Python未知参数：

Question

当我使用下面的脚本时，我得到了Unknown argument: |，我不知道为什么它不喜欢|。我在Windows上使用Python2.7.11：

import subprocess
from subprocess import Popen, PIPE, STDOUT
import time

command = 'VSPipe.exe --y4m script.vpy - | ffmpeg.exe -f yuv4mpegpipe -i - -c:v prores -an output.mov'

process1 = Popen(command, stderr=PIPE, shell=False)

while True:
    line = process1.stderr.readline().decode('utf-8')
    print line
    time.sleep(2)

更新:使用下面的建议，我现在已经尝试过了，但是我得到了pipe:: Operation not permitted。我做错了什么？

import subprocess
from subprocess import Popen, PIPE, STDOUT
import time

command1 = 'VSPipe.exe --y4m script.vpy -'
command2 = 'ffmpeg.exe -f yuv4mpegpipe -i - -c:v prores -an output.mov'

process1 = Popen(command1, stdout=PIPE)
process2 = Popen(command2, stdin=process1.stdout, stderr=PIPE)

print process2.communicate()

另一个更新:因此，使用下面的建议，并尝试其他东西，我一直得到相同的结果pipe:: Operation not permitted。这是完整的sdterr，我还能尝试什么呢？

"F:/ffmpeg/VapourSynth/VSPipe.exe" --y4m "C:/Users/myself/Desktop/script.vpy" - 
"F:/ffmpeg/ffmpeg.exe" -f yuv4mpegpipe -i - -c:v prores -an -y "//192.168.0.100/media/temp/OutMov.mov"
ffmpeg version N-77203-gb8e5b1d Copyright (c) 2000-2015 the FFmpeg developers
  built with gcc 5.2.0 (GCC)
  configuration: --arch=x86 --target-os=mingw32 --cross-prefix=/Users/myself/Desktop/Download/ffmpeg-windows-build-helpers-master/sandbox/mingw-w64-i686/bin/i686-w64-mingw32- --pkg-config=pkg-config --disable-w32threads --enable-gpl --enable-libsoxr --enable-fontconfig --enable-libass --enable-libutvideo --enable-libbluray --enable-iconv --enable-libtwolame --extra-cflags=-DLIBTWOLAME_STATIC --enable-libzvbi --enable-libcaca --enable-libmodplug --extra-libs=-lstdc++ --extra-libs=-lpng --enable-libvidstab --enable-libx265 --enable-decklink --extra-libs=-loleaut32 --enable-libx264 --enable-libxvid --enable-libmp3lame --enable-version3 --enable-zlib --enable-librtmp --enable-libvorbis --enable-libtheora --enable-libspeex --enable-libopenjpeg --enable-gnutls --enable-libgsm --enable-libfreetype --enable-libopus --enable-frei0r --enable-filter=frei0r --enable-libvo-aacenc --enable-bzlib --enable-libxavs --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libvo-amrwbenc --enable-libschroedinger --enable-libvpx --enable-libilbc --enable-libwavpack --enable-libwebp --enable-libgme --enable-dxva2 --enable-libdcadec --enable-avisynth --enable-gray --enable-libopenh264 --extra-libs=-lpsapi --extra-cflags= --enable-static --disable-shared --prefix=/Users/myself/Desktop/Download/ffmpeg-windows-build-helpers-master/sandbox/mingw-w64-i686/i686-w64-mingw32 --enable-nonfree --enable-libfdk-aac --disable-libfaac --enable-nvenc --enable-runtime-cpudetect
  libavutil      55. 10.100 / 55. 10.100
  libavcodec     57. 17.100 / 57. 17.100
  libavformat    57. 19.100 / 57. 19.100
  libavdevice    57.  0.100 / 57.  0.100
  libavfilter     6. 20.100 /  6. 20.100
  libswscale      4.  0.100 /  4.  0.100
  libswresample   2.  0.101 /  2.  0.101
  libpostproc    54.  0.100 / 54.  0.100
pipe:: Operation not permitted

