common_video/h264/sps_parser_unittest.cc - src - Git at Google

 /*
  *  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/sps_parser.h"

 #include <cstddef>
 #include <cstdint>
 #include <optional>
 #include <span>

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

 namespace webrtc {

 // Example SPS can be generated with ffmpeg. Here's an example set of commands,
 // runnable on OS X:
 // 1) Generate a video, from the camera:
 // ffmpeg -f avfoundation -i "0" -video_size 640x360 camera.mov
 //
 // 2) Scale the video to the desired size:
 // ffmpeg -i camera.mov -vf scale=640x360 scaled.mov
 //
 // 3) Get just the H.264 bitstream in AnnexB:
 // ffmpeg -i scaled.mov -vcodec copy -vbsf h264_mp4toannexb -an out.h264
 //
 // 4) Open out.h264 and find the SPS, generally everything between the first
 // two start codes (0 0 0 1 or 0 0 1). The first byte should be 0x67,
 // which should be stripped out before being passed to the parser.

 static const size_t kSpsBufferMaxSize = 256;

 // Generates a fake SPS with basically everything empty but the width/height.
 // 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(uint16_t width,
                      uint16_t height,
                      int id,
                      uint32_t log2_max_frame_num_minus4,
                      uint32_t log2_max_pic_order_cnt_lsb_minus4,
                      Buffer* out_buffer) {
   uint8_t rbsp[kSpsBufferMaxSize] = {0};
   BitBufferWriter writer(rbsp, kSpsBufferMaxSize);
   // Profile byte.
   writer.WriteUInt8(0);
   // Constraint sets and reserved zero bits.
   writer.WriteUInt8(0);
   // level_idc.
   writer.WriteUInt8(0x3u);
   // seq_paramter_set_id.
   writer.WriteExponentialGolomb(id);
   // Profile is not special, so we skip all the chroma format settings.

   // Now some bit magic.
   // log2_max_frame_num_minus4: ue(v).
   writer.WriteExponentialGolomb(log2_max_frame_num_minus4);
   // pic_order_cnt_type: ue(v). 0 is the type we want.
   writer.WriteExponentialGolomb(0);
   // log2_max_pic_order_cnt_lsb_minus4: ue(v). 0 is fine.
   writer.WriteExponentialGolomb(log2_max_pic_order_cnt_lsb_minus4);
   // max_num_ref_frames: ue(v). 0 is fine.
   writer.WriteExponentialGolomb(0);
   // 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 = (width + 15) / 16 - 1;

   uint16_t height_in_map_units_minus1 = (height + 15) / 16 - 1;
   // Write each as ue(v).
   writer.WriteExponentialGolomb(width_in_mbs_minus1);
   writer.WriteExponentialGolomb(height_in_map_units_minus1);
   // frame_mbs_only_flag: u(1). Progressive.
   writer.WriteBits(1, 1);
   // direct_8x8_inference_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 - (width % 16)) % 16) / 2);
   writer.WriteExponentialGolomb(0);
   // Top/bottom.
   writer.WriteExponentialGolomb(((16 - (height % 16)) % 16) / 2);
   writer.WriteExponentialGolomb(0);

   // vui_parameters_present_flag: u(1)
   writer.WriteBits(0, 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++;
   }

   out_buffer->Clear();
   H264::WriteRbsp(std::span(rbsp, byte_count), out_buffer);
 }

 TEST(H264SpsParserTest, TestSampleSPSHdLandscape) {
   // SPS for a 1280x720 camera capture from ffmpeg on osx. Contains
   // emulation bytes but no cropping.
   const uint8_t buffer[] = {0x7A, 0x00, 0x1F, 0xBC, 0xD9, 0x40, 0x50, 0x05,
                             0xBA, 0x10, 0x00, 0x00, 0x03, 0x00, 0xC0, 0x00,
                             0x00, 0x2A, 0xE0, 0xF1, 0x83, 0x19, 0x60};
   std::optional<SpsParser::SpsState> sps = SpsParser::ParseSps(buffer);
   ASSERT_TRUE(sps.has_value());
   EXPECT_EQ(1280u, sps->width);
   EXPECT_EQ(720u, sps->height);
 }

 TEST(H264SpsParserTest, TestSampleSPSVgaLandscape) {
   // SPS for a 640x360 camera capture from ffmpeg on osx. Contains emulation
   // bytes and cropping (360 isn't divisible by 16).
   const uint8_t buffer[] = {0x7A, 0x00, 0x1E, 0xBC, 0xD9, 0x40, 0xA0, 0x2F,
                             0xF8, 0x98, 0x40, 0x00, 0x00, 0x03, 0x01, 0x80,
                             0x00, 0x00, 0x56, 0x83, 0xC5, 0x8B, 0x65, 0x80};
   std::optional<SpsParser::SpsState> sps = SpsParser::ParseSps(buffer);
   ASSERT_TRUE(sps.has_value());
   EXPECT_EQ(640u, sps->width);
   EXPECT_EQ(360u, sps->height);
 }

