api/video_codecs/h264_profile_level_id.cc - src - Git at Google

 /*
  *  Copyright (c) 2021 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 "api/video_codecs/h264_profile_level_id.h"

 #include <cstdio>
 #include <cstdlib>
 #include <string>

 #include "rtc_base/arraysize.h"
 #include "rtc_base/checks.h"

 namespace webrtc {

 namespace {

 const char kProfileLevelId[] = "profile-level-id";

 // For level_idc=11 and profile_idc=0x42, 0x4D, or 0x58, the constraint set3
 // flag specifies if level 1b or level 1.1 is used.
 const uint8_t kConstraintSet3Flag = 0x10;

 // Convert a string of 8 characters into a byte where the positions containing
 // character c will have their bit set. For example, c = 'x', str = "x1xx0000"
 // will return 0b10110000. constexpr is used so that the pattern table in
 // kProfilePatterns is statically initialized.
 constexpr uint8_t ByteMaskString(char c, const char (&str)[9]) {
   return (str[0] == c) << 7 | (str[1] == c) << 6 | (str[2] == c) << 5 |
          (str[3] == c) << 4 | (str[4] == c) << 3 | (str[5] == c) << 2 |
          (str[6] == c) << 1 | (str[7] == c) << 0;
 }

 // Class for matching bit patterns such as "x1xx0000" where 'x' is allowed to be
 // either 0 or 1.
 class BitPattern {
  public:
   explicit constexpr BitPattern(const char (&str)[9])
       : mask_(~ByteMaskString('x', str)),
         masked_value_(ByteMaskString('1', str)) {}

   bool IsMatch(uint8_t value) const { return masked_value_ == (value & mask_); }

  private:
   const uint8_t mask_;
   const uint8_t masked_value_;
 };

 // Table for converting between profile_idc/profile_iop to H264Profile.
 struct ProfilePattern {
   const uint8_t profile_idc;
   const BitPattern profile_iop;
   const H264Profile profile;
 };

 // This is from https://tools.ietf.org/html/rfc6184#section-8.1.
 constexpr ProfilePattern kProfilePatterns[] = {
     {0x42, BitPattern("x1xx0000"), H264Profile::kProfileConstrainedBaseline},
     {0x4D, BitPattern("1xxx0000"), H264Profile::kProfileConstrainedBaseline},
     {0x58, BitPattern("11xx0000"), H264Profile::kProfileConstrainedBaseline},
     {0x42, BitPattern("x0xx0000"), H264Profile::kProfileBaseline},
     {0x58, BitPattern("10xx0000"), H264Profile::kProfileBaseline},
     {0x4D, BitPattern("0x0x0000"), H264Profile::kProfileMain},
     {0x64, BitPattern("00000000"), H264Profile::kProfileHigh},
     {0x64, BitPattern("00001100"), H264Profile::kProfileConstrainedHigh}};

 struct LevelConstraint {
   const int max_macroblocks_per_second;
   const int max_macroblock_frame_size;
   const H264Level level;
 };

 // This is from ITU-T H.264 (02/2016) Table A-1 – Level limits.
 static constexpr LevelConstraint kLevelConstraints[] = {
     {1485, 99, H264Level::kLevel1},
     {1485, 99, H264Level::kLevel1_b},
     {3000, 396, H264Level::kLevel1_1},
     {6000, 396, H264Level::kLevel1_2},
     {11880, 396, H264Level::kLevel1_3},
     {11880, 396, H264Level::kLevel2},
     {19800, 792, H264Level::kLevel2_1},
     {20250, 1620, H264Level::kLevel2_2},
     {40500, 1620, H264Level::kLevel3},
     {108000, 3600, H264Level::kLevel3_1},
     {216000, 5120, H264Level::kLevel3_2},
     {245760, 8192, H264Level::kLevel4},
     {245760, 8192, H264Level::kLevel4_1},
     {522240, 8704, H264Level::kLevel4_2},
     {589824, 22080, H264Level::kLevel5},
     {983040, 36864, H264Level::kLevel5_1},
     {2073600, 36864, H264Level::kLevel5_2},
 };

