);
+  data[0] = ConvertVideoRotationToCVOByte(rotation);
+  return true;
+}
+
+bool VideoOrientation::Parse(rtc::ArrayView<const uint8_t> data,
+                             uint8_t* value) {
+  if (data.size() != 1)
+    return false;
+  *value = data[0];
+  return true;
+}
+
+bool VideoOrientation::Write(rtc::ArrayView<uint8_t> data, uint8_t value) {
+  RTC_DCHECK_EQ(data.size(), 1);
+  data[0] = value;
+  return true;
+}
+
+//   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   | len=2 |   MIN delay           |   MAX delay           |
+//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+bool PlayoutDelayLimits::Parse(rtc::ArrayView<const uint8_t> data,
+                               VideoPlayoutDelay* playout_delay) {
+  RTC_DCHECK(playout_delay);
+  if (data.size() != 3)
+    return false;
+  uint32_t raw = ByteReader<uint32_t, 3>::ReadBigEndian(data.data());
+  uint16_t min_raw = (raw >> 12);
+  uint16_t max_raw = (raw & 0xfff);
+  return playout_delay->Set(min_raw * kGranularity, max_raw * kGranularity);
+}
+
+bool PlayoutDelayLimits::Write(rtc::ArrayView<uint8_t> data,
+                               const VideoPlayoutDelay& playout_delay) {
+  RTC_DCHECK_EQ(data.size(), 3);
+
+  // Convert TimeDelta to value to be sent on extension header.
+  auto idiv = [](TimeDelta num, TimeDelta den) { return num.us() / den.us(); };
+  int64_t min_delay = idiv(playout_delay.min(), kGranularity);
+  int64_t max_delay = idiv(playout_delay.max(), kGranularity);
+
+  // Double check min/max boundaries guaranteed by the `VideoPlayouDelay` type.
+  RTC_DCHECK_GE(min_delay, 0);
+  RTC_DCHECK_LT(min_delay, 1 << 12);
+  RTC_DCHECK_GE(max_delay, 0);
+  RTC_DCHECK_LT(max_delay, 1 << 12);
+
+  ByteWriter<uint32_t, 3>::WriteBigEndian(data.data(),
+                                          (min_delay << 12) | max_delay);
+  return true;
+}
+
+#if defined(WEBRTC_MOZILLA_BUILD)
+// CSRCAudioLevel
+//  Sample Audio Level Encoding Using the One-Byte Header Format
+//  Note that the range of len is 1 to 15 which is encoded as 0 to 14
+//  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   | len=2 |0|   level 1   |0|   level 2   |0|   level 3   |
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+
+constexpr RTPExtensionType CsrcAudioLevel::kId;
+constexpr const char* CsrcAudioLevel::kUri;
+
+bool CsrcAudioLevel::Parse(rtc::ArrayView<const uint8_t> data,
+                           CsrcAudioLevelList* csrcAudioLevels) {
+  if (data.size() < 1 || data.size() > kRtpCsrcSize)
+    return false;
+  csrcAudioLevels->numAudioLevels = data.size();
+  for(uint8_t i = 0; i < csrcAudioLevels->numAudioLevels; i++) {
+    // Ensure range is 0 to 127 inclusive
+    csrcAudioLevels->arrOfAudioLevels[i] = 0x7f & data[i];
+  }
+  return true;
+}
+
+size_t CsrcAudioLevel::ValueSize(const CsrcAudioLevelList& csrcAudioLevels) {
+  return csrcAudioLevels.numAudioLevels;
+}
+
+bool CsrcAudioLevel::Write(rtc::ArrayView<uint8_t> data,
+                           const CsrcAudioLevelList& csrcAudioLevels) {
+  RTC_DCHECK_GE(csrcAudioLevels.numAudioLevels, 0);
+  for(uint8_t i = 0; i < csrcAudioLevels.numAudioLevels; i++) {
+    data[i] = csrcAudioLevels.arrOfAudioLevels[i] & 0x7f;
+  }
+  // This extension if used must have at least one audio level
+  return csrcAudioLevels.numAudioLevels;
+}
+#endif
+
+// Video Content Type.