 TEST(H264SpsParserTest, TestSampleSPSWeirdResolution) {
   // SPS for a 200x400 camera capture from ffmpeg on osx. Horizontal and
   // veritcal crop (neither dimension is divisible by 16).
   const uint8_t buffer[] = {0x7A, 0x00, 0x0D, 0xBC, 0xD9, 0x43, 0x43, 0x3E,
                             0x5E, 0x10, 0x00, 0x00, 0x03, 0x00, 0x60, 0x00,
                             0x00, 0x15, 0xA0, 0xF1, 0x42, 0x99, 0x60};
   std::optional<SpsParser::SpsState> sps = SpsParser::ParseSps(buffer);
   ASSERT_TRUE(sps.has_value());
   EXPECT_EQ(200u, sps->width);
   EXPECT_EQ(400u, sps->height);
 }

 TEST(H264SpsParserTest, TestSyntheticSPSQvgaLandscape) {
   Buffer buffer;
   GenerateFakeSps(320u, 180u, 1, 0, 0, &buffer);
   std::optional<SpsParser::SpsState> sps = SpsParser::ParseSps(buffer);
   ASSERT_TRUE(sps.has_value());
   EXPECT_EQ(320u, sps->width);
   EXPECT_EQ(180u, sps->height);
   EXPECT_EQ(1u, sps->id);
 }

 TEST(H264SpsParserTest, TestSyntheticSPSWeirdResolution) {
   Buffer buffer;
   GenerateFakeSps(156u, 122u, 2, 0, 0, &buffer);
   std::optional<SpsParser::SpsState> sps = SpsParser::ParseSps(buffer);
   ASSERT_TRUE(sps.has_value());
   EXPECT_EQ(156u, sps->width);
   EXPECT_EQ(122u, sps->height);
   EXPECT_EQ(2u, sps->id);
 }

 TEST(H264SpsParserTest, TestSampleSPSWithScalingLists) {
   // SPS from a 1920x1080 video. Contains scaling lists (and vertical cropping).
   const uint8_t buffer[] = {0x64, 0x00, 0x2a, 0xad, 0x84, 0x01, 0x0c, 0x20,
                             0x08, 0x61, 0x00, 0x43, 0x08, 0x02, 0x18, 0x40,
                             0x10, 0xc2, 0x00, 0x84, 0x3b, 0x50, 0x3c, 0x01,
                             0x13, 0xf2, 0xcd, 0xc0, 0x40, 0x40, 0x50, 0x00,
                             0x00, 0x00, 0x10, 0x00, 0x00, 0x01, 0xe8, 0x40};
   std::optional<SpsParser::SpsState> sps = SpsParser::ParseSps(buffer);
   ASSERT_TRUE(sps.has_value());
   EXPECT_EQ(1920u, sps->width);
   EXPECT_EQ(1080u, sps->height);
 }

 TEST(H264SpsParserTest, TestLog2MaxFrameNumMinus4) {
   Buffer buffer;
   GenerateFakeSps(320u, 180u, 1, 0, 0, &buffer);
   std::optional<SpsParser::SpsState> sps = SpsParser::ParseSps(buffer);
   ASSERT_TRUE(sps.has_value());
   EXPECT_EQ(320u, sps->width);
   EXPECT_EQ(180u, sps->height);
   EXPECT_EQ(1u, sps->id);
   EXPECT_EQ(4u, sps->log2_max_frame_num);

   GenerateFakeSps(320u, 180u, 1, 12, 0, &buffer);
   sps = SpsParser::ParseSps(buffer);
   ASSERT_TRUE(sps.has_value());
   EXPECT_EQ(320u, sps->width);
   EXPECT_EQ(180u, sps->height);
   EXPECT_EQ(1u, sps->id);
   EXPECT_EQ(16u, sps->log2_max_frame_num);

   GenerateFakeSps(320u, 180u, 1, 13, 0, &buffer);
   EXPECT_FALSE(SpsParser::ParseSps(buffer));
 }

 TEST(H264SpsParserTest, TestLog2MaxPicOrderCntMinus4) {
   Buffer buffer;
   GenerateFakeSps(320u, 180u, 1, 0, 0, &buffer);
   std::optional<SpsParser::SpsState> sps = SpsParser::ParseSps(buffer);
   ASSERT_TRUE(sps.has_value());
   EXPECT_EQ(320u, sps->width);
   EXPECT_EQ(180u, sps->height);
   EXPECT_EQ(1u, sps->id);
   EXPECT_EQ(4u, sps->log2_max_pic_order_cnt_lsb);

   GenerateFakeSps(320u, 180u, 1, 0, 12, &buffer);
   EXPECT_TRUE(static_cast<bool>(sps = SpsParser::ParseSps(buffer)));
   EXPECT_EQ(320u, sps->width);
   EXPECT_EQ(180u, sps->height);
   EXPECT_EQ(1u, sps->id);
   EXPECT_EQ(16u, sps->log2_max_pic_order_cnt_lsb);

   GenerateFakeSps(320u, 180u, 1, 0, 13, &buffer);
   EXPECT_FALSE(SpsParser::ParseSps(buffer));
 }

