common_video/h264/sps_vui_rewriter_unittest.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 <cstdint>
 #include <vector>

 #include "common_video/h264/h264_common.h"
 #include "common_video/h264/sps_vui_rewriter.h"
 #include "rtc_base/bit_buffer.h"
 #include "rtc_base/buffer.h"
 #include "rtc_base/logging.h"
 #include "test/gmock.h"
 #include "test/gtest.h"

 namespace webrtc {

 enum SpsMode {
   kNoRewriteRequired_VuiOptimal,
   kRewriteRequired_NoVui,
   kRewriteRequired_NoBitstreamRestriction,
   kRewriteRequired_VuiSuboptimal,
 };

 static const size_t kSpsBufferMaxSize = 256;
 static const size_t kWidth = 640;
 static const size_t kHeight = 480;

 static const uint8_t kStartSequence[] = {0x00, 0x00, 0x00, 0x01};
 static const uint8_t kSpsNaluType[] = {H264::NaluType::kSps};
 static const uint8_t kIdr1[] = {H264::NaluType::kIdr, 0xFF, 0x00, 0x00, 0x04};
 static const uint8_t kIdr2[] = {H264::NaluType::kIdr, 0xFF, 0x00, 0x11};

 // Generates a fake SPS with basically everything empty and with characteristics
 // based off SpsMode.
 // Pass in a buffer of at least kSpsBufferMaxSize.
 // The fake SPS that this generates also always has at least one emulation byte
 // at offset 2, since the first two bytes are always 0, and has a 0x3 as the
 // level_idc, to make sure the parser doesn't eat all 0x3 bytes.
 void GenerateFakeSps(SpsMode mode, rtc::Buffer* out_buffer) {
   uint8_t rbsp[kSpsBufferMaxSize] = {0};
   rtc::BitBufferWriter writer(rbsp, kSpsBufferMaxSize);
   // Profile byte.
   writer.WriteUInt8(0);
   // Constraint sets and reserved zero bits.
   writer.WriteUInt8(0);
   // level_idc.
   writer.WriteUInt8(3);
   // seq_paramter_set_id.
   writer.WriteExponentialGolomb(0);
   // Profile is not special, so we skip all the chroma format settings.

   // Now some bit magic.
   // log2_max_frame_num_minus4: ue(v). 0 is fine.
   writer.WriteExponentialGolomb(0);
   // pic_order_cnt_type: ue(v).
   writer.WriteExponentialGolomb(0);
   // log2_max_pic_order_cnt_lsb_minus4: ue(v). 0 is fine.
   writer.WriteExponentialGolomb(0);

   // max_num_ref_frames: ue(v). Use 1, to make optimal/suboptimal more obvious.
   writer.WriteExponentialGolomb(1);
   // gaps_in_frame_num_value_allowed_flag: u(1).
   writer.WriteBits(0, 1);
   // Next are width/height. First, calculate the mbs/map_units versions.
   uint16_t width_in_mbs_minus1 = (kWidth + 15) / 16 - 1;

   // For the height, we're going to define frame_mbs_only_flag, so we need to
   // divide by 2. See the parser for the full calculation.
   uint16_t height_in_map_units_minus1 = ((kHeight + 15) / 16 - 1) / 2;
   // Write each as ue(v).
   writer.WriteExponentialGolomb(width_in_mbs_minus1);
   writer.WriteExponentialGolomb(height_in_map_units_minus1);
   // frame_mbs_only_flag: u(1). Needs to be false.
   writer.WriteBits(0, 1);
   // mb_adaptive_frame_field_flag: u(1).
   writer.WriteBits(0, 1);
   // direct_8x8_inferene_flag: u(1).
   writer.WriteBits(0, 1);
   // frame_cropping_flag: u(1). 1, so we can supply crop.
   writer.WriteBits(1, 1);
   // Now we write the left/right/top/bottom crop. For simplicity, we'll put all
   // the crop at the left/top.
   // We picked a 4:2:0 format, so the crops are 1/2 the pixel crop values.
   // Left/right.
   writer.WriteExponentialGolomb(((16 - (kWidth % 16)) % 16) / 2);
   writer.WriteExponentialGolomb(0);
   // Top/bottom.
   writer.WriteExponentialGolomb(((16 - (kHeight % 16)) % 16) / 2);
   writer.WriteExponentialGolomb(0);

