Portable Ithaca capture node: one install for every Jetson

Extract the install that was applied by hand to the Jetson Nano into a single
checkout that builds itself for whatever Jetson it lands on.

The two nodes on the rig share no JetPack — tegra210 caps at 4, tegra234 needs
5+ — so nothing binary is portable between them. The source and the procedure
are: install.sh detects the platform (L4T / JetPack / SoC), installs deps,
builds the OrbbecSDK and the preview server from source locally, and generates
a per-user config and systemd unit. The tested bridge.py ships verbatim; all
machine-specific paths live in the generated config, so it stays unmodified —
its one hardcoded path is made home-relative.

The retired GStreamer/RTSP target is dropped: the direct route encodes no video.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

server/CMakeLists.txt

@@ -0,0 +1,93 @@
+# Copyright (c) French Touch Factory. All Rights Reserved.
+#
+# Builds the one preview server, ithaca_rgbd_server, against an already-built
+# OrbbecSDK v2. Deliberately outside the SDK tree: reconfiguring the SDK on an
+# older Jetson can break the recorder build that already works, so we link the
+# library it produced instead of building inside it.
+#
+# Portable across Jetson generations by construction: every SDK path comes from a
+# cache variable that build_server.sh fills from OB_SDK_ROOT, and nothing here is
+# tied to one L4T, one home directory, or one arm64 build folder name.
+#
+# The retired GStreamer/RTSP target is gone — the direct route encodes no video,
+# so GStreamer is not a dependency any more.
+
+cmake_minimum_required(VERSION 3.10)
+project(ithaca_node_server CXX)
+
+# Where the SDK source (headers) and its build output (libs, generated headers,
+# extensions) live. build_server.sh passes these; the defaults match the layout
+# build_sdk.sh produces.
+set(OB_SDK_ROOT "$ENV{HOME}/OrbbecSDK_v2" CACHE PATH
+    "OrbbecSDK v2 source root (headers)")
+set(OB_SDK_BUILD "" CACHE PATH
+    "OrbbecSDK v2 build output (lib/, lib/extensions/)")
+set(OB_SDK_GENERATED "" CACHE PATH
+    "OrbbecSDK generated headers, where Export.h lands")
+
+# The build folder is named per platform (linux_arm64, linux_aarch64, ...), so it
+# is discovered rather than assumed when the caller did not pass it.
+if(NOT OB_SDK_BUILD)
+    file(GLOB _ob_build_candidates "${OB_SDK_ROOT}/build/linux_*")
+    if(_ob_build_candidates)
+        list(GET _ob_build_candidates 0 OB_SDK_BUILD)
+    else()
+        set(OB_SDK_BUILD "${OB_SDK_ROOT}/build")
+    endif()
+endif()
+if(NOT OB_SDK_GENERATED)
+    set(OB_SDK_GENERATED "${OB_SDK_ROOT}/build/src/generated")
+endif()
+
+if(NOT EXISTS "${OB_SDK_ROOT}/include/libobsensor/ObSensor.hpp")
+    message(FATAL_ERROR "OrbbecSDK headers not found under ${OB_SDK_ROOT}/include "
+                        "— set OB_SDK_ROOT or run scripts/build_sdk.sh first.")
+endif()
+if(NOT EXISTS "${OB_SDK_BUILD}/lib/libOrbbecSDK.so")
+    message(FATAL_ERROR "libOrbbecSDK.so not found in ${OB_SDK_BUILD}/lib "
+                        "— build the SDK first (scripts/build_sdk.sh).")
+endif()
+if(NOT EXISTS "${OB_SDK_GENERATED}/Export.h")
+    message(FATAL_ERROR "Export.h not found in ${OB_SDK_GENERATED} "
+                        "— the SDK is not fully built yet.")
+endif()
+
+# Directory-scoped rather than target_link_directories(): that one needs CMake
+# >= 3.13 and the oldest supported Jetson (Nano, JetPack 4) ships 3.10.2. Must
+# precede add_executable().
+link_directories("${OB_SDK_BUILD}/lib")
+
+add_executable(ithaca_rgbd_server ithaca_rgbd_server.cpp)
+set_property(TARGET ithaca_rgbd_server PROPERTY CXX_STANDARD 14)
+target_compile_options(ithaca_rgbd_server PRIVATE -Wall -Wextra -O2)
+
+# Where the depth engine and filter plugins are loaded from at runtime.
+target_compile_definitions(ithaca_rgbd_server PRIVATE
+    OB_EXTENSIONS_DIR="${OB_SDK_BUILD}/lib/extensions")
+
+# SYSTEM: the SDK's public headers are not warning-clean and this builds -Wall
+# -Wextra. ObTypes.h includes Export.h, which the SDK generates into its build
+# tree rather than shipping in include/, hence both directories.
+target_include_directories(ithaca_rgbd_server SYSTEM PRIVATE
+    "${OB_SDK_ROOT}/include"
+    "${OB_SDK_GENERATED}")
+
+# libjpeg by absolute path, not -ljpeg: the SDK ships its own libjpeg.a in the
+# directory link_directories() adds above, built without its SIMD objects — the
+# linker would pick it first and fail on jsimd_* symbols. Only C2D alignment
+# needs an encoder at all.
+find_library(SYSTEM_JPEG NAMES jpeg PATHS
+    /usr/lib/aarch64-linux-gnu /usr/lib/arm-linux-gnueabihf NO_DEFAULT_PATH)
+if(NOT SYSTEM_JPEG)
+    message(FATAL_ERROR "system libjpeg not found — install libjpeg-turbo8-dev.")
+endif()
+
+target_link_libraries(ithaca_rgbd_server PRIVATE OrbbecSDK lz4 ${SYSTEM_JPEG} pthread)
+
+# The SDK lives outside any standard search path; without an rpath the binary
+# only runs from a shell that already exports LD_LIBRARY_PATH.
+set_target_properties(ithaca_rgbd_server PROPERTIES
+    BUILD_RPATH   "${OB_SDK_BUILD}/lib"
+    INSTALL_RPATH "${OB_SDK_BUILD}/lib")
+
+install(TARGETS ithaca_rgbd_server RUNTIME DESTINATION bin)