The FPV Camera serves a video stream as the first person view (FPV) of the Robot. This makes it possible to see the position of the Robot and anything in its way.

A 3d Printed mount for the Bosch40x40 profile was made to stick a polie on it so that the camera gets a better view. The camera is set in a case which was designed with a litte roof to prevent raindrops on the lense.

[picture of 40×40 clip with pole and camera case(n/a)]

The following hardware is used for capturing and broadcasting the video stream:

• Raspberry Pi 4B (8GB) by element14
• element14 Raspberry Pi CSI camera v.2 NoIR
• USB-C cable
• Heatsinks
• Fan
• Case
• SD-Card

The SD-Card has been flashed with an Ubuntu 20.10 arm64-raspi OS. The Pi is configured with the following user:

• user name: pi
• password: farmrobot

Its connectable via ethernet or build in wifi module.

An initial update has been run:

sudo apt update && sudo apt upgrade

Also some config changes have been made:

sudo nano /boot/firmware/config.txt [gpu_mem=512 ; start_x=1]

sudo apt install v4l-utils
sudo apt install ffmpeg
sudo apt install openssh-server sudo ufw allow ssh ssh pi@farmrobot

Bash script stream.sh:

ffmpeg -f v4l2 -input_format h264 -video_size 852x480 -framerate 5 -i /dev/video0>
-c:v h264 -preset veryfast -b:v 500k -maxrate 500k -bufsize 10k \
-pix_fmt yuv420p -g 10 \
-f flv "rtmp://ingest_server/streamkey" 

Using v4l2m2m encoder to have arm64 hardware support to efficiently encode a efficient h.265 stream which is sent via rtmp to a server which reencodes to hls to view video stream in a browser.

Building ffmpeg from source for the newest release and support for v4l_m2m hardware encoding on 64 bit arm.

cd/home/pi/ mkdir -p ~/ffmpeg_sources ~/ffmpeg_build ~/bin

(installing to /home/pi/bin/ to avoid conflicts with the system package folder)

According to https://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu a lot of dependancies have to be installed beforehand:

sudo apt-get update -qq && sudo apt-get -y install \
autoconf \
automake \
build-essential \
cmake \
git-core \
libass-dev \
libfreetype6-dev \
libgnutls28-dev \
libsdl2-dev \
libtool \
libva-dev \
libvdpau-dev \
libvorbis-dev \
libxcb1-dev \
libxcb-shm0-dev \
libxcb-xfixes0-dev \
meson \
ninja-build \
pkg-config \
texinfo \
wget \
yasm \
zlib1g-dev \
libunistring-dev

installing libaries, chosing wich are needed:

NASM (An assembler used by some libraries.)

cd ~/ffmpeg_sources &&
wget https://www.nasm.us/pub/nasm/releasebuilds/2.15.05/nasm-2.15.05.tar.bz2 &&
tar xjvf nasm-2.15.05.tar.bz2 &&
cd nasm-2.15.05 &&
./autogen.sh &&
PATH="$HOME/bin:$PATH" ./configure --prefix="$HOME/ffmpeg_build" --bindir="$HOME/bin" &&
make -j 4 &&
make install

libx264 (H.264 video encoder, fallback)

cd ~/ffmpeg_sources &&
git -C x264 pull 2> /dev/null || git clone --depth 1 https://code.videolan.org/videolan/x264.git &&
cd x264 &&
PATH="$HOME/bin:$PATH" PKG_CONFIG_PATH="$HOME/ffmpeg_build/lib/pkgconfig" ./configure --prefix="$HOME/ffmpeg_build" --bindir="$HOME/bin" --enable-static --enable-pic &&
PATH="$HOME/bin:$PATH" make -j 4 &&
make install

libx265 (H.265/HEVC video encoder)

sudo apt-get install libnuma-dev &&
cd ~/ffmpeg_sources &&
git -C x265_git pull 2> /dev/null || git clone https://bitbucket.org/multicoreware/x265_git &&
cd x265_git/build/linux &&
PATH="$HOME/bin:$PATH" cmake -G "Unix Makefiles" -DCMAKE_INSTALL_PREFIX="$HOME/ffmpeg_build" -DENABLE_SHARED=off ../../source &&
PATH="$HOME/bin:$PATH" make -j 4 &&
make install