 }  // anonymous namespace

 absl::optional<H264ProfileLevelId> ParseH264ProfileLevelId(const char* str) {
   // The string should consist of 3 bytes in hexadecimal format.
   if (strlen(str) != 6u)
     return absl::nullopt;
   const uint32_t profile_level_id_numeric = strtol(str, nullptr, 16);
   if (profile_level_id_numeric == 0)
     return absl::nullopt;

   // Separate into three bytes.
   const uint8_t level_idc =
       static_cast<uint8_t>(profile_level_id_numeric & 0xFF);
   const uint8_t profile_iop =
       static_cast<uint8_t>((profile_level_id_numeric >> 8) & 0xFF);
   const uint8_t profile_idc =
       static_cast<uint8_t>((profile_level_id_numeric >> 16) & 0xFF);

   // Parse level based on level_idc and constraint set 3 flag.
   H264Level level_casted = static_cast<H264Level>(level_idc);
   H264Level level;

   switch (level_casted) {
     case H264Level::kLevel1_1:
       level = (profile_iop & kConstraintSet3Flag) != 0 ? H264Level::kLevel1_b
                                                        : H264Level::kLevel1_1;
       break;
     case H264Level::kLevel1:
     case H264Level::kLevel1_2:
     case H264Level::kLevel1_3:
     case H264Level::kLevel2:
     case H264Level::kLevel2_1:
     case H264Level::kLevel2_2:
     case H264Level::kLevel3:
     case H264Level::kLevel3_1:
     case H264Level::kLevel3_2:
     case H264Level::kLevel4:
     case H264Level::kLevel4_1:
     case H264Level::kLevel4_2:
     case H264Level::kLevel5:
     case H264Level::kLevel5_1:
     case H264Level::kLevel5_2:
       level = level_casted;
       break;
     default:
       // Unrecognized level_idc.
       return absl::nullopt;
   }

   // Parse profile_idc/profile_iop into a Profile enum.
   for (const ProfilePattern& pattern : kProfilePatterns) {
     if (profile_idc == pattern.profile_idc &&
         pattern.profile_iop.IsMatch(profile_iop)) {
       return H264ProfileLevelId(pattern.profile, level);
     }
   }

   // Unrecognized profile_idc/profile_iop combination.
   return absl::nullopt;
 }

 absl::optional<H264Level> H264SupportedLevel(int max_frame_pixel_count,
                                              float max_fps) {
   static const int kPixelsPerMacroblock = 16 * 16;

   for (int i = arraysize(kLevelConstraints) - 1; i >= 0; --i) {
     const LevelConstraint& level_constraint = kLevelConstraints[i];
     if (level_constraint.max_macroblock_frame_size * kPixelsPerMacroblock <=
             max_frame_pixel_count &&
         level_constraint.max_macroblocks_per_second <=
             max_fps * level_constraint.max_macroblock_frame_size) {
       return level_constraint.level;
     }
   }

   // No level supported.
   return absl::nullopt;
 }

 absl::optional<H264ProfileLevelId> ParseSdpForH264ProfileLevelId(
     const SdpVideoFormat::Parameters& params) {
   // TODO(magjed): The default should really be kProfileBaseline and kLevel1
   // according to the spec: https://tools.ietf.org/html/rfc6184#section-8.1. In
   // order to not break backwards compatibility with older versions of WebRTC
   // where external codecs don't have any parameters, use
   // kProfileConstrainedBaseline kLevel3_1 instead. This workaround will only be
   // done in an interim period to allow external clients to update their code.
   // http://crbug/webrtc/6337.
   static const H264ProfileLevelId kDefaultProfileLevelId(
       H264Profile::kProfileConstrainedBaseline, H264Level::kLevel3_1);

   const auto profile_level_id_it = params.find(kProfileLevelId);
   return (profile_level_id_it == params.end())
              ? kDefaultProfileLevelId
              : ParseH264ProfileLevelId(profile_level_id_it->second.c_str());
 }

