How to Build an Automated Testing Suite with FFmpeg FATE

This guide provides a comprehensive walkthrough on how to set up, configure, and run an automated testing suite using the FFmpeg Automated Testing Environment (FATE). You will learn how to download the necessary test samples, configure FFmpeg to recognize them, execute local regression tests, and set up automated shell scripts for continuous integration.

Understanding FATE

FATE is the official regression testing system utilized by the FFmpeg project to ensure that code changes do not introduce bugs, break APIs, or degrade processing performance. By comparing the output of your build against reference files, FATE validates audio/video decoding, encoding, demuxing, muxing, and filtering behaviors.

Step 1: Prepare the Prerequisites

Before setting up FATE, ensure your system has the standard build tools and dependencies installed. You will need: * A C compiler (GCC or Clang) * GNU Make * Git (to clone the FFmpeg repository) * Rsync (to download the extensive FATE test suite samples)

Clone the official FFmpeg repository to your local machine:

git clone https://git.ffmpeg.org/ffmpeg.git ffmpeg
cd ffmpeg

Step 2: Download the FATE Test Samples

FATE compares build outputs against a standard suite of media files. This suite is large and must be downloaded via rsync. Define a local directory where you want to store these samples and run the following command from the root of your cloned FFmpeg directory:

make fate-rsync SAMPLES=/path/to/your/fate-suite

Ensure the path you specify is persistent, as the automated suite will need to reference this directory every time it runs.

Step 3: Configure FFmpeg with FATE Path

To link your compiled binary to the test suite, you must configure your FFmpeg build with the path to the downloaded samples. Run the configure script with the --samples flag:

./configure --samples=/path/to/your/fate-suite

If you plan to run tests on external libraries (like libx264, libvpx, or libopus), ensure you enable those libraries during this configuration step (e.g., --enable-gpl --enable-libx264). FATE automatically skips tests for components that are not enabled in your current build.

Step 4: Run FATE Locally

Once configuration is complete, compile FFmpeg and execute the test suite using GNU Make:

make -j$(nproc)
make fate

The system will execute hundreds of tests sequentially. A successful run will output test passed for each test case. If a test fails, FATE will output a diff showing the discrepancy between your build’s output and the official reference.

To run a specific test rather than the entire suite, you can target it directly:

make fate-filter-transpose

Step 5: Automating FATE Runs

To turn this setup into a fully automated testing suite (ideal for cron jobs or CI/CD pipelines), use the built-in FATE automated shell script. FFmpeg provides a template configuration file located in the source tree.

  1. Copy the configuration template:

    cp doc/fate_config.sh.template fate_config.sh

  2. Edit fate_config.sh to match your local paths and build specifications. Key variables to configure include:

    • slot: A unique name for your testing build.
    • src: Path to your FFmpeg source code directory.
    • build_dir: Path where compilation will occur.
    • samples: Path to your fate-suite directory.
    • make: Path to your GNU Make executable.
    • tar: Path to your tar utility.

  3. Execute the automated test script:

    tests/fate.sh fate_config.sh

This script will automatically update the git source, compile the codebase, execute the test suite, and generate a comprehensive log file. You can hook this script into a nightly cron job or your Jenkins/GitHub Actions pipeline to achieve true continuous automated testing.