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/*
* Copyright 2024 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 "media/base/codec_comparators.h"
#include <cstddef>
#include <optional>
#include <string>
#include <vector>
#include "absl/algorithm/container.h"
#include "absl/functional/any_invocable.h"
#include "absl/strings/match.h"
#include "absl/strings/string_view.h"
#include "api/rtp_parameters.h"
#include "api/video_codecs/av1_profile.h"
#include "api/video_codecs/h264_profile_level_id.h"
#ifdef RTC_ENABLE_H265
#include "api/video_codecs/h265_profile_tier_level.h"
#endif
#include "api/video_codecs/vp9_profile.h"
#include "media/base/codec.h"
#include "media/base/media_constants.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
#include "rtc_base/string_encode.h"
namespace webrtc {
namespace {
using cricket::Codec;
// TODO(bugs.webrtc.org/15847): remove code duplication of IsSameCodecSpecific
// in api/video_codecs/sdp_video_format.cc
std::string GetFmtpParameterOrDefault(const CodecParameterMap& params,
const std::string& name,
const std::string& default_value) {
const auto it = params.find(name);
if (it != params.end()) {
return it->second;
}
return default_value;
}
bool HasParameter(const CodecParameterMap& params, const std::string& name) {
return params.find(name) != params.end();
}
std::string H264GetPacketizationModeOrDefault(const CodecParameterMap& params) {
// If packetization-mode is not present, default to "0".
// https://tools.ietf.org/html/rfc6184#section-6.2
return GetFmtpParameterOrDefault(params, cricket::kH264FmtpPacketizationMode,
"0");
}
bool H264IsSamePacketizationMode(const CodecParameterMap& left,
const CodecParameterMap& right) {
return H264GetPacketizationModeOrDefault(left) ==
H264GetPacketizationModeOrDefault(right);
}
std::string AV1GetTierOrDefault(const CodecParameterMap& params) {
// If the parameter is not present, the tier MUST be inferred to be 0.
// https://aomediacodec.github.io/av1-rtp-spec/#72-sdp-parameters
return GetFmtpParameterOrDefault(params, cricket::kAv1FmtpTier, "0");
}
bool AV1IsSameTier(const CodecParameterMap& left,
const CodecParameterMap& right) {
return AV1GetTierOrDefault(left) == AV1GetTierOrDefault(right);
}
std::string AV1GetLevelIdxOrDefault(const CodecParameterMap& params) {
// If the parameter is not present, it MUST be inferred to be 5 (level 3.1).
// https://aomediacodec.github.io/av1-rtp-spec/#72-sdp-parameters
return GetFmtpParameterOrDefault(params, cricket::kAv1FmtpLevelIdx, "5");
}
bool AV1IsSameLevelIdx(const CodecParameterMap& left,
const CodecParameterMap& right) {
return AV1GetLevelIdxOrDefault(left) == AV1GetLevelIdxOrDefault(right);
}
#ifdef RTC_ENABLE_H265
std::string GetH265TxModeOrDefault(const CodecParameterMap& params) {
// If TxMode is not present, a value of "SRST" must be inferred.
// https://tools.ietf.org/html/rfc7798@section-7.1
return GetFmtpParameterOrDefault(params, cricket::kH265FmtpTxMode, "SRST");
}
bool IsSameH265TxMode(const CodecParameterMap& left,
const CodecParameterMap& right) {
return absl::EqualsIgnoreCase(GetH265TxModeOrDefault(left),
GetH265TxModeOrDefault(right));
}
#endif
// Some (video) codecs are actually families of codecs and rely on parameters
// to distinguish different incompatible family members.
bool IsSameCodecSpecific(const std::string& name1,
const CodecParameterMap& params1,
const std::string& name2,
const CodecParameterMap& params2) {
// The names might not necessarily match, so check both.
