add ffmpeg action to build an universal package

.github/workflows/ffmpeg.yml

@@ -0,0 +1,52 @@
+name: ffmpeg-build
+concurrency: 
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+on: 
+  workflow_dispatch:
+
+jobs:
+  build:
+    name: Build
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [macos-12]
+       
+    steps:
+      # macos 11.0 默认环境变了,要指定
+      - name: prepare env
+        if: ${{ matrix.os == 'macos-11' }}
+        run: |
+          softwareupdate --all --install --force
+          sudo xcode-select --print-path
+          sudo xcode-select --switch /Library/Developer/CommandLineTools             
+       
+      - name: build ffmpeg
+        run: |
+          mkdir build
+         
+          brew install autoconf automake libtool
+          brew install nasm
+          export VCPKG_OSX_ARCHITECTURES="x86_64 arm64"
+          vcpkg install ffmpeg[core,avcodec,avformat,mp3lame,opus,speex,swresample,vorbis,fdk-aac,gpl]:arm64-osx-dynamic --x-install-root=build
+          vcpkg install ffmpeg[core,avcodec,avformat,mp3lame,opus,speex,swresample,vorbis,fdk-aac,gpl]:x64-osx-dynamic --x-install-root=build
+          ls -al build/arm64-osx-dynamic/lib
+          ls -al build/
+          lipo -info build/arm64-osx-dynamic/lib/libavco*
+
+          cd build
+          lipo -create -output libavcodec.dylib arm64-osx-dynamic/lib/libavcodec.dylib x64-osx-dynamic/lib/libavcodec.dylib
+          lipo -create -output libspeex.dylib arm64-osx-dynamic/lib/libspeex.dylib x64-osx-dynamic/lib/libspeex.dylib
+          lipo -detailed_info libavcodec.dylib
+          lipo -detailed_info libspeex.dylib
+
+      - uses: actions/upload-artifact@v2
+        with:
+          name: build
+          path: build/*
+
+      - uses: actions/upload-artifact@v2
+        with:
+          name: build-lipo
+          path: build/*.dylib