Repo created

TMessagesProj/jni/voip/webrtc/common_video/h264/OWNERS

@@ -0,0 +1 @@
+ssilkin@webrtc.org

TMessagesProj/jni/voip/webrtc/common_video/h264/h264_bitstream_parser.cc

@@ -0,0 +1,299 @@
+/*
+ *  Copyright (c) 2015 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 "common_video/h264/h264_bitstream_parser.h"
+
+#include <stdlib.h>
+
+#include <cstdint>
+#include <vector>
+
+#include "common_video/h264/h264_common.h"
+#include "rtc_base/bitstream_reader.h"
+#include "rtc_base/logging.h"
+
+namespace webrtc {
+namespace {
+
+constexpr int kMaxAbsQpDeltaValue = 51;
+constexpr int kMinQpValue = 0;
+constexpr int kMaxQpValue = 51;
+
+}  // namespace
+
+H264BitstreamParser::H264BitstreamParser() = default;
+H264BitstreamParser::~H264BitstreamParser() = default;
+
+H264BitstreamParser::Result H264BitstreamParser::ParseNonParameterSetNalu(
+    const uint8_t* source,
+    size_t source_length,
+    uint8_t nalu_type) {
+  if (!sps_ || !pps_)
+    return kInvalidStream;
+
+  last_slice_qp_delta_ = absl::nullopt;
+  const std::vector<uint8_t> slice_rbsp =
+      H264::ParseRbsp(source, source_length);
+  if (slice_rbsp.size() < H264::kNaluTypeSize)
+    return kInvalidStream;
+
+  BitstreamReader slice_reader(slice_rbsp);
+  slice_reader.ConsumeBits(H264::kNaluTypeSize * 8);
+
+  // Check to see if this is an IDR slice, which has an extra field to parse
+  // out.
+  bool is_idr = (source[0] & 0x0F) == H264::NaluType::kIdr;
+  uint8_t nal_ref_idc = (source[0] & 0x60) >> 5;
+
+  // first_mb_in_slice: ue(v)
+  slice_reader.ReadExponentialGolomb();
+  // slice_type: ue(v)
+  uint32_t slice_type = slice_reader.ReadExponentialGolomb();
+  // slice_type's 5..9 range is used to indicate that all slices of a picture
+  // have the same value of slice_type % 5, we don't care about that, so we map
+  // to the corresponding 0..4 range.
+  slice_type %= 5;
+  // pic_parameter_set_id: ue(v)
+  slice_reader.ReadExponentialGolomb();
+  if (sps_->separate_colour_plane_flag == 1) {
+    // colour_plane_id
+    slice_reader.ConsumeBits(2);
+  }
+  // frame_num: u(v)
+  // Represented by log2_max_frame_num bits.
+  slice_reader.ConsumeBits(sps_->log2_max_frame_num);
+  bool field_pic_flag = false;
+  if (sps_->frame_mbs_only_flag == 0) {
+    // field_pic_flag: u(1)
+    field_pic_flag = slice_reader.Read<bool>();
+    if (field_pic_flag) {
+      // bottom_field_flag: u(1)
+      slice_reader.ConsumeBits(1);
+    }
+  }
+  if (is_idr) {
+    // idr_pic_id: ue(v)
+    slice_reader.ReadExponentialGolomb();
+  }
+  // pic_order_cnt_lsb: u(v)
+  // Represented by sps_.log2_max_pic_order_cnt_lsb bits.
+  if (sps_->pic_order_cnt_type == 0) {
+    slice_reader.ConsumeBits(sps_->log2_max_pic_order_cnt_lsb);
+    if (pps_->bottom_field_pic_order_in_frame_present_flag && !field_pic_flag) {
+      // delta_pic_order_cnt_bottom: se(v)
+      slice_reader.ReadExponentialGolomb();
+    }
+  }
+  if (sps_->pic_order_cnt_type == 1 &&
+      !sps_->delta_pic_order_always_zero_flag) {
+    // delta_pic_order_cnt[0]: se(v)
+    slice_reader.ReadExponentialGolomb();
+    if (pps_->bottom_field_pic_order_in_frame_present_flag && !field_pic_flag) {
+      // delta_pic_order_cnt[1]: se(v)
+      slice_reader.ReadExponentialGolomb();
+    }
+  }
+  if (pps_->redundant_pic_cnt_present_flag) {
+    // redundant_pic_cnt: ue(v)
+    slice_reader.ReadExponentialGolomb();
+  }
+  if (slice_type == H264::SliceType::kB) {
+    // direct_spatial_mv_pred_flag: u(1)
+    slice_reader.ConsumeBits(1);
+  }
+  switch (slice_type) {
+    case H264::SliceType::kP:
+    case H264::SliceType::kB:
+    case H264::SliceType::kSp:
+      // num_ref_idx_active_override_flag: u(1)
+      if (slice_reader.Read<bool>()) {
+        // num_ref_idx_l0_active_minus1: ue(v)
+        slice_reader.ReadExponentialGolomb();
+        if (slice_type == H264::SliceType::kB) {
+          // num_ref_idx_l1_active_minus1: ue(v)
+          slice_reader.ReadExponentialGolomb();
+        }
+      }
+      break;
+    default:
+      break;
+  }
+  if (!slice_reader.Ok()) {
+    return kInvalidStream;
+  }
+  // assume nal_unit_type != 20 && nal_unit_type != 21:
+  if (nalu_type == 20 || nalu_type == 21) {
+    RTC_LOG(LS_ERROR) << "Unsupported nal unit type.";
+    return kUnsupportedStream;
+  }
+  // if (nal_unit_type == 20 || nal_unit_type == 21)
+  //   ref_pic_list_mvc_modification()
+  // else
+  {
+    // ref_pic_list_modification():
+    // `slice_type` checks here don't use named constants as they aren't named
+    // in the spec for this segment. Keeping them consistent makes it easier to
+    // verify that they are both the same.
+    if (slice_type % 5 != 2 && slice_type % 5 != 4) {
+      // ref_pic_list_modification_flag_l0: u(1)
+      if (slice_reader.Read<bool>()) {
+        uint32_t modification_of_pic_nums_idc;
+        do {
+          // modification_of_pic_nums_idc: ue(v)
+          modification_of_pic_nums_idc = slice_reader.ReadExponentialGolomb();
+          if (modification_of_pic_nums_idc == 0 ||
+              modification_of_pic_nums_idc == 1) {
+            // abs_diff_pic_num_minus1: ue(v)
+            slice_reader.ReadExponentialGolomb();
+          } else if (modification_of_pic_nums_idc == 2) {
+            // long_term_pic_num: ue(v)
+            slice_reader.ReadExponentialGolomb();
+          }
+        } while (modification_of_pic_nums_idc != 3 && slice_reader.Ok());
+      }
+    }
+    if (slice_type % 5 == 1) {
+      // ref_pic_list_modification_flag_l1: u(1)
+      if (slice_reader.Read<bool>()) {
+        uint32_t modification_of_pic_nums_idc;
+        do {
+          // modification_of_pic_nums_idc: ue(v)
+          modification_of_pic_nums_idc = slice_reader.ReadExponentialGolomb();
+          if (modification_of_pic_nums_idc == 0 ||
+              modification_of_pic_nums_idc == 1) {
+            // abs_diff_pic_num_minus1: ue(v)
+            slice_reader.ReadExponentialGolomb();
+          } else if (modification_of_pic_nums_idc == 2) {
+            // long_term_pic_num: ue(v)
+            slice_reader.ReadExponentialGolomb();
+          }
+        } while (modification_of_pic_nums_idc != 3 && slice_reader.Ok());
+      }
+    }
+  }
+  if (!slice_reader.Ok()) {
+    return kInvalidStream;
+  }
+  // TODO(pbos): Do we need support for pred_weight_table()?
+  if ((pps_->weighted_pred_flag && (slice_type == H264::SliceType::kP ||
+                                    slice_type == H264::SliceType::kSp)) ||
+      (pps_->weighted_bipred_idc == 1 && slice_type == H264::SliceType::kB)) {
+    RTC_LOG(LS_ERROR) << "Streams with pred_weight_table unsupported.";
+    return kUnsupportedStream;
+  }
+  // if ((weighted_pred_flag && (slice_type == P || slice_type == SP)) ||
+  //    (weighted_bipred_idc == 1 && slice_type == B)) {
+  //  pred_weight_table()
+  // }
+  if (nal_ref_idc != 0) {
+    // dec_ref_pic_marking():
+    if (is_idr) {
+      // no_output_of_prior_pics_flag: u(1)
+      // long_term_reference_flag: u(1)
+      slice_reader.ConsumeBits(2);
+    } else {
+      // adaptive_ref_pic_marking_mode_flag: u(1)
+      if (slice_reader.Read<bool>()) {
+        uint32_t memory_management_control_operation;
+        do {
+          // memory_management_control_operation: ue(v)
+          memory_management_control_operation =
+              slice_reader.ReadExponentialGolomb();
+          if (memory_management_control_operation == 1 ||
+              memory_management_control_operation == 3) {
+            // difference_of_pic_nums_minus1: ue(v)
+            slice_reader.ReadExponentialGolomb();
+          }
+          if (memory_management_control_operation == 2) {
+            // long_term_pic_num: ue(v)
+            slice_reader.ReadExponentialGolomb();
+          }
+          if (memory_management_control_operation == 3 ||
+              memory_management_control_operation == 6) {
+            // long_term_frame_idx: ue(v)
+            slice_reader.ReadExponentialGolomb();
+          }
+          if (memory_management_control_operation == 4) {
+            // max_long_term_frame_idx_plus1: ue(v)
+            slice_reader.ReadExponentialGolomb();
+          }
+        } while (memory_management_control_operation != 0 && slice_reader.Ok());
+      }
+    }
+  }
+  if (pps_->entropy_coding_mode_flag && slice_type != H264::SliceType::kI &&
+      slice_type != H264::SliceType::kSi) {
+    // cabac_init_idc: ue(v)
+    slice_reader.ReadExponentialGolomb();
+  }
+
+  int last_slice_qp_delta = slice_reader.ReadSignedExponentialGolomb();
+  if (!slice_reader.Ok()) {
+    return kInvalidStream;
+  }
+  if (abs(last_slice_qp_delta) > kMaxAbsQpDeltaValue) {
+    // Something has gone wrong, and the parsed value is invalid.
+    RTC_LOG(LS_WARNING) << "Parsed QP value out of range.";
+    return kInvalidStream;
+  }
+
+  last_slice_qp_delta_ = last_slice_qp_delta;
+  return kOk;
+}
+
+void H264BitstreamParser::ParseSlice(const uint8_t* slice, size_t length) {
+  H264::NaluType nalu_type = H264::ParseNaluType(slice[0]);
+  switch (nalu_type) {
+    case H264::NaluType::kSps: {
+      sps_ = SpsParser::ParseSps(slice + H264::kNaluTypeSize,
+                                 length - H264::kNaluTypeSize);
+      if (!sps_)
+        RTC_DLOG(LS_WARNING) << "Unable to parse SPS from H264 bitstream.";
+      break;
+    }
+    case H264::NaluType::kPps: {
+      pps_ = PpsParser::ParsePps(slice + H264::kNaluTypeSize,
+                                 length - H264::kNaluTypeSize);
+      if (!pps_)
+        RTC_DLOG(LS_WARNING) << "Unable to parse PPS from H264 bitstream.";
+      break;
+    }
+    case H264::NaluType::kAud:
+    case H264::NaluType::kSei:
+    case H264::NaluType::kPrefix:
+      break;  // Ignore these nalus, as we don't care about their contents.
+    default:
+      Result res = ParseNonParameterSetNalu(slice, length, nalu_type);
+      if (res != kOk)
+        RTC_DLOG(LS_INFO) << "Failed to parse bitstream. Error: " << res;
+      break;
+  }
+}
+
+void H264BitstreamParser::ParseBitstream(
+    rtc::ArrayView<const uint8_t> bitstream) {
+  std::vector<H264::NaluIndex> nalu_indices =
+      H264::FindNaluIndices(bitstream.data(), bitstream.size());
+  for (const H264::NaluIndex& index : nalu_indices)
+    ParseSlice(bitstream.data() + index.payload_start_offset,
+               index.payload_size);
+}
+
+absl::optional<int> H264BitstreamParser::GetLastSliceQp() const {
+  if (!last_slice_qp_delta_ || !pps_)
+    return absl::nullopt;
+  const int qp = 26 + pps_->pic_init_qp_minus26 + *last_slice_qp_delta_;
+  if (qp < kMinQpValue || qp > kMaxQpValue) {
+    RTC_LOG(LS_ERROR) << "Parsed invalid QP from bitstream.";
+    return absl::nullopt;
+  }
+  return qp;
+}
+
+}  // namespace webrtc

