ci: update Linux build image to Ubuntu 20.04

.github/workflows/build-linux-image.yml

@@ -26,8 +26,9 @@ concurrency:
   cancel-in-progress: true
 
 env:
-  IMAGE_NAME: crossdesk/ubuntu22.04
+  IMAGE_NAME: crossdesk/ubuntu20.04
-  STACK_TAG: buildenv-cuda12.6.3-xmake3.0.9-rust1.92.0
+  STACK_TAG: buildenv-cuda12.6.3-gcc10-cmake3.31.6-pipewire0.3.48-xmake3.0.9-rust1.92.0
+  CMAKE_VERSION: 3.31.6
   XMAKE_VERSION: 3.0.9
   RUST_VERSION: 1.92.0
   RUSTUP_VERSION: 1.28.2
@@ -44,11 +45,11 @@ jobs:
           - arch: amd64
             platform: linux/amd64
             runner: ubuntu-24.04
-            base_image: nvidia/cuda:12.6.3-devel-ubuntu22.04
+            base_image: nvidia/cuda:12.6.3-devel-ubuntu20.04
           - arch: arm64
             platform: linux/arm64
             runner: ubuntu-24.04-arm
-            base_image: ubuntu:22.04
+            base_image: ubuntu:20.04
     steps:
       - name: Set candidate tag
         id: image
@@ -86,6 +87,7 @@ jobs:
           sbom: false
           build-args: |
             BASE_IMAGE=${{ matrix.base_image }}
+            CMAKE_VERSION=${{ env.CMAKE_VERSION }}
             XMAKE_VERSION=${{ env.XMAKE_VERSION }}
             RUST_VERSION=${{ env.RUST_VERSION }}
             RUSTUP_VERSION=${{ env.RUSTUP_VERSION }}

.github/workflows/build.yml

@@ -29,12 +29,12 @@ jobs:
         include:
           - arch: amd64
             runner: ubuntu-24.04
-            image: crossdesk/ubuntu22.04:buildenv-cuda12.6.3-xmake3.0.9-rust1.92.0
+            image: crossdesk/ubuntu20.04:buildenv-cuda12.6.3-gcc10-cmake3.31.6-pipewire0.3.48-xmake3.0.9-rust1.92.0
             package_script: ./scripts/linux/pkg_amd64.sh
 
           - arch: arm64
             runner: ubuntu-24.04-arm
-            image: crossdesk/ubuntu22.04:buildenv-cuda12.6.3-xmake3.0.9-rust1.92.0
+            image: crossdesk/ubuntu20.04:buildenv-cuda12.6.3-gcc10-cmake3.31.6-pipewire0.3.48-xmake3.0.9-rust1.92.0
             package_script: ./scripts/linux/pkg_arm64.sh
 
     container:
@@ -106,26 +106,30 @@ jobs:
       - name: Ensure Wayland build dependencies
         shell: bash
         run: |
-          if pkg-config --exists dbus-1 libdrm libpipewire-0.3 libspa-0.2; then
+          if pkg-config --exists dbus-1 libdrm && \
+             test -f /opt/crossdesk-pipewire-sdk/include/pipewire-0.3/pipewire/pipewire.h && \
+             test -f /opt/crossdesk-pipewire-sdk/include/spa-0.2/spa/param/video/format-utils.h; then
             exit 0
           fi
 
           apt-get update
           apt-get install -y --no-install-recommends \
             libdbus-1-dev \
-            libdrm-dev \
+            libdrm-dev
-            libpipewire-0.3-dev \
-            libspa-0.2-dev
           rm -rf /var/lib/apt/lists/*
 
-          pkg-config --exists dbus-1 libdrm libpipewire-0.3 libspa-0.2
+          install-crossdesk-pipewire-sdk
+          pkg-config --exists dbus-1 libdrm
+          test -f /opt/crossdesk-pipewire-sdk/include/pipewire-0.3/pipewire/pipewire.h
+          test -f /opt/crossdesk-pipewire-sdk/include/spa-0.2/spa/param/video/format-utils.h
 
       - name: Build CrossDesk
         env:
           CUDA_PATH: /usr/local/cuda
           XMAKE_GLOBALDIR: /data
         run: |
-          xmake f --CROSSDESK_VERSION=${LEGAL_VERSION} --USE_CUDA=true --USE_WAYLAND=true --root -y
+          xmake f --CROSSDESK_VERSION=${LEGAL_VERSION} --USE_CUDA=true --USE_WAYLAND=true \
+            --cc=gcc-10 --cxx=g++-10 --root -y
           xmake b -vy --root crossdesk
 
