Add Opus audio library and configure FFmpeg to use it

Opus support was enabled in 2ddfd51810e0. This commit adds the Opus
library and configures FFmpeg to be compiled with Opus support.

NOTE: It may be required to run `cmake -U '*FFMPEG_LIBRARIES*' .` in
your Blender build directory in order to refresh the `FFMPEG_LIBRARIES`
setting and add libopus.

1 files changed, 35 insertions, 0 deletions

diff --git a/build_files/build_environment/cmake/opus.cmake b/build_files/build_environment/cmake/opus.cmake
new file mode 100644
index 00000000000..abaad94fa28
--- /dev/null
+++ b/build_files/build_environment/cmake/opus.cmake
@@ -0,0 +1,35 @@
+# ***** BEGIN GPL LICENSE BLOCK *****
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+#
+# ***** END GPL LICENSE BLOCK *****
+
+ExternalProject_Add(external_opus
+  URL ${OPUS_URI}
+  DOWNLOAD_DIR ${DOWNLOAD_DIR}
+  URL_HASH SHA256=${OPUS_HASH}
+  PREFIX ${BUILD_DIR}/opus
+  CONFIGURE_COMMAND ${CONFIGURE_ENV} && cd ${BUILD_DIR}/opus/src/external_opus/ && ${CONFIGURE_COMMAND} --prefix=${LIBDIR}/opus
+    --disable-shared
+    --enable-static
+    --with-pic
+  BUILD_COMMAND ${CONFIGURE_ENV} && cd ${BUILD_DIR}/opus/src/external_opus/ && make -j${MAKE_THREADS}
+  INSTALL_COMMAND ${CONFIGURE_ENV} && cd ${BUILD_DIR}/opus/src/external_opus/ && make install
+  INSTALL_DIR ${LIBDIR}/opus
+)
+
+if(MSVC)
+  set_target_properties(external_opus PROPERTIES FOLDER Mingw)
+endif()