 TEST(H264SpsParserTest, TestInvalidSpsId) {
   Buffer buffer;
   // Valid sps.id = 31
   GenerateFakeSps(320u, 180u, 31, 0, 0, &buffer);
   EXPECT_NE(SpsParser::ParseSps(buffer), std::nullopt);

   // Invalid sps.id = 32
   GenerateFakeSps(320u, 180u, 32, 0, 0, &buffer);
   EXPECT_EQ(SpsParser::ParseSps(buffer), std::nullopt);
 }

 void GenerateCustomSps(uint32_t width_in_mbs_minus1,
                        uint32_t height_in_map_units_minus1,
                        bool frame_mbs_only_flag,
                        bool frame_cropping_flag,
                        uint32_t crop_left,
                        uint32_t crop_right,
                        uint32_t crop_top,
                        uint32_t crop_bottom,
                        Buffer* out_buffer,
                        uint8_t profile_idc = 0,
                        uint32_t chroma_format_idc = 1) {
   uint8_t rbsp[kSpsBufferMaxSize] = {0};
   BitBufferWriter writer(rbsp, kSpsBufferMaxSize);
   writer.WriteUInt8(profile_idc);
   writer.WriteUInt8(0);
   writer.WriteUInt8(0x3u);
   writer.WriteExponentialGolomb(0);  // sps_id = 0
   if (profile_idc == 100) {
     writer.WriteExponentialGolomb(chroma_format_idc);
     if (chroma_format_idc == 3) {
       writer.WriteBits(0, 1);  // separate_colour_plane_flag
     }
     writer.WriteExponentialGolomb(0);  // bit_depth_luma_minus8
     writer.WriteExponentialGolomb(0);  // bit_depth_chroma_minus8
     writer.WriteBits(0, 1);            // qpprime_y_zero_transform_bypass_flag
     writer.WriteBits(0, 1);            // seq_scaling_matrix_present_flag
   }
   writer.WriteExponentialGolomb(0);  // log2_max_frame_num_minus4
   writer.WriteExponentialGolomb(0);  // pic_order_cnt_type
   writer.WriteExponentialGolomb(0);  // log2_max_pic_order_cnt_lsb_minus4
   writer.WriteExponentialGolomb(0);  // max_num_ref_frames
   writer.WriteBits(0, 1);            // gaps_in_frame_num_value_allowed_flag

   writer.WriteExponentialGolomb(width_in_mbs_minus1);
   writer.WriteExponentialGolomb(height_in_map_units_minus1);
   writer.WriteBits(frame_mbs_only_flag ? 1 : 0, 1);
   if (!frame_mbs_only_flag) {
     writer.WriteBits(0, 1);  // mb_adaptive_frame_field_flag
   }
   writer.WriteBits(0, 1);  // direct_8x8_inference_flag
   if (frame_cropping_flag) {
     writer.WriteBits(1, 1);
     writer.WriteExponentialGolomb(crop_left);
     writer.WriteExponentialGolomb(crop_right);
     writer.WriteExponentialGolomb(crop_top);
     writer.WriteExponentialGolomb(crop_bottom);
   } else {
     writer.WriteBits(0, 1);
   }
   writer.WriteBits(0, 1);  // vui_parameters_present_flag

   size_t byte_count, bit_offset;
   writer.GetCurrentOffset(&byte_count, &bit_offset);
   if (bit_offset > 0) {
     byte_count++;
   }
   out_buffer->Clear();
   H264::WriteRbsp(std::span(rbsp, byte_count), out_buffer);
 }

 TEST(H264SpsParserTest, RejectsPicWidthOverflow) {
   Buffer buffer;
   // Dimensions that would wrap around in 32-bit arithmetic (16 * 0x10000000)
   // are safely computed in 64-bit and rejected by IsValidResolution exceeding
   // Level 5.2 limits.
   GenerateCustomSps(/*width_in_mbs_minus1=*/0x0FFFFFFF,
                     /*height_in_map_units_minus1=*/10,
                     /*frame_mbs_only_flag=*/true,
                     /*frame_cropping_flag=*/false, 0, 0, 0, 0, &buffer);
   EXPECT_EQ(SpsParser::ParseSps(buffer), std::nullopt);
 }

 TEST(H264SpsParserTest, RejectsPicHeightOverflow) {
   Buffer buffer;
   // Dimensions that would wrap around in 32-bit arithmetic (32 * 0x08000000)
   // are safely computed in 64-bit and rejected by IsValidResolution exceeding
   // Level 5.2 limits.
   GenerateCustomSps(/*width_in_mbs_minus1=*/10,
                     /*height_in_map_units_minus1=*/0x07FFFFFF,
                     /*frame_mbs_only_flag=*/false,
                     /*frame_cropping_flag=*/false, 0, 0, 0, 0, &buffer);
   EXPECT_EQ(SpsParser::ParseSps(buffer), std::nullopt);
 }

