webrtc/modules/rtp_rtcp/source/rtp_header_extensions.cc - src - Git at Google

 /*
  *  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 "webrtc/modules/rtp_rtcp/source/rtp_header_extensions.h"

 #include "webrtc/modules/rtp_rtcp/include/rtp_cvo.h"
 #include "webrtc/modules/rtp_rtcp/source/byte_io.h"
 #include "webrtc/rtc_base/checks.h"
 #include "webrtc/rtc_base/logging.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 [RFC5285]. 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               |
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 constexpr RTPExtensionType AbsoluteSendTime::kId;
 constexpr uint8_t AbsoluteSendTime::kValueSizeBytes;
 constexpr const char* AbsoluteSendTime::kUri;

 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(uint8_t* data, uint32_t time_24bits) {
   RTC_DCHECK_LE(time_24bits, 0x00FFFFFF);
   ByteWriter<uint32_t, 3>::WriteBigEndian(data, time_24bits);
   return true;
 }

 // An RTP Header Extension for Client-to-Mixer Audio Level Indication
 //
 // https://datatracker.ietf.org/doc/draft-lennox-avt-rtp-audio-level-exthdr/
 //
 // 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     |
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 //
 constexpr RTPExtensionType AudioLevel::kId;
 constexpr uint8_t AudioLevel::kValueSizeBytes;
 constexpr const char* AudioLevel::kUri;

 bool AudioLevel::Parse(rtc::ArrayView<const uint8_t> data,
                        bool* voice_activity,
                        uint8_t* audio_level) {
   if (data.size() != 1)
     return false;
   *voice_activity = (data[0] & 0x80) != 0;
   *audio_level = data[0] & 0x7F;
   return true;
 }

 bool AudioLevel::Write(uint8_t* data,
                        bool voice_activity,
                        uint8_t audio_level) {
   RTC_CHECK_LE(audio_level, 0x7f);
   data[0] = (voice_activity ? 0x80 : 0x00) | audio_level;
   return true;
 }

 // 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 [RFC5285]. 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              |
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 constexpr RTPExtensionType TransmissionOffset::kId;
 constexpr uint8_t TransmissionOffset::kValueSizeBytes;
 constexpr const char* TransmissionOffset::kUri;

 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(uint8_t* data, int32_t rtp_time) {
   RTC_DCHECK_LE(rtp_time, 0x00ffffff);
   ByteWriter<int32_t, 3>::WriteBigEndian(data, rtp_time);
   return true;
 }

 //   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 |
 //  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 constexpr RTPExtensionType TransportSequenceNumber::kId;
 constexpr uint8_t TransportSequenceNumber::kValueSizeBytes;
 constexpr const char* TransportSequenceNumber::kUri;

 bool TransportSequenceNumber::Parse(rtc::ArrayView<const uint8_t> data,
                                     uint16_t* value) {
   if (data.size() != 2)
     return false;
   *value = ByteReader<uint16_t>::ReadBigEndian(data.data());
   return true;
 }

 bool TransportSequenceNumber::Write(uint8_t* data, uint16_t value) {
   ByteWriter<uint16_t>::WriteBigEndian(data, value);
   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|
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 constexpr RTPExtensionType VideoOrientation::kId;
 constexpr uint8_t VideoOrientation::kValueSizeBytes;
 constexpr const char* VideoOrientation::kUri;

 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(uint8_t* data, VideoRotation rotation) {
   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(uint8_t* data, uint8_t value) {
   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           |
 //  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 constexpr RTPExtensionType PlayoutDelayLimits::kId;
 constexpr uint8_t PlayoutDelayLimits::kValueSizeBytes;
 constexpr const char* PlayoutDelayLimits::kUri;

 bool PlayoutDelayLimits::Parse(rtc::ArrayView<const uint8_t> data,
                                PlayoutDelay* 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);
   if (min_raw > max_raw)
     return false;
   playout_delay->min_ms = min_raw * kGranularityMs;
   playout_delay->max_ms = max_raw * kGranularityMs;
   return true;
 }

 bool PlayoutDelayLimits::Write(uint8_t* data,
                                const PlayoutDelay& playout_delay) {
   RTC_DCHECK_LE(0, playout_delay.min_ms);
   RTC_DCHECK_LE(playout_delay.min_ms, playout_delay.max_ms);
   RTC_DCHECK_LE(playout_delay.max_ms, kMaxMs);
   // Convert MS to value to be sent on extension header.
   uint32_t min_delay = playout_delay.min_ms / kGranularityMs;
   uint32_t max_delay = playout_delay.max_ms / kGranularityMs;
   ByteWriter<uint32_t, 3>::WriteBigEndian(data, (min_delay << 12) | max_delay);
   return true;
 }