       - name: Package
@@ -133,13 +137,19 @@ jobs:
           chmod +x ${{ matrix.package_script }}
           ${{ matrix.package_script }} ${LEGAL_VERSION}
 
-      - name: Verify packaged Ubuntu 22.04 glibc baseline
+      - name: Verify Ubuntu 20.04 package dependency resolution
+        run: |
+          PACKAGE_FILE="${GITHUB_WORKSPACE}/crossdesk-linux-${{ matrix.arch }}-${LEGAL_VERSION}.deb"
+          apt-get update
+          apt-get install --simulate "${PACKAGE_FILE}"
+
+      - name: Verify packaged Ubuntu 20.04 glibc baseline
         run: |
           PACKAGE_FILE="${GITHUB_WORKSPACE}/crossdesk-linux-${{ matrix.arch }}-${LEGAL_VERSION}.deb"
           VERIFY_DIR="${RUNNER_TEMP}/crossdesk-glibc-${{ matrix.arch }}"
           install -d "${VERIFY_DIR}"
           dpkg-deb --extract "${PACKAGE_FILE}" "${VERIFY_DIR}"
-          verify-crossdesk-glibc-baseline "${VERIFY_DIR}" 2.35
+          verify-crossdesk-glibc-baseline "${VERIFY_DIR}" 2.31
 
       - name: Upload artifact
         uses: actions/upload-artifact@v6

README.md

@@ -32,7 +32,7 @@ CrossDesk 是 [MiniRTC](https://github.com/kunkundi/minirtc.git) 实时音视频
 |----------------|---------------------------|
 | **Windows** | Windows 10 及以上 (64 位) |
 | **macOS** | macOS Intel 15.0 及以上 ( 大于 14.0 小于 15.0 的版本可自行编译实现兼容 )<br> macOS Apple Silicon 14.0 及以上 |
-| **Linux** | Ubuntu 22.04 及以上 ( 低版本可自行编译实现兼容 ) |
+| **Linux** | Ubuntu 20.04 及以上 |
 
 ## 使用
 
@@ -80,27 +80,39 @@ Windows 安装包会自动打包 `crossdesk_service.exe` 和 `crossdesk_session_
 
 依赖：
 - [xmake](https://xmake.io/#/guide/installation)
-- [cmake](https://cmake.org/download/)
+- [cmake](https://cmake.org/download/) 3.21 及以上
 
 ### Linux
 
-Linux 构建目前支持 Ubuntu 22.04 及以上版本的 amd64 和 arm64。先安装基础编译依赖：
+Linux 构建支持 Ubuntu 20.04 及以上版本的 amd64 和 arm64。发布安装包以
+Ubuntu 20.04/glibc 2.31 为兼容基线。先安装基础编译依赖：
 
 ```bash
 sudo apt-get update
 sudo apt-get install -y \
-  git curl unzip build-essential cmake pkg-config binutils dpkg-dev \
+  git curl unzip build-essential gcc-10 g++-10 python3-pip \
+  pkg-config binutils dpkg-dev \
   libx11-dev libxext-dev libxrender-dev libxft-dev libxrandr-dev \
   libxinerama-dev libxcursor-dev libxi-dev libxfixes-dev libxv-dev \
   libxtst-dev libxcb-randr0-dev libxcb-xtest0-dev libxcb-xinerama0-dev \
   libxcb-shape0-dev libxcb-xkb-dev libxcb-xfixes0-dev libxcb-shm0-dev \
   libasound2-dev libsndio-dev libpulse-dev
+
+# Ubuntu 20.04 自带的 CMake 3.16 不满足 Slint 1.17 的要求
+python3 -m pip install --user cmake==3.31.6
+export PATH="$HOME/.local/bin:$PATH"
 ```
 
+Ubuntu 20.04 默认的 GCC 9 缺少 Slint C++ API 所需的部分 C++20 标准库，
+因此上述命令同时安装并在后续配置中指定 GCC 10。
+
 需要启用 Wayland 捕获或 DRM 捕获时，再安装对应依赖：
 
 ```bash
-sudo apt-get install -y libdbus-1-dev libpipewire-0.3-dev libdrm-dev
+sudo apt-get install -y libdbus-1-dev libdrm-dev
+
+# Ubuntu 22.04 及以上也可以直接安装系统开发包
+# sudo apt-get install -y libpipewire-0.3-dev libspa-0.2-dev
 ```
 
 下载子模块并编译 Release 版本：
@@ -112,7 +124,11 @@ cd crossdesk
 # 已经克隆过仓库时执行这一行
 git submodule update --init --recursive
 
