python 操作音视频的选择：ffmpeg-python 对比 pyav

ffmpeg 是音视频领域的王者，对音视频的操作，离不开 ffmpeg

在 python 生态下面使用 ffmpeg 有两个著名的库

• ffmpeg-python
• pyav

那推荐用哪个呢？

当然是后者：pyav

为什么？他两有什么区别？

那就是调用 ffmpeg 的方式不同

ffmpeg-python 是直接调用 ffmpeg 这个可执行程序来操作音视频的，这就要求你本地安装 ffmpeg。而且每次操作，都相当于是起了一个 ffmpeg进程，非常的低效。

而 pyav 是链接了 ffmpeg 的动态链接库 libav，所以不存在每次操作都启动一个 ffmpeg 进程的问题，更加高效优雅

---

使用 ffmpeg-python，如果本地没有安装 ffmpeg，就会报错如下：

In [1]: import ffmpeg
   ...: stream = ffmpeg.input('input.mp4')
   ...: stream = ffmpeg.hflip(stream)
   ...: stream = ffmpeg.output(stream, 'output.mp4')
   ...: ffmpeg.run(stream)
---------------------------------------------------------------------------
FileNotFoundError                         Traceback (most recent call last)
Cell In[1], line 5
      3 stream = ffmpeg.hflip(stream)
      4 stream = ffmpeg.output(stream, 'output.mp4')
----> 5 ffmpeg.run(stream)

File /usr/local/lib/python3.11/site-packages/ffmpeg/_run.py:313, in run(stream_spec, cmd, capture_stdout, capture_stderr, input, quiet, overwrite_output)
    289 @output_operator()
    290 def run(
    291     stream_spec,
   (...)
    297     overwrite_output=False,
    298 ):
    299     """Invoke ffmpeg for the supplied node graph.
    300 
    301     Args:
   (...)
    311     Returns: (out, err) tuple containing captured stdout and stderr data.
    312     """
--> 313     process = run_async(
    314         stream_spec,
    315         cmd,
    316         pipe_stdin=input is not None,
    317         pipe_stdout=capture_stdout,
    318         pipe_stderr=capture_stderr,
    319         quiet=quiet,
    320         overwrite_output=overwrite_output,
    321     )
    322     out, err = process.communicate(input)
    323     retcode = process.poll()

File /usr/local/lib/python3.11/site-packages/ffmpeg/_run.py:284, in run_async(stream_spec, cmd, pipe_stdin, pipe_stdout, pipe_stderr, quiet, overwrite_output)
    282 stdout_stream = subprocess.PIPE if pipe_stdout or quiet else None
    283 stderr_stream = subprocess.PIPE if pipe_stderr or quiet else None
--> 284 return subprocess.Popen(
    285     args, stdin=stdin_stream, stdout=stdout_stream, stderr=stderr_stream
    286 )

File /usr/local/lib/python3.11/subprocess.py:1026, in Popen.__init__(self, args, bufsize, executable, stdin, stdout, stderr, preexec_fn, close_fds, shell, cwd, env, universal_newlines, startupinfo, creationflags, restore_signals, start_new_session, pass_fds, user, group, extra_groups, encoding, errors, text, umask, pipesize, process_group)
   1022         if self.text_mode:
   1023             self.stderr = io.TextIOWrapper(self.stderr,
   1024                     encoding=encoding, errors=errors)
-> 1026     self._execute_child(args, executable, preexec_fn, close_fds,
   1027                         pass_fds, cwd, env,
   1028                         startupinfo, creationflags, shell,
   1029                         p2cread, p2cwrite,
   1030                         c2pread, c2pwrite,
   1031                         errread, errwrite,
   1032                         restore_signals,
   1033                         gid, gids, uid, umask,
   1034                         start_new_session, process_group)
   1035 except:
   1036     # Cleanup if the child failed starting.
   1037     for f in filter(None, (self.stdin, self.stdout, self.stderr)):

File /usr/local/lib/python3.11/subprocess.py:1950, in Popen._execute_child(self, args, executable, preexec_fn, close_fds, pass_fds, cwd, env, startupinfo, creationflags, shell, p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite, restore_signals, gid, gids, uid, umask, start_new_session, process_group)
   1948     if errno_num != 0:
   1949         err_msg = os.strerror(errno_num)
-> 1950     raise child_exception_type(errno_num, err_msg, err_filename)
   1951 raise child_exception_type(err_msg)

FileNotFoundError: [Errno 2] No such file or directory: 'ffmpeg'