   // Finally! The VUI.
   // vui_parameters_present_flag: u(1)
   if (mode == kRewriteRequired_NoVui) {
     writer.WriteBits(0, 1);
   } else {
     writer.WriteBits(1, 1);
     // VUI time. 8 flags to ignore followed by the bitstream restriction flag.
     writer.WriteBits(0, 8);
     if (mode == kRewriteRequired_NoBitstreamRestriction) {
       writer.WriteBits(0, 1);
     } else {
       writer.WriteBits(1, 1);
       // Write some defaults. Shouldn't matter for parsing, though.
       // motion_vectors_over_pic_boundaries_flag: u(1)
       writer.WriteBits(1, 1);
       // max_bytes_per_pic_denom: ue(v)
       writer.WriteExponentialGolomb(2);
       // max_bits_per_mb_denom: ue(v)
       writer.WriteExponentialGolomb(1);
       // log2_max_mv_length_horizontal: ue(v)
       // log2_max_mv_length_vertical: ue(v)
       writer.WriteExponentialGolomb(16);
       writer.WriteExponentialGolomb(16);

       // Next are the limits we care about.
       // max_num_reorder_frames: ue(v)
       // max_dec_frame_buffering: ue(v)
       if (mode == kRewriteRequired_VuiSuboptimal) {
         writer.WriteExponentialGolomb(4);
         writer.WriteExponentialGolomb(4);
       } else {
         writer.WriteExponentialGolomb(0);
         writer.WriteExponentialGolomb(1);
       }
     }
   }

   // Get the number of bytes written (including the last partial byte).
   size_t byte_count, bit_offset;
   writer.GetCurrentOffset(&byte_count, &bit_offset);
   if (bit_offset > 0) {
     byte_count++;
   }

   H264::WriteRbsp(rbsp, byte_count, out_buffer);
 }

 void TestSps(SpsMode mode, SpsVuiRewriter::ParseResult expected_parse_result) {
   rtc::LogMessage::LogToDebug(rtc::LS_VERBOSE);
   rtc::Buffer original_sps;
   GenerateFakeSps(mode, &original_sps);

   absl::optional<SpsParser::SpsState> sps;
   rtc::Buffer rewritten_sps;
   SpsVuiRewriter::ParseResult result = SpsVuiRewriter::ParseAndRewriteSps(
       original_sps.data(), original_sps.size(), &sps, &rewritten_sps,
       SpsVuiRewriter::Direction::kIncoming);
   EXPECT_EQ(expected_parse_result, result);
   ASSERT_TRUE(sps);
   EXPECT_EQ(sps->width, kWidth);
   EXPECT_EQ(sps->height, kHeight);
   if (mode != kRewriteRequired_NoVui) {
     EXPECT_EQ(sps->vui_params_present, 1u);
   }

   if (result == SpsVuiRewriter::ParseResult::kVuiRewritten) {
     // Ensure that added/rewritten SPS is parsable.
     rtc::Buffer tmp;
     result = SpsVuiRewriter::ParseAndRewriteSps(
         rewritten_sps.data(), rewritten_sps.size(), &sps, &tmp,
         SpsVuiRewriter::Direction::kIncoming);
     EXPECT_EQ(SpsVuiRewriter::ParseResult::kVuiOk, result);
     ASSERT_TRUE(sps);
     EXPECT_EQ(sps->width, kWidth);
     EXPECT_EQ(sps->height, kHeight);
     EXPECT_EQ(sps->vui_params_present, 1u);
   }
 }

 #define REWRITE_TEST(test_name, mode, expected_parse_result) \
   TEST(SpsVuiRewriterTest, test_name) { TestSps(mode, expected_parse_result); }