TMessagesProj/jni/voip/webrtc/common_video/h264/h264_bitstream_parser.h

@@ -0,0 +1,58 @@
+/*
+ *  Copyright (c) 2015 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.
+ */
+
+#ifndef COMMON_VIDEO_H264_H264_BITSTREAM_PARSER_H_
+#define COMMON_VIDEO_H264_H264_BITSTREAM_PARSER_H_
+#include <stddef.h>
+#include <stdint.h>
+
+#include "absl/types/optional.h"
+#include "api/video_codecs/bitstream_parser.h"
+#include "common_video/h264/pps_parser.h"
+#include "common_video/h264/sps_parser.h"
+
+namespace webrtc {
+
+// Stateful H264 bitstream parser (due to SPS/PPS). Used to parse out QP values
+// from the bitstream.
+// TODO(pbos): Unify with RTP SPS parsing and only use one H264 parser.
+// TODO(pbos): If/when this gets used on the receiver side CHECKs must be
+// removed and gracefully abort as we have no control over receive-side
+// bitstreams.
+class H264BitstreamParser : public BitstreamParser {
+ public:
+  H264BitstreamParser();
+  ~H264BitstreamParser() override;
+
+  void ParseBitstream(rtc::ArrayView<const uint8_t> bitstream) override;
+  absl::optional<int> GetLastSliceQp() const override;
+
+ protected:
+  enum Result {
+    kOk,
+    kInvalidStream,
+    kUnsupportedStream,
+  };
+  void ParseSlice(const uint8_t* slice, size_t length);
+  Result ParseNonParameterSetNalu(const uint8_t* source,
+                                  size_t source_length,
+                                  uint8_t nalu_type);
+
+  // SPS/PPS state, updated when parsing new SPS/PPS, used to parse slices.
+  absl::optional<SpsParser::SpsState> sps_;
+  absl::optional<PpsParser::PpsState> pps_;
+
+  // Last parsed slice QP.
+  absl::optional<int32_t> last_slice_qp_delta_;
+};
+
+}  // namespace webrtc
+
+#endif  // COMMON_VIDEO_H264_H264_BITSTREAM_PARSER_H_

TMessagesProj/jni/voip/webrtc/common_video/h264/h264_common.cc

@@ -0,0 +1,116 @@
+/*
+ *  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 "common_video/h264/h264_common.h"
+
+#include <cstdint>
+
+namespace webrtc {
+namespace H264 {
+
+const uint8_t kNaluTypeMask = 0x1F;
+
+std::vector<NaluIndex> FindNaluIndices(const uint8_t* buffer,
+                                       size_t buffer_size) {
+  // This is sorta like Boyer-Moore, but with only the first optimization step:
+  // given a 3-byte sequence we're looking at, if the 3rd byte isn't 1 or 0,
+  // skip ahead to the next 3-byte sequence. 0s and 1s are relatively rare, so
+  // this will skip the majority of reads/checks.
+  std::vector<NaluIndex> sequences;
+  if (buffer_size < kNaluShortStartSequenceSize)
+    return sequences;
+
+  static_assert(kNaluShortStartSequenceSize >= 2,
+                "kNaluShortStartSequenceSize must be larger or equals to 2");
+  const size_t end = buffer_size - kNaluShortStartSequenceSize;
+  for (size_t i = 0; i < end;) {
+    if (buffer[i + 2] > 1) {
+      i += 3;
+    } else if (buffer[i + 2] == 1) {
+      if (buffer[i + 1] == 0 && buffer[i] == 0) {
+        // We found a start sequence, now check if it was a 3 of 4 byte one.
+        NaluIndex index = {i, i + 3, 0};
+        if (index.start_offset > 0 && buffer[index.start_offset - 1] == 0)
+          --index.start_offset;
+
+        // Update length of previous entry.
+        auto it = sequences.rbegin();
+        if (it != sequences.rend())
+          it->payload_size = index.start_offset - it->payload_start_offset;
+
+        sequences.push_back(index);
+      }
+
+      i += 3;
+    } else {
+      ++i;
+    }
+  }
+
+  // Update length of last entry, if any.
+  auto it = sequences.rbegin();
+  if (it != sequences.rend())
+    it->payload_size = buffer_size - it->payload_start_offset;
+
+  return sequences;
+}
+
+NaluType ParseNaluType(uint8_t data) {
+  return static_cast<NaluType>(data & kNaluTypeMask);
+}
+
+std::vector<uint8_t> ParseRbsp(const uint8_t* data, size_t length) {
+  std::vector<uint8_t> out;
+  out.reserve(length);
+
+  for (size_t i = 0; i < length;) {
+    // Be careful about over/underflow here. byte_length_ - 3 can underflow, and
+    // i + 3 can overflow, but byte_length_ - i can't, because i < byte_length_
+    // above, and that expression will produce the number of bytes left in
+    // the stream including the byte at i.
+    if (length - i >= 3 && !data[i] && !data[i + 1] && data[i + 2] == 3) {
+      // Two rbsp bytes.
+      out.push_back(data[i++]);
+      out.push_back(data[i++]);
+      // Skip the emulation byte.
+      i++;
+    } else {
+      // Single rbsp byte.
+      out.push_back(data[i++]);
+    }
+  }
+  return out;
+}
+
+void WriteRbsp(const uint8_t* bytes, size_t length, rtc::Buffer* destination) {
+  static const uint8_t kZerosInStartSequence = 2;
+  static const uint8_t kEmulationByte = 0x03u;
+  size_t num_consecutive_zeros = 0;
+  destination->EnsureCapacity(destination->size() + length);
+
+  for (size_t i = 0; i < length; ++i) {
+    uint8_t byte = bytes[i];
+    if (byte <= kEmulationByte &&
+        num_consecutive_zeros >= kZerosInStartSequence) {
+      // Need to escape.
+      destination->AppendData(kEmulationByte);
+      num_consecutive_zeros = 0;
+    }
+    destination->AppendData(byte);
+    if (byte == 0) {
+      ++num_consecutive_zeros;
+    } else {
+      num_consecutive_zeros = 0;
+    }
+  }
+}
+
+}  // namespace H264
+}  // namespace webrtc

