Patch libvpx with RTC rate control added.

We have to patch libvpx here instead of enabling this in OWT SDK since
some of the referenced libvpx headers are referencing internal libvpx headers
in the format of relative path.

Author: taste1981

scripts/prepare_dev.py

@@ -18,6 +18,8 @@
 THIRD_PARTY_PATH = os.path.join(HOME_PATH, 'third_party')
 LIBSRTP_PATH = os.path.join(THIRD_PARTY_PATH, 'libsrtp')
 FFMPEG_PATH = os.path.join(THIRD_PARTY_PATH, 'ffmpeg')
+LIBVPX_PATH = os.path.join(THIRD_PARTY_PATH, 'libvpx')
+LIBVPX_SOURCE_PATH = os.path.join(LIBVPX_PATH, 'source/libvpx')
 WEBRTC_OVERRIDES_PATH = os.path.join(THIRD_PARTY_PATH, 'webrtc_overrides')
 BUILD_PATH = os.path.join(HOME_PATH, 'build')
 CONFIG_PATH = os.path.join(BUILD_PATH, 'config')
@@ -43,6 +45,8 @@
     ('0014-Fix-missing-ffmpeg-configure-item-for-msvc-build.patch', FFMPEG_PATH),
     ('0015-Remove-custom-d8-dependency.patch', BUILD_PATH),
     ('0016-Remove-deprecated-create_srcjar-property.patch', THIRD_PARTY_PATH)
+    ('0015-vp9-add-rate-control-interface-for-RTC.patch', LIBVPX_SOURCE_PATH),
+    ('0016-Build-libvpx-with-RTC-rate-control-impl-included.patch', LIBVPX_PATH) 
 ]
 
 def _patch(ignoreFailures=False):

talk/owt/BUILD.gn

@@ -4,6 +4,27 @@
 
 import("//build_overrides/webrtc.gni")
 import("//testing/test.gni")
+
+# Introduced for using libvpx config files. We only enable libvpx rate
+# controller for VP9 on Windows.
+if (is_win) {
+  os_category = current_os
+
+  if (current_cpu == "x86") {
+    cpu_arch_full = "ia32"
+  } else if (current_cpu == "x64") {
+    cpu_arch_full = "x64"
+  } else if (current_cpu == "arm") {
+    if (arm_use_neon) {
+      cpu_arch_full = "arm-neon"
+    } else if (is_android) {
+      cpu_arch_full = "arm-neon-cpu-detect"
+    } else {
+      cpu_arch_full = "arm"
+    }
+  }
+}
+
 if (is_android) {
   import("//build/config/android/config.gni")
   import("//build/config/android/rules.gni")
@@ -208,9 +229,19 @@ static_library("owt_sdk_base") {
       "sdk/base/win/sysmem_allocator.h",
       "sdk/base/win/videorendererwin.cc",
       "sdk/base/win/videorendererwin.h",
+      "sdk/base/win/vp9ratecontrol.cc",
+      "sdk/base/win/vp9ratecontrol.h",
+      #"sdk/base/win/vp9temporallayers.cc",
+      #"sdk/base/win/vp9temporallayers.h",
       "sdk/base/windowcapturer.cc",
     ]
     public_deps += [ "//third_party/webrtc/modules/audio_device:audio_device_module_from_input_and_output" ]
+    public_deps += [ "//third_party/libvpx" ]
+    include_dirs += [
+      "//third_party/libvpx/source/config",
+      "//third_party/libvpx/source/config/$os_category/$cpu_arch_full",
+      "//third_party/libvpx/source/libvpx",
+    ]
   }
   if (is_linux) {
     if (owt_msdk_header_root != "") {