 TEST(H264SpsParserTest, RejectsCropUnderflow) {
   Buffer buffer;
   // uncropped width = 16 * (19 + 1) = 320.
   // Chroma 4:2:0 -> crop unit is 2.
   // crop_left = 100, crop_right = 100 -> total crop = 400 > 320.
   GenerateCustomSps(/*width_in_mbs_minus1=*/19,
                     /*height_in_map_units_minus1=*/10,
                     /*frame_mbs_only_flag=*/true,
                     /*frame_cropping_flag=*/true,
                     /*crop_left=*/100, /*crop_right=*/100,
                     /*crop_top=*/0, /*crop_bottom=*/0, &buffer);
   EXPECT_EQ(SpsParser::ParseSps(buffer), std::nullopt);
 }

 TEST(H264SpsParserTest, RejectsCropEqualToDimensions) {
   Buffer buffer;
   // uncropped width = 16 * (19 + 1) = 320.
   // Chroma 4:2:0 -> crop unit is 2.
   // crop_left = 80, crop_right = 80 -> total crop = 320 == 320 -> width 0.
   GenerateCustomSps(/*width_in_mbs_minus1=*/19,
                     /*height_in_map_units_minus1=*/10,
                     /*frame_mbs_only_flag=*/true,
                     /*frame_cropping_flag=*/true,
                     /*crop_left=*/80, /*crop_right=*/80,
                     /*crop_top=*/0, /*crop_bottom=*/0, &buffer);
   EXPECT_EQ(SpsParser::ParseSps(buffer), std::nullopt);
 }

 TEST(H264SpsParserTest, RejectsInvalidChromaFormatIdc) {
   Buffer buffer;
   GenerateCustomSps(/*width_in_mbs_minus1=*/19,
                     /*height_in_map_units_minus1=*/10,
                     /*frame_mbs_only_flag=*/true,
                     /*frame_cropping_flag=*/false, 0, 0, 0, 0, &buffer,
                     /*profile_idc=*/100, /*chroma_format_idc=*/4);
   EXPECT_EQ(SpsParser::ParseSps(buffer), std::nullopt);
 }

 TEST(H264SpsParserTest, AcceptsMaxLevel52Resolution) {
   Buffer buffer;
   // 4096x2304: width_in_mbs_minus1 = 255 (256 MBs), height_in_mbs_minus1 = 143
   // (144 MBs)
   GenerateCustomSps(/*width_in_mbs_minus1=*/255,
                     /*height_in_map_units_minus1=*/143,
                     /*frame_mbs_only_flag=*/true,
                     /*frame_cropping_flag=*/false, 0, 0, 0, 0, &buffer);
   std::optional<SpsParser::SpsState> sps = SpsParser::ParseSps(buffer);
   ASSERT_TRUE(sps.has_value());
   EXPECT_EQ(sps->width, 4096u);
   EXPECT_EQ(sps->height, 2304u);
 }

 TEST(H264SpsParserTest, RejectsResolutionExceedingLevel52MaxFS) {
   Buffer buffer;
   // 4096x2320 = 256x145 MBs = 37120 MBs > 36864
   GenerateCustomSps(/*width_in_mbs_minus1=*/255,
                     /*height_in_map_units_minus1=*/144,
                     /*frame_mbs_only_flag=*/true,
                     /*frame_cropping_flag=*/false, 0, 0, 0, 0, &buffer);
   EXPECT_EQ(SpsParser::ParseSps(buffer), std::nullopt);
 }

 TEST(H264SpsParserTest, InterlacedCropping420) {
   Buffer buffer;
   // 320x320 uncropped: width_in_mbs = 20 (minus 1 = 19),
   // height_in_map_units = 10 (minus 1 = 9) with frame_mbs_only_flag = false:
   // uncropped height = 16 * 2 * 10 = 320.
   // Chroma format 4:2:0: crop_unit_x = 2, crop_unit_y = 2 * (2 - 0) = 4.
   GenerateCustomSps(/*width_in_mbs_minus1=*/19,
                     /*height_in_map_units_minus1=*/9,
                     /*frame_mbs_only_flag=*/false,
                     /*frame_cropping_flag=*/true,
                     /*crop_left=*/2, /*crop_right=*/3,
                     /*crop_top=*/2, /*crop_bottom=*/3, &buffer,
                     /*profile_idc=*/100, /*chroma_format_idc=*/1);
   std::optional<SpsParser::SpsState> sps = SpsParser::ParseSps(buffer);
   ASSERT_TRUE(sps.has_value());
   EXPECT_EQ(sps->width, 320u - 2u * (2 + 3));   // 310
   EXPECT_EQ(sps->height, 320u - 4u * (2 + 3));  // 300
 }

 TEST(H264SpsParserTest, RejectsInterlacedCropUnderflow) {
   Buffer buffer;
   // uncropped height = 16 * 2 * 10 = 320.
   // Chroma 4:2:0 interlaced -> crop unit y is 4.
   // crop_top = 40, crop_bottom = 40 -> total crop y = 4 * 80 = 320 >= 320.
   GenerateCustomSps(/*width_in_mbs_minus1=*/19,
                     /*height_in_map_units_minus1=*/9,
                     /*frame_mbs_only_flag=*/false,
                     /*frame_cropping_flag=*/true,
                     /*crop_left=*/0, /*crop_right=*/0,
                     /*crop_top=*/40, /*crop_bottom=*/40, &buffer,
                     /*profile_idc=*/100, /*chroma_format_idc=*/1);
   EXPECT_EQ(SpsParser::ParseSps(buffer), std::nullopt);
 }