TMessagesProj/jni/voip/webrtc/common_video/h264/h264_common.h

@@ -0,0 +1,92 @@
+/*
+ *  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.
+ */
+
+#ifndef COMMON_VIDEO_H264_H264_COMMON_H_
+#define COMMON_VIDEO_H264_H264_COMMON_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <vector>
+
+#include "rtc_base/buffer.h"
+#include "rtc_base/system/rtc_export.h"
+
+namespace webrtc {
+
+namespace H264 {
+// The size of a full NALU start sequence {0 0 0 1}, used for the first NALU
+// of an access unit, and for SPS and PPS blocks.
+const size_t kNaluLongStartSequenceSize = 4;
+
+// The size of a shortened NALU start sequence {0 0 1}, that may be used if
+// not the first NALU of an access unit or an SPS or PPS block.
+const size_t kNaluShortStartSequenceSize = 3;
+
+// The size of the NALU type byte (1).
+const size_t kNaluTypeSize = 1;
+
+enum NaluType : uint8_t {
+  kSlice = 1,
+  kIdr = 5,
+  kSei = 6,
+  kSps = 7,
+  kPps = 8,
+  kAud = 9,
+  kEndOfSequence = 10,
+  kEndOfStream = 11,
+  kFiller = 12,
+  kPrefix = 14,
+  kStapA = 24,
+  kFuA = 28
+};
+
+enum SliceType : uint8_t { kP = 0, kB = 1, kI = 2, kSp = 3, kSi = 4 };
+
+struct NaluIndex {
+  // Start index of NALU, including start sequence.
+  size_t start_offset;
+  // Start index of NALU payload, typically type header.
+  size_t payload_start_offset;
+  // Length of NALU payload, in bytes, counting from payload_start_offset.
+  size_t payload_size;
+};
+
+// Returns a vector of the NALU indices in the given buffer.
+RTC_EXPORT std::vector<NaluIndex> FindNaluIndices(const uint8_t* buffer,
+                                                  size_t buffer_size);
+
+// Get the NAL type from the header byte immediately following start sequence.
+RTC_EXPORT NaluType ParseNaluType(uint8_t data);
+
+// Methods for parsing and writing RBSP. See section 7.4.1 of the H264 spec.
+//
+// The following sequences are illegal, and need to be escaped when encoding:
+// 00 00 00 -> 00 00 03 00
+// 00 00 01 -> 00 00 03 01
+// 00 00 02 -> 00 00 03 02
+// And things in the source that look like the emulation byte pattern (00 00 03)
+// need to have an extra emulation byte added, so it's removed when decoding:
+// 00 00 03 -> 00 00 03 03
+//
+// Decoding is simply a matter of finding any 00 00 03 sequence and removing
+// the 03 emulation byte.
+
+// Parse the given data and remove any emulation byte escaping.
+std::vector<uint8_t> ParseRbsp(const uint8_t* data, size_t length);
+
+// Write the given data to the destination buffer, inserting and emulation
+// bytes in order to escape any data the could be interpreted as a start
+// sequence.
+void WriteRbsp(const uint8_t* bytes, size_t length, rtc::Buffer* destination);
+}  // namespace H264
+}  // namespace webrtc
+
+#endif  // COMMON_VIDEO_H264_H264_COMMON_H_

TMessagesProj/jni/voip/webrtc/common_video/h264/pps_parser.cc

@@ -0,0 +1,160 @@
+/*
+ *  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 "common_video/h264/pps_parser.h"
+
+#include <cstdint>
+#include <limits>
+#include <vector>
+
+#include "absl/numeric/bits.h"
+#include "common_video/h264/h264_common.h"
+#include "rtc_base/bitstream_reader.h"
+#include "rtc_base/checks.h"
+
+namespace webrtc {
+namespace {
+constexpr int kMaxPicInitQpDeltaValue = 25;
+constexpr int kMinPicInitQpDeltaValue = -26;
+}  // namespace
+
+// General note: this is based off the 02/2014 version of the H.264 standard.
+// You can find it on this page:
+// http://www.itu.int/rec/T-REC-H.264
+
+absl::optional<PpsParser::PpsState> PpsParser::ParsePps(const uint8_t* data,
+                                                        size_t length) {
+  // First, parse out rbsp, which is basically the source buffer minus emulation
+  // bytes (the last byte of a 0x00 0x00 0x03 sequence). RBSP is defined in
+  // section 7.3.1 of the H.264 standard.
+  return ParseInternal(H264::ParseRbsp(data, length));
+}
+
+bool PpsParser::ParsePpsIds(const uint8_t* data,
+                            size_t length,
+                            uint32_t* pps_id,
+                            uint32_t* sps_id) {
+  RTC_DCHECK(pps_id);
+  RTC_DCHECK(sps_id);
+  // First, parse out rbsp, which is basically the source buffer minus emulation
+  // bytes (the last byte of a 0x00 0x00 0x03 sequence). RBSP is defined in
+  // section 7.3.1 of the H.264 standard.
+  std::vector<uint8_t> unpacked_buffer = H264::ParseRbsp(data, length);
+  BitstreamReader reader(unpacked_buffer);
+  *pps_id = reader.ReadExponentialGolomb();
+  *sps_id = reader.ReadExponentialGolomb();
+  return reader.Ok();
+}
+
+absl::optional<uint32_t> PpsParser::ParsePpsIdFromSlice(const uint8_t* data,
+                                                        size_t length) {
+  std::vector<uint8_t> unpacked_buffer = H264::ParseRbsp(data, length);
+  BitstreamReader slice_reader(unpacked_buffer);
+
+  // first_mb_in_slice: ue(v)
+  slice_reader.ReadExponentialGolomb();
+  // slice_type: ue(v)
+  slice_reader.ReadExponentialGolomb();
+  // pic_parameter_set_id: ue(v)
+  uint32_t slice_pps_id = slice_reader.ReadExponentialGolomb();
+  if (!slice_reader.Ok()) {
+    return absl::nullopt;
+  }
+  return slice_pps_id;
+}
+
+absl::optional<PpsParser::PpsState> PpsParser::ParseInternal(
+    rtc::ArrayView<const uint8_t> buffer) {
+  BitstreamReader reader(buffer);
+  PpsState pps;
+  pps.id = reader.ReadExponentialGolomb();
+  pps.sps_id = reader.ReadExponentialGolomb();
+
+  // entropy_coding_mode_flag: u(1)
+  pps.entropy_coding_mode_flag = reader.Read<bool>();
+  // bottom_field_pic_order_in_frame_present_flag: u(1)
+  pps.bottom_field_pic_order_in_frame_present_flag = reader.Read<bool>();
+
+  // num_slice_groups_minus1: ue(v)
+  uint32_t num_slice_groups_minus1 = reader.ReadExponentialGolomb();
+  if (num_slice_groups_minus1 > 0) {
+    // slice_group_map_type: ue(v)
+    uint32_t slice_group_map_type = reader.ReadExponentialGolomb();
+    if (slice_group_map_type == 0) {
+      for (uint32_t i_group = 0;
+           i_group <= num_slice_groups_minus1 && reader.Ok(); ++i_group) {
+        // run_length_minus1[iGroup]: ue(v)
+        reader.ReadExponentialGolomb();
+      }
+    } else if (slice_group_map_type == 1) {
+      // TODO(sprang): Implement support for dispersed slice group map type.
+      // See 8.2.2.2 Specification for dispersed slice group map type.
+    } else if (slice_group_map_type == 2) {
+      for (uint32_t i_group = 0;
+           i_group <= num_slice_groups_minus1 && reader.Ok(); ++i_group) {
+        // top_left[iGroup]: ue(v)
+        reader.ReadExponentialGolomb();
+        // bottom_right[iGroup]: ue(v)
+        reader.ReadExponentialGolomb();
+      }
+    } else if (slice_group_map_type == 3 || slice_group_map_type == 4 ||
+               slice_group_map_type == 5) {
+      // slice_group_change_direction_flag: u(1)
+      reader.ConsumeBits(1);
+      // slice_group_change_rate_minus1: ue(v)
+      reader.ReadExponentialGolomb();
+    } else if (slice_group_map_type == 6) {
+      // pic_size_in_map_units_minus1: ue(v)
+      uint32_t pic_size_in_map_units = reader.ReadExponentialGolomb() + 1;
+      int slice_group_id_bits = 1 + absl::bit_width(num_slice_groups_minus1);
+
+      // slice_group_id: array of size pic_size_in_map_units, each element
+      // is represented by ceil(log2(num_slice_groups_minus1 + 1)) bits.
+      int64_t bits_to_consume =
+          int64_t{slice_group_id_bits} * pic_size_in_map_units;
+      if (!reader.Ok() || bits_to_consume > std::numeric_limits<int>::max()) {
+        return absl::nullopt;
+      }
+      reader.ConsumeBits(bits_to_consume);
+    }
+  }
+  // num_ref_idx_l0_default_active_minus1: ue(v)
+  reader.ReadExponentialGolomb();
+  // num_ref_idx_l1_default_active_minus1: ue(v)
+  reader.ReadExponentialGolomb();
+  // weighted_pred_flag: u(1)
+  pps.weighted_pred_flag = reader.Read<bool>();
+  // weighted_bipred_idc: u(2)
+  pps.weighted_bipred_idc = reader.ReadBits(2);
+
+  // pic_init_qp_minus26: se(v)
+  pps.pic_init_qp_minus26 = reader.ReadSignedExponentialGolomb();
+  // Sanity-check parsed value
+  if (!reader.Ok() || pps.pic_init_qp_minus26 > kMaxPicInitQpDeltaValue ||
+      pps.pic_init_qp_minus26 < kMinPicInitQpDeltaValue) {
+    return absl::nullopt;
+  }
+  // pic_init_qs_minus26: se(v)
+  reader.ReadExponentialGolomb();
+  // chroma_qp_index_offset: se(v)
+  reader.ReadExponentialGolomb();
+  // deblocking_filter_control_present_flag: u(1)
+  // constrained_intra_pred_flag: u(1)
+  reader.ConsumeBits(2);
+  // redundant_pic_cnt_present_flag: u(1)
+  pps.redundant_pic_cnt_present_flag = reader.ReadBit();
+  if (!reader.Ok()) {
+    return absl::nullopt;
+  }
+
+  return pps;
+}
+
+}  // namespace webrtc