 // 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  |
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 constexpr RTPExtensionType VideoContentTypeExtension::kId;
 constexpr uint8_t VideoContentTypeExtension::kValueSizeBytes;
 constexpr const char* VideoContentTypeExtension::kUri;

 bool VideoContentTypeExtension::Parse(rtc::ArrayView<const uint8_t> data,
                                       VideoContentType* content_type) {
   if (data.size() == 1 &&
       data[0] < static_cast<uint8_t>(VideoContentType::TOTAL_CONTENT_TYPES)) {
     *content_type = static_cast<VideoContentType>(data[0]);
     return true;
   }
   return false;
 }

 bool VideoContentTypeExtension::Write(uint8_t* data,
                                       VideoContentType content_type) {
   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.
 //    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 2
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 //   |  ID   | len=11|  encode start ms delta          | encode finish |
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 //   | ms delta      |  packetizer finish ms delta     | pacer exit    |
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 //   | ms delta      |  network timestamp ms delta     | network2 time-|
 //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 //   | stamp ms delta|
 //   +-+-+-+-+-+-+-+-+

 constexpr RTPExtensionType VideoTimingExtension::kId;
 constexpr uint8_t VideoTimingExtension::kValueSizeBytes;
 constexpr const char* VideoTimingExtension::kUri;

 bool VideoTimingExtension::Parse(rtc::ArrayView<const uint8_t> data,
                                  VideoSendTiming* timing) {
   RTC_DCHECK(timing);
   if (data.size() != kValueSizeBytes)
     return false;
   timing->encode_start_delta_ms =
       ByteReader<uint16_t>::ReadBigEndian(data.data());
   timing->encode_finish_delta_ms = ByteReader<uint16_t>::ReadBigEndian(
       data.data() + 2 * VideoSendTiming::kEncodeFinishDeltaIdx);
   timing->packetization_finish_delta_ms = ByteReader<uint16_t>::ReadBigEndian(
       data.data() + 2 * VideoSendTiming::kPacketizationFinishDeltaIdx);
   timing->pacer_exit_delta_ms = ByteReader<uint16_t>::ReadBigEndian(
       data.data() + 2 * VideoSendTiming::kPacerExitDeltaIdx);
   timing->network_timstamp_delta_ms = ByteReader<uint16_t>::ReadBigEndian(
       data.data() + 2 * VideoSendTiming::kNetworkTimestampDeltaIdx);
   timing->network2_timstamp_delta_ms = ByteReader<uint16_t>::ReadBigEndian(
       data.data() + 2 * VideoSendTiming::kNetwork2TimestampDeltaIdx);
   timing->is_timing_frame = true;
   return true;
 }

 bool VideoTimingExtension::Write(uint8_t* data, const VideoSendTiming& timing) {
   ByteWriter<uint16_t>::WriteBigEndian(data, timing.encode_start_delta_ms);
   ByteWriter<uint16_t>::WriteBigEndian(
       data + 2 * VideoSendTiming::kEncodeFinishDeltaIdx,
       timing.encode_finish_delta_ms);
   ByteWriter<uint16_t>::WriteBigEndian(
       data + 2 * VideoSendTiming::kPacketizationFinishDeltaIdx,
       timing.packetization_finish_delta_ms);
   ByteWriter<uint16_t>::WriteBigEndian(
       data + 2 * VideoSendTiming::kPacerExitDeltaIdx,
       timing.pacer_exit_delta_ms);
   ByteWriter<uint16_t>::WriteBigEndian(
       data + 2 * VideoSendTiming::kNetworkTimestampDeltaIdx, 0);  // reserved
   ByteWriter<uint16_t>::WriteBigEndian(
       data + 2 * VideoSendTiming::kNetwork2TimestampDeltaIdx, 0);  // reserved
   return true;
 }

 bool VideoTimingExtension::Write(uint8_t* data,
                                  uint16_t time_delta_ms,
                                  uint8_t idx) {
   RTC_DCHECK_LT(idx, 6);
   ByteWriter<uint16_t>::WriteBigEndian(data + 2 * idx, time_delta_ms);
   return true;
 }