 absl::optional<std::string> H264ProfileLevelIdToString(
     const H264ProfileLevelId& profile_level_id) {
   // Handle special case level == 1b.
   if (profile_level_id.level == H264Level::kLevel1_b) {
     switch (profile_level_id.profile) {
       case H264Profile::kProfileConstrainedBaseline:
         return {"42f00b"};
       case H264Profile::kProfileBaseline:
         return {"42100b"};
       case H264Profile::kProfileMain:
         return {"4d100b"};
       // Level 1b is not allowed for other profiles.
       default:
         return absl::nullopt;
     }
   }

   const char* profile_idc_iop_string;
   switch (profile_level_id.profile) {
     case H264Profile::kProfileConstrainedBaseline:
       profile_idc_iop_string = "42e0";
       break;
     case H264Profile::kProfileBaseline:
       profile_idc_iop_string = "4200";
       break;
     case H264Profile::kProfileMain:
       profile_idc_iop_string = "4d00";
       break;
     case H264Profile::kProfileConstrainedHigh:
       profile_idc_iop_string = "640c";
       break;
     case H264Profile::kProfileHigh:
       profile_idc_iop_string = "6400";
       break;
     // Unrecognized profile.
     default:
       return absl::nullopt;
   }

   char str[7];
   snprintf(str, 7u, "%s%02x", profile_idc_iop_string, profile_level_id.level);
   return {str};
 }

 bool H264IsSameProfile(const SdpVideoFormat::Parameters& params1,
                        const SdpVideoFormat::Parameters& params2) {
   const absl::optional<H264ProfileLevelId> profile_level_id =
       ParseSdpForH264ProfileLevelId(params1);
   const absl::optional<H264ProfileLevelId> other_profile_level_id =
       ParseSdpForH264ProfileLevelId(params2);
   // Compare H264 profiles, but not levels.
   return profile_level_id && other_profile_level_id &&
          profile_level_id->profile == other_profile_level_id->profile;
 }

 }  // namespace webrtc
	/*
	* Copyright (c) 2021 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 "api/video_codecs/h264_profile_level_id.h"

	#include <cstdio>
	#include <cstdlib>
	#include <string>

	#include "rtc_base/arraysize.h"
	#include "rtc_base/checks.h"

	namespace webrtc {

	namespace {

	const char kProfileLevelId[] = "profile-level-id";

	// For level_idc=11 and profile_idc=0x42, 0x4D, or 0x58, the constraint set3
	// flag specifies if level 1b or level 1.1 is used.
	const uint8_t kConstraintSet3Flag = 0x10;

	// Convert a string of 8 characters into a byte where the positions containing
	// character c will have their bit set. For example, c = 'x', str = "x1xx0000"
	// will return 0b10110000. constexpr is used so that the pattern table in
	// kProfilePatterns is statically initialized.
	constexpr uint8_t ByteMaskString(char c, const char (&str)[9]) {
	return (str[0] == c) << 7 \| (str[1] == c) << 6 \| (str[2] == c) << 5 \|
	(str[3] == c) << 4 \| (str[4] == c) << 3 \| (str[5] == c) << 2 \|
	(str[6] == c) << 1 \| (str[7] == c) << 0;
	}

	// Class for matching bit patterns such as "x1xx0000" where 'x' is allowed to be
	// either 0 or 1.
	class BitPattern {
	public:
	explicit constexpr BitPattern(const char (&str)[9])
	: mask_(~ByteMaskString('x', str)),
	masked_value_(ByteMaskString('1', str)) {}

	bool IsMatch(uint8_t value) const { return masked_value_ == (value & mask_); }

	private:
	const uint8_t mask_;
	const uint8_t masked_value_;
	};

	// Table for converting between profile_idc/profile_iop to H264Profile.
	struct ProfilePattern {
	const uint8_t profile_idc;
	const BitPattern profile_iop;
	const H264Profile profile;
	};

