AVcodec error when building

[da-the-dev]

Describe the bug
While building the app (step 3 in building instructions, section for Linux) I get an error described below

To Reproduce
Steps to reproduce the behavior:

1. Follow building instructions for Linux

Expected behavior
A successful installation of Audacium.

Additional information (please complete the following information):

• OS: Arch Linux x86_64

Additional context
Here's the important bit of the build log

[ 63%] Building CXX object src/CMakeFiles/Audacium.dir/ActiveProjects.cpp.o
In file included from /home/sv-cheats-1/audacium/src/AudacityApp.cpp:83:
/home/sv-cheats-1/audacium/src/FFmpeg.h:544:7: error: conflicting declaration of C function ‘AVCodec* avcodec_find_encoder(AVCodecID)’
  544 |       avcodec_find_encoder,
      |       ^~~~~~~~~~~~~~~~~~~~
/home/sv-cheats-1/audacium/src/FFmpeg.h:451:16: note: in definition of macro ‘FFMPEG_FUNCTION_WITH_RETURN’
  451 |       inline r n a                                                      \
      |                ^
In file included from /usr/include/libavcodec/avcodec.h:40,
                 from /home/sv-cheats-1/audacium/src/FFmpeg.h:48,
                 from /home/sv-cheats-1/audacium/src/AudacityApp.cpp:83:
/usr/include/libavcodec/codec.h:392:16: note: previous declaration ‘const AVCodec* avcodec_find_encoder(AVCodecID)’
  392 | const AVCodec *avcodec_find_encoder(enum AVCodecID id);
      |                ^~~~~~~~~~~~~~~~~~~~
In file included from /home/sv-cheats-1/audacium/src/AudacityApp.cpp:83:
/home/sv-cheats-1/audacium/src/FFmpeg.h:550:7: error: conflicting declaration of C function ‘AVCodec* avcodec_find_encoder_by_name(const char*)’
  550 |       avcodec_find_encoder_by_name,
      |       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/sv-cheats-1/audacium/src/FFmpeg.h:451:16: note: in definition of macro ‘FFMPEG_FUNCTION_WITH_RETURN’
  451 |       inline r n a                                                      \
      |                ^
In file included from /usr/include/libavcodec/avcodec.h:40,
                 from /home/sv-cheats-1/audacium/src/FFmpeg.h:48,
                 from /home/sv-cheats-1/audacium/src/AudacityApp.cpp:83:
/usr/include/libavcodec/codec.h:400:16: note: previous declaration ‘const AVCodec* avcodec_find_encoder_by_name(const char*)’
  400 | const AVCodec *avcodec_find_encoder_by_name(const char *name);
      |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /home/sv-cheats-1/audacium/src/AudacityApp.cpp:83:
/home/sv-cheats-1/audacium/src/FFmpeg.h:556:7: error: conflicting declaration of C function ‘AVCodec* avcodec_find_decoder(AVCodecID)’
  556 |       avcodec_find_decoder,
      |       ^~~~~~~~~~~~~~~~~~~~
/home/sv-cheats-1/audacium/src/FFmpeg.h:451:16: note: in definition of macro ‘FFMPEG_FUNCTION_WITH_RETURN’
  451 |       inline r n a                                                      \
      |                ^
In file included from /usr/include/libavcodec/avcodec.h:40,
                 from /home/sv-cheats-1/audacium/src/FFmpeg.h:48,
                 from /home/sv-cheats-1/audacium/src/AudacityApp.cpp:83:
/usr/include/libavcodec/codec.h:376:16: note: previous declaration ‘const AVCodec* avcodec_find_decoder(AVCodecID)’
  376 | const AVCodec *avcodec_find_decoder(enum AVCodecID id);
      |                ^~~~~~~~~~~~~~~~~~~~
In file included from /home/sv-cheats-1/audacium/src/AudacityApp.cpp:83:
/home/sv-cheats-1/audacium/src/FFmpeg.h:634:7: error: conflicting declaration of C function ‘int avformat_open_input(AVFormatContext**, const char*, AVInputFormat*, AVDictionary**)’
  634 |       avformat_open_input,
      |       ^~~~~~~~~~~~~~~~~~~
/home/sv-cheats-1/audacium/src/FFmpeg.h:451:16: note: in definition of macro ‘FFMPEG_FUNCTION_WITH_RETURN’