 }  // namespace webrtc
	/*
	* 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/sps_parser.h"

	#include <cstddef>
	#include <cstdint>
	#include <optional>
	#include <span>

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

	namespace webrtc {

	// Example SPS can be generated with ffmpeg. Here's an example set of commands,
	// runnable on OS X:
	// 1) Generate a video, from the camera:
	// ffmpeg -f avfoundation -i "0" -video_size 640x360 camera.mov
	//
	// 2) Scale the video to the desired size:
	// ffmpeg -i camera.mov -vf scale=640x360 scaled.mov
	//
	// 3) Get just the H.264 bitstream in AnnexB:
	// ffmpeg -i scaled.mov -vcodec copy -vbsf h264_mp4toannexb -an out.h264
	//
	// 4) Open out.h264 and find the SPS, generally everything between the first
	// two start codes (0 0 0 1 or 0 0 1). The first byte should be 0x67,
	// which should be stripped out before being passed to the parser.

	static const size_t kSpsBufferMaxSize = 256;

	// Generates a fake SPS with basically everything empty but the width/height.
	// 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(uint16_t width,
	uint16_t height,
	int id,
	uint32_t log2_max_frame_num_minus4,
	uint32_t log2_max_pic_order_cnt_lsb_minus4,
	Buffer* out_buffer) {
	uint8_t rbsp[kSpsBufferMaxSize] = {0};
	BitBufferWriter writer(rbsp, kSpsBufferMaxSize);
	// Profile byte.
	writer.WriteUInt8(0);
	// Constraint sets and reserved zero bits.
	writer.WriteUInt8(0);
	// level_idc.
	writer.WriteUInt8(0x3u);
	// seq_paramter_set_id.
	writer.WriteExponentialGolomb(id);
	// Profile is not special, so we skip all the chroma format settings.

	// Now some bit magic.
	// log2_max_frame_num_minus4: ue(v).
	writer.WriteExponentialGolomb(log2_max_frame_num_minus4);
	// pic_order_cnt_type: ue(v). 0 is the type we want.
	writer.WriteExponentialGolomb(0);
	// log2_max_pic_order_cnt_lsb_minus4: ue(v). 0 is fine.
	writer.WriteExponentialGolomb(log2_max_pic_order_cnt_lsb_minus4);
	// max_num_ref_frames: ue(v). 0 is fine.
	writer.WriteExponentialGolomb(0);
	// 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 = (width + 15) / 16 - 1;

	uint16_t height_in_map_units_minus1 = (height + 15) / 16 - 1;
	// Write each as ue(v).
	writer.WriteExponentialGolomb(width_in_mbs_minus1);
	writer.WriteExponentialGolomb(height_in_map_units_minus1);
	// frame_mbs_only_flag: u(1). Progressive.
	writer.WriteBits(1, 1);
	// direct_8x8_inference_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 - (width % 16)) % 16) / 2);
	writer.WriteExponentialGolomb(0);
	// Top/bottom.
	writer.WriteExponentialGolomb(((16 - (height % 16)) % 16) / 2);
	writer.WriteExponentialGolomb(0);

	// vui_parameters_present_flag: u(1)
	writer.WriteBits(0, 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++;
	}

	out_buffer->Clear();
	H264::WriteRbsp(std::span(rbsp, byte_count), out_buffer);
	}

	TEST(H264SpsParserTest, TestSampleSPSHdLandscape) {
	// SPS for a 1280x720 camera capture from ffmpeg on osx. Contains
	// emulation bytes but no cropping.
	const uint8_t buffer[] = {0x7A, 0x00, 0x1F, 0xBC, 0xD9, 0x40, 0x50, 0x05,
	0xBA, 0x10, 0x00, 0x00, 0x03, 0x00, 0xC0, 0x00,
	0x00, 0x2A, 0xE0, 0xF1, 0x83, 0x19, 0x60};
	std::optional<SpsParser::SpsState> sps = SpsParser::ParseSps(buffer);
	ASSERT_TRUE(sps.has_value());
	EXPECT_EQ(1280u, sps->width);
	EXPECT_EQ(720u, sps->height);
	}

	TEST(H264SpsParserTest, TestSampleSPSVgaLandscape) {
	// SPS for a 640x360 camera capture from ffmpeg on osx. Contains emulation
	// bytes and cropping (360 isn't divisible by 16).
	const uint8_t buffer[] = {0x7A, 0x00, 0x1E, 0xBC, 0xD9, 0x40, 0xA0, 0x2F,
	0xF8, 0x98, 0x40, 0x00, 0x00, 0x03, 0x01, 0x80,
	0x00, 0x00, 0x56, 0x83, 0xC5, 0x8B, 0x65, 0x80};
	std::optional<SpsParser::SpsState> sps = SpsParser::ParseSps(buffer);
	ASSERT_TRUE(sps.has_value());
	EXPECT_EQ(640u, sps->width);
	EXPECT_EQ(360u, sps->height);
	}

