This example combines and integrates two simpler examples, the video decoder and the deep learning server.
The video decoder uses openh264 to decode an H264 video into individual frames, which are converted to RGB and made palatable to an object detector built on top of the Darknet neural network framework. The output is a list of detected objects, associated with their detection probability, and an optional prediction image showing each detected object in a bounding box.

• Install wasi sdk 14 and set WASI_SDK_ROOT to point to its installation directory:

  $ export WASI_VERSION=14 && \
  export WASI_VERSION_FULL=${WASI_VERSION}.0 && \
  wget https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-${WASI_VERSION}/wasi-sdk-${WASI_VERSION_FULL}-linux.tar.gz && \
  tar xvf wasi-sdk-${WASI_VERSION_FULL}-linux.tar.gz && \
  echo "export WASI_SDK_ROOT=\"${PWD}/wasi-sdk-${WASI_VERSION_FULL}\"" >> ~/.bashrc && \
  . ~/.bashrc

• Install nasm (Ubuntu):

  $ apt-get update && apt-get install -y nasm

• Clone the repo and update the submodules:

  $ git clone https://github.com/veracruz-project/video-object-detection -b main && \
  cd video-object-detection && \
  git submodule update --init

• Build openh264, openh264-dec, darknet and the main program (VOD) to WebAssembly:

  $ make

• Build VOD as a native binary (optional):

  $ make -f Makefile_native

• Download the YOLO models and configuration files and the COCO object list:

  $ mkdir -p program_data && \
  wget -P program_data \
  https://github.com/veracruz-project/video-object-detection/releases/download/20230406/yolov3.weights \
  https://github.com/veracruz-project/video-object-detection/releases/download/20230406/yolov3-tiny.weights \
  https://github.com/veracruz-project/video-object-detection/releases/download/20230406/yolov3.cfg \
  https://github.com/veracruz-project/video-object-detection/releases/download/20230406/yolov3-tiny.cfg \
  https://github.com/veracruz-project/video-object-detection/releases/download/20230406/coco.names

• Generate the alphabet (optional). Requires imagemagick:

  $ apt-get update && apt-get install -y imagemagick && \
  make generate_alphabet

• Cut the MP4 video to a specific amount of frames (optional):

  $ ffmpeg -i in.mp4 -vf trim=start_frame=0:end_frame=<END_FRAME> -an in_cut.mp4

• Generate the input H.264 video from the MP4 video:

  $ ffmpeg -i in.mp4 -map 0:0 -vcodec copy -an -f h264 in.h264

• Note that an example H264 video is available in the release assets:

  $ mkdir -p video_input && \
  wget -P video_input https://github.com/veracruz-project/video-object-detection/releases/download/20230406/in.h264

• The program is expecting the following file tree:

  + output/           (prediction images outputted by the program)
  + program_data/     (data read by the program)
  +-- coco.names      (list of detectable objects)
  +-- labels/         (alphabet (optional))
  +---- *.png
  +-- yolov3.cfg      (configuration)
  +-- yolov3.weights  (model)
  + video_input/
  +-- in.h264         (H264 video)
  

Running the program outside Veracruz is useful to validate the program without considering the policy and the TEE backend it runs on.
There are several ways to do that. In any case the file tree must be mirrored on the executing machine.
Trick: To run VOD faster, replace the big YOLO model (yolov3.*) with the tiny one (yolov3-tiny.*).

• Build as a native binary (cf. build steps above)
• Run:

  $ mkdir -p output && \
  ./detector

• Install wasmtime
• Run:

  $ mkdir -p output && \
  wasmtime --dir=. detector.wasm

• Build the freestanding execution engine
• Run:

  $ mkdir -p program && \
  cp detector.wasm program && \
  mkdir -p output && \
  RUST_LOG=info RUST_BACKTRACE=1 freestanding-execution-engine -i video_input -i program -i program_data -i output -r program/detector.wasm

An application (program, data and policy) can't be validated until the program and data are provisioned by a Veracruz client to the Runtime Manager, the policy gets verified and the program successfully executes within the enclave.
The crux of an end-to-end deployment is to get the policy file right. To that end, a collection of deployment scripts are provided and take care of generating the certificates and the policy based on the program's file tree.

• Build Veracruz
• Depending on your environment and how you want to run VOD (WebAssembly program or provisioned native module), run the appropriate deployment script (./deploy_*.sh) inside a Docker container (the same as the one used to build Veracruz). This will generate the policy, deploy the Veracruz components and run the computation. Note that you must separately build the native module sandboxer prior to running dynamic or provisioned native modules. Also note that provisioned native modules are not supported on Nitro yet, so just ignore deploy_nitro_pnm.sh for now
• The prediction images can be found in the executing directory