+//
+// E.g. default video or screenshare.
+//
+//    0                   1
+//    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//   |  ID   | len=0 | Content type  |
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+bool VideoContentTypeExtension::Parse(rtc::ArrayView<const uint8_t> data,
+                                      VideoContentType* content_type) {
+  if (data.size() == 1 &&
+      videocontenttypehelpers::IsValidContentType(data[0])) {
+    // Only the lowest bit of ContentType has a defined meaning.
+    // Due to previous, now removed, usage of 5 more bits, values with
+    // those bits set are accepted as valid, but we mask them out before
+    // converting to a VideoContentType.
+    *content_type = static_cast<VideoContentType>(data[0] & 0x1);
+    return true;
+  }
+  return false;
+}
+
+bool VideoContentTypeExtension::Write(rtc::ArrayView<uint8_t> data,
+                                      VideoContentType content_type) {
+  RTC_DCHECK_EQ(data.size(), 1);
+  data[0] = static_cast<uint8_t>(content_type);
+  return true;
+}
+
+// Video Timing.
+// 6 timestamps in milliseconds counted from capture time stored in rtp header:
+// encode start/finish, packetization complete, pacer exit and reserved for
+// modification by the network modification. `flags` is a bitmask and has the
+// following allowed values:
+// 0 = Valid data, but no flags available (backwards compatibility)
+// 1 = Frame marked as timing frame due to cyclic timer.
+// 2 = Frame marked as timing frame due to size being outside limit.
+// 255 = Invalid. The whole timing frame extension should be ignored.
+//
+//    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   | len=12|     flags     |     encode start ms delta     |
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//   |    encode finish ms delta     |  packetizer finish ms delta   |
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//   |     pacer exit ms delta       |  network timestamp ms delta   |
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//   |  network2 timestamp ms delta  |
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+bool VideoTimingExtension::Parse(rtc::ArrayView<const uint8_t> data,
+                                 VideoSendTiming* timing) {
+  RTC_DCHECK(timing);
+  // TODO(sprang): Deprecate support for old wire format.
+  ptrdiff_t off = 0;
+  switch (data.size()) {
+    case kValueSizeBytes - 1:
+      timing->flags = 0;
+      off = 1;  // Old wire format without the flags field.
+      break;
+    case kValueSizeBytes:
+      timing->flags = ByteReader<uint8_t>::ReadBigEndian(data.data());
+      break;
+    default:
+      return false;
+  }
+
+  timing->encode_start_delta_ms = ByteReader<uint16_t>::ReadBigEndian(
+      data.data() + kEncodeStartDeltaOffset - off);
+  timing->encode_finish_delta_ms = ByteReader<uint16_t>::ReadBigEndian(
+      data.data() + kEncodeFinishDeltaOffset - off);
+  timing->packetization_finish_delta_ms = ByteReader<uint16_t>::ReadBigEndian(
+      data.data() + kPacketizationFinishDeltaOffset - off);
+  timing->pacer_exit_delta_ms = ByteReader<uint16_t>::ReadBigEndian(
+      data.data() + kPacerExitDeltaOffset - off);
+  timing->network_timestamp_delta_ms = ByteReader<uint16_t>::ReadBigEndian(
+      data.data() + kNetworkTimestampDeltaOffset - off);
+  timing->network2_timestamp_delta_ms = ByteReader<uint16_t>::ReadBigEndian(
+      data.data() + kNetwork2TimestampDeltaOffset - off);
+  return true;
+}
+
+bool VideoTimingExtension::Write(rtc::ArrayView<uint8_t> data,
+                                 const VideoSendTiming& timing) {
+  RTC_DCHECK_EQ(data.size(), 1 + 2 * 6);
+  ByteWriter<uint8_t>::WriteBigEndian(data.data() + kFlagsOffset, timing.flags);
+  ByteWriter<uint16_t>::WriteBigEndian(data.data() + kEncodeStartDeltaOffset,
+                                       timing.encode_start_delta_ms);
+  ByteWriter<uint16_t>::WriteBigEndian(data.data() + kEncodeFinishDeltaOffset,