	TEST(H264SpsParserTest, TestSampleSPSWeirdResolution) {
	// SPS for a 200x400 camera capture from ffmpeg on osx. Horizontal and
	// veritcal crop (neither dimension is divisible by 16).
	const uint8_t buffer[] = {0x7A, 0x00, 0x0D, 0xBC, 0xD9, 0x43, 0x43, 0x3E,
	0x5E, 0x10, 0x00, 0x00, 0x03, 0x00, 0x60, 0x00,
	0x00, 0x15, 0xA0, 0xF1, 0x42, 0x99, 0x60};
	std::optional<SpsParser::SpsState> sps = SpsParser::ParseSps(buffer);
	ASSERT_TRUE(sps.has_value());
	EXPECT_EQ(200u, sps->width);
	EXPECT_EQ(400u, sps->height);
	}

	TEST(H264SpsParserTest, TestSyntheticSPSQvgaLandscape) {
	Buffer buffer;
	GenerateFakeSps(320u, 180u, 1, 0, 0, &buffer);
	std::optional<SpsParser::SpsState> sps = SpsParser::ParseSps(buffer);
	ASSERT_TRUE(sps.has_value());
	EXPECT_EQ(320u, sps->width);
	EXPECT_EQ(180u, sps->height);
	EXPECT_EQ(1u, sps->id);
	}

	TEST(H264SpsParserTest, TestSyntheticSPSWeirdResolution) {
	Buffer buffer;
	GenerateFakeSps(156u, 122u, 2, 0, 0, &buffer);
	std::optional<SpsParser::SpsState> sps = SpsParser::ParseSps(buffer);
	ASSERT_TRUE(sps.has_value());
	EXPECT_EQ(156u, sps->width);
	EXPECT_EQ(122u, sps->height);
	EXPECT_EQ(2u, sps->id);
	}

	TEST(H264SpsParserTest, TestSampleSPSWithScalingLists) {
	// SPS from a 1920x1080 video. Contains scaling lists (and vertical cropping).
	const uint8_t buffer[] = {0x64, 0x00, 0x2a, 0xad, 0x84, 0x01, 0x0c, 0x20,
	0x08, 0x61, 0x00, 0x43, 0x08, 0x02, 0x18, 0x40,
	0x10, 0xc2, 0x00, 0x84, 0x3b, 0x50, 0x3c, 0x01,
	0x13, 0xf2, 0xcd, 0xc0, 0x40, 0x40, 0x50, 0x00,
	0x00, 0x00, 0x10, 0x00, 0x00, 0x01, 0xe8, 0x40};
	std::optional<SpsParser::SpsState> sps = SpsParser::ParseSps(buffer);
	ASSERT_TRUE(sps.has_value());
	EXPECT_EQ(1920u, sps->width);
	EXPECT_EQ(1080u, sps->height);
	}

	TEST(H264SpsParserTest, TestLog2MaxFrameNumMinus4) {
	Buffer buffer;
	GenerateFakeSps(320u, 180u, 1, 0, 0, &buffer);
	std::optional<SpsParser::SpsState> sps = SpsParser::ParseSps(buffer);
	ASSERT_TRUE(sps.has_value());
	EXPECT_EQ(320u, sps->width);
	EXPECT_EQ(180u, sps->height);
	EXPECT_EQ(1u, sps->id);
	EXPECT_EQ(4u, sps->log2_max_frame_num);

	GenerateFakeSps(320u, 180u, 1, 12, 0, &buffer);
	sps = SpsParser::ParseSps(buffer);
	ASSERT_TRUE(sps.has_value());
	EXPECT_EQ(320u, sps->width);
	EXPECT_EQ(180u, sps->height);
	EXPECT_EQ(1u, sps->id);
	EXPECT_EQ(16u, sps->log2_max_frame_num);

	GenerateFakeSps(320u, 180u, 1, 13, 0, &buffer);
	EXPECT_FALSE(SpsParser::ParseSps(buffer));
	}

	TEST(H264SpsParserTest, TestLog2MaxPicOrderCntMinus4) {
	Buffer buffer;
	GenerateFakeSps(320u, 180u, 1, 0, 0, &buffer);
	std::optional<SpsParser::SpsState> sps = SpsParser::ParseSps(buffer);
	ASSERT_TRUE(sps.has_value());
	EXPECT_EQ(320u, sps->width);
	EXPECT_EQ(180u, sps->height);
	EXPECT_EQ(1u, sps->id);
	EXPECT_EQ(4u, sps->log2_max_pic_order_cnt_lsb);

	GenerateFakeSps(320u, 180u, 1, 0, 12, &buffer);
	EXPECT_TRUE(static_cast<bool>(sps = SpsParser::ParseSps(buffer)));
	EXPECT_EQ(320u, sps->width);
	EXPECT_EQ(180u, sps->height);
	EXPECT_EQ(1u, sps->id);
	EXPECT_EQ(16u, sps->log2_max_pic_order_cnt_lsb);