TMessagesProj/jni/voip/webrtc/common_video/h264/pps_parser.h

@@ -0,0 +1,60 @@
+/*
+ *  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.
+ */
+
+#ifndef COMMON_VIDEO_H264_PPS_PARSER_H_
+#define COMMON_VIDEO_H264_PPS_PARSER_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include "absl/types/optional.h"
+#include "api/array_view.h"
+
+namespace webrtc {
+
+// A class for parsing out picture parameter set (PPS) data from a H264 NALU.
+class PpsParser {
+ public:
+  // The parsed state of the PPS. Only some select values are stored.
+  // Add more as they are actually needed.
+  struct PpsState {
+    PpsState() = default;
+
+    bool bottom_field_pic_order_in_frame_present_flag = false;
+    bool weighted_pred_flag = false;
+    bool entropy_coding_mode_flag = false;
+    uint32_t weighted_bipred_idc = false;
+    uint32_t redundant_pic_cnt_present_flag = 0;
+    int pic_init_qp_minus26 = 0;
+    uint32_t id = 0;
+    uint32_t sps_id = 0;
+  };
+
+  // Unpack RBSP and parse PPS state from the supplied buffer.
+  static absl::optional<PpsState> ParsePps(const uint8_t* data, size_t length);
+
+  static bool ParsePpsIds(const uint8_t* data,
+                          size_t length,
+                          uint32_t* pps_id,
+                          uint32_t* sps_id);
+
+  static absl::optional<uint32_t> ParsePpsIdFromSlice(const uint8_t* data,
+                                                      size_t length);
+
+ protected:
+  // Parse the PPS state, for a buffer where RBSP decoding has already been
+  // performed.
+  static absl::optional<PpsState> ParseInternal(
+      rtc::ArrayView<const uint8_t> buffer);
+};
+
+}  // namespace webrtc
+
+#endif  // COMMON_VIDEO_H264_PPS_PARSER_H_

TMessagesProj/jni/voip/webrtc/common_video/h264/sps_parser.cc

@@ -0,0 +1,227 @@
+/*
+ *  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 "common_video/h264/sps_parser.h"
+
+#include <cstdint>
+#include <vector>
+
+#include "common_video/h264/h264_common.h"
+#include "rtc_base/bitstream_reader.h"
+
+namespace {
+constexpr int kScalingDeltaMin = -128;
+constexpr int kScaldingDeltaMax = 127;
+}  // namespace
+
+namespace webrtc {
+
+SpsParser::SpsState::SpsState() = default;
+SpsParser::SpsState::SpsState(const SpsState&) = default;
+SpsParser::SpsState::~SpsState() = default;
+
+// General note: this is based off the 02/2014 version of the H.264 standard.
+// You can find it on this page:
+// http://www.itu.int/rec/T-REC-H.264
+
+// Unpack RBSP and parse SPS state from the supplied buffer.
+absl::optional<SpsParser::SpsState> SpsParser::ParseSps(const uint8_t* data,
+                                                        size_t length) {
+  std::vector<uint8_t> unpacked_buffer = H264::ParseRbsp(data, length);
+  BitstreamReader reader(unpacked_buffer);
+  return ParseSpsUpToVui(reader);
+}
+
+absl::optional<SpsParser::SpsState> SpsParser::ParseSpsUpToVui(
+    BitstreamReader& reader) {
+  // Now, we need to use a bitstream reader to parse through the actual AVC SPS
+  // format. See Section 7.3.2.1.1 ("Sequence parameter set data syntax") of the
+  // H.264 standard for a complete description.
+  // Since we only care about resolution, we ignore the majority of fields, but
+  // we still have to actively parse through a lot of the data, since many of
+  // the fields have variable size.
+  // We're particularly interested in:
+  // chroma_format_idc -> affects crop units
+  // pic_{width,height}_* -> resolution of the frame in macroblocks (16x16).
+  // frame_crop_*_offset -> crop information
+
+  SpsState sps;
+
+  // chroma_format_idc will be ChromaArrayType if separate_colour_plane_flag is
+  // 0. It defaults to 1, when not specified.
+  uint32_t chroma_format_idc = 1;
+
+  // profile_idc: u(8). We need it to determine if we need to read/skip chroma
+  // formats.
+  uint8_t profile_idc = reader.Read<uint8_t>();
+  // constraint_set0_flag through constraint_set5_flag + reserved_zero_2bits
+  // 1 bit each for the flags + 2 bits + 8 bits for level_idc = 16 bits.
+  reader.ConsumeBits(16);
+  // seq_parameter_set_id: ue(v)
+  sps.id = reader.ReadExponentialGolomb();
+  sps.separate_colour_plane_flag = 0;
+  // See if profile_idc has chroma format information.
+  if (profile_idc == 100 || profile_idc == 110 || profile_idc == 122 ||
+      profile_idc == 244 || profile_idc == 44 || profile_idc == 83 ||
+      profile_idc == 86 || profile_idc == 118 || profile_idc == 128 ||
+      profile_idc == 138 || profile_idc == 139 || profile_idc == 134) {
+    // chroma_format_idc: ue(v)
+    chroma_format_idc = reader.ReadExponentialGolomb();
+    if (chroma_format_idc == 3) {
+      // separate_colour_plane_flag: u(1)
+      sps.separate_colour_plane_flag = reader.ReadBit();
+    }
+    // bit_depth_luma_minus8: ue(v)
+    reader.ReadExponentialGolomb();
+    // bit_depth_chroma_minus8: ue(v)
+    reader.ReadExponentialGolomb();
+    // qpprime_y_zero_transform_bypass_flag: u(1)
+    reader.ConsumeBits(1);
+    // seq_scaling_matrix_present_flag: u(1)
+    if (reader.Read<bool>()) {
+      // Process the scaling lists just enough to be able to properly
+      // skip over them, so we can still read the resolution on streams
+      // where this is included.
+      int scaling_list_count = (chroma_format_idc == 3 ? 12 : 8);
+      for (int i = 0; i < scaling_list_count; ++i) {
+        // seq_scaling_list_present_flag[i]  : u(1)
+        if (reader.Read<bool>()) {
+          int last_scale = 8;
+          int next_scale = 8;
+          int size_of_scaling_list = i < 6 ? 16 : 64;
+          for (int j = 0; j < size_of_scaling_list; j++) {
+            if (next_scale != 0) {
+              // delta_scale: se(v)
+              int delta_scale = reader.ReadSignedExponentialGolomb();
+              if (!reader.Ok() || delta_scale < kScalingDeltaMin ||
+                  delta_scale > kScaldingDeltaMax) {
+                return absl::nullopt;
+              }
+              next_scale = (last_scale + delta_scale + 256) % 256;
+            }
+            if (next_scale != 0)
+              last_scale = next_scale;
+          }
+        }
+      }
+    }
+  }
+  // log2_max_frame_num and log2_max_pic_order_cnt_lsb are used with
+  // BitstreamReader::ReadBits, which can read at most 64 bits at a time. We
+  // also have to avoid overflow when adding 4 to the on-wire golomb value,
+  // e.g., for evil input data, ReadExponentialGolomb might return 0xfffc.
+  const uint32_t kMaxLog2Minus4 = 12;
+
+  // log2_max_frame_num_minus4: ue(v)
+  uint32_t log2_max_frame_num_minus4 = reader.ReadExponentialGolomb();
+  if (!reader.Ok() || log2_max_frame_num_minus4 > kMaxLog2Minus4) {
+    return absl::nullopt;
+  }
+  sps.log2_max_frame_num = log2_max_frame_num_minus4 + 4;
+
+  // pic_order_cnt_type: ue(v)
+  sps.pic_order_cnt_type = reader.ReadExponentialGolomb();
+  if (sps.pic_order_cnt_type == 0) {
+    // log2_max_pic_order_cnt_lsb_minus4: ue(v)
+    uint32_t log2_max_pic_order_cnt_lsb_minus4 = reader.ReadExponentialGolomb();
+    if (!reader.Ok() || log2_max_pic_order_cnt_lsb_minus4 > kMaxLog2Minus4) {
+      return absl::nullopt;
+    }
+    sps.log2_max_pic_order_cnt_lsb = log2_max_pic_order_cnt_lsb_minus4 + 4;
+  } else if (sps.pic_order_cnt_type == 1) {
+    // delta_pic_order_always_zero_flag: u(1)
+    sps.delta_pic_order_always_zero_flag = reader.ReadBit();
+    // offset_for_non_ref_pic: se(v)
+    reader.ReadExponentialGolomb();
+    // offset_for_top_to_bottom_field: se(v)
+    reader.ReadExponentialGolomb();
+    // num_ref_frames_in_pic_order_cnt_cycle: ue(v)
+    uint32_t num_ref_frames_in_pic_order_cnt_cycle =
+        reader.ReadExponentialGolomb();
+    for (size_t i = 0; i < num_ref_frames_in_pic_order_cnt_cycle; ++i) {
+      // offset_for_ref_frame[i]: se(v)
+      reader.ReadExponentialGolomb();
+      if (!reader.Ok()) {
+        return absl::nullopt;
+      }
+    }
+  }
+  // max_num_ref_frames: ue(v)
+  sps.max_num_ref_frames = reader.ReadExponentialGolomb();
+  // gaps_in_frame_num_value_allowed_flag: u(1)
+  reader.ConsumeBits(1);
+  //
+  // IMPORTANT ONES! Now we're getting to resolution. First we read the pic
+  // width/height in macroblocks (16x16), which gives us the base resolution,
+  // and then we continue on until we hit the frame crop offsets, which are used
+  // to signify resolutions that aren't multiples of 16.
+  //
+  // pic_width_in_mbs_minus1: ue(v)
+  sps.width = 16 * (reader.ReadExponentialGolomb() + 1);
+  // pic_height_in_map_units_minus1: ue(v)
+  uint32_t pic_height_in_map_units_minus1 = reader.ReadExponentialGolomb();
+  // frame_mbs_only_flag: u(1)
+  sps.frame_mbs_only_flag = reader.ReadBit();
+  if (!sps.frame_mbs_only_flag) {
+    // mb_adaptive_frame_field_flag: u(1)
+    reader.ConsumeBits(1);
+  }
+  sps.height =
+      16 * (2 - sps.frame_mbs_only_flag) * (pic_height_in_map_units_minus1 + 1);
+  // direct_8x8_inference_flag: u(1)
+  reader.ConsumeBits(1);
+  //
+  // MORE IMPORTANT ONES! Now we're at the frame crop information.
+  //
+  uint32_t frame_crop_left_offset = 0;
+  uint32_t frame_crop_right_offset = 0;
+  uint32_t frame_crop_top_offset = 0;
+  uint32_t frame_crop_bottom_offset = 0;
+  // frame_cropping_flag: u(1)
+  if (reader.Read<bool>()) {
+    // frame_crop_{left, right, top, bottom}_offset: ue(v)
+    frame_crop_left_offset = reader.ReadExponentialGolomb();
+    frame_crop_right_offset = reader.ReadExponentialGolomb();
+    frame_crop_top_offset = reader.ReadExponentialGolomb();
+    frame_crop_bottom_offset = reader.ReadExponentialGolomb();
+  }
+  // vui_parameters_present_flag: u(1)
+  sps.vui_params_present = reader.ReadBit();
+
+  // Far enough! We don't use the rest of the SPS.
+  if (!reader.Ok()) {
+    return absl::nullopt;
+  }
+
+  // Figure out the crop units in pixels. That's based on the chroma format's
+  // sampling, which is indicated by chroma_format_idc.
+  if (sps.separate_colour_plane_flag || chroma_format_idc == 0) {
+    frame_crop_bottom_offset *= (2 - sps.frame_mbs_only_flag);
+    frame_crop_top_offset *= (2 - sps.frame_mbs_only_flag);
+  } else if (!sps.separate_colour_plane_flag && chroma_format_idc > 0) {
+    // Width multipliers for formats 1 (4:2:0) and 2 (4:2:2).
+    if (chroma_format_idc == 1 || chroma_format_idc == 2) {
+      frame_crop_left_offset *= 2;
+      frame_crop_right_offset *= 2;
+    }
+    // Height multipliers for format 1 (4:2:0).
+    if (chroma_format_idc == 1) {
+      frame_crop_top_offset *= 2;
+      frame_crop_bottom_offset *= 2;
+    }
+  }
+  // Subtract the crop for each dimension.
+  sps.width -= (frame_crop_left_offset + frame_crop_right_offset);
+  sps.height -= (frame_crop_top_offset + frame_crop_bottom_offset);
+
+  return sps;
+}
+
+}  // namespace webrtc

