On windows 10, bug on _check_executable and on formatting a ffmpeg cmd to execute

Hello, hope this will be useful for someone.

Checklist

I have searched related issues but cannot get the expected help: Yes
I have read the FAQ documentation but cannot get the expected help: Yes
The unexpected results still exist in the latest version.: Yes

Describe the Issue Two bugs here can be triggered by the same code snippet on Windows.

First bug : When a mmcv function needs an external command (ffmpeg in my case), it triggers mmcv.utils.py : check_prerequisites() function, which calls _check_executable() for the existence of ffmpeg, by testing "which ffmpeg" as a shell command. As which is a linux only command, this triggers a "RuntimeError: Prerequisites not meet."
Second bug : When a mmcv function is formatting a shell command for ffmpeg, it seems to lack robustness on spaces in Windows paths.

Reproduction

What command, code, or script did you run? The two bugs can be triggered with :

mmcv.video.resize_video(in_file='C:/Users/Name Surname/Documents/prog/test_windows_linux_mmcv/input/in.mp4',
                        out_file='C:/Users/Name Surname/Documents/prog/test_windows_linux_mmcv/output/out.mp4',
                        size=(512, 214),
                        log_level='warning')

Did you make any modifications on the code? Did you understand what you have modified? No modification have been made to trigger the errors.

Environment

Please run python -c "from mmcv.utils import collect_env; print(collect_env())" to collect necessary environment information and paste it here.

I'm using Windows 10, and this is the result of collect_env():

'tail' n'est pas reconnu en tant que commande interne
ou externe, un programme ex�cutable ou un fichier de commandes.
'gcc' n'est pas reconnu en tant que commande interne
ou externe, un programme ex�cutable ou un fichier de commandes.
{'sys.platform': 'win32', 'Python': '3.9.12 (main, Apr  4 2022, 05:22:27) [MSC v.1916 64 bit (AMD64)]', 'CUDA available': True, 'GPU 0': 'NVIDIA GeForce GTX 1660 Ti', 'CUDA_HOME': 'C:\\Program Files\\NVIDIA GPU Computing Toolkit\\CUDA\\v11.3', 'NVCC': 'Not Available', 'GCC': 'n/a', 'PyTorch': '1.11.0', 'PyTorch compiling details': 'PyTorch built with:\n  - C++ Version: 199711\n  - MSVC 192829337\n  - Intel(R) Math Kernel Library Version 2020.0.2 Product Build 20200624 for Intel(R) 64 architecture applications\n  - Intel(R) MKL-DNN v2.5.2 (Git Hash a9302535553c73243c632ad3c4c80beec3d19a1e)\n  - OpenMP 2019\n  - LAPACK is enabled (usually provided by MKL)\n  - CPU capability usage: AVX2\n  - CUDA Runtime 11.3\n  - NVCC architecture flags: -gencode;arch=compute_37,code=sm_37;-gencode;arch=compute_50,code=sm_50;-gencode;arch=compute_60,code=sm_60;-gencode;arch=compute_61,code=sm_61;-gencode;arch=compute_70,code=sm_70;-gencode;arch=compute_75,code=sm_75;-gencode;arch=compute_80,code=sm_80;-gencode;arch=compute_86,code=sm_86;-gencode;arch=compute_37,code=compute_37\n  - CuDNN 8.2\n  - Magma 2.5.4\n  - Build settings: BLAS_INFO=mkl, BUILD_TYPE=Release, CUDA_VERSION=11.3, CUDNN_VERSION=8.2.0, CXX_COMPILER=C:/cb/pytorch_1000000000000/work/tmp_bin/sccache-cl.exe, CXX_FLAGS=/DWIN32 /D_WINDOWS /GR /EHsc /w /bigobj -DUSE_PTHREADPOOL -openmp:experimental -IC:/cb/pytorch_1000000000000/work/mkl/include -DNDEBUG -DUSE_KINETO -DLIBKINETO_NOCUPTI -DUSE_FBGEMM -DUSE_XNNPACK -DSYMBOLICATE_MOBILE_DEBUG_HANDLE -DEDGE_PROFILER_USE_KINETO, LAPACK_INFO=mkl, PERF_WITH_AVX=1, PERF_WITH_AVX2=1, PERF_WITH_AVX512=1, TORCH_VERSION=1.11.0, USE_CUDA=ON, USE_CUDNN=ON, USE_EXCEPTION_PTR=1, USE_GFLAGS=OFF, USE_GLOG=OFF, USE_MKL=ON, USE_MKLDNN=OFF, USE_MPI=OFF, USE_NCCL=OFF, USE_NNPACK=OFF, USE_OPENMP=ON, USE_ROCM=OFF, \n', 'TorchVision': '0.12.0', 'OpenCV': '4.5.4', 'MMCV': '1.4.8', 'MMCV Compiler': 'MSVC 192930143', 'MMCV CUDA Compiler': '11.3'}

You may add addition that may be helpful for locating the problem, such as I installed in a conda environment, with
```
conda install pip
pip install mmcv-full==1.4.8
```

Error traceback First bug traceback :

'which' n'est pas reconnu en tant que commande interne
ou externe, un programme ex�cutable ou un fichier de commandes.
Traceback (most recent call last):
  File "C:\Users\David Traparic\Documents\prog\test_windows_linux_mmcv\trigger_bug_2.py", line 27, in <module>
    mmcv.video.resize_video(in_file='C:/Users/David Traparic/Documents/prog/test_windows_linux_mmcv/input/in.mp4',
  File "C:\Users\David Traparic\miniconda3\envs\testmmcv\lib\site-packages\mmcv\utils\misc.py", line 235, in wrapped_func
Prerequisites "ffmpeg" are required in method "resize_video" but not found, please install them first.
    raise RuntimeError('Prerequisites not meet.')
RuntimeError: Prerequisites not meet.

Second bug traceback (when first is fixed):

C:/Users/David: No such file or directory

Bug fix

First bug fix : In mmcv.utils.misc.py,

def _check_executable(cmd):
if subprocess.call(f'which {cmd}', shell=True) != 0:
    return False
else:
    return True

can be replaced by this to fix it:

import platform
def _check_executable(cmd):
    if platform.system() == 'Linux':
        if subprocess.call(f'which {cmd}', shell=True) != 0:
            return False
        else:
            return True
    if platform.system() == 'Windows':
        if subprocess.call(f'where {cmd}', shell=True) != 0:
            return False
        else:
            return True

Second bug : In mmcv.video.processing.py, inside convert_video() function,

cmd = f'ffmpeg -y {pre_options} -i {in_file} {" ".join(options)} ' \
      f'{out_file}'

can be replaced by this to fix it:

cmd = f'ffmpeg -y {pre_options} -i "{in_file}" {" ".join(options)} ' \
      f'"{out_file}"'

I have not tested the fixes on Linux, so I can't be sure it does not break anything.

open-mmlab / mmcv

On windows 10, bug on _check_executable and on formatting a ffmpeg cmd to execute #2470