从相机捕获原始视频并传送到ffplay中时，视频向侧面移动

时间：2018-09-18 16:11:56

标签： ffmpeg avfoundation

我正在尝试使用ffmpeg（macOS 10.12）从相机捕获视频，并使用ffplay和rawvideo选项将其通过管道传输到-v copy中： 

ffmpeg -f avfoundation -pixel_format 0rgb -framerate 25 -video_size 1280x720 -i "0" -map 0:v -c copy -f rawvideo - | ffplay -f rawvideo -video_size 1280x720 -pixel_format 0rgb -i -

视频捕获效果很好，但是它会不断向侧面移动（请参阅所附的屏幕截图）。这可能是什么问题？

enter image description here

更新完整的ffmpeg日志输出：

$ ffmpeg -f avfoundation -pixel_format 0rgb -framerate 25 -video_size 1280x720 -i "0" -map 0:v -c copy -f rawvideo - | ffplay -f rawvideo -video_size 1280x720 -pixel_format 0rgb -i -
ffmpeg version 4.0.2ffplay version 4.0.2 Copyright © 2003-2018 the FFmpeg developers Copyright © 2000-2018 the FFmpeg developers

  built with Apple LLVM version 9.0.0 (clang-900.0.39.2)
  built with Apple LLVM version 9.0.0 (clang-900.0.39.2)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/4.0.2 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-gpl --enable-ffplay --enable-libfontconfig --enable-libfreetype --enable-libmp3lame --enable-libx264 --enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma
  configuration: --prefix=/usr/local/Cellar/ffmpeg/4.0.2 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-gpl --enable-ffplay --enable-libfontconfig --enable-libfreetype --enable-libmp3lame --enable-libx264 --enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma
  libavutil      56. 14.100 / 56. 14.100
  libavutil      56. 14.100 / 56. 14.100
  libavcodec     58. 18.100 / 58. 18.100
  libavformat    58. 12.100 / 58. 12.100
  libavcodec     58. 18.100 / 58. 18.100
  libavdevice    58.  3.100 / 58.  3.100
  libavformat    58. 12.100 / 58. 12.100
  libavfilter     7. 16.100 /  7. 16.100
  libavdevice    58.  3.100 / 58.  3.100
  libavresample   4.  0.  0 /  4.  0.  0
  libavfilter     7. 16.100 /  7. 16.100
  libswscale      5.  1.100 /  5.  1.100
  libswresample   3.  1.100 /  3.  1.100
  libavresample   4.  0.  0 /  4.  0.  0
  libpostproc    55.  1.100 / 55.  1.100
  libswscale      5.  1.100 /  5.  1.100
  libswresample   3.  1.100 /  3.  1.100
  libpostproc    55.  1.100 / 55.  1.100
2018-09-20 09:33:28.013 ffmpeg[45781:16452887] Error loading /Library/Audio/Plug-Ins/HAL/SeratoVirtualAudioPlugIn.plugin/Contents/MacOS/SeratoVirtualAudioPlugIn:  dlopen(/Library/Audio/Plug-Ins/HAL/SeratoVirtualAudioPlugIn.plugin/Contents/MacOS/SeratoVirtualAudioPlugIn, 262): no suitable image found.  Did find:
    /Library/Audio/Plug-Ins/HAL/SeratoVirtualAudioPlugIn.plugin/Contents/MacOS/SeratoVirtualAudioPlugIn: mach-o, but wrong architecture
    /Library/Audio/Plug-Ins/HAL/SeratoVirtualAudioPlugIn.plugin/Contents/MacOS/SeratoVirtualAudioPlugIn: mach-o, but wrong architecture
2018-09-20 09:33:28.013 ffmpeg[45781:16452887] Cannot find function pointer New_SHP_PlugIn for factory 834FC054-C1CC-11D6-BD01-00039315CD46 in CFBundle/CFPlugIn 0x7fe63b506d00 </Library/Audio/Plug-Ins/HAL/SeratoVirtualAudioPlugIn.plugin> (bundle, not loaded)
