postprocessing: Split existing postproc stages into loadable so files

Split the existing postprocessing stages into 3 .so files:
- Core stages
- OpenCV stages
- TFLite stages

These are installed into the /<system lib>/rpicam-apps-postproc/
directory.

Additionally, switch enable_tflite and enable_opencv meson option types
to "feature".

Signed-off-by: Naushir Patuck <[email protected]>

.github/workflows/rpicam-apps-test.yml

@@ -56,7 +56,7 @@ jobs:
         clean: true
 
     - name: Configure meson
-      run: meson setup ${{github.workspace}}/build --pkg-config-path=${{env.LIBCAMERA_LKG_DIR}}/lib/aarch64-linux-gnu/pkgconfig/ -Dbuildtype=release -Denable_drm=false -Denable_egl=false -Denable_qt=false -Denable_opencv=false -Denable_tflite=false -Denable_libav=false
+      run: meson setup ${{github.workspace}}/build --pkg-config-path=${{env.LIBCAMERA_LKG_DIR}}/lib/aarch64-linux-gnu/pkgconfig/ -Dbuildtype=release -Denable_drm=false -Denable_egl=false -Denable_qt=false -Denable_opencv='disabled' -Denable_tflite='disabled' -Denable_libav=false
       timeout-minutes: 5
 
     - name: Build

meson.build

@@ -51,8 +51,6 @@ subdir('preview')
 subdir('post_processing_stages')
 subdir('utils')
 
-add_project_arguments(cpp_arguments, language : 'cpp')
-
 rpicam_app = library(
     'rpicam_app',
     rpicam_app_src,
@@ -61,6 +59,7 @@ rpicam_app = library(
     install : true,
     name_prefix : '',
     dependencies : rpicam_app_dep,
+    cpp_args : cpp_arguments,
 )
 
 # Install a symlink to the old library name for legacy purposes.

meson_options.txt

@@ -19,13 +19,13 @@ option('enable_qt',
         description : 'Enable QT preview window support')
 
 option('enable_opencv',
-        type : 'boolean',
-        value : true,
+        type : 'feature',
+        value : 'disabled',
         description : 'Enable OpenCV postprocessing support')
 
 option('enable_tflite',
-        type : 'boolean',
-        value : false,
+        type : 'feature',
+        value : 'disabled',
         description : 'Enable Tensorflow Lite postprocessing support')
 
 option('neon_flags',

post_processing_stages/meson.build

@@ -1,55 +1,85 @@
-posproc_libdir = get_option('prefix') / get_option('libdir') / 'rpicam-apps-pp'
+posproc_libdir = get_option('prefix') / get_option('libdir') / 'rpicam-apps-postproc'
 
 conf_data = configuration_data()
 conf_data.set('POSTPROC_LIB_DIR', '"' + posproc_libdir + '"')
 configure_file(output : 'postproc_lib.h', configuration : conf_data)
 
+# Core postprocessing framework files.
 rpicam_app_src += files([
-    'hdr_stage.cpp',
     'histogram.cpp',
-    'motion_detect_stage.cpp',
-    'negate_stage.cpp',
     'post_processing_stage.cpp',
     'pwl.cpp',
 ])
 
-post_processing_headers = files([
-    'histogram.hpp',
-    'object_detect.hpp',
-    'post_processing_stage.hpp',
-    'pwl.hpp',
-    'segmentation.hpp',
-    'tf_stage.hpp',
+# Core postprocessing stages.
+core_postproc_src = files([
+    'hdr_stage.cpp',
+    'motion_detect_stage.cpp',
+    'negate_stage.cpp',
 ])
 
-enable_opencv = get_option('enable_opencv')
-opencv_dep = dependency('opencv4', required : false)
-if enable_opencv and opencv_dep.found()
-    rpicam_app_src += files([
+core_postproc_lib = shared_module('core-postproc', core_postproc_src,
+                                  include_directories : '../..',
+                                  dependencies : libcamera_dep,
+                                  cpp_args : cpp_arguments,
+                                  install : true,
+                                  install_dir : posproc_libdir,
+                                  name_prefix : '',
+                                 )
+
+# OpenCV based postprocessing stages.
+enable_opencv = false
+opencv_dep = dependency('opencv4', required : get_option('enable_opencv'))
+if opencv_dep.found()
+    opencv_postproc_src = files([
         'sobel_cv_stage.cpp',
         'face_detect_cv_stage.cpp',
         'annotate_cv_stage.cpp',
         'plot_pose_cv_stage.cpp',
         'object_detect_draw_cv_stage.cpp',
     ])
-    rpicam_app_dep += opencv_dep
-else
-    enable_opencv = false
+
+    opencv_postproc_lib = shared_module('opencv-postproc', opencv_postproc_src,
+                                        include_directories : '../..',
+                                        dependencies : [libcamera_dep, opencv_dep],
+                                        cpp_args : cpp_arguments,
+                                        install : true,
+                                        install_dir : posproc_libdir,
+                                        name_prefix : '',
+                                       )
+    enable_opencv = true
 endif
 
-enable_tflite = get_option('enable_tflite')
-tflite_dep = dependency('tensorflow-lite', required : false)
-if enable_tflite and tflite_dep.found()
-    rpicam_app_src += files([
+# TFlite based postprocessing stages.
+enable_tflite = false
+tflite_dep = dependency('tensorflow-lite', required : get_option('enable_tflite'))
+if tflite_dep.found()
+    tflite_postproc_src = files([
         'tf_stage.cpp',
         'object_classify_tf_stage.cpp',
         'pose_estimation_tf_stage.cpp',
         'object_detect_tf_stage.cpp',
         'segmentation_tf_stage.cpp',
     ])
-    rpicam_app_dep += tflite_dep
-else
-    enable_tflite = false
+
+    tflite_postproc_lib = shared_module('tflite-postproc', tflite_postproc_src,
+                                        include_directories : '../..',
+                                        dependencies : [libcamera_dep, tflite_dep],
+                                        cpp_args : cpp_arguments,
+                                        install : true,
+                                        install_dir : posproc_libdir,
+                                        name_prefix : '',
+                                       )
+    enable_tflite = true
 endif
 
+post_processing_headers = files([
+    'histogram.hpp',
+    'object_detect.hpp',
+    'post_processing_stage.hpp',
+    'pwl.hpp',
+    'segmentation.hpp',
+    'tf_stage.hpp',
+])
+
 install_headers(post_processing_headers, subdir: meson.project_name() / 'post_processing_stages')