TMessagesProj/jni/voip/webrtc/common_video/h264/sps_parser.h

@@ -0,0 +1,53 @@
+/*
+ *  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.
+ */
+
+#ifndef COMMON_VIDEO_H264_SPS_PARSER_H_
+#define COMMON_VIDEO_H264_SPS_PARSER_H_
+
+#include "absl/types/optional.h"
+#include "rtc_base/bitstream_reader.h"
+#include "rtc_base/system/rtc_export.h"
+
+namespace webrtc {
+
+// A class for parsing out sequence parameter set (SPS) data from an H264 NALU.
+class RTC_EXPORT SpsParser {
+ public:
+  // The parsed state of the SPS. Only some select values are stored.
+  // Add more as they are actually needed.
+  struct RTC_EXPORT SpsState {
+    SpsState();
+    SpsState(const SpsState&);
+    ~SpsState();
+
+    uint32_t width = 0;
+    uint32_t height = 0;
+    uint32_t delta_pic_order_always_zero_flag = 0;
+    uint32_t separate_colour_plane_flag = 0;
+    uint32_t frame_mbs_only_flag = 0;
+    uint32_t log2_max_frame_num = 4;          // Smallest valid value.
+    uint32_t log2_max_pic_order_cnt_lsb = 4;  // Smallest valid value.
+    uint32_t pic_order_cnt_type = 0;
+    uint32_t max_num_ref_frames = 0;
+    uint32_t vui_params_present = 0;
+    uint32_t id = 0;
+  };
+
+  // Unpack RBSP and parse SPS state from the supplied buffer.
+  static absl::optional<SpsState> ParseSps(const uint8_t* data, size_t length);
+
+ protected:
+  // Parse the SPS state, up till the VUI part, for a buffer where RBSP
+  // decoding has already been performed.
+  static absl::optional<SpsState> ParseSpsUpToVui(BitstreamReader& reader);
+};
+
+}  // namespace webrtc
+#endif  // COMMON_VIDEO_H264_SPS_PARSER_H_

