From c596dd5eb660b3a3263d9fafb0d21c11cce08d96 Mon Sep 17 00:00:00 2001
From: Qiu Jianlin <jianlin.qiu@intel.com>
Date: Mon, 2 Dec 2024 13:08:53 +0800
Subject: [PATCH] Fix setCodecPreference issue with asymmetrical send/recv
 level
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For an offer in sendrecv direction, if for example it can send H.265
level 5.2 while receiving 6.0, setCodecPreferences on offerer's transceiver will currently remove H.265 from the offer SDP, since currently we do a precise level match on send_recv_codecs with the codecs from setCodecPreferences.
Update the matching logic to ignore the level when matching.

Bug: chromium:41480904
Change-Id: Id0f89cbf117ce62249a99257dcce18b35f407cb9
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/369960
Reviewed-by: Sergey Silkin <ssilkin@webrtc.org>
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Commit-Queue: Sergey Silkin <ssilkin@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#43477}
---
 pc/media_session.cc          | 13 ++++-----
 pc/media_session_unittest.cc | 55 ++++++++++++++++++++++++++++++++++++
 2 files changed, 60 insertions(+), 8 deletions(-)

diff --git a/pc/media_session.cc b/pc/media_session.cc
index 3e0d762d10..9cb82347b5 100644
--- a/pc/media_session.cc
+++ b/pc/media_session.cc
@@ -736,14 +736,11 @@ std::vector<Codec> MatchCodecPreference(
   for (const auto& codec_preference : codec_preferences) {
     auto found_codec = absl::c_find_if(
         supported_codecs, [&codec_preference](const Codec& codec) {
-          webrtc::RtpCodecParameters codec_parameters =
-              codec.ToCodecParameters();
-          return codec_parameters.name == codec_preference.name &&
-                 codec_parameters.kind == codec_preference.kind &&
-                 codec_parameters.num_channels ==
-                     codec_preference.num_channels &&
-                 codec_parameters.clock_rate == codec_preference.clock_rate &&
-                 codec_parameters.parameters == codec_preference.parameters;
+          // We should not filter out the codec in |codec_preferences| if it
+          // has a higher level than the codec in |supported_codecs|, as the
+          // codec in |supported_codecs| may be only with lower level in
+          // |send_codecs_| and |recv_codecs_| for the same codec.
+          return IsSameRtpCodecIgnoringLevel(codec, codec_preference);
         });
 
     if (found_codec != supported_codecs.end()) {
diff --git a/pc/media_session_unittest.cc b/pc/media_session_unittest.cc
index 8b35c41299..fa71feec0c 100644
--- a/pc/media_session_unittest.cc
+++ b/pc/media_session_unittest.cc
@@ -5923,6 +5923,61 @@ TEST_F(VideoCodecsOfferH265LevelIdTest,
   EXPECT_TRUE(CodecsMatch(MAKE_VECTOR(kVideoCodecsH265Level4), acd->codecs()));
   CheckH265Level(acd->codecs(), kVideoCodecsH265Level4LevelId);
 }
+
+TEST_F(VideoCodecsOfferH265LevelIdTest,
+       SendOnlyOffererEncode40Decode60AnswererEncode60Decode52WithPreference) {
+  const std::vector<Codec> offerer_send_codecs =
+      MAKE_VECTOR(kVideoCodecsH265Level4);
+  const std::vector<Codec> offerer_recv_codecs =
+      MAKE_VECTOR(kVideoCodecsH265Level6);
+  const std::vector<Codec> offerer_sendrecv_codecs =
+      MAKE_VECTOR(kVideoCodecsH265Level4);
+  const std::vector<Codec> answerer_send_codecs =
+      MAKE_VECTOR(kVideoCodecsH265Level6);
+  const std::vector<Codec> answerer_recv_codecs =
+      MAKE_VECTOR(kVideoCodecsH265Level52);
+  sf_offerer_.set_video_codecs(offerer_send_codecs, offerer_recv_codecs);
+  sf_answerer_.set_video_codecs(answerer_send_codecs, answerer_recv_codecs);
+  EXPECT_EQ(offerer_sendrecv_codecs, sf_offerer_.video_sendrecv_codecs());
+
+  MediaSessionOptions opts;
+  AddMediaDescriptionOptions(MEDIA_TYPE_VIDEO, "video",
+                             RtpTransceiverDirection::kSendRecv, kActive,
+                             &opts);
+
+  AttachSenderToMediaDescriptionOptions("video", MEDIA_TYPE_VIDEO, kVideoTrack1,
+                                        {kMediaStream1}, 1, &opts);
+  std::vector<webrtc::RtpCodecCapability> preferences;
+  for (const auto& codec : sf_offerer_.video_recv_codecs()) {
+    preferences.push_back(webrtc::ToRtpCodecCapability(codec));
+  }
+  opts.media_description_options[0].codec_preferences = preferences;
+
+  std::unique_ptr<SessionDescription> offer =
+      sf_offerer_.CreateOfferOrError(opts, nullptr).MoveValue();
+  ASSERT_TRUE(offer.get());
+  const ContentInfo* oc = offer->GetContentByName("video");
+  ASSERT_TRUE(oc);
+  const MediaContentDescription* ocd = oc->media_description();
+  EXPECT_TRUE(CodecsMatch(MAKE_VECTOR(kVideoCodecsH265Level4), ocd->codecs()));
+  CheckH265Level(ocd->codecs(), kVideoCodecsH265Level4LevelId);
+
+  MediaSessionOptions answer_opts;
+  AddMediaDescriptionOptions(MEDIA_TYPE_VIDEO, "video",
+                             RtpTransceiverDirection::kRecvOnly, kActive,
+                             &answer_opts);
+
+  std::unique_ptr<SessionDescription> answer =
+      sf_answerer_.CreateAnswerOrError(offer.get(), answer_opts, nullptr)
+          .MoveValue();
+  ASSERT_TRUE(answer.get());
+  const ContentInfo* ac = answer->GetContentByName("video");
+  ASSERT_TRUE(ac);
+  const MediaContentDescription* acd = ac->media_description();
+  EXPECT_TRUE(CodecsMatch(MAKE_VECTOR(kVideoCodecsH265Level4), acd->codecs()));
+  CheckH265Level(acd->codecs(), kVideoCodecsH265Level4LevelId);
+}
+
 #endif
 
 }  // namespace