 REWRITE_TEST(VuiAlreadyOptimal,
              kNoRewriteRequired_VuiOptimal,
              SpsVuiRewriter::ParseResult::kVuiOk)
 REWRITE_TEST(RewriteFullVui,
              kRewriteRequired_NoVui,
              SpsVuiRewriter::ParseResult::kVuiRewritten)
 REWRITE_TEST(AddBitstreamRestriction,
              kRewriteRequired_NoBitstreamRestriction,
              SpsVuiRewriter::ParseResult::kVuiRewritten)
 REWRITE_TEST(RewriteSuboptimalVui,
              kRewriteRequired_VuiSuboptimal,
              SpsVuiRewriter::ParseResult::kVuiRewritten)

 TEST(SpsVuiRewriterTest, ParseOutgoingBitstreamOptimalVui) {
   rtc::LogMessage::LogToDebug(rtc::LS_VERBOSE);

   rtc::Buffer optimal_sps;
   GenerateFakeSps(kNoRewriteRequired_VuiOptimal, &optimal_sps);

   rtc::Buffer buffer;
   const size_t kNumNalus = 2;
   size_t nalu_offsets[kNumNalus];
   size_t nalu_lengths[kNumNalus];
   buffer.AppendData(kStartSequence);
   nalu_offsets[0] = buffer.size();
   nalu_lengths[0] = optimal_sps.size();
   buffer.AppendData(optimal_sps);
   buffer.AppendData(kStartSequence);
   nalu_offsets[1] = buffer.size();
   nalu_lengths[1] = sizeof(kIdr1);
   buffer.AppendData(kIdr1);

   rtc::Buffer modified_buffer;
   size_t modified_nalu_offsets[kNumNalus];
   size_t modified_nalu_lengths[kNumNalus];

   SpsVuiRewriter::ParseOutgoingBitstreamAndRewriteSps(
       buffer, kNumNalus, nalu_offsets, nalu_lengths, &modified_buffer,
       modified_nalu_offsets, modified_nalu_lengths);

   EXPECT_THAT(
       std::vector<uint8_t>(modified_buffer.data(),
                            modified_buffer.data() + modified_buffer.size()),
       ::testing::ElementsAreArray(buffer.data(), buffer.size()));
   EXPECT_THAT(std::vector<size_t>(modified_nalu_offsets,
                                   modified_nalu_offsets + kNumNalus),
               ::testing::ElementsAreArray(nalu_offsets, kNumNalus));
   EXPECT_THAT(std::vector<size_t>(modified_nalu_lengths,
                                   modified_nalu_lengths + kNumNalus),
               ::testing::ElementsAreArray(nalu_lengths, kNumNalus));
 }

 TEST(SpsVuiRewriterTest, ParseOutgoingBitstreamNoVui) {
   rtc::LogMessage::LogToDebug(rtc::LS_VERBOSE);

   rtc::Buffer sps;
   GenerateFakeSps(kRewriteRequired_NoVui, &sps);

   rtc::Buffer buffer;
   const size_t kNumNalus = 3;
   size_t nalu_offsets[kNumNalus];
   size_t nalu_lengths[kNumNalus];
   buffer.AppendData(kStartSequence);
   nalu_offsets[0] = buffer.size();
   nalu_lengths[0] = sizeof(kIdr1);
   buffer.AppendData(kIdr1);
   buffer.AppendData(kStartSequence);
   nalu_offsets[1] = buffer.size();
   nalu_lengths[1] = sizeof(kSpsNaluType) + sps.size();
   buffer.AppendData(kSpsNaluType);
   buffer.AppendData(sps);
   buffer.AppendData(kStartSequence);
   nalu_offsets[2] = buffer.size();
   nalu_lengths[2] = sizeof(kIdr2);
   buffer.AppendData(kIdr2);

   rtc::Buffer optimal_sps;
   GenerateFakeSps(kNoRewriteRequired_VuiOptimal, &optimal_sps);

