Add a SimulcastStream::GetScalabilityMode2 method that returns an optional.

A call to GetScalabilityMode was added for logging purpose and causes an expectation failure for tests using 4 temporal layers.
Plan is to remove the old GetScalabilityMode and keep only the one that returns an optional.

Change-Id: I0e37a496bb621d9754d6572ef5838b58193aa183
Bug: b/327381318
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/341520
Reviewed-by: Henrik Andreassson <henrika@webrtc.org>
Commit-Queue: Jeremy Leconte <jleconte@google.com>
Cr-Commit-Position: refs/heads/main@{#41838}

api/video_codecs/simulcast_stream.cc

@@ -10,6 +10,7 @@
 
 #include "api/video_codecs/simulcast_stream.h"
 
+#include "absl/types/optional.h"
 #include "rtc_base/checks.h"
 
 namespace webrtc {
@@ -34,4 +35,17 @@ ScalabilityMode SimulcastStream::GetScalabilityMode() const {
   return scalability_modes[numberOfTemporalLayers - 1];
 }
 
+// TODO(b/327381318): Rename to GetScalabilityMode.
+absl::optional<ScalabilityMode> SimulcastStream::GetScalabilityMode2() const {
+  static const ScalabilityMode scalability_modes[3] = {
+      ScalabilityMode::kL1T1,
+      ScalabilityMode::kL1T2,
+      ScalabilityMode::kL1T3,
+  };
+  if (numberOfTemporalLayers < 1 || numberOfTemporalLayers > 3) {
+    return absl::nullopt;
+  }
+  return scalability_modes[numberOfTemporalLayers - 1];
+}
+
 }  // namespace webrtc

api/video_codecs/simulcast_stream.h

@@ -11,6 +11,7 @@
 #ifndef API_VIDEO_CODECS_SIMULCAST_STREAM_H_
 #define API_VIDEO_CODECS_SIMULCAST_STREAM_H_
 
+#include "absl/types/optional.h"
 #include "api/video_codecs/scalability_mode.h"
 
 namespace webrtc {
@@ -22,6 +23,8 @@ struct SimulcastStream {
   // setting to ScalabilityMode.
   unsigned char GetNumberOfTemporalLayers() const;
   ScalabilityMode GetScalabilityMode() const;
+  // TODO(b/327381318): Rename to GetScalabilityMode.
+  absl::optional<ScalabilityMode> GetScalabilityMode2() const;
   void SetNumberOfTemporalLayers(unsigned char n);
 
   int width = 0;

api/video_codecs/video_codec.cc

@@ -92,9 +92,13 @@ std::string VideoCodec::ToString() const {
     ss << ", Simulcast: {";
     for (size_t i = 0; i < numberOfSimulcastStreams; ++i) {
       const SimulcastStream stream = simulcastStream[i];
-      ss << "[" << stream.width << "x" << stream.height << " "
-         << ScalabilityModeToString(stream.GetScalabilityMode())
-         << (stream.active ? ", active" : ", inactive") << "]";
+      absl::optional<ScalabilityMode> scalability_mode =
+          stream.GetScalabilityMode2();
+      if (scalability_mode.has_value()) {
+        ss << "[" << stream.width << "x" << stream.height << " "
+           << ScalabilityModeToString(*scalability_mode)
+           << (stream.active ? ", active" : ", inactive") << "]";
+      }
     }
     ss << "}";
   }

media/engine/simulcast_encoder_adapter.cc

@@ -19,6 +19,7 @@
 #include <utility>
 
 #include "absl/algorithm/container.h"
+#include "absl/types/optional.h"
 #include "api/field_trials_view.h"
 #include "api/scoped_refptr.h"
 #include "api/transport/field_trial_based_config.h"
@@ -808,7 +809,8 @@ webrtc::VideoCodec SimulcastEncoderAdapter::MakeStreamCodec(
   // By default, `scalability_mode` comes from SimulcastStream when
   // SimulcastEncoderAdapter is used. This allows multiple encodings of L1Tx,
   // but SimulcastStream currently does not support multiple spatial layers.
-  ScalabilityMode scalability_mode = stream_params.GetScalabilityMode();
+  absl::optional<ScalabilityMode> scalability_mode =
+      stream_params.GetScalabilityMode2();
   // To support the full set of scalability modes in the event that this is the
   // only active encoding, prefer VideoCodec::GetScalabilityMode() if all other
   // encodings are inactive.
@@ -821,10 +823,12 @@ webrtc::VideoCodec SimulcastEncoderAdapter::MakeStreamCodec(
       }
     }
     if (only_active_stream) {
-      scalability_mode = codec.GetScalabilityMode().value();
+      scalability_mode = codec.GetScalabilityMode();
     }
   }
-  codec_params.SetScalabilityMode(scalability_mode);
+  if (scalability_mode.has_value()) {
+    codec_params.SetScalabilityMode(*scalability_mode);
+  }
   // Settings that are based on stream/resolution.
   if (is_lowest_quality_stream) {
     // Settings for lowest spatial resolutions.

video/video_stream_encoder.cc

@@ -1158,18 +1158,22 @@ void VideoStreamEncoder::ReconfigureEncoder() {
   rtc::SimpleStringBuilder log_stream(log_stream_buf);
   log_stream << "ReconfigureEncoder: simulcast streams: ";
   for (size_t i = 0; i < codec.numberOfSimulcastStreams; ++i) {
-    log_stream << "{" << i << ": " << codec.simulcastStream[i].width << "x"
-               << codec.simulcastStream[i].height << " "
-               << ScalabilityModeToString(
-                      codec.simulcastStream[i].GetScalabilityMode())
-               << ", min_kbps: " << codec.simulcastStream[i].minBitrate
-               << ", target_kbps: " << codec.simulcastStream[i].targetBitrate
-               << ", max_kbps: " << codec.simulcastStream[i].maxBitrate
-               << ", max_fps: " << codec.simulcastStream[i].maxFramerate
-               << ", max_qp: " << codec.simulcastStream[i].qpMax << ", num_tl: "
-               << codec.simulcastStream[i].numberOfTemporalLayers
-               << ", active: "
-               << (codec.simulcastStream[i].active ? "true" : "false") << "}";
+    absl::optional<ScalabilityMode> scalability_mode =
+        codec.simulcastStream[i].GetScalabilityMode2();
+    if (scalability_mode) {
+      log_stream << "{" << i << ": " << codec.simulcastStream[i].width << "x"
+                 << codec.simulcastStream[i].height << " "
+                 << ScalabilityModeToString(*scalability_mode)
+                 << ", min_kbps: " << codec.simulcastStream[i].minBitrate
+                 << ", target_kbps: " << codec.simulcastStream[i].targetBitrate
+                 << ", max_kbps: " << codec.simulcastStream[i].maxBitrate
+                 << ", max_fps: " << codec.simulcastStream[i].maxFramerate
+                 << ", max_qp: " << codec.simulcastStream[i].qpMax
+                 << ", num_tl: "
+                 << codec.simulcastStream[i].numberOfTemporalLayers
+                 << ", active: "
+                 << (codec.simulcastStream[i].active ? "true" : "false") << "}";
+    }
   }
   if (encoder_config_.codec_type == kVideoCodecVP9 ||
       encoder_config_.codec_type == kVideoCodecAV1) {