python执行ffmpeg命令

能拿到ffmpeg正常输出

ffmpeg抛出异常时可以拿到异常信息

返回ffmpeg处理进度

以下代码依赖的pexpect,progressbar需要安装下

import pexpect

import subprocess

import progressbar

import logging

def exec_progress(command, video_duration_seconds):

"""

执行ffmpeg命令，并根据ffmpeg输出中的"time=xxx"匹配进度, ffmpeg执行失败时抛出FfmpegException

:param command: ffmpeg命令

:param video_duration_seconds: 视频总时长

"""

thread = pexpect.spawn(command)

cpl = thread.compile_pattern_list([pexpect.EOF,

"frame=.*time=([\d:\.]*)(.*)",

'(.+)'])

progress = progressbar.ProgressBar(max_value=video_duration_seconds).start()

output_list = []

while True:

i = thread.expect_list(cpl, timeout=None)

if i == 0:

progress.finish()

break

elif i == 1:

seconds = duration_to_seconds(thread.match.group(1))

progress.update(seconds)

elif i == 2:

logging.debug(thread.match.group(0))

output_list.append(thread.match.group(0))

pass

thread.close()

if thread.exitstatus:

raise FfmpegException(thread.exitstatus, command, "\n".join(output_list))

def exec_output(command):

"""

执行ffmpeg命令并返回所有输出，如果执行失败，抛出FfmpegException

:param command: ffmpeg命令

:return: ffmpeg标准输出

"""

try:

process = subprocess.check_output(command, shell=True, stderr=subprocess.STDOUT)

return process

except subprocess.CalledProcessError as err:

raise FfmpegException(err.returncode, err.cmd, err.output)

# 这个方法应该单独抽到别的模块

def duration_to_seconds(duration):

time_arr = duration[0:duration.find(".")].split(":")

if len(time_arr) == 3:

return int(time_arr[0]) * 3600 + int(time_arr[1]) * 60 + int(time_arr[2])

logging.error("unrecognized duration %s", duration)

return 0

class FfmpegException(Exception):

"""

使用ffmpeg报错时抛出

"""

def __init__(self, returncode, cmd, output=None):

self.returncode = returncode

self.cmd = cmd

self.output = output

def __str__(self):

return "Command '%s' returned non-zero exit status %d" % (self.cmd, self.returncode)

简单说明下

exec_progress执行耗时较长需要实时拿到处理进度的场景，如压缩，裁剪等

exec_output执行耗时较短直接拿到输出结果的场景，如获取视频信息等