  451 |       inline r n a                                                      \
      |                ^
In file included from /home/sv-cheats-1/audacium/src/FFmpeg.h:49,
                 from /home/sv-cheats-1/audacium/src/AudacityApp.cpp:83:
/usr/include/libavformat/avformat.h:2097:5: note: previous declaration ‘int avformat_open_input(AVFormatContext**, const char*, const AVInputFormat*, AVDictionary**)’
 2097 | int avformat_open_input(AVFormatContext **ps, const char *url,
      |     ^~~~~~~~~~~~~~~~~~~
In file included from /home/sv-cheats-1/audacium/src/AudacityApp.cpp:83:
/home/sv-cheats-1/audacium/src/FFmpeg.h:716:7: error: conflicting declaration of C function ‘AVOutputFormat* av_guess_format(const char*, const char*, const char*)’
  716 |       av_guess_format,
      |       ^~~~~~~~~~~~~~~
/home/sv-cheats-1/audacium/src/FFmpeg.h:451:16: note: in definition of macro ‘FFMPEG_FUNCTION_WITH_RETURN’
  451 |       inline r n a                                                      \
      |                ^
In file included from /home/sv-cheats-1/audacium/src/FFmpeg.h:49,
                 from /home/sv-cheats-1/audacium/src/AudacityApp.cpp:83:
/usr/include/libavformat/avformat.h:2480:23: note: previous declaration ‘const AVOutputFormat* av_guess_format(const char*, const char*, const char*)’
 2480 | const AVOutputFormat *av_guess_format(const char *short_name,
      |                       ^~~~~~~~~~~~~~~
In file included from /home/sv-cheats-1/audacium/src/AudacityApp.cpp:83:
/home/sv-cheats-1/audacium/src/FFmpeg.h: In constructor ‘AVPacketEx::AVPacketEx()’:
/home/sv-cheats-1/audacium/src/FFmpeg.h:887:21: warning: ‘void av_init_packet(AVPacket*)’ is deprecated [-Wdeprecated-declarations]
  887 |       av_init_packet(this);
      |       ~~~~~~~~~~~~~~^~~~~~
/home/sv-cheats-1/audacium/src/FFmpeg.h:738:7: note: declared here
  738 |       av_init_packet,
      |       ^~~~~~~~~~~~~~
/home/sv-cheats-1/audacium/src/FFmpeg.h:461:19: note: in definition of macro ‘FFMPEG_FUNCTION_NO_RETURN’
  461 |       inline void n a                                                   \
      |                   ^
/home/sv-cheats-1/audacium/src/FFmpeg.h: In member function ‘void AVPacketEx::steal(AVPacketEx&&)’:
/home/sv-cheats-1/audacium/src/FFmpeg.h:921:21: warning: ‘void av_init_packet(AVPacket*)’ is deprecated [-Wdeprecated-declarations]
  921 |       av_init_packet(&that);
      |       ~~~~~~~~~~~~~~^~~~~~~
/home/sv-cheats-1/audacium/src/FFmpeg.h:738:7: note: declared here
  738 |       av_init_packet,
      |       ^~~~~~~~~~~~~~
/home/sv-cheats-1/audacium/src/FFmpeg.h:461:19: note: in definition of macro ‘FFMPEG_FUNCTION_NO_RETURN’
  461 |       inline void n a                                                   \
      |                   ^
[ 63%] Building CXX object src/CMakeFiles/Audacium.dir/AutoRecoveryDialog.cpp.o
[ 63%] Building CXX object src/CMakeFiles/Audacium.dir/BatchCommandDialog.cpp.o
[ 63%] Building CXX object src/CMakeFiles/Audacium.dir/BatchCommands.cpp.o
[ 63%] Building CXX object src/CMakeFiles/Audacium.dir/BatchProcessDialog.cpp.o
[ 63%] Building CXX object src/CMakeFiles/Audacium.dir/Benchmark.cpp.o
[ 63%] Building CXX object src/CMakeFiles/Audacium.dir/CellularPanel.cpp.o
[ 63%] Building CXX object src/CMakeFiles/Audacium.dir/Clipboard.cpp.o
[ 64%] Building CXX object src/CMakeFiles/Audacium.dir/CommonCommandFlags.cpp.o
[ 64%] Building CXX object src/CMakeFiles/Audacium.dir/DBConnection.cpp.o
make[2]: *** [src/CMakeFiles/Audacium.dir/build.make:173: src/CMakeFiles/Audacium.dir/AudacityApp.cpp.o] Error 1
make[2]: *** Waiting for unfinished jobs....
make[1]: *** [CMakeFiles/Makefile2:1259: src/CMakeFiles/Audacium.dir/all] Error 2
make: *** [Makefile:156: all] Error 2