Torchvision backend does not work

I am not able to run torchvision as the backend while running SlowFast. I came across some people mentioning that they managed to run torchvision after they reinstalled it from source, however, I am still not able to use it after reinstalling it from the source. I can still build torchvision from source but receive the warning: "ffmpeg version not found, installing without ffmpeg support" and then, when I run SlowFast, it fails to fetch the videos.

You can find the packages I have installed below and I would really appreciate it if you can share your versions, especially:

- torch, torchvision
- pytorchvideo
- PyAV
- FFMPEG

in case you are able to run SlowFast with torchvision as the backend.

Here is my _pip list_ output:

> Package Version Location
> ----------------------- --------- ---------------------------------
> absl-py 1.1.0
> antlr4-python3-runtime 4.9.3
> av 9.2.0
> black 22.3.0
> brotlipy 0.7.0
> cachetools 5.2.0
> certifi 2022.6.15
> cffi 1.14.6
> charset-normalizer 2.1.0
> click 8.1.3
> cloudpickle 2.1.0
> colorama 0.4.5
> cryptography 37.0.2
> cycler 0.11.0
> Cython 0.29.30
> decorator 5.1.1
> detectron2 0.6 /home/alp/Desktop/detectron2_repo
> fairscale 0.4.6
> fonttools 4.34.4
> future 0.18.2
> fvcore 0.1.5
> google-auth 2.9.0
> google-auth-oauthlib 0.4.6
> grpcio 1.47.0
> hydra-core 1.2.0
> idna 3.3
> imageio 2.9.0
> imageio-ffmpeg 0.4.7
> importlib-metadata 4.12.0
> iopath 0.1.9
> joblib 1.1.0
> kiwisolver 1.4.3
> Markdown 3.3.7
> matplotlib 3.5.2
> mkl-fft 1.3.1
> mkl-random 1.2.2
> mkl-service 2.4.0
> moviepy 1.0.3
> mypy-extensions 0.4.3
> networkx 2.8.4
> numpy 1.22.3
> oauthlib 3.2.0
> olefile 0.46
> omegaconf 2.2.2
> opencv-python 4.6.0.66
> packaging 21.3
> pandas 1.4.3
> parameterized 0.8.1
> pathspec 0.9.0
> Pillow 8.2.0
> pip 21.2.4
> platformdirs 2.5.2
> portalocker 2.4.0
> proglog 0.1.9
> protobuf 3.19.4
> psutil 5.9.1
> pyasn1 0.4.8
> pyasn1-modules 0.2.8
> pycocotools 2.0.4
> pycparser 2.21
> pydot 1.4.2
> pyOpenSSL 22.0.0
> pyparsing 3.0.9
> PySocks 1.7.1
> python-dateutil 2.8.2
> pytorchvideo 0.1.5
> pytz 2022.1
> PyYAML 6.0
> requests 2.28.1
> requests-oauthlib 1.3.1
> rsa 4.8
> scikit-learn 1.1.1
> scipy 1.9.0rc2
> setuptools 61.2.0
> simplejson 3.17.6
> six 1.16.0
> sklearn 0.0
> slowfast 1.0 /home/alp/Desktop/SlowFast
> tabulate 0.8.10
> tensorboard 2.9.1
> tensorboard-data-server 0.6.1
> tensorboard-plugin-wit 1.8.1
> termcolor 1.1.0
> threadpoolctl 3.1.0
> timm 0.5.4
> tomli 2.0.1
> torch 1.12.0
> torchaudio 0.12.0
> torchvision 0.13.0
> tqdm 4.64.0
> typing_extensions 4.3.0
> urllib3 1.26.10
> Werkzeug 2.1.2
> wheel 0.37.1
> yacs 0.1.8
> zipp 3.8.0