 // RtpStreamId.
 constexpr RTPExtensionType RtpStreamId::kId;
 constexpr const char* RtpStreamId::kUri;

 bool RtpStreamId::Parse(rtc::ArrayView<const uint8_t> data, StreamId* rsid) {
   if (data.empty() || data[0] == 0)  // Valid rsid can't be empty.
     return false;
   rsid->Set(data);
   RTC_DCHECK(!rsid->empty());
   return true;
 }

 bool RtpStreamId::Write(uint8_t* data, const StreamId& rsid) {
   RTC_DCHECK_GE(rsid.size(), 1);
   RTC_DCHECK_LE(rsid.size(), StreamId::kMaxSize);
   memcpy(data, rsid.data(), rsid.size());
   return true;
 }

 bool RtpStreamId::Parse(rtc::ArrayView<const uint8_t> data, std::string* rsid) {
   if (data.empty() || data[0] == 0)  // Valid rsid can't be empty.
     return false;
   const char* str = 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 rsid shouldn't contain it.
   rsid->assign(str, strnlen(str, data.size()));
   RTC_DCHECK(!rsid->empty());
   return true;
 }

 bool RtpStreamId::Write(uint8_t* data, const std::string& rsid) {
   RTC_DCHECK_GE(rsid.size(), 1);
   RTC_DCHECK_LE(rsid.size(), StreamId::kMaxSize);
   memcpy(data, rsid.data(), rsid.size());
   return true;
 }

 // RepairedRtpStreamId.
 constexpr RTPExtensionType RepairedRtpStreamId::kId;
 constexpr const char* RepairedRtpStreamId::kUri;

 // RtpStreamId and RepairedRtpStreamId use the same format to store rsid.
 bool RepairedRtpStreamId::Parse(rtc::ArrayView<const uint8_t> data,
                                 StreamId* rsid) {
   return RtpStreamId::Parse(data, rsid);
 }

 size_t RepairedRtpStreamId::ValueSize(const StreamId& rsid) {
   return RtpStreamId::ValueSize(rsid);
 }

 bool RepairedRtpStreamId::Write(uint8_t* data, const StreamId& rsid) {
   return RtpStreamId::Write(data, rsid);
 }

 bool RepairedRtpStreamId::Parse(rtc::ArrayView<const uint8_t> data,
                                 std::string* rsid) {
   return RtpStreamId::Parse(data, rsid);
 }

 size_t RepairedRtpStreamId::ValueSize(const std::string& rsid) {
   return RtpStreamId::ValueSize(rsid);
 }

 bool RepairedRtpStreamId::Write(uint8_t* data, const std::string& rsid) {
   return RtpStreamId::Write(data, rsid);
 }

 }  // namespace webrtc
	/*
	* 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 "webrtc/modules/rtp_rtcp/source/rtp_header_extensions.h"

	#include "webrtc/modules/rtp_rtcp/include/rtp_cvo.h"
	#include "webrtc/modules/rtp_rtcp/source/byte_io.h"
	#include "webrtc/rtc_base/checks.h"
	#include "webrtc/rtc_base/logging.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 [RFC5285]. 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 \|
	// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	constexpr RTPExtensionType AbsoluteSendTime::kId;
	constexpr uint8_t AbsoluteSendTime::kValueSizeBytes;
	constexpr const char* AbsoluteSendTime::kUri;

	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(uint8_t* data, uint32_t time_24bits) {
	RTC_DCHECK_LE(time_24bits, 0x00FFFFFF);
	ByteWriter<uint32_t, 3>::WriteBigEndian(data, time_24bits);
	return true;
	}

	// An RTP Header Extension for Client-to-Mixer Audio Level Indication
	//
	// https://datatracker.ietf.org/doc/draft-lennox-avt-rtp-audio-level-exthdr/
	//
	// 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 \|
	// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	//
	constexpr RTPExtensionType AudioLevel::kId;
	constexpr uint8_t AudioLevel::kValueSizeBytes;
	constexpr const char* AudioLevel::kUri;

	bool AudioLevel::Parse(rtc::ArrayView<const uint8_t> data,
	bool* voice_activity,
	uint8_t* audio_level) {
	if (data.size() != 1)
	return false;
	*voice_activity = (data[0] & 0x80) != 0;
	*audio_level = data[0] & 0x7F;
	return true;
	}

	bool AudioLevel::Write(uint8_t* data,
	bool voice_activity,
	uint8_t audio_level) {
	RTC_CHECK_LE(audio_level, 0x7f);
	data[0] = (voice_activity ? 0x80 : 0x00) \| audio_level;
	return true;
	}

	// 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 [RFC5285]. 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 \|
	// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	constexpr RTPExtensionType TransmissionOffset::kId;
	constexpr uint8_t TransmissionOffset::kValueSizeBytes;
	constexpr const char* TransmissionOffset::kUri;