	// This is from https://tools.ietf.org/html/rfc6184#section-8.1.
	constexpr ProfilePattern kProfilePatterns[] = {
	{0x42, BitPattern("x1xx0000"), H264Profile::kProfileConstrainedBaseline},
	{0x4D, BitPattern("1xxx0000"), H264Profile::kProfileConstrainedBaseline},
	{0x58, BitPattern("11xx0000"), H264Profile::kProfileConstrainedBaseline},
	{0x42, BitPattern("x0xx0000"), H264Profile::kProfileBaseline},
	{0x58, BitPattern("10xx0000"), H264Profile::kProfileBaseline},
	{0x4D, BitPattern("0x0x0000"), H264Profile::kProfileMain},
	{0x64, BitPattern("00000000"), H264Profile::kProfileHigh},
	{0x64, BitPattern("00001100"), H264Profile::kProfileConstrainedHigh}};

	struct LevelConstraint {
	const int max_macroblocks_per_second;
	const int max_macroblock_frame_size;
	const H264Level level;
	};

	// This is from ITU-T H.264 (02/2016) Table A-1 – Level limits.
	static constexpr LevelConstraint kLevelConstraints[] = {
	{1485, 99, H264Level::kLevel1},
	{1485, 99, H264Level::kLevel1_b},
	{3000, 396, H264Level::kLevel1_1},
	{6000, 396, H264Level::kLevel1_2},
	{11880, 396, H264Level::kLevel1_3},
	{11880, 396, H264Level::kLevel2},
	{19800, 792, H264Level::kLevel2_1},
	{20250, 1620, H264Level::kLevel2_2},
	{40500, 1620, H264Level::kLevel3},
	{108000, 3600, H264Level::kLevel3_1},
	{216000, 5120, H264Level::kLevel3_2},
	{245760, 8192, H264Level::kLevel4},
	{245760, 8192, H264Level::kLevel4_1},
	{522240, 8704, H264Level::kLevel4_2},
	{589824, 22080, H264Level::kLevel5},
	{983040, 36864, H264Level::kLevel5_1},
	{2073600, 36864, H264Level::kLevel5_2},
	};

	} // anonymous namespace

	absl::optional<H264ProfileLevelId> ParseH264ProfileLevelId(const char* str) {
	// The string should consist of 3 bytes in hexadecimal format.
	if (strlen(str) != 6u)
	return absl::nullopt;
	const uint32_t profile_level_id_numeric = strtol(str, nullptr, 16);
	if (profile_level_id_numeric == 0)
	return absl::nullopt;

	// Separate into three bytes.
	const uint8_t level_idc =
	static_cast<uint8_t>(profile_level_id_numeric & 0xFF);
	const uint8_t profile_iop =
	static_cast<uint8_t>((profile_level_id_numeric >> 8) & 0xFF);
	const uint8_t profile_idc =
	static_cast<uint8_t>((profile_level_id_numeric >> 16) & 0xFF);

	// Parse level based on level_idc and constraint set 3 flag.
	H264Level level_casted = static_cast<H264Level>(level_idc);
	H264Level level;

	switch (level_casted) {
	case H264Level::kLevel1_1:
	level = (profile_iop & kConstraintSet3Flag) != 0 ? H264Level::kLevel1_b
	: H264Level::kLevel1_1;
	break;
	case H264Level::kLevel1:
	case H264Level::kLevel1_2:
	case H264Level::kLevel1_3:
	case H264Level::kLevel2:
	case H264Level::kLevel2_1:
	case H264Level::kLevel2_2:
	case H264Level::kLevel3:
	case H264Level::kLevel3_1:
	case H264Level::kLevel3_2:
	case H264Level::kLevel4:
	case H264Level::kLevel4_1:
	case H264Level::kLevel4_2:
	case H264Level::kLevel5:
	case H264Level::kLevel5_1:
	case H264Level::kLevel5_2:
	level = level_casted;
	break;
	default:
	// Unrecognized level_idc.
	return absl::nullopt;
	}