-xmake f -m release --USE_CUDA=false -y
+# Ubuntu 20.04 没有 PipeWire 0.3 开发包，安装仅用于编译的头文件 SDK。
+# 已安装发行版 PipeWire 0.3 开发包时可跳过此步骤。
+sudo ./docker/linux-build/install-pipewire-sdk.sh
+
+xmake f -m release --USE_CUDA=false --cc=gcc-10 --cxx=g++-10 -y
 xmake b -vy crossdesk
 ```
 
@@ -121,7 +137,8 @@ amd64 构建结果位于 `build/linux/x86_64/release/crossdesk`，arm64 构建
 启用 Wayland 和 DRM 的配置示例：
 
 ```bash
-xmake f -m release --USE_WAYLAND=true --USE_DRM=true --USE_CUDA=false -y
+xmake f -m release --USE_WAYLAND=true --USE_DRM=true --USE_CUDA=false \
+  --cc=gcc-10 --cxx=g++-10 -y
 xmake b -vy crossdesk
 ```
 
@@ -136,6 +153,8 @@ xmake b -vy crossdesk
 ```
 
 打包脚本会将 Slint 共享运行库安装到软件包私有目录 `/usr/lib/crossdesk`，无需用户另外安装 `libslint_cpp.so`。
+PipeWire 不属于强制运行时依赖：程序在运行时检测宿主系统的 PipeWire 0.3，
+没有该运行库时仍可使用 X11（以及构建时启用的 DRM）捕获。
 
 ### 通用编译选项
 
@@ -158,7 +177,7 @@ xmake r crossdesk
 
 ### 无 CUDA 环境下的开发支持
 
-对于**未安装 CUDA 环境的 Linux 开发者，如果希望编译后的成果物拥有硬件编解码能力**，这里提供了预配置的 [Ubuntu 22.04 Docker 镜像](https://hub.docker.com/r/crossdesk/ubuntu22.04)。该镜像内置必要的构建依赖，可在容器中开箱即用，无需额外配置即可直接编译项目。
+对于**未安装 CUDA 环境的 Linux 开发者，如果希望编译后的成果物拥有硬件编解码能力**，这里提供了预配置的 [Ubuntu 20.04 兼容构建镜像](https://hub.docker.com/r/crossdesk/ubuntu20.04)。该镜像内置必要的构建依赖，可生成兼容 glibc 2.31 的单一 Linux 安装包。
 
 进入容器，下载工程后执行：
 ```

README_EN.md

@@ -32,7 +32,7 @@ CrossDesk is an experimental application of [MiniRTC](https://github.com/kunkund
 |-----------|-----------------|
 | **Windows** | Windows 10 or later (64-bit) |
 | **macOS** | macOS Intel 15.0 or later *(versions between 14.0 and 15.0 can be built manually for compatibility)*<br>macOS Apple Silicon 14.0 or later |
-| **Linux** | Ubuntu 22.04 or later *(older versions can be built manually for compatibility)* |
+| **Linux** | Ubuntu 20.04 or later |
 
 
 ## Usage
@@ -85,27 +85,41 @@ If the remote Windows service is not installed, not running, or temporarily unav
 
 Requirements:
 - [xmake](https://xmake.io/#/guide/installation)
-- [cmake](https://cmake.org/download/)
+- [cmake](https://cmake.org/download/) 3.21 or later
 
 ### Linux
 
-Linux builds currently support Ubuntu 22.04 or later on amd64 and arm64. Install the base build dependencies first:
+Linux builds support Ubuntu 20.04 or later on amd64 and arm64. Release packages
+use Ubuntu 20.04/glibc 2.31 as their compatibility baseline. Install the base
+build dependencies first:
 
 ```bash
 sudo apt-get update
 sudo apt-get install -y \
-  git curl unzip build-essential cmake pkg-config binutils dpkg-dev \
+  git curl unzip build-essential gcc-10 g++-10 python3-pip \
+  pkg-config binutils dpkg-dev \
   libx11-dev libxext-dev libxrender-dev libxft-dev libxrandr-dev \
   libxinerama-dev libxcursor-dev libxi-dev libxfixes-dev libxv-dev \
   libxtst-dev libxcb-randr0-dev libxcb-xtest0-dev libxcb-xinerama0-dev \
   libxcb-shape0-dev libxcb-xkb-dev libxcb-xfixes0-dev libxcb-shm0-dev \
   libasound2-dev libsndio-dev libpulse-dev
+
+# Ubuntu 20.04's CMake 3.16 is too old for Slint 1.17.
+python3 -m pip install --user cmake==3.31.6
+export PATH="$HOME/.local/bin:$PATH"
 ```
 
+Ubuntu 20.04's default GCC 9 lacks parts of the C++20 standard library needed
+by Slint's C++ API, so the commands above install GCC 10 and the configuration
+below selects it explicitly.
+
 Install the optional dependencies when Wayland capture or DRM capture is enabled:
 
