Move VP8 SupportsScalabilityMode utility to its own build target

Intended to let Vp8TemporalLayersFactory (an api/ target) reuse
this function, without depending on the codec implementation, and
without introducing a dependency cycle with the webrtc_vp8 build
target.

Bug: webrtc:11607
Change-Id: I671422e994e1005da8c7d768e8dd8ff795553e51
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/261308
Commit-Queue: Niels Moller <nisse@webrtc.org>
Reviewed-by: Åsa Persson <asapersson@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#36816}

api/video_codecs/BUILD.gn

@@ -136,7 +136,10 @@ rtc_source_set("video_encoder_factory_template_libvpx_vp8_adapter") {
   allow_poison = [ "software_video_codecs" ]
   public = [ "video_encoder_factory_template_libvpx_vp8_adapter.h" ]
 
-  deps = [ "../../modules/video_coding:webrtc_vp8" ]
+  deps = [
+    "../../modules/video_coding:webrtc_vp8",
+    "../../modules/video_coding:webrtc_vp8_scalability",
+  ]
 }
 
 rtc_source_set("video_encoder_factory_template_libvpx_vp9_adapter") {

api/video_codecs/video_encoder_factory_template_libvpx_vp8_adapter.h

@@ -15,6 +15,7 @@
 #include <vector>
 
 #include "modules/video_coding/codecs/vp8/include/vp8.h"
+#include "modules/video_coding/codecs/vp8/vp8_scalability.h"
 
 namespace webrtc {
 struct LibvpxVp8EncoderTemplateAdapter {
@@ -28,7 +29,7 @@ struct LibvpxVp8EncoderTemplateAdapter {
   }
 
   static bool IsScalabilityModeSupported(ScalabilityMode scalability_mode) {
-    return VP8Encoder::SupportsScalabilityMode(scalability_mode);
+    return VP8SupportsScalabilityMode(scalability_mode);
   }
 };
 }  // namespace webrtc

media/BUILD.gn

@@ -214,6 +214,7 @@ rtc_library("rtc_internal_video_codecs") {
     "../modules/video_coding:webrtc_h264",
     "../modules/video_coding:webrtc_multiplex",
     "../modules/video_coding:webrtc_vp8",
+    "../modules/video_coding:webrtc_vp8_scalability",
     "../modules/video_coding:webrtc_vp9",
     "../modules/video_coding/codecs/av1:av1_svc_config",
     "../modules/video_coding/codecs/av1:libaom_av1_decoder",

media/engine/internal_encoder_factory.cc

@@ -20,6 +20,7 @@
 #include "modules/video_coding/codecs/av1/libaom_av1_encoder_supported.h"
 #include "modules/video_coding/codecs/h264/include/h264.h"
 #include "modules/video_coding/codecs/vp8/include/vp8.h"
+#include "modules/video_coding/codecs/vp8/vp8_scalability.h"
 #include "modules/video_coding/codecs/vp9/include/vp9.h"
 #include "modules/video_coding/svc/scalability_mode_util.h"
 #include "rtc_base/logging.h"
@@ -73,7 +74,7 @@ VideoEncoderFactory::CodecSupport InternalEncoderFactory::QueryCodecSupport(
       return kUnsupported;
     }
     if (absl::EqualsIgnoreCase(format.name, cricket::kVp8CodecName)) {
-      if (!VP8Encoder::SupportsScalabilityMode(*scalability_mode)) {
+      if (!VP8SupportsScalabilityMode(*scalability_mode)) {
         return kUnsupported;
       }
     } else if (absl::EqualsIgnoreCase(format.name, cricket::kVp9CodecName)) {

modules/video_coding/BUILD.gn

@@ -662,7 +662,6 @@ rtc_library("webrtc_vp8") {
     "../../api/video:encoded_image",
     "../../api/video:video_frame",
     "../../api/video:video_rtp_headers",
-    "../../api/video_codecs:scalability_mode",
     "../../api/video_codecs:video_codecs_api",
     "../../api/video_codecs:vp8_temporal_layers_factory",
     "../../common_video",
@@ -689,6 +688,14 @@ rtc_library("webrtc_vp8") {
   }
 }
 
