diff --git a/.github/workflows/build_gpl.yml b/.github/workflows/build_gpl.yml
index 570f0d5..077a36a 100644
--- a/.github/workflows/build_gpl.yml
+++ b/.github/workflows/build_gpl.yml
@@ -10,7 +10,7 @@ env:
 #  GITHUB_ENV: https://docs.github.com/en/actions/learn-github-actions/environment-variables#about-environment-variables
   FF_VERSION: ${{ vars.FF_VER }} # TODO: latest release if triggered by schedule
   LLVM_VER: ${{ vars.LLVM_VER }}
-  LLVM_VER_DEFAULT: 18
+  LLVM_VER_DEFAULT: 19
   NINJA_STATUS: '[%f/%t %e %r]'
   SF_PW_MAPPED: ${{ secrets.SF_PW }}
   SF_USER_MAPPED: ${{ secrets.SF_USER }}
diff --git a/README.md b/README.md
index 031a66d..2f1706e 100644
--- a/README.md
+++ b/README.md
@@ -19,7 +19,7 @@ Linux, android, macOS, iOS, raspberry pi(legacy OSes), windows build:**[![Build
 
 ## Features
 
-- [Support single FFmpeg shared library](tools/mklibffmpeg.sh): ffmpeg.dll, libffmpeg.so, libffmpeg.dylib
+- [Support single FFmpeg shared library](tools/mklibffmpeg.sh): ffmpeg.dll, libffmpeg.so, libffmpeg.dylib, [FFmpeg.framework](tools/dylib2framework.sh)
 - modern toolchain support: clang+lld, cross build for almost all platforms on any host OS
 - multiple targets build and configure simultaneously
 - ssl
@@ -45,5 +45,18 @@ Linux, android, macOS, iOS, raspberry pi(legacy OSes), windows build:**[![Build
 - ?: in plan
 - Empty: won't support
 
+## Fork and Custom Build by Github Actions
+You can request to add your configuration. If not accepted, customize yourself and build by github actions
+- Fork the repo
+- Set actions variables used by workflows in github repo settings
+    - FF_VER: `master`, or version, e.g. `7.0`, `6.1`
+    - LINUX_SYSROOT_ID: any characters, used to update sysroot cache
+    - LLVM_VER: llvm version, e.g. `20`, used by linux and windows build. Available versions can be found in https://apt.llvm.org
+    - VCVER: [msvcrt](https://sourceforge.net/projects/avbuild/files/dep/msvcrt-dev.7z/download) version, e.g. `14.28.29333`. used by windows clang build
+    - WINSDKVER: [windows sdk](https://sourceforge.net/projects/avbuild/files/dep/winsdk.7z/download) version, e.g. `10.0.22621.0`. used by windows clang build
+    - VC_LTL_VER: VC-LTL5 version, e.g. `5.1.1`. used by windows build with LTL
+- Edit workflow files(build.yml, build_gpl.yml). Remove unused jobs, e.g. sourceforge upload
+- Download ffmpeg binaries from workflow artifacts
+
 ## TODO
 - Azure pipeline/github action: vs2022+WSL