 ```bash
-sudo apt-get install -y libdbus-1-dev libpipewire-0.3-dev libdrm-dev
+sudo apt-get install -y libdbus-1-dev libdrm-dev
+
+# Ubuntu 22.04 and later can alternatively use the distribution packages.
+# sudo apt-get install -y libpipewire-0.3-dev libspa-0.2-dev
 ```
 
 Clone the submodules and build a release binary:
@@ -117,7 +131,12 @@ cd crossdesk
 # Run this when the repository has already been cloned
 git submodule update --init --recursive
 
-xmake f -m release --USE_CUDA=false -y
+# Ubuntu 20.04 has no PipeWire 0.3 development package. Install the
+# header-only SDK used during compilation. Skip this when the distribution's
+# PipeWire 0.3 development packages are already installed.
+sudo ./docker/linux-build/install-pipewire-sdk.sh
+
+xmake f -m release --USE_CUDA=false --cc=gcc-10 --cxx=g++-10 -y
 xmake b -vy crossdesk
 ```
 
@@ -126,7 +145,8 @@ The amd64 binary is written to `build/linux/x86_64/release/crossdesk`; the arm64
 Example configuration with Wayland and DRM capture enabled:
 
 ```bash
-xmake f -m release --USE_WAYLAND=true --USE_DRM=true --USE_CUDA=false -y
+xmake f -m release --USE_WAYLAND=true --USE_DRM=true --USE_CUDA=false \
+  --cc=gcc-10 --cxx=g++-10 -y
 xmake b -vy crossdesk
 ```
 
@@ -141,6 +161,9 @@ Build a Debian package after compiling a release binary on the matching architec
 ```
 
 The package scripts install the shared Slint runtime in the private `/usr/lib/crossdesk` directory, so users do not need to install `libslint_cpp.so` separately.
+PipeWire is not a mandatory runtime dependency. CrossDesk detects the host's
+PipeWire 0.3 runtime dynamically and can still use X11 capture (and DRM when
+enabled at build time) when it is unavailable.
 
 ### Common build options
 
@@ -163,8 +186,8 @@ xmake r crossdesk
 
 #### Development Without CUDA Environment
 
-For **Linux developers who do not have a CUDA environment installed and want to enable hardware codec feature**, a preconfigured [Ubuntu 22.04 Docker image](https://hub.docker.com/r/crossdesk/ubuntu22.04) is provided.  
+For **Linux developers who do not have a CUDA environment installed and want to enable hardware codec feature**, a preconfigured [Ubuntu 20.04 compatibility build image](https://hub.docker.com/r/crossdesk/ubuntu20.04) is provided.
-This image comes with all required build dependencies and allows you to build the project directly inside the container without any additional setup.
+This image contains the required build dependencies and produces a single Linux package compatible with the glibc 2.31 baseline.
 
 After entering the container, download the project and run:
 ```

docker/linux-build/Dockerfile

@@ -1,15 +1,16 @@
 # syntax=docker/dockerfile:1.7
 
-ARG BASE_IMAGE=nvidia/cuda:12.6.3-devel-ubuntu22.04
+ARG BASE_IMAGE=nvidia/cuda:12.6.3-devel-ubuntu20.04
 FROM ${BASE_IMAGE}
 
 ARG TARGETARCH
+ARG CMAKE_VERSION=3.31.6
 ARG XMAKE_VERSION=3.0.9
 ARG RUST_VERSION=1.92.0
 ARG RUSTUP_VERSION=1.28.2
 
 LABEL org.opencontainers.image.title="CrossDesk Linux build environment" \
-      org.opencontainers.image.description="Ubuntu 22.04 build environment for CrossDesk" \
+      org.opencontainers.image.description="Ubuntu 20.04 compatibility build environment for CrossDesk" \
       org.opencontainers.image.source="https://github.com/kunkundi/crossdesk" \
       org.opencontainers.image.licenses="GPL-3.0-only"
 