   rtc::Buffer expected_buffer;
   size_t expected_nalu_offsets[kNumNalus];
   size_t expected_nalu_lengths[kNumNalus];
   expected_buffer.AppendData(kStartSequence);
   expected_nalu_offsets[0] = expected_buffer.size();
   expected_nalu_lengths[0] = sizeof(kIdr1);
   expected_buffer.AppendData(kIdr1);
   expected_buffer.AppendData(kStartSequence);
   expected_nalu_offsets[1] = expected_buffer.size();
   expected_nalu_lengths[1] = sizeof(kSpsNaluType) + optimal_sps.size();
   expected_buffer.AppendData(kSpsNaluType);
   expected_buffer.AppendData(optimal_sps);
   expected_buffer.AppendData(kStartSequence);
   expected_nalu_offsets[2] = expected_buffer.size();
   expected_nalu_lengths[2] = sizeof(kIdr2);
   expected_buffer.AppendData(kIdr2);

   rtc::Buffer modified_buffer;
   size_t modified_nalu_offsets[kNumNalus];
   size_t modified_nalu_lengths[kNumNalus];

   SpsVuiRewriter::ParseOutgoingBitstreamAndRewriteSps(
       buffer, kNumNalus, nalu_offsets, nalu_lengths, &modified_buffer,
       modified_nalu_offsets, modified_nalu_lengths);

   EXPECT_THAT(
       std::vector<uint8_t>(modified_buffer.data(),
                            modified_buffer.data() + modified_buffer.size()),
       ::testing::ElementsAreArray(expected_buffer.data(),
                                   expected_buffer.size()));
   EXPECT_THAT(std::vector<size_t>(modified_nalu_offsets,
                                   modified_nalu_offsets + kNumNalus),
               ::testing::ElementsAreArray(expected_nalu_offsets, kNumNalus));
   EXPECT_THAT(std::vector<size_t>(modified_nalu_lengths,
                                   modified_nalu_lengths + kNumNalus),
               ::testing::ElementsAreArray(expected_nalu_lengths, kNumNalus));
 }
 }  // 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 <cstdint>
	#include <vector>

	#include "common_video/h264/h264_common.h"
	#include "common_video/h264/sps_vui_rewriter.h"
	#include "rtc_base/bit_buffer.h"
	#include "rtc_base/buffer.h"
	#include "rtc_base/logging.h"
	#include "test/gmock.h"
	#include "test/gtest.h"

	namespace webrtc {

	enum SpsMode {
	kNoRewriteRequired_VuiOptimal,
	kRewriteRequired_NoVui,
	kRewriteRequired_NoBitstreamRestriction,
	kRewriteRequired_VuiSuboptimal,
	};

	static const size_t kSpsBufferMaxSize = 256;
	static const size_t kWidth = 640;
	static const size_t kHeight = 480;

	static const uint8_t kStartSequence[] = {0x00, 0x00, 0x00, 0x01};
	static const uint8_t kSpsNaluType[] = {H264::NaluType::kSps};
	static const uint8_t kIdr1[] = {H264::NaluType::kIdr, 0xFF, 0x00, 0x00, 0x04};
	static const uint8_t kIdr2[] = {H264::NaluType::kIdr, 0xFF, 0x00, 0x11};

	// Generates a fake SPS with basically everything empty and with characteristics
	// based off SpsMode.
	// Pass in a buffer of at least kSpsBufferMaxSize.
	// The fake SPS that this generates also always has at least one emulation byte
	// at offset 2, since the first two bytes are always 0, and has a 0x3 as the
	// level_idc, to make sure the parser doesn't eat all 0x3 bytes.
	void GenerateFakeSps(SpsMode mode, rtc::Buffer* out_buffer) {
	uint8_t rbsp[kSpsBufferMaxSize] = {0};
	rtc::BitBufferWriter writer(rbsp, kSpsBufferMaxSize);
	// Profile byte.
	writer.WriteUInt8(0);
	// Constraint sets and reserved zero bits.
	writer.WriteUInt8(0);
	// level_idc.
	writer.WriteUInt8(3);
	// seq_paramter_set_id.
	writer.WriteExponentialGolomb(0);
	// Profile is not special, so we skip all the chroma format settings.