auto either_name_matches = [&](const std::string name) {
return absl::EqualsIgnoreCase(name, name1) ||
absl::EqualsIgnoreCase(name, name2);
};
if (either_name_matches(cricket::kH264CodecName))
return H264IsSameProfile(params1, params2) &&
H264IsSamePacketizationMode(params1, params2);
if (either_name_matches(cricket::kVp9CodecName))
return VP9IsSameProfile(params1, params2);
if (either_name_matches(cricket::kAv1CodecName))
return AV1IsSameProfile(params1, params2) &&
AV1IsSameTier(params1, params2) &&
AV1IsSameLevelIdx(params1, params2);
#ifdef RTC_ENABLE_H265
if (either_name_matches(cricket::kH265CodecName)) {
return H265IsSameProfile(params1, params2) &&
H265IsSameTier(params1, params2) &&
IsSameH265TxMode(params1, params2);
}
#endif
return true;
}
bool ReferencedCodecsMatch(const std::vector<Codec>& codecs1,
const int codec1_id,
const std::vector<Codec>& codecs2,
const int codec2_id) {
const Codec* codec1 = FindCodecById(codecs1, codec1_id);
const Codec* codec2 = FindCodecById(codecs2, codec2_id);
return codec1 != nullptr && codec2 != nullptr && codec1->Matches(*codec2);
}
bool MatchesWithReferenceAttributesAndComparator(
const Codec& codec_to_match,
const Codec& potential_match,
absl::AnyInvocable<bool(int, int)> reference_comparator) {
if (!MatchesWithCodecRules(codec_to_match, potential_match)) {
return false;
}
Codec::ResiliencyType resiliency_type = codec_to_match.GetResiliencyType();
if (resiliency_type == Codec::ResiliencyType::kRtx) {
int apt_value_1 = 0;
int apt_value_2 = 0;
if (!codec_to_match.GetParam(cricket::kCodecParamAssociatedPayloadType,
&apt_value_1) ||
!potential_match.GetParam(cricket::kCodecParamAssociatedPayloadType,
&apt_value_2)) {
RTC_LOG(LS_WARNING) << "RTX missing associated payload type.";
return false;
}
if (reference_comparator(apt_value_1, apt_value_2)) {
return true;
}
return false;
}
if (resiliency_type == Codec::ResiliencyType::kRed) {
auto red_parameters_1 =
codec_to_match.params.find(cricket::kCodecParamNotInNameValueFormat);
auto red_parameters_2 =
potential_match.params.find(cricket::kCodecParamNotInNameValueFormat);
bool has_parameters_1 = red_parameters_1 != codec_to_match.params.end();
bool has_parameters_2 = red_parameters_2 != potential_match.params.end();
// If codec_to_match has unassigned PT and no parameter,
// we assume that it'll be assigned later and return a match.
// Note - this should be deleted. It's untidy.
if (potential_match.id == Codec::kIdNotSet && !has_parameters_2) {
return true;
}
if (codec_to_match.id == Codec::kIdNotSet && !has_parameters_1) {
return true;
}
if (has_parameters_1 && has_parameters_2) {
// Different levels of redundancy between offer and answer are
// since RED is considered to be declarative.
std::vector<absl::string_view> redundant_payloads_1 =
rtc::split(red_parameters_1->second, '/');
std::vector<absl::string_view> redundant_payloads_2 =
rtc::split(red_parameters_2->second, '/');
if (redundant_payloads_1.size() > 0 && redundant_payloads_2.size() > 0) {
// Mixed reference codecs (i.e. 111/112) are not supported.
for (size_t i = 1; i < redundant_payloads_1.size(); i++) {
if (redundant_payloads_1[i] != redundant_payloads_1[0]) {
return false;
}
}
for (size_t i = 1; i < redundant_payloads_2.size(); i++) {
if (redundant_payloads_2[i] != redundant_payloads_2[0]) {
return false;
}
}
int red_value_1;
int red_value_2;
if (rtc::FromString(redundant_payloads_1[0], &red_value_1) &&
rtc::FromString(redundant_payloads_2[0], &red_value_2)) {
if (reference_comparator(red_value_1, red_value_2)) {
return true;
}
}
return false;
}
}
if (!has_parameters_1 && !has_parameters_2) {
// Both parameters are missing. Happens for video RED.
return true;
}
return false;
}
return true; // Not a codec with a PT-valued reference.