@@ -22,6 +23,8 @@ ENV DEBIAN_FRONTEND=noninteractive \
     XMAKE_GLOBALDIR=/data \
     XMAKE_ROOT=y \
     CUDA_PATH=/usr/local/cuda \
+    CC=/usr/bin/gcc-10 \
+    CXX=/usr/bin/g++-10 \
     PATH=/root/.local/bin:/opt/cargo/bin:/usr/local/bin:${PATH}
 
 SHELL ["/bin/bash", "-o", "pipefail", "-c"]
@@ -35,13 +38,14 @@ RUN apt-get update \
         build-essential \
         ca-certificates \
         ccache \
-        cmake \
         curl \
         dbus \
         dpkg-dev \
         file \
         flex \
         gettext \
+        gcc-10 \
+        g++-10 \
         git \
         libasound2-dev \
         libdbus-1-dev \
@@ -52,11 +56,9 @@ RUN apt-get update \
         libfreetype6-dev \
         libgl1-mesa-dev \
         libmount-dev \
-        libpipewire-0.3-dev \
         libpulse-dev \
         libreadline-dev \
         libsndio-dev \
-        libspa-0.2-dev \
         libssl-dev \
         libtool \
         libx11-dev \
@@ -95,6 +97,22 @@ RUN apt-get update \
         zlib1g-dev \
     && rm -rf /var/lib/apt/lists/*
 
+# Slint 1.17 requires CMake 3.21 or newer, while Ubuntu 20.04 provides 3.16.
+# PyPI publishes pinned manylinux2014 wheels for both amd64 and arm64.
+RUN python3 -m pip install --no-cache-dir "cmake==${CMAKE_VERSION}" \
+    && cmake --version | grep -F "cmake version ${CMAKE_VERSION}"
+
+# Ubuntu 20.04 only ships PipeWire 0.2. Install the Ubuntu 22.04-era 0.3.48
+# headers as a build-only SDK. CrossDesk loads the host's PipeWire 0.3 runtime
+# with dlopen(), so no PipeWire shared library is copied into release packages.
+COPY docker/linux-build/install-pipewire-sdk.sh \
+    /usr/local/bin/install-crossdesk-pipewire-sdk
+
+RUN chmod 0755 /usr/local/bin/install-crossdesk-pipewire-sdk \
+    && install-crossdesk-pipewire-sdk \
+    && grep -F "#define PW_MICRO 48" \
+        /opt/crossdesk-pipewire-sdk/include/pipewire-0.3/pipewire/version.h
+
 RUN export GITHUB_ACTIONS=true \
     && curl -fsSL https://xmake.io/shget.text \
         | bash -s -- "v${XMAKE_VERSION}" \
@@ -136,7 +154,8 @@ COPY submodules/minirtc/thirdparty ./submodules/minirtc/thirdparty
 # CrossDesk's exact dependency graph. Source files are intentionally excluded
 # from the Docker context; source-only changes therefore reuse this layer.
 RUN xmake repo -u --root \
-    && xmake f -m release --USE_CUDA=true --USE_WAYLAND=true --root -y \
+    && xmake f -m release --USE_CUDA=true --USE_WAYLAND=true \
+        --cc=gcc-10 --cxx=g++-10 --root -y \
     && rm -rf /data/.xmake/cache /tmp/crossdesk-dependencies \
     && mkdir -p /workspace
 

docker/linux-build/README.md

@@ -1,7 +1,8 @@
 # CrossDesk Linux 构建镜像
 
-这个目录维护 CrossDesk 专用的 Ubuntu 22.04 构建环境。镜像包含 xmake、
+这个目录维护 CrossDesk 专用的 Ubuntu 20.04 兼容构建环境。镜像包含 GCC 10、
-Rust、Linux 开发库（包括 D-Bus、DRM、PipeWire 和 SPA）以及根据项目
+CMake 3.31、xmake、Rust、Linux 开发库（包括 D-Bus、DRM，以及仅用于编译的
+PipeWire 0.3/SPA 头文件 SDK）以及根据项目
 `xmake.lua` 提前编译好的依赖。
 
 ## 发布方式
@@ -11,14 +12,19 @@ Rust、Linux 开发库（包括 D-Bus、DRM、PipeWire 和 SPA）以及根据项
 全部通过后再合并为同一个 multi-arch 镜像：
 
 ```text
-crossdesk/ubuntu22.04:buildenv-cuda12.6.3-xmake3.0.9-rust1.92.0
+crossdesk/ubuntu20.04:buildenv-cuda12.6.3-gcc10-cmake3.31.6-pipewire0.3.48-xmake3.0.9-rust1.92.0
 ```
 
