camera deploy script and makefile and readme

camera_example/Makefile

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+# Build on the device. Needs:
+#   apt install g++ pkg-config libcamera-dev libevent-dev libjpeg-turbo8-dev
+# (Raspberry Pi OS Bullseye+; on older releases the turbo package is libjpeg-dev.)
+
+CXX      ?= g++
+CXXFLAGS ?= -O2 -std=c++17 -pipe -Wall -Wextra
+PKGS      = libcamera libevent libevent_pthreads libturbojpeg
+
+camera: camera.cpp event_loop.cpp event_loop.hpp
+	$(CXX) $(CXXFLAGS) camera.cpp event_loop.cpp \
+		$(shell pkg-config --cflags --libs $(PKGS)) -lpthread \
+		-o camera
+
+clean:
+	rm -f camera
+
+.PHONY: clean

camera_example/README.md

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+# camera_example
+
+libcamera viewfinder (XRGB8888) -> libjpeg-turbo -> TCP. One client at a time.
+
+Wire format: `[uint32 BE jpeg_size][jpeg_bytes]` repeating.
+
+Knobs are constants at the top of `camera.cpp` (fps, quality, AF mode, lens
+position, port, resolution).
+
+## Build on the Pi
+
+    apt install g++ pkg-config libcamera-dev libevent-dev libjpeg-turbo8-dev
+    make
+
+## Cross-build (x86 -> armv6l) on a Nix host
+
+    nix build
+
+The resulting binary links against `/nix/store`, so it only runs on a Pi that
+has those libs available (i.e. nix installed). For a vanilla Pi OS target,
+use the Makefile on the device, or `./deploy.sh user@host` to rsync+build.
+
+## Receive
+
+Any TCP client that reads the framed JPEGs. Quick check:
+
+    nc <pi-ip> 5000 | ffplay -f mjpeg -

camera_example/deploy.sh

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+#!/usr/bin/env sh
+# Push sources to the Pi and build there.
+#   usage:  ./deploy.sh me@10.91.51.165
+set -eu
+host=${1:-me@10.91.51.165}
+rsync -az --delete --exclude=camera --exclude=result \
+  ./ "$host:~/camera_example/"
+ssh "$host" 'cd ~/camera_example && make -j"$(nproc)"'
+echo "built at $host:~/camera_example/camera"