+                                       timing.encode_finish_delta_ms);
+  ByteWriter<uint16_t>::WriteBigEndian(
+      data.data() + kPacketizationFinishDeltaOffset,
+      timing.packetization_finish_delta_ms);
+  ByteWriter<uint16_t>::WriteBigEndian(data.data() + kPacerExitDeltaOffset,
+                                       timing.pacer_exit_delta_ms);
+  ByteWriter<uint16_t>::WriteBigEndian(
+      data.data() + kNetworkTimestampDeltaOffset,
+      timing.network_timestamp_delta_ms);
+  ByteWriter<uint16_t>::WriteBigEndian(
+      data.data() + kNetwork2TimestampDeltaOffset,
+      timing.network2_timestamp_delta_ms);
+  return true;
+}
+
+bool VideoTimingExtension::Write(rtc::ArrayView<uint8_t> data,
+                                 uint16_t time_delta_ms,
+                                 uint8_t offset) {
+  RTC_DCHECK_GE(data.size(), offset + 2);
+  RTC_DCHECK_LE(offset, kValueSizeBytes - sizeof(uint16_t));
+  ByteWriter<uint16_t>::WriteBigEndian(data.data() + offset, time_delta_ms);
+  return true;
+}
+
+// Color space including HDR metadata as an optional field.
+//
+// RTP header extension to carry color space information and optionally HDR
+// metadata. The float values in the HDR metadata struct are upscaled by a
+// static factor and transmitted as unsigned integers.
+//
+// Data layout of color space with HDR metadata (two-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       |   length=28   |   primaries   |   transfer    |
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//   |    matrix     |range+chr.sit. |         luminance_max         |
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//   |         luminance_min         |            mastering_metadata.|
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//   |primary_r.x and .y             |            mastering_metadata.|
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//   |primary_g.x and .y             |            mastering_metadata.|
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//   |primary_b.x and .y             |            mastering_metadata.|
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//   |white.x and .y                 |    max_content_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     |
+//   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//   |range+chr.sit. |
+//   +-+-+-+-+-+-+-+-+
+bool ColorSpaceExtension::Parse(rtc::ArrayView<const uint8_t> data,
+                                ColorSpace* color_space) {
+  RTC_DCHECK(color_space);
+  if (data.size() != kValueSizeBytes &&
+      data.size() != kValueSizeBytesWithoutHdrMetadata)
+    return false;
+
+  size_t offset = 0;
+  // Read color space information.
+  if (!color_space->set_primaries_from_uint8(data[offset++]))
+    return false;
+  if (!color_space->set_transfer_from_uint8(data[offset++]))
+    return false;
+  if (!color_space->set_matrix_from_uint8(data[offset++]))
+    return false;
+
+  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.
+  if (data.size() == kValueSizeBytesWithoutHdrMetadata) {
+    color_space->set_hdr_metadata(nullptr);
+  } else {
+    HdrMetadata hdr_metadata;
+    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);
+  return true;
+}
+
+bool ColorSpaceExtension::Write(rtc::ArrayView<uint8_t> data,
+                                const ColorSpace& color_space) {
+  RTC_DCHECK_EQ(data.size(), ValueSize(color_space));
+  size_t offset = 0;
+  // Write color space information.
+  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()) {
+    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) {
+  uint16_t chromaticity_x_scaled = ByteReader<uint16_t>::ReadBigEndian(data);
+  uint16_t chromaticity_y_scaled =
+      ByteReader<uint16_t>::ReadBigEndian(data + 2);
+  p->x = static_cast<float>(chromaticity_x_scaled) / kChromaticityDenominator;
+  p->y = static_cast<float>(chromaticity_y_scaled) / kChromaticityDenominator;
+  return 4;  // Return number of bytes read.