TMessagesProj/jni/voip/webrtc/common_video/h264/sps_vui_rewriter.cc

@@ -0,0 +1,611 @@
+/*
+ *  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 "common_video/h264/sps_vui_rewriter.h"
+
+#include <string.h>
+
+#include <algorithm>
+#include <cstdint>
+#include <vector>
+
+#include "api/video/color_space.h"
+#include "common_video/h264/h264_common.h"
+#include "common_video/h264/sps_parser.h"
+#include "rtc_base/bit_buffer.h"
+#include "rtc_base/bitstream_reader.h"
+#include "rtc_base/checks.h"
+#include "rtc_base/logging.h"
+#include "system_wrappers/include/metrics.h"
+
+namespace webrtc {
+
+namespace {
+
+// The maximum expected growth from adding a VUI to the SPS. It's actually
+// closer to 24 or so, but better safe than sorry.
+const size_t kMaxVuiSpsIncrease = 64;
+
+const char* kSpsValidHistogramName = "WebRTC.Video.H264.SpsValid";
+enum SpsValidEvent {
+  kReceivedSpsVuiOk = 1,
+  kReceivedSpsRewritten = 2,
+  kReceivedSpsParseFailure = 3,
+  kSentSpsPocOk = 4,
+  kSentSpsVuiOk = 5,
+  kSentSpsRewritten = 6,
+  kSentSpsParseFailure = 7,
+  kSpsRewrittenMax = 8
+};
+
+#define RETURN_FALSE_ON_FAIL(x)                                        \
+  do {                                                                 \
+    if (!(x)) {                                                        \
+      RTC_LOG_F(LS_ERROR) << " (line:" << __LINE__ << ") FAILED: " #x; \
+      return false;                                                    \
+    }                                                                  \
+  } while (0)
+
+uint8_t CopyUInt8(BitstreamReader& source, rtc::BitBufferWriter& destination) {
+  uint8_t tmp = source.Read<uint8_t>();
+  if (!destination.WriteUInt8(tmp)) {
+    source.Invalidate();
+  }
+  return tmp;
+}
+
+uint32_t CopyExpGolomb(BitstreamReader& source,
+                       rtc::BitBufferWriter& destination) {
+  uint32_t tmp = source.ReadExponentialGolomb();
+  if (!destination.WriteExponentialGolomb(tmp)) {
+    source.Invalidate();
+  }
+  return tmp;
+}
+
+uint32_t CopyBits(int bits,
+                  BitstreamReader& source,
+                  rtc::BitBufferWriter& destination) {
+  RTC_DCHECK_GT(bits, 0);
+  RTC_DCHECK_LE(bits, 32);
+  uint64_t tmp = source.ReadBits(bits);
+  if (!destination.WriteBits(tmp, bits)) {
+    source.Invalidate();
+  }
+  return tmp;
+}
+
+bool CopyAndRewriteVui(const SpsParser::SpsState& sps,
+                       BitstreamReader& source,
+                       rtc::BitBufferWriter& destination,
+                       const webrtc::ColorSpace* color_space,
+                       SpsVuiRewriter::ParseResult& out_vui_rewritten);
+
+void CopyHrdParameters(BitstreamReader& source,
+                       rtc::BitBufferWriter& destination);
+bool AddBitstreamRestriction(rtc::BitBufferWriter* destination,
+                             uint32_t max_num_ref_frames);
+bool IsDefaultColorSpace(const ColorSpace& color_space);
+bool AddVideoSignalTypeInfo(rtc::BitBufferWriter& destination,
+                            const ColorSpace& color_space);
+bool CopyOrRewriteVideoSignalTypeInfo(
+    BitstreamReader& source,
+    rtc::BitBufferWriter& destination,
+    const ColorSpace* color_space,
+    SpsVuiRewriter::ParseResult& out_vui_rewritten);
+bool CopyRemainingBits(BitstreamReader& source,
+                       rtc::BitBufferWriter& destination);
+}  // namespace
+
+void SpsVuiRewriter::UpdateStats(ParseResult result, Direction direction) {
+  switch (result) {
+    case SpsVuiRewriter::ParseResult::kVuiRewritten:
+      RTC_HISTOGRAM_ENUMERATION(
+          kSpsValidHistogramName,
+          direction == SpsVuiRewriter::Direction::kIncoming
+              ? SpsValidEvent::kReceivedSpsRewritten
+              : SpsValidEvent::kSentSpsRewritten,
+          SpsValidEvent::kSpsRewrittenMax);
+      break;
+    case SpsVuiRewriter::ParseResult::kVuiOk:
+      RTC_HISTOGRAM_ENUMERATION(
+          kSpsValidHistogramName,
+          direction == SpsVuiRewriter::Direction::kIncoming
+              ? SpsValidEvent::kReceivedSpsVuiOk
+              : SpsValidEvent::kSentSpsVuiOk,
+          SpsValidEvent::kSpsRewrittenMax);
+      break;
+    case SpsVuiRewriter::ParseResult::kFailure:
+      RTC_HISTOGRAM_ENUMERATION(
+          kSpsValidHistogramName,
+          direction == SpsVuiRewriter::Direction::kIncoming
+              ? SpsValidEvent::kReceivedSpsParseFailure
+              : SpsValidEvent::kSentSpsParseFailure,
+          SpsValidEvent::kSpsRewrittenMax);
+      break;
+  }
+}
+
+SpsVuiRewriter::ParseResult SpsVuiRewriter::ParseAndRewriteSps(
+    const uint8_t* buffer,
+    size_t length,
+    absl::optional<SpsParser::SpsState>* sps,
+    const webrtc::ColorSpace* color_space,
+    rtc::Buffer* destination) {
+  // Create temporary RBSP decoded buffer of the payload (exlcuding the
+  // leading nalu type header byte (the SpsParser uses only the payload).
+  std::vector<uint8_t> rbsp_buffer = H264::ParseRbsp(buffer, length);
+  BitstreamReader source_buffer(rbsp_buffer);
+  absl::optional<SpsParser::SpsState> sps_state =
+      SpsParser::ParseSpsUpToVui(source_buffer);
+  if (!sps_state)
+    return ParseResult::kFailure;
+
+  *sps = sps_state;
+
+  // We're going to completely muck up alignment, so we need a BitBufferWriter
+  // to write with.
+  rtc::Buffer out_buffer(length + kMaxVuiSpsIncrease);
+  rtc::BitBufferWriter sps_writer(out_buffer.data(), out_buffer.size());
+
+  // Check how far the SpsParser has read, and copy that data in bulk.
+  RTC_DCHECK(source_buffer.Ok());
+  size_t total_bit_offset =
+      rbsp_buffer.size() * 8 - source_buffer.RemainingBitCount();
+  size_t byte_offset = total_bit_offset / 8;
+  size_t bit_offset = total_bit_offset % 8;
+  memcpy(out_buffer.data(), rbsp_buffer.data(),
+         byte_offset + (bit_offset > 0 ? 1 : 0));  // OK to copy the last bits.
+
+  // SpsParser will have read the vui_params_present flag, which we want to
+  // modify, so back off a bit;
+  if (bit_offset == 0) {
+    --byte_offset;
+    bit_offset = 7;
+  } else {
+    --bit_offset;
+  }
+  sps_writer.Seek(byte_offset, bit_offset);
+
+  ParseResult vui_updated;
+  if (!CopyAndRewriteVui(*sps_state, source_buffer, sps_writer, color_space,
+                         vui_updated)) {
+    RTC_LOG(LS_ERROR) << "Failed to parse/copy SPS VUI.";
+    return ParseResult::kFailure;
+  }
+
+  if (vui_updated == ParseResult::kVuiOk) {
+    // No update necessary after all, just return.
+    return vui_updated;
+  }
+
+  if (!CopyRemainingBits(source_buffer, sps_writer)) {
+    RTC_LOG(LS_ERROR) << "Failed to parse/copy SPS VUI.";
+    return ParseResult::kFailure;
+  }
+
+  // Pad up to next byte with zero bits.
+  sps_writer.GetCurrentOffset(&byte_offset, &bit_offset);
+  if (bit_offset > 0) {
+    sps_writer.WriteBits(0, 8 - bit_offset);
+    ++byte_offset;
+    bit_offset = 0;
+  }
+
+  RTC_DCHECK(byte_offset <= length + kMaxVuiSpsIncrease);
+  RTC_CHECK(destination != nullptr);
+
+  out_buffer.SetSize(byte_offset);
+
+  // Write updates SPS to destination with added RBSP
+  H264::WriteRbsp(out_buffer.data(), out_buffer.size(), destination);
+
+  return ParseResult::kVuiRewritten;
+}
+
+SpsVuiRewriter::ParseResult SpsVuiRewriter::ParseAndRewriteSps(
+    const uint8_t* buffer,
+    size_t length,
+    absl::optional<SpsParser::SpsState>* sps,
+    const webrtc::ColorSpace* color_space,
+    rtc::Buffer* destination,
+    Direction direction) {
+  ParseResult result =
+      ParseAndRewriteSps(buffer, length, sps, color_space, destination);
+  UpdateStats(result, direction);
+  return result;
+}
+
+rtc::Buffer SpsVuiRewriter::ParseOutgoingBitstreamAndRewrite(
+    rtc::ArrayView<const uint8_t> buffer,
+    const webrtc::ColorSpace* color_space) {
+  std::vector<H264::NaluIndex> nalus =
+      H264::FindNaluIndices(buffer.data(), buffer.size());
+
+  // Allocate some extra space for potentially adding a missing VUI.
+  rtc::Buffer output_buffer(/*size=*/0, /*capacity=*/buffer.size() +
+                                            nalus.size() * kMaxVuiSpsIncrease);
+
+  for (const H264::NaluIndex& nalu : nalus) {
+    // Copy NAL unit start code.
+    const uint8_t* start_code_ptr = buffer.data() + nalu.start_offset;
+    const size_t start_code_length =
+        nalu.payload_start_offset - nalu.start_offset;
+    const uint8_t* nalu_ptr = buffer.data() + nalu.payload_start_offset;
+    const size_t nalu_length = nalu.payload_size;
+
+    if (H264::ParseNaluType(nalu_ptr[0]) == H264::NaluType::kSps) {
+      // Check if stream uses picture order count type 0, and if so rewrite it
+      // to enable faster decoding. Streams in that format incur additional
+      // delay because it allows decode order to differ from render order.
+      // The mechanism used is to rewrite (edit or add) the SPS's VUI to contain
+      // restrictions on the maximum number of reordered pictures. This reduces
+      // latency significantly, though it still adds about a frame of latency to
+      // decoding.
+      // Note that we do this rewriting both here (send side, in order to
+      // protect legacy receive clients) in RtpDepacketizerH264::ParseSingleNalu
+      // (receive side, in orderer to protect us from unknown or legacy send
+      // clients).
+      absl::optional<SpsParser::SpsState> sps;
+      rtc::Buffer output_nalu;
+
+      // Add the type header to the output buffer first, so that the rewriter
+      // can append modified payload on top of that.
+      output_nalu.AppendData(nalu_ptr[0]);
+
+      ParseResult result = ParseAndRewriteSps(
+          nalu_ptr + H264::kNaluTypeSize, nalu_length - H264::kNaluTypeSize,
+          &sps, color_space, &output_nalu, Direction::kOutgoing);
+      if (result == ParseResult::kVuiRewritten) {
+        output_buffer.AppendData(start_code_ptr, start_code_length);
+        output_buffer.AppendData(output_nalu.data(), output_nalu.size());
+        continue;
+      }
+    } else if (H264::ParseNaluType(nalu_ptr[0]) == H264::NaluType::kAud) {
+      // Skip the access unit delimiter copy.
+      continue;
+    }
+
+    // vui wasn't rewritten and it is not aud, copy the nal unit as is.
+    output_buffer.AppendData(start_code_ptr, start_code_length);
+    output_buffer.AppendData(nalu_ptr, nalu_length);
+  }
+  return output_buffer;
+}
+
+namespace {
+bool CopyAndRewriteVui(const SpsParser::SpsState& sps,
+                       BitstreamReader& source,
+                       rtc::BitBufferWriter& destination,
+                       const webrtc::ColorSpace* color_space,
+                       SpsVuiRewriter::ParseResult& out_vui_rewritten) {
+  out_vui_rewritten = SpsVuiRewriter::ParseResult::kVuiOk;
+
+  //
+  // vui_parameters_present_flag: u(1)
+  //
+  RETURN_FALSE_ON_FAIL(destination.WriteBits(1, 1));
+
+  // ********* IMPORTANT! **********
+  // Now we're at the VUI, so we want to (1) add it if it isn't present, and
+  // (2) rewrite frame reordering values so no reordering is allowed.
+  if (!sps.vui_params_present) {
+    // Write a simple VUI with the parameters we want and 0 for all other flags.
+
+    // aspect_ratio_info_present_flag, overscan_info_present_flag. Both u(1).
+    RETURN_FALSE_ON_FAIL(destination.WriteBits(0, 2));
+
+    uint32_t video_signal_type_present_flag =
+        (color_space && !IsDefaultColorSpace(*color_space)) ? 1 : 0;
+    RETURN_FALSE_ON_FAIL(
+        destination.WriteBits(video_signal_type_present_flag, 1));
+    if (video_signal_type_present_flag) {
+      RETURN_FALSE_ON_FAIL(AddVideoSignalTypeInfo(destination, *color_space));
+    }
+    // chroma_loc_info_present_flag, timing_info_present_flag,
+    // nal_hrd_parameters_present_flag, vcl_hrd_parameters_present_flag,
+    // pic_struct_present_flag, All u(1)
+    RETURN_FALSE_ON_FAIL(destination.WriteBits(0, 5));
+    // bitstream_restriction_flag: u(1)
+    RETURN_FALSE_ON_FAIL(destination.WriteBits(1, 1));
+    RETURN_FALSE_ON_FAIL(
+        AddBitstreamRestriction(&destination, sps.max_num_ref_frames));
+
+    out_vui_rewritten = SpsVuiRewriter::ParseResult::kVuiRewritten;
+  } else {
+    // Parse out the full VUI.