	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(uint8_t* data, int32_t rtp_time) {
	RTC_DCHECK_LE(rtp_time, 0x00ffffff);
	ByteWriter<int32_t, 3>::WriteBigEndian(data, rtp_time);
	return true;
	}

	// 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 \|
	// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	constexpr RTPExtensionType TransportSequenceNumber::kId;
	constexpr uint8_t TransportSequenceNumber::kValueSizeBytes;
	constexpr const char* TransportSequenceNumber::kUri;

	bool TransportSequenceNumber::Parse(rtc::ArrayView<const uint8_t> data,
	uint16_t* value) {
	if (data.size() != 2)
	return false;
	*value = ByteReader<uint16_t>::ReadBigEndian(data.data());
	return true;
	}

	bool TransportSequenceNumber::Write(uint8_t* data, uint16_t value) {
	ByteWriter<uint16_t>::WriteBigEndian(data, value);
	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\|
	// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	constexpr RTPExtensionType VideoOrientation::kId;
	constexpr uint8_t VideoOrientation::kValueSizeBytes;
	constexpr const char* VideoOrientation::kUri;

	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(uint8_t* data, VideoRotation rotation) {
	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(uint8_t* data, uint8_t value) {
	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 \|
	// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	constexpr RTPExtensionType PlayoutDelayLimits::kId;
	constexpr uint8_t PlayoutDelayLimits::kValueSizeBytes;
	constexpr const char* PlayoutDelayLimits::kUri;

	bool PlayoutDelayLimits::Parse(rtc::ArrayView<const uint8_t> data,
	PlayoutDelay* 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);
	if (min_raw > max_raw)
	return false;
	playout_delay->min_ms = min_raw * kGranularityMs;
	playout_delay->max_ms = max_raw * kGranularityMs;
	return true;
	}

	bool PlayoutDelayLimits::Write(uint8_t* data,
	const PlayoutDelay& playout_delay) {
	RTC_DCHECK_LE(0, playout_delay.min_ms);
	RTC_DCHECK_LE(playout_delay.min_ms, playout_delay.max_ms);
	RTC_DCHECK_LE(playout_delay.max_ms, kMaxMs);
	// Convert MS to value to be sent on extension header.
	uint32_t min_delay = playout_delay.min_ms / kGranularityMs;
	uint32_t max_delay = playout_delay.max_ms / kGranularityMs;
	ByteWriter<uint32_t, 3>::WriteBigEndian(data, (min_delay << 12) \| max_delay);
	return true;
	}

	// 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 \|
	// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	constexpr RTPExtensionType VideoContentTypeExtension::kId;
	constexpr uint8_t VideoContentTypeExtension::kValueSizeBytes;
	constexpr const char* VideoContentTypeExtension::kUri;

	bool VideoContentTypeExtension::Parse(rtc::ArrayView<const uint8_t> data,
	VideoContentType* content_type) {
	if (data.size() == 1 &&
	data[0] < static_cast<uint8_t>(VideoContentType::TOTAL_CONTENT_TYPES)) {
	*content_type = static_cast<VideoContentType>(data[0]);
	return true;
	}
	return false;
	}

	bool VideoContentTypeExtension::Write(uint8_t* data,
	VideoContentType content_type) {
	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.
	// 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 2
	// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	// \| ID \| len=11\| encode start ms delta \| encode finish \|
	// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	// \| ms delta \| packetizer finish ms delta \| pacer exit \|
	// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	// \| ms delta \| network timestamp ms delta \| network2 time-\|
	// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	// \| stamp ms delta\|
	// +-+-+-+-+-+-+-+-+

	constexpr RTPExtensionType VideoTimingExtension::kId;
	constexpr uint8_t VideoTimingExtension::kValueSizeBytes;
	constexpr const char* VideoTimingExtension::kUri;

	bool VideoTimingExtension::Parse(rtc::ArrayView<const uint8_t> data,
	VideoSendTiming* timing) {
	RTC_DCHECK(timing);
	if (data.size() != kValueSizeBytes)
	return false;
	timing->encode_start_delta_ms =
	ByteReader<uint16_t>::ReadBigEndian(data.data());
	timing->encode_finish_delta_ms = ByteReader<uint16_t>::ReadBigEndian(
	data.data() + 2 * VideoSendTiming::kEncodeFinishDeltaIdx);
	timing->packetization_finish_delta_ms = ByteReader<uint16_t>::ReadBigEndian(
	data.data() + 2 * VideoSendTiming::kPacketizationFinishDeltaIdx);
	timing->pacer_exit_delta_ms = ByteReader<uint16_t>::ReadBigEndian(
	data.data() + 2 * VideoSendTiming::kPacerExitDeltaIdx);
	timing->network_timstamp_delta_ms = ByteReader<uint16_t>::ReadBigEndian(
	data.data() + 2 * VideoSendTiming::kNetworkTimestampDeltaIdx);
	timing->network2_timstamp_delta_ms = ByteReader<uint16_t>::ReadBigEndian(
	data.data() + 2 * VideoSendTiming::kNetwork2TimestampDeltaIdx);
	timing->is_timing_frame = true;
	return true;
	}

