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1366x744（效果很好）

tag-icon • tag-icon ffmpeg screen-recorder
1366x744（效果很好）

我正在尝试使用 ffmpeg 录制整个屏幕 (1366x768)，但如果我将视频大小设置为超过某个大小，就会出现段错误。从输出中可以看出，我在发布此问题前不到 1 小时就从源代码进行了编译。

1366x744（效果很好）

λ ./ffmpeg -f x11grab -r 25 -s 1366x744 -i :0.0+0,24 -vcodec libx264  -threads 0 screen.mkv
ffmpeg version 2.5.1 Copyright (c) 2000-2014 the FFmpeg developers
  built on Dec 18 2014 20:32:54 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
  configuration: --enable-gpl --enable-version3 --enable-nonfree --enable-postproc --enable-pthreads --enable-libfaac --enable-libmp3lame --enable-libtheora --enable-libx264 --enable-libxvid --enable-x11grab --enable-libvorbis
  libavutil      54. 15.100 / 54. 15.100
  libavcodec     56. 13.100 / 56. 13.100
  libavformat    56. 15.102 / 56. 15.102
  libavdevice    56.  3.100 / 56.  3.100
  libavfilter     5.  2.103 /  5.  2.103
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  1.100 /  1.  1.100
  libpostproc    53.  3.100 / 53.  3.100
[x11grab @ 0x1ab6f20] Stream #0: not enough frames to estimate rate; consider increasing probesize
Input #0, x11grab, from ':0.0+0,24':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: rawvideo (BGRA / 0x41524742), bgra, 1366x744, 25 fps, 25 tbr, 1000k tbn, 25 tbc
File 'screen.mkv' already exists. Overwrite ? [y/N] n
Not overwriting - exiting

1366x745（段错误）

λ ./ffmpeg -f x11grab -r 25 -s 1366x745 -i :0.0+0,24 -vcodec libx264  -threads 0 screen.mkv
ffmpeg version 2.5.1 Copyright (c) 2000-2014 the FFmpeg developers
  built on Dec 18 2014 20:32:54 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
  configuration: --enable-gpl --enable-version3 --enable-nonfree --enable-postproc --enable-pthreads --enable-libfaac --enable-libmp3lame --enable-libtheora --enable-libx264 --enable-libxvid --enable-x11grab --enable-libvorbis
  libavutil      54. 15.100 / 54. 15.100
  libavcodec     56. 13.100 / 56. 13.100
  libavformat    56. 15.102 / 56. 15.102
  libavdevice    56.  3.100 / 56.  3.100
  libavfilter     5.  2.103 /  5.  2.103
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  1.100 /  1.  1.100
  libpostproc    53.  3.100 / 53.  3.100
[1]    31332 segmentation fault (core dumped)  ./ffmpeg -f x11grab -r 25 -s 1366x745 -i :0.0+0,24 -vcodec libx264 -threads 0

这里我遗漏了什么吗？

答案1

您的 y 偏移设置为 24。将此值添加到您的输入视频尺寸将得出一个大于您的屏幕尺寸的值 (745 + 24 = 769)。

分段错误看起来很奇怪，因为我认为它ffmpeg应该提供一个不直观的错误信息。例如：

X Error of failed request:  BadMatch (invalid parameter attributes)
  Major opcode of failed request:  142 (MIT-SHM)
  Minor opcode of failed request:  4 (X_ShmGetImage)
  Serial number of failed request:  11
  Current serial number in output stream:  11

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