Compilation fails on 3.0.0 if ffmpeg disabled

Looks like if compiling with

 -Daudacity_use_ffmpeg:STRING=off

results in a compilation failure.


[1/142] cd /backup/obj/usr/ports/audio/audacity3/work/audacity-minsrc-3.0.0
&& /usr/local/bin/cmake -D GIT=/usr/local/bin/git -D
_PRVDIR=/backup/obj/usr/ports/audio/audacity3/work/.build/src/private
-P /backup/obj/usr/ports/audio/audacity3/work/audacity-minsrc-3.0.0/cmake-proxies/cmake-modules/Version.cmake
[2/142] /usr/bin/c++ -DAudacity_EXPORTS -DBUILDING_AUDACITY -DCMAKE
-DHAVE_LRINT -DHAVE_LRINTF -DHAVE_MLOCK -DWXINTL_NO_GETTEXT_MACRO
-DWXUSINGDLL -D_FILE_OFFSET_BITS=64 -D_THREAD_SAFE -D__WXGTK__
-Isrc/private -I/backup/obj/usr/ports/audio/audacity3/work/audacity-minsrc-3.0.0/include
-I/backup/obj/usr/ports/audio/audacity3/work/audacity-minsrc-3.0.0/src
-I/usr/local/lib/wx/include/gtk3-unicode-3.1
-I/usr/local/include/wx-3.1
-I/backup/obj/usr/ports/audio/audacity3/work/audacity-minsrc-3.0.0/lib-src/lame
-I/backup/obj/usr/ports/audio/audacity3/work/audacity-minsrc-3.0.0/lib-src/portsmf/include
-I/backup/obj/usr/ports/audio/audacity3/work/audacity-minsrc-3.0.0/lib-src/libnyquist
-I/backup/obj/usr/ports/audio/audacity3/work/audacity-minsrc-3.0.0/lib-src/portmixer/include
-I/backup/obj/usr/ports/audio/audacity3/work/audacity-minsrc-3.0.0/lib-src/libsbsms/include
-isystem /usr/local/include -isystem /usr/local/include/opus -isystem
/usr/local/include/soundtouch -isystem /usr/local/include/glib-2.0
-isystem /usr/local/lib/glib-2.0/include -isystem
/usr/local/include/gtk-3.0 -isystem /usr/local/include/pango-1.0
-isystem /usr/local/include/fribidi -isystem /usr/local/include/cairo
-isystem /usr/local/include/pixman-1 -isystem
/usr/local/include/freetype2 -isystem /usr/local/include/libdrm
-isystem /usr/local/include/libpng16 -isystem
/usr/local/include/harfbuzz -isystem /usr/local/include/gdk-pixbuf-2.0
-isystem /usr/local/include/gio-unix-2.0 -isystem
/usr/local/include/libepoll-shim -isystem /usr/local/include/atk-1.0
-isystem /usr/local/include/at-spi2-atk/2.0 -isystem
/usr/local/include/dbus-1.0 -isystem /usr/local/lib/dbus-1.0/include
-isystem /usr/local/include/at-spi-2.0 -O2 -pipe -march=westmere
-fstack-protector-strong -fno-strict-aliasing -O2 -pipe
-march=westmere -fstack-protector-strong -fno-strict-aliasing
-Wno-underaligned-exception-object -Werror=return-type
-Werror=dangling-else -Werror=return-stack-address -D_THREAD_SAFE
-pthread -std=gnu++14 -MD -MT
src/CMakeFiles/Audacity.dir/import/Import.cpp.o -MF
src/CMakeFiles/Audacity.dir/import/Import.cpp.o.d -o
src/CMakeFiles/Audacity.dir/import/Import.cpp.o -c
/backup/obj/usr/ports/audio/audacity3/work/audacity-minsrc-3.0.0/src/import/Import.cpp
FAILED: src/CMakeFiles/Audacity.dir/import/Import.cpp.o
/usr/bin/c++ -DAudacity_EXPORTS -DBUILDING_AUDACITY -DCMAKE
-DHAVE_LRINT -DHAVE_LRINTF -DHAVE_MLOCK -DWXINTL_NO_GETTEXT_MACRO
-DWXUSINGDLL -D_FILE_OFFSET_BITS=64 -D_THREAD_SAFE -D__WXGTK__
-Isrc/private -I/backup/obj/usr/ports/audio/audacity3/work/audacity-minsrc-3.0.0/include
-I/backup/obj/usr/ports/audio/audacity3/work/audacity-minsrc-3.0.0/src
-I/usr/local/lib/wx/include/gtk3-unicode-3.1
-I/usr/local/include/wx-3.1
-I/backup/obj/usr/ports/audio/audacity3/work/audacity-minsrc-3.0.0/lib-src/lame
-I/backup/obj/usr/ports/audio/audacity3/work/audacity-minsrc-3.0.0/lib-src/portsmf/include
-I/backup/obj/usr/ports/audio/audacity3/work/audacity-minsrc-3.0.0/lib-src/libnyquist
-I/backup/obj/usr/ports/audio/audacity3/work/audacity-minsrc-3.0.0/lib-src/portmixer/include
-I/backup/obj/usr/ports/audio/audacity3/work/audacity-minsrc-3.0.0/lib-src/libsbsms/include
-isystem /usr/local/include -isystem /usr/local/include/opus -isystem
/usr/local/include/soundtouch -isystem /usr/local/include/glib-2.0
-isystem /usr/local/lib/glib-2.0/include -isystem
/usr/local/include/gtk-3.0 -isystem /usr/local/include/pango-1.0
-isystem /usr/local/include/fribidi -isystem /usr/local/include/cairo
-isystem /usr/local/include/pixman-1 -isystem
/usr/local/include/freetype2 -isystem /usr/local/include/libdrm
-isystem /usr/local/include/libpng16 -isystem
/usr/local/include/harfbuzz -isystem /usr/local/include/gdk-pixbuf-2.0
-isystem /usr/local/include/gio-unix-2.0 -isystem
/usr/local/include/libepoll-shim -isystem /usr/local/include/atk-1.0
-isystem /usr/local/include/at-spi2-atk/2.0 -isystem
/usr/local/include/dbus-1.0 -isystem /usr/local/lib/dbus-1.0/include
-isystem /usr/local/include/at-spi-2.0 -O2 -pipe -march=westmere
-fstack-protector-strong -fno-strict-aliasing -O2 -pipe
-march=westmere -fstack-protector-strong -fno-strict-aliasing
-Wno-underaligned-exception-object -Werror=return-type
-Werror=dangling-else -Werror=return-stack-address -D_THREAD_SAFE
-pthread -std=gnu++14 -MD -MT
src/CMakeFiles/Audacity.dir/import/Import.cpp.o -MF
src/CMakeFiles/Audacity.dir/import/Import.cpp.o.d -o
src/CMakeFiles/Audacity.dir/import/Import.cpp.o -c
/backup/obj/usr/ports/audio/audacity3/work/audacity-minsrc-3.0.0/src/import/Import.cpp
/backup/obj/usr/ports/audio/audacity3/work/audacity-minsrc-3.0.0/src/import/Import.cpp:806:20:
error: use of undeclared identifier 'FFmpegLibsInst'
                  !FFmpegLibsInst()
                   ^
1 error generated.
ninja: build stopped: subcommand failed.
*** Error code 1

Stop.