	GenerateFakeSps(320u, 180u, 1, 0, 13, &buffer);
	EXPECT_FALSE(SpsParser::ParseSps(buffer));
	}

	TEST(H264SpsParserTest, TestInvalidSpsId) {
	Buffer buffer;
	// Valid sps.id = 31
	GenerateFakeSps(320u, 180u, 31, 0, 0, &buffer);
	EXPECT_NE(SpsParser::ParseSps(buffer), std::nullopt);

	// Invalid sps.id = 32
	GenerateFakeSps(320u, 180u, 32, 0, 0, &buffer);
	EXPECT_EQ(SpsParser::ParseSps(buffer), std::nullopt);
	}

	void GenerateCustomSps(uint32_t width_in_mbs_minus1,
	uint32_t height_in_map_units_minus1,
	bool frame_mbs_only_flag,
	bool frame_cropping_flag,
	uint32_t crop_left,
	uint32_t crop_right,
	uint32_t crop_top,
	uint32_t crop_bottom,
	Buffer* out_buffer,
	uint8_t profile_idc = 0,
	uint32_t chroma_format_idc = 1) {
	uint8_t rbsp[kSpsBufferMaxSize] = {0};
	BitBufferWriter writer(rbsp, kSpsBufferMaxSize);
	writer.WriteUInt8(profile_idc);
	writer.WriteUInt8(0);
	writer.WriteUInt8(0x3u);
	writer.WriteExponentialGolomb(0); // sps_id = 0
	if (profile_idc == 100) {
	writer.WriteExponentialGolomb(chroma_format_idc);
	if (chroma_format_idc == 3) {
	writer.WriteBits(0, 1); // separate_colour_plane_flag
	}
	writer.WriteExponentialGolomb(0); // bit_depth_luma_minus8
	writer.WriteExponentialGolomb(0); // bit_depth_chroma_minus8
	writer.WriteBits(0, 1); // qpprime_y_zero_transform_bypass_flag
	writer.WriteBits(0, 1); // seq_scaling_matrix_present_flag
	}
	writer.WriteExponentialGolomb(0); // log2_max_frame_num_minus4
	writer.WriteExponentialGolomb(0); // pic_order_cnt_type
	writer.WriteExponentialGolomb(0); // log2_max_pic_order_cnt_lsb_minus4
	writer.WriteExponentialGolomb(0); // max_num_ref_frames
	writer.WriteBits(0, 1); // gaps_in_frame_num_value_allowed_flag

	writer.WriteExponentialGolomb(width_in_mbs_minus1);
	writer.WriteExponentialGolomb(height_in_map_units_minus1);
	writer.WriteBits(frame_mbs_only_flag ? 1 : 0, 1);
	if (!frame_mbs_only_flag) {
	writer.WriteBits(0, 1); // mb_adaptive_frame_field_flag
	}
	writer.WriteBits(0, 1); // direct_8x8_inference_flag
	if (frame_cropping_flag) {
	writer.WriteBits(1, 1);
	writer.WriteExponentialGolomb(crop_left);
	writer.WriteExponentialGolomb(crop_right);
	writer.WriteExponentialGolomb(crop_top);
	writer.WriteExponentialGolomb(crop_bottom);
	} else {
	writer.WriteBits(0, 1);
	}
	writer.WriteBits(0, 1); // vui_parameters_present_flag

	size_t byte_count, bit_offset;
	writer.GetCurrentOffset(&byte_count, &bit_offset);
	if (bit_offset > 0) {
	byte_count++;
	}
	out_buffer->Clear();
	H264::WriteRbsp(std::span(rbsp, byte_count), out_buffer);
	}

	TEST(H264SpsParserTest, RejectsPicWidthOverflow) {
	Buffer buffer;
	// Dimensions that would wrap around in 32-bit arithmetic (16 * 0x10000000)
	// are safely computed in 64-bit and rejected by IsValidResolution exceeding
	// Level 5.2 limits.
	GenerateCustomSps(/width_in_mbs_minus1=/0x0FFFFFFF,
	/height_in_map_units_minus1=/10,
	/frame_mbs_only_flag=/true,
	/frame_cropping_flag=/false, 0, 0, 0, 0, &buffer);
	EXPECT_EQ(SpsParser::ParseSps(buffer), std::nullopt);
	}

	TEST(H264SpsParserTest, RejectsPicHeightOverflow) {
	Buffer buffer;
	// Dimensions that would wrap around in 32-bit arithmetic (32 * 0x08000000)
	// are safely computed in 64-bit and rejected by IsValidResolution exceeding
	// Level 5.2 limits.
	GenerateCustomSps(/width_in_mbs_minus1=/10,
	/height_in_map_units_minus1=/0x07FFFFFF,
	/frame_mbs_only_flag=/false,
	/frame_cropping_flag=/false, 0, 0, 0, 0, &buffer);
	EXPECT_EQ(SpsParser::ParseSps(buffer), std::nullopt);
	}