	// Now some bit magic.
	// log2_max_frame_num_minus4: ue(v). 0 is fine.
	writer.WriteExponentialGolomb(0);
	// pic_order_cnt_type: ue(v).
	writer.WriteExponentialGolomb(0);
	// log2_max_pic_order_cnt_lsb_minus4: ue(v). 0 is fine.
	writer.WriteExponentialGolomb(0);

	// max_num_ref_frames: ue(v). Use 1, to make optimal/suboptimal more obvious.
	writer.WriteExponentialGolomb(1);
	// gaps_in_frame_num_value_allowed_flag: u(1).
	writer.WriteBits(0, 1);
	// Next are width/height. First, calculate the mbs/map_units versions.
	uint16_t width_in_mbs_minus1 = (kWidth + 15) / 16 - 1;

	// For the height, we're going to define frame_mbs_only_flag, so we need to
	// divide by 2. See the parser for the full calculation.
	uint16_t height_in_map_units_minus1 = ((kHeight + 15) / 16 - 1) / 2;
	// Write each as ue(v).
	writer.WriteExponentialGolomb(width_in_mbs_minus1);
	writer.WriteExponentialGolomb(height_in_map_units_minus1);
	// frame_mbs_only_flag: u(1). Needs to be false.
	writer.WriteBits(0, 1);
	// mb_adaptive_frame_field_flag: u(1).
	writer.WriteBits(0, 1);
	// direct_8x8_inferene_flag: u(1).
	writer.WriteBits(0, 1);
	// frame_cropping_flag: u(1). 1, so we can supply crop.
	writer.WriteBits(1, 1);
	// Now we write the left/right/top/bottom crop. For simplicity, we'll put all
	// the crop at the left/top.
	// We picked a 4:2:0 format, so the crops are 1/2 the pixel crop values.
	// Left/right.
	writer.WriteExponentialGolomb(((16 - (kWidth % 16)) % 16) / 2);
	writer.WriteExponentialGolomb(0);
	// Top/bottom.
	writer.WriteExponentialGolomb(((16 - (kHeight % 16)) % 16) / 2);
	writer.WriteExponentialGolomb(0);

	// Finally! The VUI.
	// vui_parameters_present_flag: u(1)
	if (mode == kRewriteRequired_NoVui) {
	writer.WriteBits(0, 1);
	} else {
	writer.WriteBits(1, 1);
	// VUI time. 8 flags to ignore followed by the bitstream restriction flag.
	writer.WriteBits(0, 8);
	if (mode == kRewriteRequired_NoBitstreamRestriction) {
	writer.WriteBits(0, 1);
	} else {
	writer.WriteBits(1, 1);
	// Write some defaults. Shouldn't matter for parsing, though.
	// motion_vectors_over_pic_boundaries_flag: u(1)
	writer.WriteBits(1, 1);
	// max_bytes_per_pic_denom: ue(v)
	writer.WriteExponentialGolomb(2);
	// max_bits_per_mb_denom: ue(v)
	writer.WriteExponentialGolomb(1);
	// log2_max_mv_length_horizontal: ue(v)
	// log2_max_mv_length_vertical: ue(v)
	writer.WriteExponentialGolomb(16);
	writer.WriteExponentialGolomb(16);

	// Next are the limits we care about.
	// max_num_reorder_frames: ue(v)
	// max_dec_frame_buffering: ue(v)
	if (mode == kRewriteRequired_VuiSuboptimal) {
	writer.WriteExponentialGolomb(4);
	writer.WriteExponentialGolomb(4);
	} else {
	writer.WriteExponentialGolomb(0);
	writer.WriteExponentialGolomb(1);
	}
	}
	}

	// Get the number of bytes written (including the last partial byte).
	size_t byte_count, bit_offset;
	writer.GetCurrentOffset(&byte_count, &bit_offset);
	if (bit_offset > 0) {
	byte_count++;
	}

