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Add test coverage for legacy VP9 SVC with media flow.

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When asking for 3 encodings of VP9, which the spec says is simulcast,
you don't get simulcast but instead you get one RTP stream sending SVC.

This results in a single "outbound-rtp" but GetParameters() still says
3 encodings are used. We know we get SVC because the scalabilityMode
from getStats() says "L3T3_KEY".

In a future CL we will add simulcast VP9 support when
`scalability_mode` is specified in the API but we'll need to continue
to support the legacy SVC code paths until that has been deprecated
and removed (https://crbug.com/webrtc/14889).

Bug: webrtc:14884
Change-Id: Ibeca44b7a0b93097ad9525e45ebbca3b7663c686
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/292581
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Evan Shrubsole <eshr@webrtc.org>
Commit-Queue: Henrik Boström <hbos@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#39278}
This commit is contained in:
Henrik Boström 2023-02-08 15:23:27 +01:00 committed by WebRTC LUCI CQ
parent 7484e62332
commit bce135a4a7
1 changed files with 53 additions and 3 deletions
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56
pc/peer_connection_simulcast_unittest.cc
View File

@ -1011,10 +1011,8 @@ class PeerConnectionSimulcastWithMediaFlowTests
std::unique_ptr<rtc::Thread> background_thread_;
};
// TODO(https://crbug.com/webrtc/14884): When VP9 simulast is supported, use
// SetCodecPreferences() and pass a test like this with VP9.
TEST_F(PeerConnectionSimulcastWithMediaFlowTests,
SimulcastSendsAllLayersWithVP8) {
SendingThreeEncodings_VP8_Simulcast) {
rtc::scoped_refptr<PeerConnectionTestWrapper> local_pc_wrapper = CreatePc();
rtc::scoped_refptr<PeerConnectionTestWrapper> remote_pc_wrapper = CreatePc();
ExchangeIceCandidates(local_pc_wrapper, remote_pc_wrapper);
@ -1050,4 +1048,56 @@ TEST_F(PeerConnectionSimulcastWithMediaFlowTests,
EXPECT_THAT(*outbound_rtps[2]->scalability_mode, StartsWith("L1T"));
}
// The legacy SVC path is triggered when VP9 us used, but `scalability_mode` has
// not been specified.
// TODO(https://crbug.com/webrtc/14889): When legacy VP9 SVC path has been
// deprecated and removed, update this test to assert that simulcast is used
// (i.e. VP9 is not treated differently than VP8).
TEST_F(PeerConnectionSimulcastWithMediaFlowTests,
SendingThreeEncodings_VP9_LegacySVC) {
rtc::scoped_refptr<PeerConnectionTestWrapper> local_pc_wrapper = CreatePc();
rtc::scoped_refptr<PeerConnectionTestWrapper> remote_pc_wrapper = CreatePc();
ExchangeIceCandidates(local_pc_wrapper, remote_pc_wrapper);
std::vector<SimulcastLayer> layers = CreateLayers({"f", "h", "q"}, true);
rtc::scoped_refptr<RtpTransceiverInterface> transceiver =
AddTransceiverWithSimulcastLayers(local_pc_wrapper, remote_pc_wrapper,
layers);
std::vector<RtpCodecCapability> codecs =
GetCapabilitiesAndRestrictToCodec(local_pc_wrapper, "VP9");
transceiver->SetCodecPreferences(codecs);
NegotiateWithSimulcastTweaks(local_pc_wrapper, remote_pc_wrapper, layers);
local_pc_wrapper->WaitForConnection();
remote_pc_wrapper->WaitForConnection();
// Wait until media is flowing. We only expect a single RTP stream.
EXPECT_TRUE_WAIT(HasOutboundRtpBytesSent(local_pc_wrapper, 1u),
kLongTimeoutForRampingUp.ms());
// Verify codec and scalability mode.
rtc::scoped_refptr<const RTCStatsReport> report = GetStats(local_pc_wrapper);
std::vector<const RTCOutboundRTPStreamStats*> outbound_rtps =
report->GetStatsOfType<RTCOutboundRTPStreamStats>();
ASSERT_EQ(outbound_rtps.size(), 1u);
EXPECT_TRUE(absl::EqualsIgnoreCase(
GetCurrentCodecMimeType(report, *outbound_rtps[0]), "video/VP9"));
EXPECT_THAT(*outbound_rtps[0]->scalability_mode, StartsWith("L3T3_KEY"));
// Despite SVC being used on a single RTP stream, GetParameters() returns the
// three encodings that we configured earlier (this is not spec-compliant but
// it is how legacy SVC behaves).
rtc::scoped_refptr<RtpSenderInterface> sender = transceiver->sender();
std::vector<RtpEncodingParameters> encodings =
sender->GetParameters().encodings;
ASSERT_EQ(encodings.size(), 3u);
// When legacy SVC is used, `scalability_mode` is not specified.
EXPECT_FALSE(encodings[0].scalability_mode.has_value());
EXPECT_FALSE(encodings[1].scalability_mode.has_value());
EXPECT_FALSE(encodings[2].scalability_mode.has_value());
}
// TODO(https://crbug.com/webrtc/14884): Add support for VP9 simulcast and test
// this using a similar test to the above but specifying and verifying
// `scalability_mode` (e.g. L1Tx).
} // namespace webrtc