更新:她是ffmpeg的报告：

F:/ffmpeg/ffmpeg.exe -f yuv4mpegpipe -i - -c:v prores -an -y //192.168.0.100/media/temp/OutMov.mov -report
ffmpeg version N-77203-gb8e5b1d Copyright (c) 2000-2015 the FFmpeg developers
  built with gcc 5.2.0 (GCC)
  configuration: --arch=x86 --target-os=mingw32 --cross-prefix=/Users/myself/Desktop/Download/ffmpeg-windows-build-helpers-master/sandbox/mingw-w64-i686/bin/i686-w64-mingw32- --pkg-config=pkg-config --disable-w32threads --enable-gpl --enable-libsoxr --enable-fontconfig --enable-libass --enable-libutvideo --enable-libbluray --enable-iconv --enable-libtwolame --extra-cflags=-DLIBTWOLAME_STATIC --enable-libzvbi --enable-libcaca --enable-libmodplug --extra-libs=-lstdc++ --extra-libs=-lpng --enable-libvidstab --enable-libx265 --enable-decklink --extra-libs=-loleaut32 --enable-libx264 --enable-libxvid --enable-libmp3lame --enable-version3 --enable-zlib --enable-librtmp --enable-libvorbis --enable-libtheora --enable-libspeex --enable-libopenjpeg --enable-gnutls --enable-libgsm --enable-libfreetype --enable-libopus --enable-frei0r --enable-filter=frei0r --enable-libvo-aacenc --enable-bzlib --enable-libxavs --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libvo-amrwbenc --enable-libschroedinger --enable-li  libavutil      55. 10.100 / 55. 10.100
  libavcodec     57. 17.100 / 57. 17.100
  libavformat    57. 19.100 / 57. 19.100
  libavdevice    57.  0.100 / 57.  0.100
  libavfilter     6. 20.100 /  6. 20.100
  libswscale      4.  0.100 /  4.  0.100
  libswresample   2.  0.101 /  2.  0.101
  libpostproc    54.  0.100 / 54.  0.100
Splitting the commandline.
Reading option '-f' ... matched as option 'f' (force format) with argument 'yuv4mpegpipe'.
Reading option '-i' ... matched as input file with argument '-'.
Reading option '-c:v' ... matched as option 'c' (codec name) with argument 'prores'.
Reading option '-an' ... matched as option 'an' (disable audio) with argument '1'.
Reading option '-y' ... matched as option 'y' (overwrite output files) with argument '1'.
Reading option '//192.168.0.100/media/temp/OutMov.mov' ... matched as output file.
Reading option '-report' ... matched as option 'report' (generate a report) with argument '1'.
Finished splitting the commandline.
Parsing a group of options: global .
Applying option y (overwrite output files) with argument 1.
Applying option report (generate a report) with argument 1.
Successfully parsed a group of options.
Parsing a group of options: input file -.
Applying option f (force format) with argument yuv4mpegpipe.
Successfully parsed a group of options.
Opening an input file: -.
[AVIOContext @ 006d9800] Statistics: 0 bytes read, 0 seeks
pipe:: Operation not permitted

更新:使用这段代码，我仍然可以得到相同的结果pipe:: Operation not permitted

import subprocess
import os
from subprocess import Popen, PIPE, STDOUT
import shlex

VsPipe = 'F:/ffmpeg/VapourSynth/VSPipe.exe'
vpyScript = 'C:/Users/myself/Desktop/Boychoir-preview_SMALL_JobID_189.vpy'
ffmpeg = 'F:/ffmpeg/ffmpeg.exe'
outputPath = '//192.168.0.100/media/temp/OutMov.mov'

command1 = shlex.split('"%s" --y4m "%s" - ' % (VsPipe, vpyScript))
command2 = shlex.split('"%s" -f yuv4mpegpipe -i - -c:v prores -an -y "%s" -report' % (ffmpeg, outputPath))

process1 = subprocess.Popen(command1, stdout=subprocess.PIPE)
ls_out, _ = process1.communicate()
process2 = subprocess.Popen(command2, stdin=subprocess.PIPE, stderr=subprocess.PIPE)

grep_out, grep_err = process2.communicate(input=ls_out)
print grep_err

更新:修复，原来是一个文件路径权限问题，感谢所有的帮助。

Answer 1

当您将shell设置为False时，如果它是字符串，则args (即第一个)参数应该是程序的名称。否则，它应该是一个字符串序列，第一个是程序，其余的是参数。

在使用管道时，外壳的重要性在于：

VSPipe.exe --y4m script.vpy - | ffmpeg.exe -f yuv4mpegpipe -i - -c:v prores -an output.mov