+rtc_source_set("webrtc_vp8_scalability") {
+  sources = [
+    "codecs/vp8/vp8_scalability.cc",
+    "codecs/vp8/vp8_scalability.h",
+  ]
+  deps = [ "../../api/video_codecs:scalability_mode" ]
+}
+
 rtc_library("webrtc_vp8_temporal_layers") {
   visibility = [ "*" ]
   sources = [

modules/video_coding/codecs/vp8/include/vp8.h

@@ -15,7 +15,6 @@
 #include <vector>
 
 #include "absl/base/attributes.h"
-#include "api/video_codecs/scalability_mode.h"
 #include "api/video_codecs/video_encoder.h"
 #include "api/video_codecs/vp8_frame_buffer_controller.h"
 #include "modules/video_coding/include/video_codec_interface.h"
@@ -40,7 +39,6 @@ class VP8Encoder {
 
   static std::unique_ptr<VideoEncoder> Create();
   static std::unique_ptr<VideoEncoder> Create(Settings settings);
-  static bool SupportsScalabilityMode(ScalabilityMode scalability_mode);
 
   ABSL_DEPRECATED("")
   static std::unique_ptr<VideoEncoder> Create(

modules/video_coding/codecs/vp8/libvpx_vp8_encoder.cc

@@ -49,9 +49,6 @@ constexpr char kVP8IosMaxNumberOfThreadFieldTrial[] =
 constexpr char kVP8IosMaxNumberOfThreadFieldTrialParameter[] = "max_thread";
 #endif
 
-constexpr ScalabilityMode kSupportedScalabilityModes[] = {
-    ScalabilityMode::kL1T1, ScalabilityMode::kL1T2, ScalabilityMode::kL1T3};
-
 constexpr char kVp8ForcePartitionResilience[] =
     "WebRTC-VP8-ForcePartitionResilience";
 
@@ -233,15 +230,6 @@ std::unique_ptr<VideoEncoder> VP8Encoder::Create(
                                             std::move(settings));
 }
 
-bool VP8Encoder::SupportsScalabilityMode(ScalabilityMode scalability_mode) {
-  for (const auto& entry : kSupportedScalabilityModes) {
-    if (entry == scalability_mode) {
-      return true;
-    }
-  }
-  return false;
-}
-
 vpx_enc_frame_flags_t LibvpxVp8Encoder::EncodeFlags(
     const Vp8FrameConfig& references) {
   RTC_DCHECK(!references.drop_frame);

modules/video_coding/codecs/vp8/vp8_scalability.cc

@@ -0,0 +1,26 @@
+/*
+ *  Copyright (c) 2022 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 "modules/video_coding/codecs/vp8/vp8_scalability.h"
+
+namespace webrtc {
+
+bool VP8SupportsScalabilityMode(ScalabilityMode scalability_mode) {
+  constexpr ScalabilityMode kSupportedScalabilityModes[] = {
+      ScalabilityMode::kL1T1, ScalabilityMode::kL1T2, ScalabilityMode::kL1T3};
+  for (const auto& entry : kSupportedScalabilityModes) {
+    if (entry == scalability_mode) {
+      return true;
+    }
+  }
+  return false;
+}
+
+}  // namespace webrtc

modules/video_coding/codecs/vp8/vp8_scalability.h

@@ -0,0 +1,22 @@
+/*
+ *  Copyright (c) 2022 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.
+ */
+
+#ifndef MODULES_VIDEO_CODING_CODECS_VP8_VP8_SCALABILITY_H_
+#define MODULES_VIDEO_CODING_CODECS_VP8_VP8_SCALABILITY_H_
+
+#include "api/video_codecs/scalability_mode.h"
+
+namespace webrtc {
+
+bool VP8SupportsScalabilityMode(ScalabilityMode scalability_mode);
+
+}  // namespace webrtc
+
+#endif  // MODULES_VIDEO_CODING_CODECS_VP8_VP8_SCALABILITY_H_