Fixing some issues with payload type mappings.

talk/session/media/mediasession_unittest.cc

Index: talk/session/media/mediasession_unittest.cc
diff --git a/talk/session/media/mediasession_unittest.cc b/talk/session/media/mediasession_unittest.cc
index 20b72e93946393e9c2f7aa9886999583c9f3cbf3..a79f0a2eca1fe40cfb195e84c29c3be42bdaaffa 100644
--- a/talk/session/media/mediasession_unittest.cc
+++ b/talk/session/media/mediasession_unittest.cc
@@ -1671,6 +1671,48 @@ TEST_F(MediaSessionDescriptionFactoryTest,
   EXPECT_EQ(new_h264_pl_type, pt_referenced_by_rtx);
 }
 
+// Create an updated offer with RTX after creating an answer to an offer
+// without RTX, and with different default payload types.
+// Verify that the added RTX codec references the correct payload type.
+TEST_F(MediaSessionDescriptionFactoryTest,
+       RespondentCreatesOfferWithRtxAfterCreatingAnswerWithoutRtx) {
+  MediaSessionOptions opts;
+  opts.recv_video = true;
+  opts.recv_audio = true;
+
+  std::vector<VideoCodec> f2_codecs = MAKE_VECTOR(kVideoCodecs2);
+  // This creates rtx for H264 with the payload type |f2_| uses.
+  AddRtxCodec(VideoCodec::CreateRtxCodec(125, kVideoCodecs2[0].id), &f2_codecs);
+  f2_.set_video_codecs(f2_codecs);
+
+  rtc::scoped_ptr<SessionDescription> offer(f1_.CreateOffer(opts, nullptr));
+  ASSERT_TRUE(offer.get() != nullptr);
+  rtc::scoped_ptr<SessionDescription> answer(
+      f2_.CreateAnswer(offer.get(), opts, nullptr));
+
+  const VideoContentDescription* vcd =
+      GetFirstVideoContentDescription(answer.get());
+
+  std::vector<VideoCodec> expected_codecs = MAKE_VECTOR(kVideoCodecsAnswer);
+  EXPECT_EQ(expected_codecs, vcd->codecs());
+
+  // Now, ensure that the RTX codec is created correctly when |f2_| creates an
+  // updated offer, even though the default payload types are different from
+  // those of |f1_|.
+  rtc::scoped_ptr<SessionDescription> updated_offer(
+      f2_.CreateOffer(opts, answer.get()));
+  ASSERT_TRUE(updated_offer);
+
+  const VideoContentDescription* updated_vcd =
+      GetFirstVideoContentDescription(updated_offer.get());
+
+  // New offer should attempt to add H263, and RTX for H264.
+  expected_codecs.push_back(kVideoCodecs2[1]);
+  AddRtxCodec(VideoCodec::CreateRtxCodec(125, kVideoCodecs1[1].id),
+              &expected_codecs);
+  EXPECT_EQ(expected_codecs, updated_vcd->codecs());
+}
+
 // Test that RTX is ignored when there is no associated payload type parameter.
 TEST_F(MediaSessionDescriptionFactoryTest, RtxWithoutApt) {
   MediaSessionOptions opts;
@@ -1779,6 +1821,41 @@ TEST_F(MediaSessionDescriptionFactoryTest,
   EXPECT_EQ(expected_codecs, vcd->codecs());
 }
 
+// Test that after one RTX codec has been negotiated, a new offer can attempt
+// to add another.

[Taylor Brandstetter, 2016/01/21 21:15:05]

Question for Peter: I'm assuming this is allowed, right? The code allowed this
before in initial offers, but not reoffers. For example, say you have codec 1,
codec 2, RTX for codec 1, RTX for codec 2.

+TEST_F(MediaSessionDescriptionFactoryTest, AddSecondRtxInNewOffer) {
+  MediaSessionOptions opts;
+  opts.recv_video = true;
+  opts.recv_audio = false;
+  std::vector<VideoCodec> f1_codecs = MAKE_VECTOR(kVideoCodecs1);
+  // This creates RTX for H264 for the offerer.
+  AddRtxCodec(VideoCodec::CreateRtxCodec(126, kVideoCodecs1[1].id), &f1_codecs);
+  f1_.set_video_codecs(f1_codecs);
+
+  rtc::scoped_ptr<SessionDescription> offer(f1_.CreateOffer(opts, nullptr));
+  ASSERT_TRUE(offer);
+  const VideoContentDescription* vcd =
+      GetFirstVideoContentDescription(offer.get());
+
+  std::vector<VideoCodec> expected_codecs = MAKE_VECTOR(kVideoCodecs1);
+  AddRtxCodec(VideoCodec::CreateRtxCodec(126, kVideoCodecs1[1].id),
+              &expected_codecs);
+  EXPECT_EQ(expected_codecs, vcd->codecs());
+
+  // Now, attempt to add RTX for H264-SVC.
+  AddRtxCodec(VideoCodec::CreateRtxCodec(125, kVideoCodecs1[0].id), &f1_codecs);
+  f1_.set_video_codecs(f1_codecs);
+
+  rtc::scoped_ptr<SessionDescription> updated_offer(
+      f1_.CreateOffer(opts, offer.get()));
+  ASSERT_TRUE(updated_offer);
+  vcd = GetFirstVideoContentDescription(updated_offer.get());
+
+  AddRtxCodec(VideoCodec::CreateRtxCodec(125, kVideoCodecs1[0].id),
+              &expected_codecs);
+  EXPECT_EQ(expected_codecs, vcd->codecs());
+}
+
 // Test that when RTX is used in conjunction with simulcast, an RTX ssrc is
 // generated for each simulcast ssrc and correctly grouped.
 TEST_F(MediaSessionDescriptionFactoryTest, SimSsrcsGenerateMultipleRtxSsrcs) {