+    // aspect_ratio_info_present_flag: u(1)
+    uint32_t aspect_ratio_info_present_flag = CopyBits(1, source, destination);
+    if (aspect_ratio_info_present_flag) {
+      // aspect_ratio_idc: u(8)
+      uint8_t aspect_ratio_idc = CopyUInt8(source, destination);
+      if (aspect_ratio_idc == 255u) {  // Extended_SAR
+        // sar_width/sar_height: u(16) each.
+        CopyBits(32, source, destination);
+      }
+    }
+    // overscan_info_present_flag: u(1)
+    uint32_t overscan_info_present_flag = CopyBits(1, source, destination);
+    if (overscan_info_present_flag) {
+      // overscan_appropriate_flag: u(1)
+      CopyBits(1, source, destination);
+    }
+
+    CopyOrRewriteVideoSignalTypeInfo(source, destination, color_space,
+                                     out_vui_rewritten);
+
+    // chroma_loc_info_present_flag: u(1)
+    uint32_t chroma_loc_info_present_flag = CopyBits(1, source, destination);
+    if (chroma_loc_info_present_flag == 1) {
+      // chroma_sample_loc_type_(top|bottom)_field: ue(v) each.
+      CopyExpGolomb(source, destination);
+      CopyExpGolomb(source, destination);
+    }
+    // timing_info_present_flag: u(1)
+    uint32_t timing_info_present_flag = CopyBits(1, source, destination);
+    if (timing_info_present_flag == 1) {
+      // num_units_in_tick, time_scale: u(32) each
+      CopyBits(32, source, destination);
+      CopyBits(32, source, destination);
+      // fixed_frame_rate_flag: u(1)
+      CopyBits(1, source, destination);
+    }
+    // nal_hrd_parameters_present_flag: u(1)
+    uint32_t nal_hrd_parameters_present_flag = CopyBits(1, source, destination);
+    if (nal_hrd_parameters_present_flag == 1) {
+      CopyHrdParameters(source, destination);
+    }
+    // vcl_hrd_parameters_present_flag: u(1)
+    uint32_t vcl_hrd_parameters_present_flag = CopyBits(1, source, destination);
+    if (vcl_hrd_parameters_present_flag == 1) {
+      CopyHrdParameters(source, destination);
+    }
+    if (nal_hrd_parameters_present_flag == 1 ||
+        vcl_hrd_parameters_present_flag == 1) {
+      // low_delay_hrd_flag: u(1)
+      CopyBits(1, source, destination);
+    }
+    // pic_struct_present_flag: u(1)
+    CopyBits(1, source, destination);
+
+    // bitstream_restriction_flag: u(1)
+    uint32_t bitstream_restriction_flag = source.ReadBit();
+    RETURN_FALSE_ON_FAIL(destination.WriteBits(1, 1));
+    if (bitstream_restriction_flag == 0) {
+      // We're adding one from scratch.
+      RETURN_FALSE_ON_FAIL(
+          AddBitstreamRestriction(&destination, sps.max_num_ref_frames));
+      out_vui_rewritten = SpsVuiRewriter::ParseResult::kVuiRewritten;
+    } else {
+      // We're replacing.
+      // motion_vectors_over_pic_boundaries_flag: u(1)
+      CopyBits(1, source, destination);
+      // max_bytes_per_pic_denom: ue(v)
+      CopyExpGolomb(source, destination);
+      // max_bits_per_mb_denom: ue(v)
+      CopyExpGolomb(source, destination);
+      // log2_max_mv_length_horizontal: ue(v)
+      CopyExpGolomb(source, destination);
+      // log2_max_mv_length_vertical: ue(v)
+      CopyExpGolomb(source, destination);
+      // ********* IMPORTANT! **********
+      // The next two are the ones we need to set to low numbers:
+      // max_num_reorder_frames: ue(v)
+      // max_dec_frame_buffering: ue(v)
+      // However, if they are already set to no greater than the numbers we
+      // want, then we don't need to be rewriting.
+      uint32_t max_num_reorder_frames = source.ReadExponentialGolomb();
+      uint32_t max_dec_frame_buffering = source.ReadExponentialGolomb();
+      RETURN_FALSE_ON_FAIL(destination.WriteExponentialGolomb(0));
+      RETURN_FALSE_ON_FAIL(
+          destination.WriteExponentialGolomb(sps.max_num_ref_frames));
+      if (max_num_reorder_frames != 0 ||
+          max_dec_frame_buffering > sps.max_num_ref_frames) {
+        out_vui_rewritten = SpsVuiRewriter::ParseResult::kVuiRewritten;
+      }
+    }
+  }
+  return source.Ok();
+}
+
+// Copies a VUI HRD parameters segment.
+void CopyHrdParameters(BitstreamReader& source,
+                       rtc::BitBufferWriter& destination) {
+  // cbp_cnt_minus1: ue(v)
+  uint32_t cbp_cnt_minus1 = CopyExpGolomb(source, destination);
+  // bit_rate_scale and cbp_size_scale: u(4) each
+  CopyBits(8, source, destination);
+  for (size_t i = 0; source.Ok() && i <= cbp_cnt_minus1; ++i) {
+    // bit_rate_value_minus1 and cbp_size_value_minus1: ue(v) each
+    CopyExpGolomb(source, destination);
+    CopyExpGolomb(source, destination);
+    // cbr_flag: u(1)
+    CopyBits(1, source, destination);
+  }
+  // initial_cbp_removal_delay_length_minus1: u(5)
+  // cbp_removal_delay_length_minus1: u(5)
+  // dbp_output_delay_length_minus1: u(5)
+  // time_offset_length: u(5)
+  CopyBits(5 * 4, source, destination);
+}
+
+// These functions are similar to webrtc::H264SpsParser::Parse, and based on the
+// same version of the H.264 standard. You can find it here:
+// http://www.itu.int/rec/T-REC-H.264
+
+// Adds a bitstream restriction VUI segment.
+bool AddBitstreamRestriction(rtc::BitBufferWriter* destination,
+                             uint32_t max_num_ref_frames) {
+  // motion_vectors_over_pic_boundaries_flag: u(1)
+  // Default is 1 when not present.
+  RETURN_FALSE_ON_FAIL(destination->WriteBits(1, 1));
+  // max_bytes_per_pic_denom: ue(v)
+  // Default is 2 when not present.
+  RETURN_FALSE_ON_FAIL(destination->WriteExponentialGolomb(2));
+  // max_bits_per_mb_denom: ue(v)
+  // Default is 1 when not present.
+  RETURN_FALSE_ON_FAIL(destination->WriteExponentialGolomb(1));
+  // log2_max_mv_length_horizontal: ue(v)
+  // log2_max_mv_length_vertical: ue(v)
+  // Both default to 16 when not present.
+  RETURN_FALSE_ON_FAIL(destination->WriteExponentialGolomb(16));
+  RETURN_FALSE_ON_FAIL(destination->WriteExponentialGolomb(16));
+
+  // ********* IMPORTANT! **********
+  // max_num_reorder_frames: ue(v)
+  RETURN_FALSE_ON_FAIL(destination->WriteExponentialGolomb(0));
+  // max_dec_frame_buffering: ue(v)
+  RETURN_FALSE_ON_FAIL(destination->WriteExponentialGolomb(max_num_ref_frames));
+  return true;
+}
+
+bool IsDefaultColorSpace(const ColorSpace& color_space) {
+  return color_space.range() != ColorSpace::RangeID::kFull &&
+         color_space.primaries() == ColorSpace::PrimaryID::kUnspecified &&
+         color_space.transfer() == ColorSpace::TransferID::kUnspecified &&
+         color_space.matrix() == ColorSpace::MatrixID::kUnspecified;
+}
+
+bool AddVideoSignalTypeInfo(rtc::BitBufferWriter& destination,
+                            const ColorSpace& color_space) {
+  // video_format: u(3).
+  RETURN_FALSE_ON_FAIL(destination.WriteBits(5, 3));  // 5 = Unspecified
+  // video_full_range_flag: u(1)
+  RETURN_FALSE_ON_FAIL(destination.WriteBits(
+      color_space.range() == ColorSpace::RangeID::kFull ? 1 : 0, 1));
+  // colour_description_present_flag: u(1)
+  RETURN_FALSE_ON_FAIL(destination.WriteBits(1, 1));
+  // colour_primaries: u(8)
+  RETURN_FALSE_ON_FAIL(
+      destination.WriteUInt8(static_cast<uint8_t>(color_space.primaries())));
+  // transfer_characteristics: u(8)
+  RETURN_FALSE_ON_FAIL(
+      destination.WriteUInt8(static_cast<uint8_t>(color_space.transfer())));
+  // matrix_coefficients: u(8)
+  RETURN_FALSE_ON_FAIL(
+      destination.WriteUInt8(static_cast<uint8_t>(color_space.matrix())));
+  return true;
+}
+
+bool CopyOrRewriteVideoSignalTypeInfo(
+    BitstreamReader& source,
+    rtc::BitBufferWriter& destination,
+    const ColorSpace* color_space,
+    SpsVuiRewriter::ParseResult& out_vui_rewritten) {
+  // Read.
+  uint32_t video_format = 5;           // H264 default: unspecified
+  uint32_t video_full_range_flag = 0;  // H264 default: limited
+  uint32_t colour_description_present_flag = 0;
+  uint8_t colour_primaries = 3;          // H264 default: unspecified
+  uint8_t transfer_characteristics = 3;  // H264 default: unspecified
+  uint8_t matrix_coefficients = 3;       // H264 default: unspecified
+  uint32_t video_signal_type_present_flag = source.ReadBit();
+  if (video_signal_type_present_flag) {
+    video_format = source.ReadBits(3);
+    video_full_range_flag = source.ReadBit();
+    colour_description_present_flag = source.ReadBit();
+    if (colour_description_present_flag) {
+      colour_primaries = source.Read<uint8_t>();
+      transfer_characteristics = source.Read<uint8_t>();
+      matrix_coefficients = source.Read<uint8_t>();
+    }
+  }
+  RETURN_FALSE_ON_FAIL(source.Ok());
+
+  // Update.
+  uint32_t video_signal_type_present_flag_override =
+      video_signal_type_present_flag;
+  uint32_t video_format_override = video_format;
+  uint32_t video_full_range_flag_override = video_full_range_flag;
+  uint32_t colour_description_present_flag_override =
+      colour_description_present_flag;
+  uint8_t colour_primaries_override = colour_primaries;
+  uint8_t transfer_characteristics_override = transfer_characteristics;
+  uint8_t matrix_coefficients_override = matrix_coefficients;
+  if (color_space) {
+    if (IsDefaultColorSpace(*color_space)) {
+      video_signal_type_present_flag_override = 0;
+    } else {
+      video_signal_type_present_flag_override = 1;
+      video_format_override = 5;  // unspecified
+
+      if (color_space->range() == ColorSpace::RangeID::kFull) {
+        video_full_range_flag_override = 1;
+      } else {
+        // ColorSpace::RangeID::kInvalid and kDerived are treated as limited.
+        video_full_range_flag_override = 0;
+      }
+
+      colour_description_present_flag_override =
+          color_space->primaries() != ColorSpace::PrimaryID::kUnspecified ||
+          color_space->transfer() != ColorSpace::TransferID::kUnspecified ||
+          color_space->matrix() != ColorSpace::MatrixID::kUnspecified;
+      colour_primaries_override =
+          static_cast<uint8_t>(color_space->primaries());
+      transfer_characteristics_override =
+          static_cast<uint8_t>(color_space->transfer());
+      matrix_coefficients_override =
+          static_cast<uint8_t>(color_space->matrix());
+    }
+  }
+
+  // Write.
+  RETURN_FALSE_ON_FAIL(
+      destination.WriteBits(video_signal_type_present_flag_override, 1));
+  if (video_signal_type_present_flag_override) {
+    RETURN_FALSE_ON_FAIL(destination.WriteBits(video_format_override, 3));
+    RETURN_FALSE_ON_FAIL(
+        destination.WriteBits(video_full_range_flag_override, 1));
+    RETURN_FALSE_ON_FAIL(
+        destination.WriteBits(colour_description_present_flag_override, 1));
+    if (colour_description_present_flag_override) {
+      RETURN_FALSE_ON_FAIL(destination.WriteUInt8(colour_primaries_override));
+      RETURN_FALSE_ON_FAIL(
+          destination.WriteUInt8(transfer_characteristics_override));
+      RETURN_FALSE_ON_FAIL(
+          destination.WriteUInt8(matrix_coefficients_override));
+    }
+  }
+
+  if (video_signal_type_present_flag_override !=
+          video_signal_type_present_flag ||
+      video_format_override != video_format ||
+      video_full_range_flag_override != video_full_range_flag ||
+      colour_description_present_flag_override !=
+          colour_description_present_flag ||
+      colour_primaries_override != colour_primaries ||
+      transfer_characteristics_override != transfer_characteristics ||
+      matrix_coefficients_override != matrix_coefficients) {
+    out_vui_rewritten = SpsVuiRewriter::ParseResult::kVuiRewritten;
+  }
+
+  return true;
+}
+
+bool CopyRemainingBits(BitstreamReader& source,
+                       rtc::BitBufferWriter& destination) {
+  // Try to get at least the destination aligned.
+  if (source.RemainingBitCount() > 0 && source.RemainingBitCount() % 8 != 0) {
+    size_t misaligned_bits = source.RemainingBitCount() % 8;
+    CopyBits(misaligned_bits, source, destination);
+  }
+  while (source.RemainingBitCount() > 0) {
+    int count = std::min(32, source.RemainingBitCount());
+    CopyBits(count, source, destination);
+  }
+  // TODO(noahric): The last byte could be all zeroes now, which we should just
+  // strip.
+  return source.Ok();
+}
+
+}  // namespace
+
+}  // namespace webrtc

