我尝试使用树莓派 3 型和摄像头模块通过 WiFi 网络传输视频，但发现与我在网上找到的其他示例存在一些不一致之处。我试图获得该视频中执行的第三次测试的结果：https://www.youtube.com/watch?v=sYGdge3T30o
我可以看到数据通过网络传输并进入fifo264在创建的文件中，我还有一个正在运行的 python 脚本，该脚本会在视频源无法再被处理之前运行几分钟。
OS X 机器上显示的视频最终崩溃。我不确定我的问题是否存在于我如何生成和发送视频（从 Raspberry Pi 端），或者是否存在于我如何使用 python 使用视频并处理它。
我正在尝试确定可能导致我的问题的平台差异，这个问题的重点是mkfifo and netcat权限以及这些程序跨平台行为方式之间可能存在的差异。
此 bash 脚本在 OS X 10.12.6 上使用。我正在尝试在端口 777 上侦听正在创建并发送到这台计算机的提要。
#!/bin/bash
if [ -p fifo264 ]
then
rm fifo264
fi
mkfifo fifo264
nc -l -v 777 > fifo264
当上面的脚本执行时./makeFifo.sh管道fifo264在工作目录中创建，并继承用户的用户权限。
sudo ./makeFifo.sh结果是ls -l as
prw-r--r-- 1 root staff 0 Feb 4 12:12 fifo264
AND
./makeFifo.sh结果是ls -l as
prw-r--r-- 1 user staff 0 Feb 4 12:12 fifo264
我还更改了 bash 脚本以提供-m 0777 with mkfifo result mkfifo -m 0777 fifo264。管道已使用适当的权限创建，但 netcat 无法建立开放777/tcp open multiling-http。我在跑nmap -sS -O localhost去测试。如果我使用机器的 IP 地址，结果是相同的。
如果我不使用 bash 脚本创建管道并从命令行执行 netcat 来侦听端口 777，我可以通过输入以下命令让 netcat 在 OS X 10.12.6 上创建开放的 777 端口sudo nc -l -v 777 > fifo264.
这导致创建一个开放的777/tcp open multiling-http但不创建管道。ls -l输出：
-rw-r--r-- 1 user staff 0 Feb 4 12:26 fifo264注意缺失的p来自权限字符串。
如果我用以下命令创建管道mkfifo fifo264从命令行，然后继续执行sudo nc -l -v 777 > fifo264，管道已创建，但 netcat 不会侦听端口 777。
将数据发送到非管道文件会产生任何延迟问题吗？这会对我用来显示提要的以下 python 脚本产生影响吗？我在 OS X 上使用 openCV 3.4 和 Python 3.6.4（我正在尝试处理视频源的机器）。videoFeed.py在下面：
import cv2
import subprocess as sp
import numpy
FFMPEG_BIN = "ffmpeg"
command = [ FFMPEG_BIN,
'-i', 'fifo264', # fifo is the named pipe
'-pix_fmt', 'bgr24', # opencv requires bgr24 pixel format.
'-vcodec', 'rawvideo',
'-an','-sn', # we want to disable audio processing (there is no audio)
'-f', 'image2pipe', '-']
pipe = sp.Popen(command, stdout = sp.PIPE, bufsize=10**8)
while True:
# Capture frame-by-frame
raw_image = pipe.stdout.read(640*480*3)
# transform the byte read into a numpy array
image = numpy.fromstring(raw_image, dtype='uint8')
image = image.reshape((480,640,3)) # Notice how height is specified first and then width
if image is not None:
cv2.imshow('Video', image)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
pipe.stdout.flush()
cv2.destroyAllWindows()
从运行 RASPBIAN STRETCH WITH DESKTOP 的 RaspberryPi Model 3 B（2017 年 11 月）开始，我使用以下 bash 脚本来传输视频streamVideo.sh.
#!/bin/bash
raspivid -vf -n -w 640 -h 480 -o - -t 0 -b 1200000 | nc -v 10.0.0.3 777
到目前为止我已经能够完成的工作总结如下：
在 OS X 机器上，我发出sudo nc -l -v 777 > fifo264从终端执行以下 nmap 扫描：
Host is up (0.00015s latency).
Not shown: 993 closed ports
PORT STATE SERVICE
80/tcp open http
445/tcp open microsoft-ds
548/tcp open afp
777/tcp open multiling-http
然后从 RaspberryPi 开始streamVideo.sh:
Connection to 10.0.0.3 777 port [tcp/moira-update] succeeded!
