Codec-Compare-Gen

Simple C++ framework to generate codec compression performance comparison data. Codecs are used to compress and decompress images using their library APIs for better encoding and decoding timing (to exclude file loading from the recorded duration), compared to calling separately built codec binaries. It also centralizes data set reading, to avoid metadata or sample handling differences.

The generated data can be displayed using Codec-Compare.

Introduction

Build tools/ccgen.cc and look at the description given by the --help flag.

The libccgen API entrypoint lies in src/framework.h.

CMake build

The following instructions are used to build the library and the ccgen command line tool.

Clone the codec-compare-gen repository. Then run from its root folder:

./deps.sh
cmake -S . -B build -DCMAKE_CXX_COMPILER=clang++
cmake --build build

Generate JSON data

Example Unix command line:

mkdir -p output/encoded
build/ccgen \
  --codec webp 444 9 \
  --codec webp2 444 6 \
  --codec jpegxl 444 7 \
  --codec avif 444 6 \
  --codec combination 444 5 \
  --lossless \
  --repeat 15 \
  --threads $(($(nproc) - 1)) \
  --progress_file "output/progress.csv" \
  --results_folder "output/" \
  --encoded_folder "output/encoded" \
  -- "tests/data"

• tests/data is used as input images.
• output/progress.csv will contain the metrics of each encoding/decoding (file size, timings, distortion). This is useful to be able to start the benchmark from where it left off in case it was halted.
• output/ will contain one JSON file per codec configuration, aggregated over all repetitions to smooth the timings.
• output/encoded will contain the compressed image files.

Tests

The following instructions are used to make sure the unit tests pass. libgtest-dev must be installed on the system. Run deps.sh if not done yet.

cmake -S . -B build -DBUILD_TESTING=ON -DCMAKE_CXX_COMPILER=clang++
cmake --build build --parallel
ctest --test-dir build --output-on-failure

C++ style

Use the following to format the code:

clang-format -style=file -i src/*.cc src/*.h tests/*.cc tools/*.cc

License

See the Apache v2.0 license file.