}
CodecParameterMap InsertDefaultParams(const std::string& name,
const CodecParameterMap& params) {
CodecParameterMap updated_params = params;
if (absl::EqualsIgnoreCase(name, cricket::kVp9CodecName)) {
if (!HasParameter(params, kVP9FmtpProfileId)) {
if (std::optional<VP9Profile> default_profile =
ParseSdpForVP9Profile({})) {
updated_params.insert(
{kVP9FmtpProfileId, VP9ProfileToString(*default_profile)});
}
}
}
if (absl::EqualsIgnoreCase(name, cricket::kAv1CodecName)) {
if (!HasParameter(params, cricket::kAv1FmtpProfile)) {
if (std::optional<AV1Profile> default_profile =
ParseSdpForAV1Profile({})) {
updated_params.insert({cricket::kAv1FmtpProfile,
AV1ProfileToString(*default_profile).data()});
}
}
if (!HasParameter(params, cricket::kAv1FmtpTier)) {
updated_params.insert({cricket::kAv1FmtpTier, AV1GetTierOrDefault({})});
}
if (!HasParameter(params, cricket::kAv1FmtpLevelIdx)) {
updated_params.insert(
{cricket::kAv1FmtpLevelIdx, AV1GetLevelIdxOrDefault({})});
}
}
if (absl::EqualsIgnoreCase(name, cricket::kH264CodecName)) {
if (!HasParameter(params, cricket::kH264FmtpPacketizationMode)) {
updated_params.insert({cricket::kH264FmtpPacketizationMode,
H264GetPacketizationModeOrDefault({})});
}
}
#ifdef RTC_ENABLE_H265
if (absl::EqualsIgnoreCase(name, cricket::kH265CodecName)) {
if (std::optional<H265ProfileTierLevel> default_params =
ParseSdpForH265ProfileTierLevel({})) {
if (!HasParameter(params, cricket::kH265FmtpProfileId)) {
updated_params.insert({cricket::kH265FmtpProfileId,
H265ProfileToString(default_params->profile)});
}
if (!HasParameter(params, cricket::kH265FmtpLevelId)) {
updated_params.insert({cricket::kH265FmtpLevelId,
H265LevelToString(default_params->level)});
}
if (!HasParameter(params, cricket::kH265FmtpTierFlag)) {
updated_params.insert({cricket::kH265FmtpTierFlag,
H265TierToString(default_params->tier)});
}
}
if (!HasParameter(params, cricket::kH265FmtpTxMode)) {
updated_params.insert(
{cricket::kH265FmtpTxMode, GetH265TxModeOrDefault({})});
}
}
#endif
return updated_params;
}
} // namespace
bool MatchesWithCodecRules(const Codec& left_codec, const Codec& right_codec) {
// Match the codec id/name based on the typical static/dynamic name rules.
// Matching is case-insensitive.
// We support the ranges [96, 127] and more recently [35, 65].
// https://www.iana.org/assignments/rtp-parameters/rtp-parameters.xhtml#rtp-parameters-1
// Within those ranges we match by codec name, outside by codec id.
// We also match by name if either ID is unassigned.
// Since no codecs are assigned an id in the range [66, 95] by us, these will
// never match.
const int kLowerDynamicRangeMin = 35;
const int kLowerDynamicRangeMax = 65;
const int kUpperDynamicRangeMin = 96;
const int kUpperDynamicRangeMax = 127;
const bool is_id_in_dynamic_range =
(left_codec.id >= kLowerDynamicRangeMin &&
left_codec.id <= kLowerDynamicRangeMax) ||
(left_codec.id >= kUpperDynamicRangeMin &&
left_codec.id <= kUpperDynamicRangeMax);
const bool is_codec_id_in_dynamic_range =
(right_codec.id >= kLowerDynamicRangeMin &&
right_codec.id <= kLowerDynamicRangeMax) ||
(right_codec.id >= kUpperDynamicRangeMin &&
right_codec.id <= kUpperDynamicRangeMax);
bool matches_id;
if ((is_id_in_dynamic_range && is_codec_id_in_dynamic_range) ||
left_codec.id == Codec::kIdNotSet || right_codec.id == Codec::kIdNotSet) {
matches_id = absl::EqualsIgnoreCase(left_codec.name, right_codec.name);
} else {
matches_id = (left_codec.id == right_codec.id);
}
auto matches_type_specific = [&]() {
switch (left_codec.type) {
case Codec::Type::kAudio:
// If a nonzero clockrate is specified, it must match the actual
// clockrate. If a nonzero bitrate is specified, it must match the
// actual bitrate, unless the codec is VBR (0), where we just force the
// supplied value. The number of channels must match exactly, with the
// exception that channels=0 is treated synonymously as channels=1, per
// RFC 4566 section 6: " [The channels] parameter is OPTIONAL and may be
// omitted if the number of channels is one."