TMessagesProj/jni/voip/webrtc/common_video/h264/sps_vui_rewriter.h

@@ -0,0 +1,72 @@
+/*
+ *  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.
+ *
+ */
+
+#ifndef COMMON_VIDEO_H264_SPS_VUI_REWRITER_H_
+#define COMMON_VIDEO_H264_SPS_VUI_REWRITER_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include "absl/types/optional.h"
+#include "api/video/color_space.h"
+#include "common_video/h264/sps_parser.h"
+#include "rtc_base/buffer.h"
+
+namespace webrtc {
+
+// A class that can parse an SPS+VUI and if necessary creates a copy with
+// updated parameters.
+// The rewriter disables frame buffering. This should force decoders to deliver
+// decoded frame immediately and, thus, reduce latency.
+// The rewriter updates video signal type parameters if external parameters are
+// provided.
+class SpsVuiRewriter : private SpsParser {
+ public:
+  enum class ParseResult { kFailure, kVuiOk, kVuiRewritten };
+  enum class Direction { kIncoming, kOutgoing };
+
+  // Parses an SPS block and if necessary copies it and rewrites the VUI.
+  // Returns kFailure on failure, kParseOk if parsing succeeded and no update
+  // was necessary and kParsedAndModified if an updated copy of buffer was
+  // written to destination. destination may be populated with some data even if
+  // no rewrite was necessary, but the end offset should remain unchanged.
+  // Unless parsing fails, the sps parameter will be populated with the parsed
+  // SPS state. This function assumes that any previous headers
+  // (NALU start, type, Stap-A, etc) have already been parsed and that RBSP
+  // decoding has been performed.
+  static ParseResult ParseAndRewriteSps(
+      const uint8_t* buffer,
+      size_t length,
+      absl::optional<SpsParser::SpsState>* sps,
+      const ColorSpace* color_space,
+      rtc::Buffer* destination,
+      Direction Direction);
+
+  // Parses NAL units from `buffer`, strips AUD blocks and rewrites VUI in SPS
+  // blocks if necessary.
+  static rtc::Buffer ParseOutgoingBitstreamAndRewrite(
+      rtc::ArrayView<const uint8_t> buffer,
+      const ColorSpace* color_space);
+
+ private:
+  static ParseResult ParseAndRewriteSps(
+      const uint8_t* buffer,
+      size_t length,
+      absl::optional<SpsParser::SpsState>* sps,
+      const ColorSpace* color_space,
+      rtc::Buffer* destination);
+
+  static void UpdateStats(ParseResult result, Direction direction);
+};
+
+}  // namespace webrtc
+
+#endif  // COMMON_VIDEO_H264_SPS_VUI_REWRITER_H_