2018-09-20 09:33:28.069 ffplay[45782:16452888] Error loading /Library/Audio/Plug-Ins/HAL/SeratoVirtualAudioPlugIn.plugin/Contents/MacOS/SeratoVirtualAudioPlugIn:  dlopen(/Library/Audio/Plug-Ins/HAL/SeratoVirtualAudioPlugIn.plugin/Contents/MacOS/SeratoVirtualAudioPlugIn, 262): no suitable image found.  Did find:
    /Library/Audio/Plug-Ins/HAL/SeratoVirtualAudioPlugIn.plugin/Contents/MacOS/SeratoVirtualAudioPlugIn: mach-o, but wrong architecture
    /Library/Audio/Plug-Ins/HAL/SeratoVirtualAudioPlugIn.plugin/Contents/MacOS/SeratoVirtualAudioPlugIn: mach-o, but wrong architecture
2018-09-20 09:33:28.069 ffplay[45782:16452888] Cannot find function pointer New_SHP_PlugIn for factory 834FC054-C1CC-11D6-BD01-00039315CD46 in CFBundle/CFPlugIn 0x7f93f3c13020 </Library/Audio/Plug-Ins/HAL/SeratoVirtualAudioPlugIn.plugin> (bundle, not loaded)
[avfoundation @ 0x7fe63c000000] Stream #0: not enough frames to estimate rate; consider increasing probesize
Input #0, avfoundation, from '0':
  Duration: N/A, start: 1054.178167, bitrate: N/A
    Stream #0:0: Video: rawvideo ([0]RGB / 0x42475200), 0rgb, 1280x720, 1000k tbr, 1000k tbn, 1000k tbc
Output #0, rawvideo, to 'pipe:':   0KB vq=    0KB sq=    0B f=0/0   
  Metadata:
    encoder         : Lavf58.12.100
    Stream #0:0: Video: rawvideo ([0]RGB / 0x42475200), 0rgb, 1280x720, q=2-31, 1000k tbr, 1000k tbn, 1000k tbc
Stream mapping:
  Stream #0:0 -> #0:0 ©
Press [q] to stop, [?] for help
Input #0, rawvideo, from 'pipe:':
  Duration: N/A, start: 0.000000, bitrate: 737280 kb/s
    Stream #0:0: Video: rawvideo ([0]RGB / 0x42475200), 0rgb, 1280x720, 737280 kb/s, 25 tbr, 25 tbn, 25 tbc
frame=   16 fps=0.0 q=-1.0 size=   57600kB time=00:00:00.60 bitrate=786437.5kbits/s speed=1.frame=   29 fps= 28 q=-1.0 size=  104401kB time=00:00:01.12 bitrate=763617.4kbits/s speed=1.frame=   42 fps= 27 q=-1.0 size=  151201kB time=00:00:01.64 bitrate=755268.5kbits/s speed=1.frame=   55 fps= 26 q=-1.0 size=  198002kB time=00:00:02.16 bitrate=750939.5kbits/s speed=1.frame=   68 fps= 26 q=-1.0 size=  244802kB time=00:00:02.68 bitrate=748290.4kbits/s speed=1.av_interleaved_write_frame(): Broken pipe=    0KB sq=    0B f=0/0   
Error writing trailer of pipe:: Broken pipe
frame=   69 fps= 26 q=-1.0 Lsize=  247650kB time=00:00:02.72 bitrate=745863.6kbits/s speed=1.01x    
video:248402kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
Exiting normally, received signal 2.

2 个答案:

答案 0 :(得分：1)

看起来像对齐/填充问题。由于ffplay似乎没有选项，因此请为ffplay尝试使用更大的视频宽度，而不是像1282或更大的1280。

答案 1 :(得分：0)

看起来avfoundation设备正在将每个额外的32个字节填充到每个数据包上，从而导致步幅的逐渐变化，表现为水平对齐的逐渐偏移。

对流进行转码会强制执行解码，从而摆脱了填充。

Frame rate very high for a muxer not efficiently supporting it的警告与该问题无关。 avfoundation设备正在注册一百万（！）的帧速率，这对于恒定帧速率混合器是一个问题，因为ffmpeg会尝试复制帧以在输出中满足该速率。 -vsync vfr避免了这个问题。

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