// Preference is ignored.
// TODO(juberti): Treat a zero clockrate as 8000Hz, the RTP default
// clockrate.
return ((right_codec.clockrate == 0 /*&& clockrate == 8000*/) ||
left_codec.clockrate == right_codec.clockrate) &&
(right_codec.bitrate == 0 || left_codec.bitrate <= 0 ||
left_codec.bitrate == right_codec.bitrate) &&
((right_codec.channels < 2 && left_codec.channels < 2) ||
left_codec.channels == right_codec.channels);
case Codec::Type::kVideo:
return IsSameCodecSpecific(left_codec.name, left_codec.params,
right_codec.name, right_codec.params);
}
};
return matches_id && matches_type_specific();
}
// Finds a codec in `codecs2` that matches `codec_to_match`, which is
// a member of `codecs1`. If `codec_to_match` is an RED or RTX codec, both
// the codecs themselves and their associated codecs must match.
std::optional<Codec> FindMatchingCodec(const std::vector<Codec>& codecs1,
const std::vector<Codec>& codecs2,
const Codec& codec_to_match) {
// `codec_to_match` should be a member of `codecs1`, in order to look up
// RED/RTX codecs' associated codecs correctly. If not, that's a programming
// error.
RTC_DCHECK(absl::c_any_of(codecs1, [&codec_to_match](const Codec& codec) {
return &codec == &codec_to_match;
}));
for (const Codec& potential_match : codecs2) {
if (MatchesWithReferenceAttributesAndComparator(
codec_to_match, potential_match,
[&codecs1, &codecs2](int a, int b) {
return ReferencedCodecsMatch(codecs1, a, codecs2, b);
})) {
return potential_match;
}
}
return std::nullopt;
}
bool IsSameRtpCodec(const Codec& codec, const RtpCodec& rtp_codec) {
RtpCodecParameters rtp_codec2 = codec.ToCodecParameters();
return absl::EqualsIgnoreCase(rtp_codec.name, rtp_codec2.name) &&
rtp_codec.kind == rtp_codec2.kind &&
rtp_codec.num_channels == rtp_codec2.num_channels &&
rtp_codec.clock_rate == rtp_codec2.clock_rate &&
InsertDefaultParams(rtp_codec.name, rtp_codec.parameters) ==
InsertDefaultParams(rtp_codec2.name, rtp_codec2.parameters);
}
bool IsSameRtpCodecIgnoringLevel(const Codec& codec,
const RtpCodec& rtp_codec) {
RtpCodecParameters rtp_codec2 = codec.ToCodecParameters();
if (!absl::EqualsIgnoreCase(rtp_codec.name, rtp_codec2.name) ||
rtp_codec.kind != rtp_codec2.kind ||
rtp_codec.num_channels != rtp_codec2.num_channels ||
rtp_codec.clock_rate != rtp_codec2.clock_rate) {
return false;
}
CodecParameterMap params1 =
InsertDefaultParams(rtp_codec.name, rtp_codec.parameters);
CodecParameterMap params2 =
InsertDefaultParams(rtp_codec2.name, rtp_codec2.parameters);
// Currently we only ignore H.265 level-id parameter.
#ifdef RTC_ENABLE_H265
if (absl::EqualsIgnoreCase(rtp_codec.name, cricket::kH265CodecName)) {
params1.erase(cricket::kH265FmtpLevelId);
params2.erase(cricket::kH265FmtpLevelId);
}
#endif
return params1 == params2;
}
} // namespace webrtc