Add master to ffmpeg binary builds (#3722)

.github/scripts/ffmpeg/build.sh

@@ -22,7 +22,11 @@ if [[ "$OSTYPE" == "msys" ]]; then
 fi
 ffmpeg_version="${FFMPEG_VERSION:-4.1.8}"
 
-archive="https://github.com/FFmpeg/FFmpeg/archive/refs/tags/n${ffmpeg_version}.tar.gz"
+if [[ "${ffmpeg_version}" == "master" ]]; then
+    archive="https://github.com/FFmpeg/FFmpeg/archive/master.tar.gz"
+else
+    archive="https://github.com/FFmpeg/FFmpeg/archive/refs/tags/n${ffmpeg_version}.tar.gz"
+fi
 
 build_dir=$(mktemp -d -t ffmpeg-build.XXXXXXXXXX)
 cleanup() {
@@ -88,7 +92,7 @@ if [[ "$(uname)" == Darwin ]]; then
         avformat=libavformat.59
         avdevice=libavdevice.59
         avfilter=libavfilter.8
-    elif [[ ${major_ver} == 6 ]]; then
+    elif [[ ${ffmpeg_version} == master || ${major_ver} == 6 ]]; then
         avutil=libavutil.58
         avcodec=libavcodec.60
         avformat=libavformat.60

.github/workflows/ffmpeg.yml

@@ -17,7 +17,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ffmpeg_version: ["4.4.4", "5.1.4", "6.1.1"]
+        ffmpeg_version: ["4.4.4", "5.1.4", "6.1.1", "master"]
     uses: pytorch/test-infra/.github/workflows/linux_job.yml@main
     with:
       job-name: Build
@@ -38,7 +38,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ffmpeg_version: ["4.4.4", "5.1.4", "6.1.1"]
+        ffmpeg_version: ["4.4.4", "5.1.4", "6.1.1", "master"]
     uses: pytorch/test-infra/.github/workflows/linux_job.yml@main
     with:
       job-name: Build
@@ -61,7 +61,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ffmpeg_version: ["4.4.4", "5.1.4", "6.1.1"]
+        ffmpeg_version: ["4.4.4", "5.1.4", "6.1.1", "master"]
         runner: ["macos-m1-12", "macos-12"]
     uses: pytorch/test-infra/.github/workflows/macos_job.yml@main
     with:
@@ -84,7 +84,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ffmpeg_version: ["4.4.4", "5.1.4", "6.1.1"]
+        ffmpeg_version: ["4.4.4", "5.1.4", "6.1.1", "master"]
     uses: pytorch/test-infra/.github/workflows/windows_job.yml@main
     with:
       job-name: Build