我正在尝试从OS X上的网络摄像头获取输入流
self.capture = pygame.camera('/dev/video{}'.format(camera),
(640, 480), 'RGB')
我收到错误（见下文），但有2条信息无法拼接在一起。乍一看，看起来我没有正确的相机（不是video4linux）。但是，在运行时
ffmpeg -f avfoundation -list_devices true -i ""
我列出了
[AVFoundation input device @ 0x7fbb45700340] [1] FULL HD 1080P Webcam
错误的下一部分讨论了帧速率。看起来帧速率稍微偏离，我接下来选择不同的帧速率。使用pygcam会有可能吗？这会解决我的问题吗？
错误：
Traceback (most recent call last):
File "webcam2.py", line 129, in <module>
VideoStreaming("52.191.118.156", 5558, 1)()
File "webcam2.py", line 22, in __call__
with self.get_camera_context(self.camera_id) as frames:
File "webcam2.py", line 89, in __enter__
size=(640, 480))
File "/Users/q433100/temp/brew-master/lib/python3.6/site-packages/imageio/core/functions.py", line 129, in get_reader
return format.get_reader(request)
File "/Users/q433100/temp/brew-master/lib/python3.6/site-packages/imageio/core/format.py", line 169, in get_reader
return self.Reader(self, request)
File "/Users/q433100/temp/brew-master/lib/python3.6/site-packages/imageio/core/format.py", line 218, in __init__
self._open(**self.request.kwargs.copy())
File "/Users/q433100/temp/brew-master/lib/python3.6/site-packages/imageio/plugins/ffmpeg.py", line 327, in _open
self._load_infos()
File "/Users/q433100/temp/brew-master/lib/python3.6/site-packages/imageio/plugins/ffmpeg.py", line 476, in _load_infos
(self.request._video, ffmpeg_err))
IndexError: No video4linux camera at <video1>.
FFMPEG STDERR OUTPUT:
ffmpeg version 3.4.1 Copyright (c) 2000-2017 the FFmpeg developers
built with Apple LLVM version 9.0.0 (clang-900.0.39.2)
configuration: --prefix=/Users/q433100/temp/brew-master/Cellar/ffmpeg/3.4.1 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-gpl --enable-libmp3lame --enable-libx264 --enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma
libavutil 55. 78.100 / 55. 78.100
libavcodec 57.107.100 / 57.107.100
libavformat 57. 83.100 / 57. 83.100
libavdevice 57. 10.100 / 57. 10.100
libavfilter 6.107.100 / 6.107.100
libavresample 3. 7. 0 / 3. 7. 0
libswscale 4. 8.100 / 4. 8.100
libswresample 2. 9.100 / 2. 9.100
libpostproc 54. 7.100 / 54. 7.100
[avfoundation @ 0x7fbb9e000a00] Selected framerate (29.970030) is not supported by the device
[avfoundation @ 0x7fbb9e000a00] Supported modes:
[avfoundation @ 0x7fbb9e000a00] 160x120@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00] 176x144@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00] 320x240@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00] 352x288@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00] 640x360@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00] 640x480@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00] 800x600@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00] 1024x576@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00] 960x720@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00] 1280x720@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00] 1392x768@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00] 1280x960@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00] 1600x896@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00] 1920x1080@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00] 160x120@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00] 176x144@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00] 320x240@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00] 352x288@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00] 640x360@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00] 640x480@[30.000030 30.000030]fps
[avfoundation @ 0x7fbb9e000a00] 800x600@[20.000000 20.000000]fps
[avfoundation @ 0x7fbb9e000a00] 1024x576@[8.000000 8.000000]fps
[avfoundation @ 0x7fbb9e000a00] 960x720@[15.000015 15.000015]fps
1: Input/output error
更新： 如果我尝试使用ffmped强制提到所支持的帧速率之一，则会出现新的错误
$ffmpeg -f avfoundation -r 30.000030 -i "1" out.mpg
ffmpeg version 3.4.1 Copyright (c) 2000-2017 the FFmpeg developers
built with Apple LLVM version 9.0.0 (clang-900.0.39.2)
configuration: --prefix=/Users/q433100/temp/brew-master/Cellar/ffmpeg/3.4.1 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-gpl --enable-libmp3lame --enable-libx264 --enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma
libavutil 55. 78.100 / 55. 78.100
libavcodec 57.107.100 / 57.107.100
libavformat 57. 83.100 / 57. 83.100
libavdevice 57. 10.100 / 57. 10.100
libavfilter 6.107.100 / 6.107.100
libavresample 3. 7. 0 / 3. 7. 0
libswscale 4. 8.100 / 4. 8.100
libswresample 2. 9.100 / 2. 9.100
libpostproc 54. 7.100 / 54. 7.100
[avfoundation @ 0x7fb3c8802600] An error occurred: The activeVideoMinFrameDuration passed is not supported by the device. Use -activeFormat.videoSupportedFrameRateRanges to discover valid ranges.1: Input/output error
更新2： 直接在ffmpeg中将输入帧速率设置为15可以正常工作。现在我只需要弄清楚如何在python中使用pygame.camera
来做到这一点$ ffmpeg -f avfoundation -r 15.000015 -i "1" out.avi