	TEST(H264SpsParserTest, RejectsCropUnderflow) {
	Buffer buffer;
	// uncropped width = 16 * (19 + 1) = 320.
	// Chroma 4:2:0 -> crop unit is 2.
	// crop_left = 100, crop_right = 100 -> total crop = 400 > 320.
	GenerateCustomSps(/width_in_mbs_minus1=/19,
	/height_in_map_units_minus1=/10,
	/frame_mbs_only_flag=/true,
	/frame_cropping_flag=/true,
	/crop_left=/100, /crop_right=/100,
	/crop_top=/0, /crop_bottom=/0, &buffer);
	EXPECT_EQ(SpsParser::ParseSps(buffer), std::nullopt);
	}

	TEST(H264SpsParserTest, RejectsCropEqualToDimensions) {
	Buffer buffer;
	// uncropped width = 16 * (19 + 1) = 320.
	// Chroma 4:2:0 -> crop unit is 2.
	// crop_left = 80, crop_right = 80 -> total crop = 320 == 320 -> width 0.
	GenerateCustomSps(/width_in_mbs_minus1=/19,
	/height_in_map_units_minus1=/10,
	/frame_mbs_only_flag=/true,
	/frame_cropping_flag=/true,
	/crop_left=/80, /crop_right=/80,
	/crop_top=/0, /crop_bottom=/0, &buffer);
	EXPECT_EQ(SpsParser::ParseSps(buffer), std::nullopt);
	}

	TEST(H264SpsParserTest, RejectsInvalidChromaFormatIdc) {
	Buffer buffer;
	GenerateCustomSps(/width_in_mbs_minus1=/19,
	/height_in_map_units_minus1=/10,
	/frame_mbs_only_flag=/true,
	/frame_cropping_flag=/false, 0, 0, 0, 0, &buffer,
	/profile_idc=/100, /chroma_format_idc=/4);
	EXPECT_EQ(SpsParser::ParseSps(buffer), std::nullopt);
	}

	TEST(H264SpsParserTest, AcceptsMaxLevel52Resolution) {
	Buffer buffer;
	// 4096x2304: width_in_mbs_minus1 = 255 (256 MBs), height_in_mbs_minus1 = 143
	// (144 MBs)
	GenerateCustomSps(/width_in_mbs_minus1=/255,
	/height_in_map_units_minus1=/143,
	/frame_mbs_only_flag=/true,
	/frame_cropping_flag=/false, 0, 0, 0, 0, &buffer);
	std::optional<SpsParser::SpsState> sps = SpsParser::ParseSps(buffer);
	ASSERT_TRUE(sps.has_value());
	EXPECT_EQ(sps->width, 4096u);
	EXPECT_EQ(sps->height, 2304u);
	}

	TEST(H264SpsParserTest, RejectsResolutionExceedingLevel52MaxFS) {
	Buffer buffer;
	// 4096x2320 = 256x145 MBs = 37120 MBs > 36864
	GenerateCustomSps(/width_in_mbs_minus1=/255,
	/height_in_map_units_minus1=/144,
	/frame_mbs_only_flag=/true,
	/frame_cropping_flag=/false, 0, 0, 0, 0, &buffer);
	EXPECT_EQ(SpsParser::ParseSps(buffer), std::nullopt);
	}

	TEST(H264SpsParserTest, InterlacedCropping420) {
	Buffer buffer;
	// 320x320 uncropped: width_in_mbs = 20 (minus 1 = 19),
	// height_in_map_units = 10 (minus 1 = 9) with frame_mbs_only_flag = false:
	// uncropped height = 16 * 2 * 10 = 320.
	// Chroma format 4:2:0: crop_unit_x = 2, crop_unit_y = 2 * (2 - 0) = 4.
	GenerateCustomSps(/width_in_mbs_minus1=/19,
	/height_in_map_units_minus1=/9,
	/frame_mbs_only_flag=/false,
	/frame_cropping_flag=/true,
	/crop_left=/2, /crop_right=/3,
	/crop_top=/2, /crop_bottom=/3, &buffer,
	/profile_idc=/100, /chroma_format_idc=/1);
	std::optional<SpsParser::SpsState> sps = SpsParser::ParseSps(buffer);
	ASSERT_TRUE(sps.has_value());
	EXPECT_EQ(sps->width, 320u - 2u * (2 + 3)); // 310
	EXPECT_EQ(sps->height, 320u - 4u * (2 + 3)); // 300
	}

	TEST(H264SpsParserTest, RejectsInterlacedCropUnderflow) {
	Buffer buffer;
	// uncropped height = 16 * 2 * 10 = 320.
	// Chroma 4:2:0 interlaced -> crop unit y is 4.
	// crop_top = 40, crop_bottom = 40 -> total crop y = 4 * 80 = 320 >= 320.
	GenerateCustomSps(/width_in_mbs_minus1=/19,
	/height_in_map_units_minus1=/9,
	/frame_mbs_only_flag=/false,
	/frame_cropping_flag=/true,
	/crop_left=/0, /crop_right=/0,
	/crop_top=/40, /crop_bottom=/40, &buffer,
	/profile_idc=/100, /chroma_format_idc=/1);
	EXPECT_EQ(SpsParser::ParseSps(buffer), std::nullopt);
	}

	} // namespace webrtc