Instructions to build universal FFmpeg XCFrameworks from source.
These binaries can run on both Intel x86_64 and arm64 (i.e. Apple Silicon) architectures.

NOTE - Pay attention to licensing requirements / considerations if / when distributing these libraries.

Pre-requisites (need to be installed on this system):

1 - Xcode 15.2 or a later version. macOS SDK version must be 11.0 or greater (for arm64).
2 - Homebrew (Instructions here: https://brew.sh/)
3 - nasm - assembler for x86 (Run "brew install nasm" ... after installing Homebrew)
4 - clang - C compiler (Run "xcode-select --install")
5 - pkg-config (Run "brew install pkg-config")

Steps:

1 - Open a terminal window.

2 - cd to the directory containing this README.txt file (and the FFmpeg build script and source code archive). This step is important. The build script will assume that you have done this and will not work otherwise.

3 - Run "./build-ffmpeg.sh" and wait till it is finished executing.

4 - The newly built FFmpeg XCFrameworks will be in the subdirectory "xcframeworks". There should be 4 of them:

    1 - libavcodec.xcframework
    2 - libavformat.xcframework
    3 - libavutil.xcframework
    4 - libswresample.xcframework
    
5 - (Optional) Using the lipo command, verify that the dylibs inside the XCFrameworks are indeed universal, supporting both x86_64 and arm64 architectures.

    Example command:    "lipo -info xcframeworks/libavcodec.xcframework/macos-arm64_x86_64/libavcodec.61.dylib"
    Example output:     "Architectures in the fat file: xcframeworks/libavcodec.xcframework/macos-arm64_x86_64/libavcodec.61.dylib are: x86_64 arm64"
    
6 - Copy (and replace if necessary) the XCFrameworks into the "Frameworks" group in the Aural Xcode project.