	// Parse profile_idc/profile_iop into a Profile enum.
	for (const ProfilePattern& pattern : kProfilePatterns) {
	if (profile_idc == pattern.profile_idc &&
	pattern.profile_iop.IsMatch(profile_iop)) {
	return H264ProfileLevelId(pattern.profile, level);
	}
	}

	// Unrecognized profile_idc/profile_iop combination.
	return absl::nullopt;
	}

	absl::optional<H264Level> H264SupportedLevel(int max_frame_pixel_count,
	float max_fps) {
	static const int kPixelsPerMacroblock = 16 * 16;

	for (int i = arraysize(kLevelConstraints) - 1; i >= 0; --i) {
	const LevelConstraint& level_constraint = kLevelConstraints[i];
	if (level_constraint.max_macroblock_frame_size * kPixelsPerMacroblock <=
	max_frame_pixel_count &&
	level_constraint.max_macroblocks_per_second <=
	max_fps * level_constraint.max_macroblock_frame_size) {
	return level_constraint.level;
	}
	}

	// No level supported.
	return absl::nullopt;
	}

	absl::optional<H264ProfileLevelId> ParseSdpForH264ProfileLevelId(
	const SdpVideoFormat::Parameters& params) {
	// TODO(magjed): The default should really be kProfileBaseline and kLevel1
	// according to the spec: https://tools.ietf.org/html/rfc6184#section-8.1. In
	// order to not break backwards compatibility with older versions of WebRTC
	// where external codecs don't have any parameters, use
	// kProfileConstrainedBaseline kLevel3_1 instead. This workaround will only be
	// done in an interim period to allow external clients to update their code.
	// http://crbug/webrtc/6337.
	static const H264ProfileLevelId kDefaultProfileLevelId(
	H264Profile::kProfileConstrainedBaseline, H264Level::kLevel3_1);

	const auto profile_level_id_it = params.find(kProfileLevelId);
	return (profile_level_id_it == params.end())
	? kDefaultProfileLevelId
	: ParseH264ProfileLevelId(profile_level_id_it->second.c_str());
	}

	absl::optional<std::string> H264ProfileLevelIdToString(
	const H264ProfileLevelId& profile_level_id) {
	// Handle special case level == 1b.
	if (profile_level_id.level == H264Level::kLevel1_b) {
	switch (profile_level_id.profile) {
	case H264Profile::kProfileConstrainedBaseline:
	return {"42f00b"};
	case H264Profile::kProfileBaseline:
	return {"42100b"};
	case H264Profile::kProfileMain:
	return {"4d100b"};
	// Level 1b is not allowed for other profiles.
	default:
	return absl::nullopt;
	}
	}

	const char* profile_idc_iop_string;
	switch (profile_level_id.profile) {
	case H264Profile::kProfileConstrainedBaseline:
	profile_idc_iop_string = "42e0";
	break;
	case H264Profile::kProfileBaseline:
	profile_idc_iop_string = "4200";
	break;
	case H264Profile::kProfileMain:
	profile_idc_iop_string = "4d00";
	break;
	case H264Profile::kProfileConstrainedHigh:
	profile_idc_iop_string = "640c";
	break;
	case H264Profile::kProfileHigh:
	profile_idc_iop_string = "6400";
	break;
	// Unrecognized profile.
	default:
	return absl::nullopt;
	}

	char str[7];
	snprintf(str, 7u, "%s%02x", profile_idc_iop_string, profile_level_id.level);
	return {str};
	}

	bool H264IsSameProfile(const SdpVideoFormat::Parameters& params1,
	const SdpVideoFormat::Parameters& params2) {
	const absl::optional<H264ProfileLevelId> profile_level_id =
	ParseSdpForH264ProfileLevelId(params1);
	const absl::optional<H264ProfileLevelId> other_profile_level_id =
	ParseSdpForH264ProfileLevelId(params2);
	// Compare H264 profiles, but not levels.
	return profile_level_id && other_profile_level_id &&
	profile_level_id->profile == other_profile_level_id->profile;
	}

	} // namespace webrtc