+}
+
+size_t ColorSpaceExtension::ParseLuminance(const uint8_t* data,
+                                           float* f,
+                                           int denominator) {
+  uint16_t luminance_scaled = ByteReader<uint16_t>::ReadBigEndian(data);
+  *f = static_cast<float>(luminance_scaled) / denominator;
+  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(
+      data + 2, std::round(p.y * kChromaticityDenominator));
+  return 4;  // Return number of bytes written.
+}
+
+size_t ColorSpaceExtension::WriteLuminance(uint8_t* data,
+                                           float f,
+                                           int denominator) {
+  RTC_DCHECK_GE(f, 0.0f);
+  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,
+                                   std::string* str) {
+  if (data.empty() || data[0] == 0)  // Valid string extension can't be empty.
+    return false;
+  const char* cstr = reinterpret_cast<const char*>(data.data());
+  // If there is a \0 character in the middle of the `data`, treat it as end
+  // of the string. Well-formed string extensions shouldn't contain it.
+  str->assign(cstr, strnlen(cstr, data.size()));
+  RTC_DCHECK(!str->empty());
+  return true;
+}
+
+bool BaseRtpStringExtension::Write(rtc::ArrayView<uint8_t> data,
+                                   absl::string_view str) {
+  if (str.size() > kMaxValueSizeBytes) {
+    return false;
+  }
+  RTC_DCHECK_EQ(data.size(), str.size());
+  RTC_DCHECK_GE(str.size(), 1);
+  memcpy(data.data(), str.data(), str.size());
+  return true;
+}
+
+// An RTP Header Extension for Inband Comfort Noise
+//
+// The form of the audio level extension block:
+//
+//  0                   1
+//  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// |  ID   | len=0 |N| level       |
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// Sample Audio Level Encoding Using the One-Byte Header Format
+//
+//  0                   1                   2
+//  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// |      ID       |     len=1     |N|    level    |
+// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// Sample Audio Level Encoding Using the Two-Byte Header Format
+bool InbandComfortNoiseExtension::Parse(rtc::ArrayView<const uint8_t> data,
+                                        absl::optional<uint8_t>* level) {
+  if (data.size() != kValueSizeBytes)
+    return false;
+  *level = (data[0] & 0b1000'0000) != 0
+               ? absl::nullopt
+               : absl::make_optional(data[0] & 0b0111'1111);
+  return true;
+}
+
+bool InbandComfortNoiseExtension::Write(rtc::ArrayView<uint8_t> data,
+                                        absl::optional<uint8_t> level) {
+  RTC_DCHECK_EQ(data.size(), kValueSizeBytes);
+  data[0] = 0b0000'0000;
+  if (level) {
+    if (*level > 127) {
+      return false;
+    }
+    data[0] = 0b1000'0000 | *level;
+  }
+  return true;
+}
+
+// VideoFrameTrackingIdExtension
+//
+//   0                   1                   2
+//   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//  |  ID   | L=1   |    video-frame-tracking-id    |
+//  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+bool VideoFrameTrackingIdExtension::Parse(rtc::ArrayView<const uint8_t> data,
+                                          uint16_t* video_frame_tracking_id) {
+  if (data.size() != kValueSizeBytes) {
+    return false;
+  }
+  *video_frame_tracking_id = ByteReader<uint16_t>::ReadBigEndian(data.data());
+  return true;
+}
+
+bool VideoFrameTrackingIdExtension::Write(rtc::ArrayView<uint8_t> data,
+                                          uint16_t video_frame_tracking_id) {
+  RTC_DCHECK_EQ(data.size(), kValueSizeBytes);
+  ByteWriter<uint16_t>::WriteBigEndian(data.data(), video_frame_tracking_id);
+  return true;
+}
+
+}  // namespace webrtc