在 OS X 机器上，我启动 python 脚本来访问 fifo264 feed。
python3 videoFeed.py
如果相机聚焦在帧中没有任何移动的静止物体上，它将流向fifo264喂养。如果我开始videoFeed.py几秒钟后，Python 脚本将从头开始显示视频源，但质量还不错，但有明显的延迟。
如果我开始videoFeed.py执行后立即streamVideo.sh来自 RaspberryPI 的脚本，延迟不存在，但图像质量很糟糕。这张截图是我在镜头前移动手时拍摄的。
您将在下面找到完整的输出videoFeed.py尝试使用视频源的 python 脚本。
ffmpeg version N-78264-g9079e99-tessus Copyright (c) 2000-2016 the FFmpeg developers
built with Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn)
configuration: --cc=/usr/bin/clang --prefix=/opt/ffmpeg --as=yasm --extra-version=tessus --enable-avisynth --enable-fontconfig --enable-gpl --enable-libass --enable-libbluray --enable-libfreetype --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopus --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzmq --enable-version3 --disable-ffplay --disable-indev=qtkit --disable-indev=x11grab_xcb
libavutil 55. 15.100 / 55. 15.100
libavcodec 57. 22.102 / 57. 22.102
libavformat 57. 23.100 / 57. 23.100
libavdevice 57. 0.100 / 57. 0.100
libavfilter 6. 27.100 / 6. 27.100
libswscale 4. 0.100 / 4. 0.100
libswresample 2. 0.101 / 2. 0.101
libpostproc 54. 0.100 / 54. 0.100
Input #0, h264, from 'fifo264':
Duration: N/A, bitrate: N/A
Stream #0:0: Video: h264 (High), yuv420p, 640x480, 25 fps, 25 tbr, 1200k tbn, 50 tbc
Output #0, image2pipe, to 'pipe:':
Metadata:
encoder : Lavf57.23.100
Stream #0:0: Video: rawvideo (BGR[24] / 0x18524742), bgr24, 640x480, q=2-31, 200 kb/s, 25 fps, 25 tbn, 25 tbc
Metadata:
encoder : Lavc57.22.102 rawvideo
Stream mapping:
Stream #0:0 -> #0:0 (h264 (native) -> rawvideo (native))
Press [q] to stop, [?] for help
[h264 @ 0x7f813c831800] error while decoding MB 6 6, bytestream -5
[h264 @ 0x7f813c831800] concealing 1003 DC, 1003 AC, 1003 MV errors in P frame
[h264 @ 0x7f813c873200] error while decoding MB 30 20, bytestream -2884320.0kbits/s speed=1.43x
[h264 @ 0x7f813c873200] concealing 419 DC, 419 AC, 419 MV errors in P frame
[NULL @ 0x7f813c808000] missing picture in access unit with size 919
[h264 @ 0x7f813c866000] no frame!
[h264 @ 0x7f813c824600] error while decoding MB 7 15, bytestream -7
[h264 @ 0x7f813c824600] concealing 642 DC, 642 AC, 642 MV errors in P frame
Error while decoding stream #0:0: Invalid data found when processing input.0kbits/s dup=2 drop=0 speed=1.42x
[h264 @ 0x7f813c858e00] error while decoding MB 39 17, bytestream -6
[h264 @ 0x7f813c858e00] concealing 530 DC, 530 AC, 530 MV errors in P frame
[h264 @ 0x7f813c821600] error while decoding MB 17 28, bytestream -6
[h264 @ 0x7f813c821600] concealing 112 DC, 112 AC, 112 MV errors in P frame
[h264 @ 0x7f813c880400] error while decoding MB 31 21, bytestream -5
[h264 @ 0x7f813c880400] concealing 378 DC, 378 AC, 378 MV errors in P frame
[h264 @ 0x7f813c83ea00] error while decoding MB 38 18, bytestream -5
[h264 @ 0x7f813c83ea00] concealing 491 DC, 491 AC, 491 MV errors in P frame
[h264 @ 0x7f813c880400] error while decoding MB 20 24, bytestream -5184320.0kbits/s dup=7 drop=0 speed=1.43x
[h264 @ 0x7f813c880400] concealing 269 DC, 269 AC, 269 MV errors in P frame
[h264 @ 0x7f813c84bc00] error while decoding MB 29 27, bytestream -6
[h264 @ 0x7f813c84bc00] concealing 140 DC, 140 AC, 140 MV errors in P frame
[h264 @ 0x7f813c83ea00] error while decoding MB 36 0, bytestream -10
[h264 @ 0x7f813c83ea00] concealing 1200 DC, 1200 AC, 1200 MV errors in P frame
