python - ffmpeg的子进程调用返回负值

Question

这是在 shell 中工作的原始命令行调用:

ffmpeg -i /Users/abc/Desktop/Test/Full_Mov.mov -vf "drawtext=fontfile=/System/Library/Fonts/Keyboard.ttf: text='SCENE BLAH BLAH - %{frame_num}': start_number=1: x=(w-tw)/2: y=h-(2*lh): fontcolor=white: fontsize=20: box=1: boxcolor=black: boxborderw=5","format=yuv420p" -f segment -segment_frames 123 -reset_timestamps 1 -c:a copy -map 0 "/Users/abc/Desktop/Test/%03d_test40.mov"

尝试通过子进程运行 ffmpeg 时获得负值，导致它失败且无法处理。我什至尝试简化调用，只运行 ffmpeg 本身，不带参数，它仍然返回负值。

import subprocess
ffmpeg = "/usr/local/bin/ffmpeg"
source = "/Users/abc/Desktop/Test/Full_Mov.mov"
destination = "/Users/abc/Desktop/Test/%03d_test40.mov"
cmd = "%s -i %s -vf \"drawtext=fontfile=/System/Library/Fonts/Keyboard.ttf: text='SCENE BLAH BLAH - %%{frame_num}': start_number=1: x=(w-tw)/2: y=h-(2*lh): fontcolor=black: fontsize=20: box=1: boxcolor=white: boxborderw=5\",\"format=yuv420p\" -f segment -segment_frames 123 -reset_timestamps 1 -c:a copy -map 0 \"%s\"" % (ffmpeg, source, destination)
log("ffmpeg cmd: %s" % cmd)
log(subprocess.check_output(cmd, shell=True))

运行完整命令时:

CalledProcessError: Command '/usr/local/bin/ffmpeg -i /Users/abc/Desktop/Full_Mov.mov -vf "drawtext=fontfile=/System/Library/Fonts/Keyboard.ttf: text='SCENE BLAH BLAH - %{frame_num}': start_number=1: x=(w-tw)/2: y=h-(2*lh): fontcolor=black: fontsize=20: box=1: boxcolor=white: boxborderw=5","format=yuv420p" -f segment -segment_frames 318 -reset_timestamps 1 -c:a copy -map 0 "/Users/abc/Desktop/Test/%03d.tmp.mov"' returned non-zero exit status -8
    raise CalledProcessError(retcode, cmd, output=output)

仅运行 ffmpeg 时没有参数:

CalledProcessError: Command '/usr/local/bin/ffmpeg' returned non-zero exit status 1
    raise CalledProcessError(retcode, cmd, output=output)

带有以下建议更改的最新输出:

subprocess.CalledProcessError: Command '['/usr/local/bin/ffmpeg', '-i', '/Users/szaharak/Desktop/Flix_Test/ep888_sq66_main_mov_2019_05_20_14_15.mov', '-vf', 'drawtext=fontfile=/System/Library/Fonts/Keyboard.ttf:', 'text=SCENE BLAH BLAH - %%{frame_num}:', 'start_number=1:', 'x=(w-tw)/2:', 'y=h-(2*lh):', 'fontcolor=black:', 'fontsize=20:', 'box=1:', 'boxcolor=white:', 'boxborderw=5', 'format=yuv420p', '-f', 'segment', '-segment_frames', '123', '-reset_timestamps', '1', '-c:a', 'copy', '-map', '0', '/Users/szaharak/Desktop/Flix_Test/%03d_test40.mov']' returned non-zero exit status 1

[NULL @ 0x7f88c3012200] Unable to find a suitable output format for 'text=SCENE BLAH BLAH - %%{frame_num}:'
text=SCENE BLAH BLAH - %%{frame_num}:: Invalid argument

这是最新的...

    >>> rc = subprocess.check_call(cmd)
ffmpeg version N-93891-ge1839283bc-tessus  https://evermeet.cx/ffmpeg/  Copyright (c) 2000-2019 the FFmpeg developers
  built with Apple LLVM version 10.0.1 (clang-1001.0.46.4)
  configuration: --cc=/usr/bin/clang --prefix=/opt/ffmpeg --extra-version=tessus --enable-avisynth --enable-fontconfig --enable-gpl --enable-libaom --enable-libass --enable-libbluray --enable-libdav1d --enable-libfreetype --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libmysofa --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopus --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-libzmq --enable-libzvbi --enable-version3 --pkg-config-flags=--static --disable-ffplay