 Docker 会根据运行机器自动选择正确架构。amd64 变体以
-`nvidia/cuda:12.6.3-devel-ubuntu22.04` 为基础；arm64 变体不包含当前构建
+`nvidia/cuda:12.6.3-devel-ubuntu20.04` 为基础；arm64 变体不包含当前构建
-用不到的 CUDA SDK。两个变体都使用 Ubuntu 22.04/glibc 2.35。
+用不到的 CUDA SDK。两个变体都使用 Ubuntu 20.04/glibc 2.31，因此生成的
-因此该镜像生成的 Linux 安装包最低支持 Ubuntu 22.04，不再保证兼容
+单一 Linux 安装包可运行在 Ubuntu 20.04 及更高版本。
-Ubuntu 20.04。
+
+Ubuntu 20.04 仓库只提供 PipeWire 0.2。镜像通过
+`install-pipewire-sdk.sh` 安装固定版本的 PipeWire 0.3.48/SPA 头文件，但不
+安装或打包 PipeWire 动态库。CrossDesk 在运行时通过 `dlopen()` 使用宿主系统
+提供的 PipeWire 0.3：Ubuntu 20.04 没有该运行库时仍可使用 X11（以及构建时
+启用的 DRM），Ubuntu 22.04 及更高版本则可使用 Wayland 捕获。
 
 每次成功发布还会生成 `sha-<完整提交 SHA>`，用于精确回滚；`latest` 和上面的
 工具链版本 tag 只会在两个架构都验证成功后更新。
@@ -27,7 +33,7 @@ Ubuntu 20.04。
 
 在仓库的 Actions secrets 中配置：
 
-- `DOCKERHUB_USERNAME`：有权推送 `crossdesk/ubuntu22.04` 的 Docker Hub 用户名
+- `DOCKERHUB_USERNAME`：有权推送 `crossdesk/ubuntu20.04` 的 Docker Hub 用户名
 - `DOCKERHUB_TOKEN`：该用户的 Docker Hub access token
 
 工作流文件进入默认分支后，也可以从 Actions 页面手动运行。为了避免首次发布

docker/linux-build/install-pipewire-sdk.sh

@@ -0,0 +1,55 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+PIPEWIRE_VERSION="0.3.48"
+PIPEWIRE_ARCHIVE_SHA256="0d218be86b3d2b548c06259c47ad8d110ee1c09f071e17c4393eeef5c880fa6f"
+INSTALL_PREFIX="${1:-/opt/crossdesk-pipewire-sdk}"
+IFS='.' read -r PIPEWIRE_VERSION_MAJOR PIPEWIRE_VERSION_MINOR \
+    PIPEWIRE_VERSION_MICRO <<< "${PIPEWIRE_VERSION}"
+
+if [[ "${INSTALL_PREFIX}" != /* ]]; then
+    echo "Install prefix must be an absolute path: ${INSTALL_PREFIX}" >&2
+    exit 2
+fi
+
+WORK_DIR="$(mktemp -d "${TMPDIR:-/tmp}/crossdesk-pipewire-sdk.XXXXXX")"
+trap 'rm -rf "${WORK_DIR}"' EXIT
+
+ARCHIVE_PATH="${WORK_DIR}/pipewire-${PIPEWIRE_VERSION}.tar.gz"
+SOURCE_DIR="${WORK_DIR}/pipewire-${PIPEWIRE_VERSION}"
+ARCHIVE_URL="https://gitlab.freedesktop.org/pipewire/pipewire/-/archive/${PIPEWIRE_VERSION}/pipewire-${PIPEWIRE_VERSION}.tar.gz"
+
+curl --proto '=https' --tlsv1.2 --fail --silent --show-error --location \
+    --retry 3 "${ARCHIVE_URL}" -o "${ARCHIVE_PATH}"
+echo "${PIPEWIRE_ARCHIVE_SHA256}  ${ARCHIVE_PATH}" | sha256sum --check -
+tar -xzf "${ARCHIVE_PATH}" -C "${WORK_DIR}"
+
+PIPEWIRE_INCLUDE_DIR="${INSTALL_PREFIX}/include/pipewire-0.3/pipewire"
+SPA_INCLUDE_DIR="${INSTALL_PREFIX}/include/spa-0.2/spa"
+
+while IFS= read -r -d '' header_path; do
+    relative_path="${header_path#${SOURCE_DIR}/src/pipewire/}"
+    install -D -m 0644 "${header_path}" \
+        "${PIPEWIRE_INCLUDE_DIR}/${relative_path}"
+done < <(find "${SOURCE_DIR}/src/pipewire" -type f -name '*.h' -print0)
+
+while IFS= read -r -d '' header_path; do
+    relative_path="${header_path#${SOURCE_DIR}/spa/include/spa/}"
+    install -D -m 0644 "${header_path}" \
+        "${SPA_INCLUDE_DIR}/${relative_path}"
+done < <(find "${SOURCE_DIR}/spa/include/spa" -type f -name '*.h' -print0)
+
+sed \
+    -e "s/@PIPEWIRE_VERSION_MAJOR@/${PIPEWIRE_VERSION_MAJOR}/g" \
+    -e "s/@PIPEWIRE_VERSION_MINOR@/${PIPEWIRE_VERSION_MINOR}/g" \
+    -e "s/@PIPEWIRE_VERSION_MICRO@/${PIPEWIRE_VERSION_MICRO}/g" \
+    -e 's/@PIPEWIRE_API_VERSION@/"0.3"/g' \
+    "${SOURCE_DIR}/src/pipewire/version.h.in" \
+    > "${PIPEWIRE_INCLUDE_DIR}/version.h"
+chmod 0644 "${PIPEWIRE_INCLUDE_DIR}/version.h"
+
+test -f "${PIPEWIRE_INCLUDE_DIR}/pipewire.h"
+test -f "${PIPEWIRE_INCLUDE_DIR}/version.h"
+test -f "${SPA_INCLUDE_DIR}/param/video/format-utils.h"
+
+echo "Installed PipeWire ${PIPEWIRE_VERSION} header SDK under ${INSTALL_PREFIX}"