	H264::WriteRbsp(rbsp, byte_count, out_buffer);
	}

	void TestSps(SpsMode mode, SpsVuiRewriter::ParseResult expected_parse_result) {
	rtc::LogMessage::LogToDebug(rtc::LS_VERBOSE);
	rtc::Buffer original_sps;
	GenerateFakeSps(mode, &original_sps);

	absl::optional<SpsParser::SpsState> sps;
	rtc::Buffer rewritten_sps;
	SpsVuiRewriter::ParseResult result = SpsVuiRewriter::ParseAndRewriteSps(
	original_sps.data(), original_sps.size(), &sps, &rewritten_sps,
	SpsVuiRewriter::Direction::kIncoming);
	EXPECT_EQ(expected_parse_result, result);
	ASSERT_TRUE(sps);
	EXPECT_EQ(sps->width, kWidth);
	EXPECT_EQ(sps->height, kHeight);
	if (mode != kRewriteRequired_NoVui) {
	EXPECT_EQ(sps->vui_params_present, 1u);
	}

	if (result == SpsVuiRewriter::ParseResult::kVuiRewritten) {
	// Ensure that added/rewritten SPS is parsable.
	rtc::Buffer tmp;
	result = SpsVuiRewriter::ParseAndRewriteSps(
	rewritten_sps.data(), rewritten_sps.size(), &sps, &tmp,
	SpsVuiRewriter::Direction::kIncoming);
	EXPECT_EQ(SpsVuiRewriter::ParseResult::kVuiOk, result);
	ASSERT_TRUE(sps);
	EXPECT_EQ(sps->width, kWidth);
	EXPECT_EQ(sps->height, kHeight);
	EXPECT_EQ(sps->vui_params_present, 1u);
	}
	}

	#define REWRITE_TEST(test_name, mode, expected_parse_result) \
	TEST(SpsVuiRewriterTest, test_name) { TestSps(mode, expected_parse_result); }

	REWRITE_TEST(VuiAlreadyOptimal,
	kNoRewriteRequired_VuiOptimal,
	SpsVuiRewriter::ParseResult::kVuiOk)
	REWRITE_TEST(RewriteFullVui,
	kRewriteRequired_NoVui,
	SpsVuiRewriter::ParseResult::kVuiRewritten)
	REWRITE_TEST(AddBitstreamRestriction,
	kRewriteRequired_NoBitstreamRestriction,
	SpsVuiRewriter::ParseResult::kVuiRewritten)
	REWRITE_TEST(RewriteSuboptimalVui,
	kRewriteRequired_VuiSuboptimal,
	SpsVuiRewriter::ParseResult::kVuiRewritten)

	TEST(SpsVuiRewriterTest, ParseOutgoingBitstreamOptimalVui) {
	rtc::LogMessage::LogToDebug(rtc::LS_VERBOSE);

	rtc::Buffer optimal_sps;
	GenerateFakeSps(kNoRewriteRequired_VuiOptimal, &optimal_sps);

	rtc::Buffer buffer;
	const size_t kNumNalus = 2;
	size_t nalu_offsets[kNumNalus];
	size_t nalu_lengths[kNumNalus];
	buffer.AppendData(kStartSequence);
	nalu_offsets[0] = buffer.size();
	nalu_lengths[0] = optimal_sps.size();
	buffer.AppendData(optimal_sps);
	buffer.AppendData(kStartSequence);
	nalu_offsets[1] = buffer.size();
	nalu_lengths[1] = sizeof(kIdr1);
	buffer.AppendData(kIdr1);

	rtc::Buffer modified_buffer;
	size_t modified_nalu_offsets[kNumNalus];
	size_t modified_nalu_lengths[kNumNalus];

	SpsVuiRewriter::ParseOutgoingBitstreamAndRewriteSps(
	buffer, kNumNalus, nalu_offsets, nalu_lengths, &modified_buffer,
	modified_nalu_offsets, modified_nalu_lengths);