并不是所有的论点都被认为是论点。VSPipe.exe的参数是--y4m和script.vpy。ffmpeg.exe的参数是-f、yuv4mpegpipe、-i等。shell是处理管道的东西--它启动两个程序(提供它们的参数)，但是它首先创建一个管道，这样stdout从第一个开始就连接到第二个stdin。

如果您没有一个支持管道的shell，您可以在python中通过启动它们来模仿它们，然后将输出从第一个传输到第二个。

Answer 2

来自子进程文档：

当您需要管道时，使用Popen和communicate()方法。

在@skyking的回答和更新的代码的基础上，看起来您只需要使用communicate()：

# Simple Windows script to confirm existence of Desktop directory in users home space
# ls -al | grep Desktop
# This requires Windows Git to be installed for unix utils like ls, grep

# NOTE: you may have problems with this if you're using built in Windows shell
# utilities like dir etc.. This is because these are built into the shell and
# aren't executables on your path. Use shell=True if you have to use these.

import os
import subprocess

# Change to home directory
os.chdir(os.path.expanduser("~"))

# Command parameters sent to Popen initializer should be lists
# Here we are only interested in the output so PIPE stdout
ls_process = subprocess.Popen(['ls', '-al'], stdout=subprocess.PIPE)

# When working with subprocess PIPE we need to use the communicate() method
# We're only interested in stdout so _ is used to throw away stderr (which will be
# None anyway since we didn't pipe stderr)
ls_out, _ = ls_process.communicate()

# We then create our second process but this time we're interested in piping the
# first command into stdin, using stdout and potentially stderr if there was a problem
grep_process = subprocess.Popen(['grep', 'Desktop'],
                                   stdin=subprocess.PIPE,
                                   stdout=subprocess.PIPE,
                                   stderr=subprocess.PIPE)

# We use communicate() again but this time we give the output string of the first command
# as a parameter to communicate()
grep_out, grep_err = grep_process.communicate(input=ls_out)

print grep_out

Subprocess是一个很难第一次获得正确的模块，在其他项目中查看它的实例是很棒的。

另一个好建议是尽量保持平台无关。即使您不打算在Windows以外的任何东西上运行这个程序，它也将帮助您避免您正在工作的系统的特性。

Answer 3

首先，我建议您在这里为所有.exe使用完全路径，这是我用来做这件事的代码。

import os
import re
import subprocess
from subprocess import Popen, PIPE, STDOUT
import shlex

def _get_locate_command_result(bin_name,
                               which_command="which", default_path=""):
    # check_output returns bytes for python3 and str for py2
    try:
        result_locate = subprocess.check_output(
            shlex.split("%s %s" % (which_command, bin_name)), env=os.environ)
        result_locate_table = re.split(r"\r?\n", result_locate.decode())
        try:
            bin_path = result_locate_table[0].strip()
        except IndexError:
            bin_path = bin_name
        return bin_path


    except subprocess.CalledProcessError:
        return default_path

适用于Windows：

path = get_locate_command_result(bin_name, which_command="where", default_path=default_path)

因此，您可以尝试这样的方法(未经测试)：

# use "" beacause of '\'
command1 = ('"%s" --y4m script.vpy -'
            % _get_locate_command_result("VSPipe.exe", "where", "VSPipe.exe"))
command2 = ('"%s" -f yuv4mpegpipe -i - -c:v prores -an output.mov'
            % _get_locate_command_result("VSPipe.exe", "where", "ffmpeg.exe"))

# Popen needs sequence of string
cmd1 = shlex.split(command1)
cmd2 = shlex.split(command2)

process1 = Popen(cmd1, stdout=PIPE)
process2 = Popen(cmd2, stdin=process1.stdout, stderr=PIPE)

print(process2.communicate())