libvpx (VP8/VP9 video encoder/decoder, another efficient video encoder, needs testing)

cd ~/ffmpeg_sources &&
git -C libvpx pull 2> /dev/null || git clone --depth 1 https://chromium.googlesource.com/webm/libvpx.git &&
cd libvpx &&
PATH="$HOME/bin:$PATH" ./configure --prefix="$HOME/ffmpeg_build" --disable-examples --disable-unit-tests --enable-vp9-highbitdepth --as=yasm &&
PATH="$HOME/bin:$PATH" make -j 4 &&
make install

libaom (AV1 video encoder/decoder)

cd ~/ffmpeg_sources &&
git -C aom pull 2> /dev/null || git clone --depth 1 https://aomedia.googlesource.com/aom &&
mkdir -p aom_build &&
cd aom_build &&
PATH="$HOME/bin:$PATH" cmake -G "Unix Makefiles" -DCMAKE_INSTALL_PREFIX="$HOME/ffmpeg_build" -DENABLE_SHARED=off -DENABLE_NASM=on ../aom &&
PATH="$HOME/bin:$PATH" make -j 4 &&
make install

libsvtav (AV1 video encoder/decoder)

cd ~/ffmpeg_sources &&
git -C SVT-AV1 pull 2> /dev/null || git clone https://gitlab.com/AOMediaCodec/SVT-AV1.git &&
mkdir -p SVT-AV1/build &&
cd SVT-AV1/build &&
PATH="$HOME/bin:$PATH" cmake -G "Unix Makefiles" -DCMAKE_INSTALL_PREFIX="$HOME/ffmpeg_build" -DCMAKE_BUILD_TYPE=Release -DBUILD_DEC=OFF -DBUILD_SHARED_LIBS=OFF .. &&
PATH="$HOME/bin:$PATH" make -j 4 &&
make install

libdav1d (AV1 decoder, much faster than the one provided by libaom Users whose distributions don't provide a recent enough version of meson (0.49.0 or newer) will need to install a more up-to-date version. This is easily done via the Python Package Index: sudo apt-get install python3-pip && pip3 install –user meson

cd ~/ffmpeg_sources &&
git -C dav1d pull 2> /dev/null || git clone --depth 1 https://code.videolan.org/videolan/dav1d.git &&
mkdir -p dav1d/build &&
cd dav1d/build &&
meson setup -Denable_tools=false -Denable_tests=false --default-library=static .. --prefix "$HOME/ffmpeg_build" --bindir="$HOME/bin" --libdir="$HOME/ffmpeg_build/lib" &&
ninja &&
ninja install

Audio libaries are probably needed for building, especially libfdk_aac for vpx libfdk-aac (AAC audio encoder)

cd ~/ffmpeg_sources &&
git -C fdk-aac pull 2> /dev/null || git clone --depth 1 https://github.com/mstorsjo/fdk-aac &&
cd fdk-aac &&
autoreconf -fiv && ./configure --prefix="$HOME/ffmpeg_build" --disable-shared &&
make -j 4 &&
make install

libmp3lame libopus

Building FFmpeg

cd ~/ffmpeg_sources &&
wget -O ffmpeg-snapshot.tar.bz2 https://ffmpeg.org/releases/ffmpeg-snapshot.tar.bz2 &&
tar xjvf ffmpeg-snapshot.tar.bz2 &&
cd ffmpeg &&
PATH="$HOME/bin:$PATH" PKG_CONFIG_PATH="$HOME/ffmpeg_build/lib/pkgconfig" ./configure
--prefix="$HOME/ffmpeg_build"
--pkg-config-flags="--static"
--extra-cflags="-I$HOME/ffmpeg_build/include"
--extra-ldflags="-L$HOME/ffmpeg_build/lib"
--extra-libs="-lpthread -lm"
--bindir="$HOME/bin"
--enable-gpl
--arch=aarch64
--enable-gnutls
--enable-libaom
--enable-libsvtav1
--enable-libdav1d
--enable-libvpx
--enable-libx264
--enable-libx265
--enable-nonfree &&
PATH="$HOME/bin:$PATH" make -j 4 &&
make install &&
hash -r

source ~/.profile

* Jonas Geßmann, Environment & Energy, jonas.gessmann@protonmail.com
* Nicolas Wiehe