support compiling against external libraries

README.md

@@ -34,6 +34,41 @@ This is embedded into all MediaMTX releases and shouldn't normally be downloaded
 
    This will produce the `build/mtxrpicam_32` or `build/mtxrpicam_64` folder (depending on the architecture).
 
+## Compile against an external libcamera
+
+1. You must be on a Raspberry Pi, running Raspberry Pi OS Bullseye
+
+2. Install build dependencies:
+
+   ```sh
+   sudo apt install -y \
+   g++ \
+   xxd \
+   wget \
+   git \
+   cmake \
+   meson \
+   pkg-config \
+   python3-jinja2 \
+   python3-yaml \
+   python3-ply
+   ```
+
+3. Make sure that the development package of your libcamera is installed, otherwise install the default one:
+
+   ```sh
+   sudo apt install -y \
+   libcamera-dev
+   ```
+
+3. Build with `--wrap-mode=default` (that disables embedded libraries):
+
+   ```sh
+   meson setup --wrap-mode=default build && DESTDIR=./prefix ninja -C build install
+   ```
+
+   This will produce the `build/mtxrpicam_32` or `build/mtxrpicam_64` folder (depending on the architecture).
+
 ## Cross-compile
 
 1. You can be on any machine you like

meson.build

@@ -8,7 +8,8 @@ project(
         'cpp_std=c++17',
         'buildtype=release',
         'strip=true',
-        'prefix=/'
+        'prefix=/',
+        'wrap_mode=forcefallback'
     ]
 )
 
@@ -33,8 +34,9 @@ cpp_args = [
 add_project_arguments(c_args, language : 'c')
 add_project_arguments(cpp_args, language : 'cpp')
 
-x264 = subproject(
+x264_dep = dependency(
     'x264',
+    fallback : ['x264', 'libx264_dep'],
     default_options : [
         'default_library=static',
         'cli=false',
@@ -43,10 +45,10 @@ x264 = subproject(
         'bit-depth=8',
         'chroma-format=all'
     ])
-x264_dep = x264.get_variable('libx264_dep')
 
-libcamera = subproject(
+libcamera_dep = dependency(
     'libcamera',
+    fallback : ['libcamera', 'libcamera_public'],
     default_options : [
         'buildtype=release',
         'strip=true',
@@ -62,21 +64,24 @@ libcamera = subproject(
         'tracing=disabled',
         'udev=disabled'
     ])
-libcamera_dep = libcamera.get_variable('libcamera_public')
 
-cmake = import('cmake')
-freetype_vars = cmake.subproject_options()
-freetype_vars.add_cmake_defines({
-    'CMAKE_BUILD_TYPE': 'Release',
-    'BUILD_SHARED_LIBS': false,
-    'FT_DISABLE_ZLIB': true,
-    'FT_DISABLE_BZIP2': true,
-    'FT_DISABLE_PNG': true,
-    'FT_DISABLE_HARFBUZZ': true,
-    'FT_DISABLE_BROTLI': true
-})
-freetype = cmake.subproject('freetype', options : freetype_vars)
-freetype_dep = freetype.dependency('freetype')
+freetype_dep = dependency('freetype2', required : false)
+if not freetype_dep.found()
+    cmake = import('cmake')
+    freetype_vars = cmake.subproject_options()
+    freetype_vars.set_override_option('wrap_mode', 'none')
+    freetype_vars.add_cmake_defines({
+        'CMAKE_BUILD_TYPE': 'Release',
+        'BUILD_SHARED_LIBS': false,
+        'FT_DISABLE_ZLIB': true,
+        'FT_DISABLE_BZIP2': true,
+        'FT_DISABLE_PNG': true,
+        'FT_DISABLE_HARFBUZZ': true,
+        'FT_DISABLE_BROTLI': true
+    })
+    freetype_proj = cmake.subproject('freetype', options : freetype_vars)
+    freetype_dep = freetype_proj.dependency('freetype')
+endif
 
 dependencies = [
     x264_dep,

post_install.sh

@@ -9,8 +9,12 @@ else
 fi
 
 mkdir -p $OUT_DIR
-cp -r ${DESTDIR}/${MESON_INSTALL_PREFIX}/share/libcamera/ipa $OUT_DIR/ipa_conf
-cp -r ${DESTDIR}/${MESON_INSTALL_PREFIX}/lib/libcamera $OUT_DIR/ipa_module
-cp ${DESTDIR}/${MESON_INSTALL_PREFIX}/lib/libcamera-base.so.9.9 $OUT_DIR/
-cp ${DESTDIR}/${MESON_INSTALL_PREFIX}/lib/libcamera.so.9.9 $OUT_DIR/
+
+if [ -f ${DESTDIR}/${MESON_INSTALL_PREFIX}/lib/libcamera.so.9.9 ]; then
+    cp -r ${DESTDIR}/${MESON_INSTALL_PREFIX}/share/libcamera/ipa $OUT_DIR/ipa_conf
+    cp -r ${DESTDIR}/${MESON_INSTALL_PREFIX}/lib/libcamera $OUT_DIR/ipa_module
+    cp ${DESTDIR}/${MESON_INSTALL_PREFIX}/lib/libcamera-base.so.9.9 $OUT_DIR/
+    cp ${DESTDIR}/${MESON_INSTALL_PREFIX}/lib/libcamera.so.9.9 $OUT_DIR/
+fi
+
 cp ${DESTDIR}/${MESON_INSTALL_PREFIX}/bin/mtxrpicam $OUT_DIR/