	EXPECT_THAT(
	std::vector<uint8_t>(modified_buffer.data(),
	modified_buffer.data() + modified_buffer.size()),
	::testing::ElementsAreArray(buffer.data(), buffer.size()));
	EXPECT_THAT(std::vector<size_t>(modified_nalu_offsets,
	modified_nalu_offsets + kNumNalus),
	::testing::ElementsAreArray(nalu_offsets, kNumNalus));
	EXPECT_THAT(std::vector<size_t>(modified_nalu_lengths,
	modified_nalu_lengths + kNumNalus),
	::testing::ElementsAreArray(nalu_lengths, kNumNalus));
	}

	TEST(SpsVuiRewriterTest, ParseOutgoingBitstreamNoVui) {
	rtc::LogMessage::LogToDebug(rtc::LS_VERBOSE);

	rtc::Buffer sps;
	GenerateFakeSps(kRewriteRequired_NoVui, &sps);

	rtc::Buffer buffer;
	const size_t kNumNalus = 3;
	size_t nalu_offsets[kNumNalus];
	size_t nalu_lengths[kNumNalus];
	buffer.AppendData(kStartSequence);
	nalu_offsets[0] = buffer.size();
	nalu_lengths[0] = sizeof(kIdr1);
	buffer.AppendData(kIdr1);
	buffer.AppendData(kStartSequence);
	nalu_offsets[1] = buffer.size();
	nalu_lengths[1] = sizeof(kSpsNaluType) + sps.size();
	buffer.AppendData(kSpsNaluType);
	buffer.AppendData(sps);
	buffer.AppendData(kStartSequence);
	nalu_offsets[2] = buffer.size();
	nalu_lengths[2] = sizeof(kIdr2);
	buffer.AppendData(kIdr2);

	rtc::Buffer optimal_sps;
	GenerateFakeSps(kNoRewriteRequired_VuiOptimal, &optimal_sps);

	rtc::Buffer expected_buffer;
	size_t expected_nalu_offsets[kNumNalus];
	size_t expected_nalu_lengths[kNumNalus];
	expected_buffer.AppendData(kStartSequence);
	expected_nalu_offsets[0] = expected_buffer.size();
	expected_nalu_lengths[0] = sizeof(kIdr1);
	expected_buffer.AppendData(kIdr1);
	expected_buffer.AppendData(kStartSequence);
	expected_nalu_offsets[1] = expected_buffer.size();
	expected_nalu_lengths[1] = sizeof(kSpsNaluType) + optimal_sps.size();
	expected_buffer.AppendData(kSpsNaluType);
	expected_buffer.AppendData(optimal_sps);
	expected_buffer.AppendData(kStartSequence);
	expected_nalu_offsets[2] = expected_buffer.size();
	expected_nalu_lengths[2] = sizeof(kIdr2);
	expected_buffer.AppendData(kIdr2);

	rtc::Buffer modified_buffer;
	size_t modified_nalu_offsets[kNumNalus];
	size_t modified_nalu_lengths[kNumNalus];

	SpsVuiRewriter::ParseOutgoingBitstreamAndRewriteSps(
	buffer, kNumNalus, nalu_offsets, nalu_lengths, &modified_buffer,
	modified_nalu_offsets, modified_nalu_lengths);

	EXPECT_THAT(
	std::vector<uint8_t>(modified_buffer.data(),
	modified_buffer.data() + modified_buffer.size()),
	::testing::ElementsAreArray(expected_buffer.data(),
	expected_buffer.size()));
	EXPECT_THAT(std::vector<size_t>(modified_nalu_offsets,
	modified_nalu_offsets + kNumNalus),
	::testing::ElementsAreArray(expected_nalu_offsets, kNumNalus));
	EXPECT_THAT(std::vector<size_t>(modified_nalu_lengths,
	modified_nalu_lengths + kNumNalus),
	::testing::ElementsAreArray(expected_nalu_lengths, kNumNalus));
	}
	} // namespace webrtc