在 Python 脚本中使用 FFProbe

Question

我是 python 的新手，这是我的第一个真正的项目，我遇到了障碍。我这里有一个 .wmv 文件，我正在使用 FFprobe 从 .wmv 文件中提取以秒为单位的持续时间。当我运行在CMD中执行以下命令时：

ffprobe -i Video2.wmv -show_entries format=duration -v quiet -of csv="p=0"

我得到了成功的输出。

但是，当我使用 os.system 时，像这样：

os.system('ffprobe -i Video2.wmv -show_entries format=duration -v quiet -of csv="p=0"')

我得到以下输出：

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

这非常令人困惑，我无法在网上找到解决这个确切问题的方法，非常感谢任何意见。

Answer 1

Python 找不到 ffprobe，因为它不在您的环境变量中。 This youtube video shows how to properly install it, as does this wikihow page（方法 2），我将从这里引用：

Enabling FFmpeg in the Command Line

Click the Start button and right-click on Computer. Select Properties from the right-click menu. In the System window, click on the “Advanced system settings” link in the left frame.

Click the Environmental Variables button in the System Properties window. It will be located at the bottom of the window.

Select the PATH entry in the "User variables" section. This is located in the first frame in the Environmental Variables window. Click the Edit button. In the “Variable value” field, enter ;c:\ffmpeg\bin after anything that's already written there. If you copied it to a different drive, change the drive letter. Click OK to save your changes. If anything is entered incorrectly in this screen, it could cause Windows to be unable to boot properly. If there is no PATH entry in the "User variables" setting, click the New button and create one. Enter PATH for the variable name. This method will enable FFmpeg for the current user. Other Windows users will not be able to run it from the command line. To enable it for everyone, enter ;c:\ffmpeg\bin in the PATH entry in "System variables". Be very careful not to delete anything that is already in this variable.

Open the command prompt. Enter the command “ffmpeg –version”. If the command prompt returns the version information for FFmpeg, then the installation was successful, and FFmpeg can be accessed from any folder in the command prompt.

If you receive a “libstdc++ -6 is missing” error, you may need to install the Microsoft Visual C++ Redistributable Package, which is available for free from Microsoft.

希望对您有所帮助。

附带说明一下，我认为 os.system 不再是像这样调用命令行的推荐方式。

我建议改用子流程（改编自代码 here）：

import subprocess
import shlex
import json
def get_duration(file_path_with_file_name):

    cmd = 'ffprobe -show_entries format=duration -v quiet -of csv="p=0"'
    args = shlex.split(cmd)
    args.append(file_path_with_file_name)
    # run the ffprobe process, decode stdout into utf-8 & convert to JSON
    ffprobe_output = subprocess.check_output(args).decode('utf-8')

    ffprobe_output = json.loads(ffprobe_output)

    return ffprobe_output