docker/linux-build/verify-build-image.sh

@@ -2,19 +2,22 @@
 set -euo pipefail
 
 EXPECTED_ARCH="${EXPECTED_ARCH:-}"
+EXPECTED_CMAKE_VERSION="${EXPECTED_CMAKE_VERSION:-3.31.6}"
 EXPECTED_XMAKE_VERSION="${EXPECTED_XMAKE_VERSION:-3.0.9}"
 EXPECTED_RUST_VERSION="${EXPECTED_RUST_VERSION:-1.92.0}"
+BUILD_CC="${CC:-/usr/bin/gcc-10}"
+BUILD_CXX="${CXX:-/usr/bin/g++-10}"
 
 # shellcheck disable=SC1091
 source /etc/os-release
-if [[ "${ID}" != "ubuntu" || "${VERSION_ID}" != "22.04" ]]; then
+if [[ "${ID}" != "ubuntu" || "${VERSION_ID}" != "20.04" ]]; then
-    echo "Expected Ubuntu 22.04, found ${ID:-unknown} ${VERSION_ID:-unknown}" >&2
+    echo "Expected Ubuntu 20.04, found ${ID:-unknown} ${VERSION_ID:-unknown}" >&2
     exit 1
 fi
 
 GLIBC_VERSION="$(getconf GNU_LIBC_VERSION | awk '{print $2}')"
-if [[ "${GLIBC_VERSION}" != "2.35" ]]; then
+if [[ "${GLIBC_VERSION}" != "2.31" ]]; then
-    echo "Expected glibc 2.35, found ${GLIBC_VERSION}" >&2
+    echo "Expected glibc 2.31, found ${GLIBC_VERSION}" >&2
     exit 1
 fi
 
@@ -28,13 +31,23 @@ XMAKE_VERSION_OUTPUT="$(xmake --version 2>&1)"
 grep -F "v${EXPECTED_XMAKE_VERSION}" <<<"${XMAKE_VERSION_OUTPUT}" >/dev/null
 rustc --version | grep -F "rustc ${EXPECTED_RUST_VERSION}" >/dev/null
 cargo --version >/dev/null
-cmake --version >/dev/null
+cmake --version | grep -F "cmake version ${EXPECTED_CMAKE_VERSION}" >/dev/null
-g++ --version >/dev/null
+"${BUILD_CC}" --version | grep -F 'gcc-10' >/dev/null
+"${BUILD_CXX}" --version | grep -F 'g++-10' >/dev/null
+printf '%s\n' \
+    '#include <concepts>' \
+    '#include <span>' \
+    'template <typename T> concept TestConcept = true;' \
+    'int main() {' \
+    '    int value = 0;' \
+    '    std::span<int> values(&value, 1);' \
+    '    static_assert(TestConcept<int>);' \
+    '    return values.empty();' \
+    '}' \
+    | "${BUILD_CXX}" -std=c++20 -fsyntax-only -x c++ -
 for pkg_config_package in \
     dbus-1 \
     libdrm \
-    libpipewire-0.3 \
-    libspa-0.2 \
     xft; do
     if ! pkg-config --exists "${pkg_config_package}"; then
         echo "Required pkg-config package is missing: ${pkg_config_package}" >&2
@@ -42,6 +55,25 @@ for pkg_config_package in \
     fi
 done
 