	bool VideoTimingExtension::Write(uint8_t* data, const VideoSendTiming& timing) {
	ByteWriter<uint16_t>::WriteBigEndian(data, timing.encode_start_delta_ms);
	ByteWriter<uint16_t>::WriteBigEndian(
	data + 2 * VideoSendTiming::kEncodeFinishDeltaIdx,
	timing.encode_finish_delta_ms);
	ByteWriter<uint16_t>::WriteBigEndian(
	data + 2 * VideoSendTiming::kPacketizationFinishDeltaIdx,
	timing.packetization_finish_delta_ms);
	ByteWriter<uint16_t>::WriteBigEndian(
	data + 2 * VideoSendTiming::kPacerExitDeltaIdx,
	timing.pacer_exit_delta_ms);
	ByteWriter<uint16_t>::WriteBigEndian(
	data + 2 * VideoSendTiming::kNetworkTimestampDeltaIdx, 0); // reserved
	ByteWriter<uint16_t>::WriteBigEndian(
	data + 2 * VideoSendTiming::kNetwork2TimestampDeltaIdx, 0); // reserved
	return true;
	}

	bool VideoTimingExtension::Write(uint8_t* data,
	uint16_t time_delta_ms,
	uint8_t idx) {
	RTC_DCHECK_LT(idx, 6);
	ByteWriter<uint16_t>::WriteBigEndian(data + 2 * idx, time_delta_ms);
	return true;
	}

	// RtpStreamId.
	constexpr RTPExtensionType RtpStreamId::kId;
	constexpr const char* RtpStreamId::kUri;

	bool RtpStreamId::Parse(rtc::ArrayView<const uint8_t> data, StreamId* rsid) {
	if (data.empty() \|\| data[0] == 0) // Valid rsid can't be empty.
	return false;
	rsid->Set(data);
	RTC_DCHECK(!rsid->empty());
	return true;
	}

	bool RtpStreamId::Write(uint8_t* data, const StreamId& rsid) {
	RTC_DCHECK_GE(rsid.size(), 1);
	RTC_DCHECK_LE(rsid.size(), StreamId::kMaxSize);
	memcpy(data, rsid.data(), rsid.size());
	return true;
	}

	bool RtpStreamId::Parse(rtc::ArrayView<const uint8_t> data, std::string* rsid) {
	if (data.empty() \|\| data[0] == 0) // Valid rsid can't be empty.
	return false;
	const char* str = 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 rsid shouldn't contain it.
	rsid->assign(str, strnlen(str, data.size()));
	RTC_DCHECK(!rsid->empty());
	return true;
	}

	bool RtpStreamId::Write(uint8_t* data, const std::string& rsid) {
	RTC_DCHECK_GE(rsid.size(), 1);
	RTC_DCHECK_LE(rsid.size(), StreamId::kMaxSize);
	memcpy(data, rsid.data(), rsid.size());
	return true;
	}

	// RepairedRtpStreamId.
	constexpr RTPExtensionType RepairedRtpStreamId::kId;
	constexpr const char* RepairedRtpStreamId::kUri;

	// RtpStreamId and RepairedRtpStreamId use the same format to store rsid.
	bool RepairedRtpStreamId::Parse(rtc::ArrayView<const uint8_t> data,
	StreamId* rsid) {
	return RtpStreamId::Parse(data, rsid);
	}

	size_t RepairedRtpStreamId::ValueSize(const StreamId& rsid) {
	return RtpStreamId::ValueSize(rsid);
	}

	bool RepairedRtpStreamId::Write(uint8_t* data, const StreamId& rsid) {
	return RtpStreamId::Write(data, rsid);
	}

	bool RepairedRtpStreamId::Parse(rtc::ArrayView<const uint8_t> data,
	std::string* rsid) {
	return RtpStreamId::Parse(data, rsid);
	}

	size_t RepairedRtpStreamId::ValueSize(const std::string& rsid) {
	return RtpStreamId::ValueSize(rsid);
	}

	bool RepairedRtpStreamId::Write(uint8_t* data, const std::string& rsid) {
	return RtpStreamId::Write(data, rsid);
	}

	} // namespace webrtc