  libavutil      56. 28.100 / 56. 28.100
  libavcodec     58. 52.102 / 58. 52.102
  libavformat    58. 27.103 / 58. 27.103
  libavdevice    58.  7.100 / 58.  7.100
  libavfilter     7. 53.101 /  7. 53.101
  libswscale      5.  4.101 /  5.  4.101
  libswresample   3.  4.100 /  3.  4.100
  libpostproc    55.  4.100 / 55.  4.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/Users/szaharak/Desktop/Flix_Test/ep888_sq66_main_mov_2019_05_20_14_15.mov':
  Metadata:
    major_brand     : qt  
    minor_version   : 537199360
    compatible_brands: qt  
    creation_time   : 2019-05-14T17:58:24.000000Z
    com.apple.quicktime.player.movie.audio.gain: 1.000000
    com.apple.quicktime.player.movie.audio.treble: 0.000000
    com.apple.quicktime.player.movie.audio.bass: 0.000000
    com.apple.quicktime.player.movie.audio.balance: 0.000000
    com.apple.quicktime.player.movie.audio.pitchshift: 0.000000
    com.apple.quicktime.player.movie.audio.mute: 
    com.apple.quicktime.player.movie.visual.brightness: 0.000000
    com.apple.quicktime.player.movie.visual.color: 1.000000
    com.apple.quicktime.player.movie.visual.tint: 0.000000
    com.apple.quicktime.player.movie.visual.contrast: 1.000000
    com.apple.quicktime.player.version: 7.6.6 (7.6.6)
    com.apple.quicktime.version: 7.7.3 (2943.14) 0x7738000 (Mac OS X, 10.11.6, 15G22010)
  Duration: 00:01:12.67, start: 0.000000, bitrate: 23379 kb/s
    Stream #0:0(eng): Video: mjpeg (Baseline) (jpeg / 0x6765706A), yuvj422p(pc, bt470bg/unknown/unknown), 1280x720 [SAR 72:72 DAR 16:9], 21838 kb/s, 24 fps, 24 tbr, 24k tbn, 24k tbc (default)
    Metadata:
      creation_time   : 2019-05-14T17:58:24.000000Z
      handler_name    : Apple Video Media Handler
      encoder         : Photo - JPEG
    Stream #0:1(eng): Audio: pcm_s16be (twos / 0x736F7774), 48000 Hz, stereo, s16, 1536 kb/s (default)
    Metadata:
      creation_time   : 2019-05-14T17:58:24.000000Z
      handler_name    : Apple Sound Media Handler
[NULL @ 0x7f8ddc8ce200] Unable to find a suitable output format for 'text=SCENE BLAH BLAH - %{frame_num}: start_number=1: x=(w-tw)/2: y=h-(2*lh): fontcolor=black: fontsize=20: box=1: boxcolor=white: boxborderw=5: format=yuv420p'
text=SCENE BLAH BLAH - %{frame_num}: start_number=1: x=(w-tw)/2: y=h-(2*lh): fontcolor=black: fontsize=20: box=1: boxcolor=white: boxborderw=5: format=yuv420p: Invalid argument
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/Cellar/python@2/2.7.15_1/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 190, in check_call
    raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['/usr/local/bin/ffmpeg', '-i', '/Users/szaharak/Desktop/Flix_Test/ep888_sq66_main_mov_2019_05_20_14_15.mov', '-vf', 'drawtext=fontfile=/System/Library/Fonts/Keyboard.ttf:', 'text=SCENE BLAH BLAH - %{frame_num}: start_number=1: x=(w-tw)/2: y=h-(2*lh): fontcolor=black: fontsize=20: box=1: boxcolor=white: boxborderw=5: format=yuv420p', '-f', 'segment', '-segment_frames', '123', '-reset_timestamps', '1', '-c:a', 'copy', '-map', '0', '/Users/szaharak/Desktop/Flix_Test/%03d_test40.mov']' returned non-zero exit status 1

Answer 1

ffmpeg命令行很棘手，因为有很多特殊的参数，错误有时难以理解，程序有时会解释/丢弃错误的参数，从而导致神秘的错误消息。

另一个困难是使用 check_output .您实际上并不需要这样做，如果程序失败，您将根本没有任何输出。

我会尝试以下(我无法测试)，即:

掉落shell=True

传递参数列表，而不是自己编写字符串。它允许忘记引用/转义。您不需要格式化命令、源和目标，因为它们是独立的参数:

不要登录，只需打印 check_call .
作为奖励，您将获得实时输出，而不是最终...

请注意，我已删除 "text=SCENE BLAH BLAH - %{frame_num}:, 中的单引号也未转义 %字符。

像这样:

cmd = [ffmpeg,"-i",source,"-vf",
      "drawtext=fontfile=/System/Library/Fonts/Keyboard.ttf:",
      "text=SCENE BLAH BLAH - %{frame_num}: start_number=1: x=(w-tw)/2: y=h-(2*lh): fontcolor=black: fontsize=20: box=1: boxcolor=white: boxborderw=5: format=yuv420p",
      "-f","segment","-segment_frames","123",
       "-reset_timestamps","1","-c:a","copy","-map","0",destination] 
log("ffmpeg cmd: %s" % cmd)
rc = subprocess.check_call(cmd)
if rc:
    raise Exception("ffmpeg failed")

对于 ffmpeg 的情况，您可以迁移到 ffmpeg python module .也可以节省一些参数解析麻烦。