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Playable Video Generation

Playable Video Generation<br> Willi Menapace, Stéphane Lathuilière, Sergey Tulyakov, Aliaksandr Siarohin, Elisa Ricci<br> CVPR 2021 (Oral)

Paper: ArXiv<br> Supplementary: Website<br> Demo: Try it Live<br>

Abstract: This paper introduces the unsupervised learning problem of playable video generation (PVG). In PVG, we aim at allowing a user to control the generated video by selecting a discrete action at every time step as when playing a video game. The difficulty of the task lies both in learning semantically consistent actions and in generating realistic videos conditioned on the user input. We propose a novel framework for PVG that is trained in a self-supervised manner on a large dataset of unlabelled videos. We employ an encoder-decoder architecture where the predicted action labels act as bottleneck. The network is constrained to learn a rich action space using, as main driving loss, a reconstruction loss on the generated video. We demonstrate the effectiveness of the proposed approach on several datasets with wide environment variety.

Overview

Given a set of completely unlabeled videos, we jointly learn a set of discrete actions and a video generation model conditioned on the learned actions. At test time, the user can control the generated video on-the-fly providing action labels as if he or she was playing a videogame. We name our method CADDY. Our architecture for unsupervised playable video generation is composed by several components. An encoder E extracts frame representations from the input sequence. A temporal model estimates the successive states using a recurrent dynamics network R and an action network A which predicts the action label corresponding to the current action performed in the input sequence. Finally, a decoder D reconstructs the input frames. The model is trained using reconstruction as the main driving loss.

Requirements

We recommend the use of Linux and of one or more CUDA compatible GPUs. We provide both a Conda environment and a Dockerfile to configure the required libraries.

Conda

The environment can be installed and activated with:

conda env create -f env.yml

conda activate video-generation

Docker

Use the Dockerfile to build the docker image:

docker build -t video-generation:1.0 .

Run the docker image mounting the root directory to /video-generation in the docker container:

docker run -it --gpus all --ipc=host -v /path/to/directory/video-generation:/video-generation video-generation:1.0 /bin/bash

Preparing Datasets

BAIR

Download the bair_256_ours.tar.gz archive from Google Drive and extract it under the data folder.

We thank Frederik Ebert and the Berkeley Artificial Intelligence Research Lab for providing us with the high resolution version of their BAIR robot-pushing dataset.

Atari Breakout

Download the breakout_v2_160_ours.tar.gz archive from Google Drive and extract it under the data folder.

Tennis

The Tennis dataset is automatically acquired from Youtube by running

./get_tennis_dataset.sh

This requires an installation of youtube-dl (Download). Please run youtube-dl -U to update the utility to the latest version. The dataset will be created at data/tennis_v4_256_ours.

Custom Datasets

Custom datasets can be created from a user-provided folder containing plain videos. Acquired video frames are sampled at the specified resolution and framerate. ffmpeg is used for the extraction and supports multiple input formats. By default only mp4 files are acquired.

python -m dataset.acquisition.convert_video_directory --video_directory <input_directory> --output_directory <output_directory> --target_size <width> <height> [--fps <fps> --video_extension <extension_of_videos> --processes <number_of_parallel_processes>]

As an example the following command transforms all mp4 videos in the tmp/my_videos directory into a 256x256px dataset sampled at 10fps and saves it in the data/my_videos folder python -m dataset.acquisition.convert_video_directory --video_directory tmp/my_videos --output_directory data/my_videos --target_size 256 256 --fps 10

Using Pretrained Models

Pretrained models in .pth.tar format are available for all the datasets and can be downloaded at the following link: Google Drive

Please place each directory under the checkpoints folder. Training and inference scripts automatically make use of the latest.pth.tar checkpoint when present in the checkpoints subfolder corresponding to the configuration in use.

Playing

When a latest.pth.tar checkpoint is present under the checkpoints folder corresponding to the current configuration, the model can be interactively used to generate videos with the following commands:

• Bair: python play.py --config configs/01_bair.yaml

• Breakout: python play.py configs/breakout/02_breakout.yaml

• Tennis: python play.py --config configs/03_tennis.yaml

A full screen window will appear and actions can be provided using number keys in the range [1, actions_count]. Number key 0 resets the generation process.

The inference process is lightweight and can be executed even in browser as in our Live Demo.

Training

The models can be trained with the following commands:

python train.py --config configs/<config_file>

The training process generates multiple files under the results and checkpoint directories a sub directory with the name corresponding to the one specified in the configuration file. In particular, the folder under the results directory will contain an images folder showing qualitative results obtained during training. The checkpoints subfolder will contain regularly saved checkpoints and the latest.pth.tar checkpoint representing the latest model parameters.

The training can be completely monitored through Weights and Biases by running before execution of the training command: wandb init

Training the model in full resolution on our datasets required the following GPU resources:

• BAIR: 4x2080Ti 44GB
• Breakout: 1x2080Ti 11GB
• Tennis: 2x2080 16GB

Lower resolution versions of the model can be trained with a single 8GB GPU.

Evaluation

Evaluation requires two steps. First, an evaluation dataset must be built. Second, evaluation is carried out on the evaluation dataset. To build the evaluation dataset please issue:

python build_evaluation_dataset.py --config configs/<config_file>

The command creates a reconstruction of the test portion of the dataset under the results/<run_name>/evaluation_dataset directory. To run evaluation issue:

python evaluate_dataset.py --config configs/evaluation/configs/<config_file>

Evaluation results are saved under the evaluation_results directory the folder specified in the configuration file with the name data.yml.