+for sdk_header in \
+    /opt/crossdesk-pipewire-sdk/include/pipewire-0.3/pipewire/pipewire.h \
+    /opt/crossdesk-pipewire-sdk/include/pipewire-0.3/pipewire/version.h \
+    /opt/crossdesk-pipewire-sdk/include/spa-0.2/spa/param/video/format-utils.h; do
+    if [[ ! -f "${sdk_header}" ]]; then
+        echo "Required PipeWire build SDK header is missing: ${sdk_header}" >&2
+        exit 1
+    fi
+done
+
+printf '%s\n' \
+    '#include <pipewire/pipewire.h>' \
+    '#include <spa/param/video/format-utils.h>' \
+    'static_assert(PW_CHECK_VERSION(0, 3, 48));' \
+    'int main() { return 0; }' \
+    | "${BUILD_CXX}" -std=c++17 -fsyntax-only -x c++ \
+        -I/opt/crossdesk-pipewire-sdk/include/pipewire-0.3 \
+        -I/opt/crossdesk-pipewire-sdk/include/spa-0.2 -
+
 for package_path in \
     "s/slint" \
     "l/libdatachannel" \

docker/linux-build/verify-glibc-baseline.sh

@@ -7,7 +7,7 @@ if [[ $# -lt 1 || $# -gt 2 ]]; then
 fi
 
 INPUT_PATH="$1"
-MAXIMUM_VERSION="${2:-2.35}"
+MAXIMUM_VERSION="${2:-2.31}"
 
 verify_elf() {
     local elf_file="$1"

scripts/linux/package_deb.sh

@@ -104,6 +104,15 @@ OUTPUT_FILE="$PROJECT_ROOT/${PKG_NAME}-linux-${DEBIAN_ARCH}-${APP_VERSION}.deb"
 install -d "$DEBIAN_DIR" "$BIN_DIR" "$PRIVATE_DIR" "$DESKTOP_DIR"
 install -m 0755 "$BUILD_BINARY" "$PRIVATE_DIR/crossdesk-bin"
 
+# PipeWire is deliberately optional. The Wayland capturer resolves PipeWire
+# 0.3 with dlopen() so the same package can run on Ubuntu 20.04 without the
+# runtime while using the host runtime on newer Ubuntu releases.
+if readelf -d "$BUILD_BINARY" \
+    | grep -qE 'Shared library: \[libpipewire-0\.3\.so'; then
+    echo "CrossDesk must not link directly to the optional PipeWire runtime" >&2
+    exit 1
+fi
+
 # Slint is intentionally built as a shared library. Keep that runtime private
 # to CrossDesk instead of relying on a non-existent distribution package.
 SLINT_NEEDED="$(readelf -d "$BUILD_BINARY" | sed -n \
@@ -147,7 +156,7 @@ Version: $DEB_VERSION
 Architecture: $DEBIAN_ARCH
 Maintainer: $MAINTAINER
 Description: $DESCRIPTION
-Depends: libc6 (>= 2.35), libstdc++6 (>= 9), libx11-6, libxext6,
+Depends: libc6 (>= 2.31), libstdc++6 (>= 10), libx11-6, libxext6,
  libxrender1, libxft2, libxrandr2, libxfixes3, libxcb1, libxcb-randr0,
  libxcb-xtest0, libxcb-xinerama0, libxcb-shape0, libxcb-xkb1,
  libxcb-xfixes0, libxv1, libxtst6, $ALSA_RUNTIME_DEP, libsndio7.0,

xmake/platform.lua

@@ -64,10 +64,12 @@ function setup_platform_settings()
                 "/usr/local/include/pipewire-0.3",
                 "/usr/include/pipewire",
                 "/usr/local/include/pipewire",
+                "/opt/crossdesk-pipewire-sdk/include/pipewire-0.3",
                 "/usr/include/spa-0.2",
                 "/usr/local/include/spa-0.2",
                 "/usr/include/spa",
-                "/usr/local/include/spa"
+                "/usr/local/include/spa",
+                "/opt/crossdesk-pipewire-sdk/include/spa-0.2"
             }, {system = true})
             for _, include_dir in ipairs(collect_dbus_arch_include_dirs()) do
                 add_includedirs(include_dir, {system = true})