Torchaudio is not detecting FFmpeg

🐛 Describe the bug

Hi everyone,

I am trying to use torchaudio with FFmpeg but for some reason it is not being detected.

import torchaudio
print(torchaudio.list_audio_backends())

I added the path 'C:\Program Files\ffmpeg\bin' to the PATH environment variable. As you can see I can execute ffmpeg from cmd. However, when I execute torchaudio.list_audio_backends() only 'soundfile' is detected. I tested this in a Python PIP (I can't use conda) virtual environment with version 3.10 and in another one with version 3.12 but, it didn't work in both. Torchaudio and torch versions are 2.2.1. I don't know if it is a problem with version compatibility but in the official documentation I saw ffmpeg 6 is supported and I checked the code which tries to load the libraries.

I checked a lot of related issues but I couldn't find the right solution.

Any suggestions are welcome!
Thanks.

Versions

Collecting environment information...

PyTorch version: 2.2.1+cpu
Is debug build: False
CUDA used to build PyTorch: Could not collect
ROCM used to build PyTorch: N/A
OS: Microsoft Windows Server 2022 Standard
GCC version: Could not collect
Clang version: Could not collect
CMake version: Could not collect
Libc version: N/A

Python version: 3.10.7 (tags/v3.10.7:6cc6b13, Sep  5 2022, 14:08:36) [MSC v.1933 64 bit (AMD64)] (64-bit runtime)
Python platform: Windows-10-10.0.20348-SP0
Is CUDA available: False
CUDA runtime version: 12.3.103
CUDA_MODULE_LOADING set to: N/A
GPU models and configuration: GPU 0: NVIDIA A100-PCIE-40GB
Nvidia driver version: 546.12
cuDNN version: Could not collect
HIP runtime version: N/A
MIOpen runtime version: N/A
Is XNNPACK available: True

CPU:
'wmic' is not recognized as an internal or external command,
operable program or batch file.

Versions of relevant libraries:

[pip3] numpy==1.26.4
[pip3] pytorch-lightning==2.2.4
[pip3] pytorch-metric-learning==2.5.0
[pip3] torch==2.2.1
[pip3] torch-audiomentations==0.11.1
[pip3] torch-pitch-shift==1.2.4
[pip3] torchaudio==2.2.1
[pip3] torchmetrics==1.4.0
[conda] Could not collect

Start by reproducing the report in a Python pip virtual environment on Windows Server 2022 with torch and torchaudio 2.2.1, then run torchaudio.list_audio_backends(). Inspect the FFmpeg library-loading code mentioned in the issue and compare it with the Windows PATH setup and FFmpeg 6 support described there. Done means identifying why only soundfile is detected and confirming the behavior or required change.