[h264 @ 0x7f813c873200] error while decoding MB 15 7, bytestream -9=184320.0kbits/s dup=9 drop=0 speed=1.42x
[h264 @ 0x7f813c873200] concealing 954 DC, 954 AC, 954 MV errors in P frame
[h264 @ 0x7f813c824600] error while decoding MB 39 0, bytestream -25
[h264 @ 0x7f813c824600] concealing 1200 DC, 1200 AC, 1200 MV errors in P frame
[h264 @ 0x7f813c84bc00] error while decoding MB 34 24, bytestream -6
[h264 @ 0x7f813c84bc00] concealing 255 DC, 255 AC, 255 MV errors in P frame
[h264 @ 0x7f813c821600] error while decoding MB 32 21, bytestream -6184320.0kbits/s dup=15 drop=0 speed=1.44x
[h264 @ 0x7f813c821600] concealing 377 DC, 377 AC, 377 MV errors in P frame
[h264 @ 0x7f813c858e00] error while decoding MB 28 22, bytestream -6
[h264 @ 0x7f813c858e00] concealing 341 DC, 341 AC, 341 MV errors in P frame
[h264 @ 0x7f813c880400] error while decoding MB 4 29, bytestream -8
[h264 @ 0x7f813c880400] concealing 85 DC, 85 AC, 85 MV errors in P frame
[h264 @ 0x7f813c873200] error while decoding MB 7 18, bytestream -6=184320.0kbits/s dup=17 drop=0 speed=1.44x
[h264 @ 0x7f813c873200] concealing 522 DC, 522 AC, 522 MV errors in P frame
[h264 @ 0x7f813c866000] error while decoding MB 31 24, bytestream -10
[h264 @ 0x7f813c866000] concealing 258 DC, 258 AC, 258 MV errors in P frame
[h264 @ 0x7f813c84bc00] error while decoding MB 23 28, bytestream -30
[h264 @ 0x7f813c84bc00] concealing 106 DC, 106 AC, 106 MV errors in P frame
[h264 @ 0x7f813c880400] error while decoding MB 15 29, bytestream -9184320.0kbits/s dup=21 drop=0 speed=1.44x
[h264 @ 0x7f813c880400] concealing 74 DC, 74 AC, 74 MV errors in P frame
[h264 @ 0x7f813c84bc00] error while decoding MB 26 26, bytestream -5
[h264 @ 0x7f813c84bc00] concealing 183 DC, 183 AC, 183 MV errors in P frame
[h264 @ 0x7f813c880400] error while decoding MB 37 14, bytestream -5
[h264 @ 0x7f813c880400] concealing 652 DC, 652 AC, 652 MV errors in P frame
[h264 @ 0x7f813c831800] error while decoding MB 36 24, bytestream -6
[h264 @ 0x7f813c831800] concealing 253 DC, 253 AC, 253 MV errors in P frame
[h264 @ 0x7f813c880400] error while decoding MB 25 26, bytestream -5184320.0kbits/s dup=23 drop=0 speed=1.44x
[h264 @ 0x7f813c880400] concealing 184 DC, 184 AC, 184 MV errors in P frame
[h264 @ 0x7f813c824600] error while decoding MB 37 2, bytestream -6
[h264 @ 0x7f813c824600] concealing 1132 DC, 1132 AC, 1132 MV errors in P frame
[h264 @ 0x7f813c84bc00] error while decoding MB 33 23, bytestream -7
[h264 @ 0x7f813c84bc00] concealing 296 DC, 296 AC, 296 MV errors in P frame
[h264 @ 0x7f813c821600] error while decoding MB 32 16, bytestream -5184320.0kbits/s dup=26 drop=0 speed=1.44x
[h264 @ 0x7f813c821600] concealing 577 DC, 577 AC, 577 MV errors in P frame
[h264 @ 0x7f813c880400] error while decoding MB 1 26, bytestream -6
[h264 @ 0x7f813c880400] concealing 208 DC, 208 AC, 208 MV errors in P frame
[h264 @ 0x7f813c84bc00] error while decoding MB 32 12, bytestream -6184320.0kbits/s dup=28 drop=0 speed=1.43x
[h264 @ 0x7f813c84bc00] concealing 737 DC, 737 AC, 737 MV errors in P frame
[h264 @ 0x7f813c880400] error while decoding MB 27 26, bytestream -8
[h264 @ 0x7f813c880400] concealing 182 DC, 182 AC, 182 MV errors in P frame
[h264 @ 0x7f813c84bc00] error while decoding MB 27 27, bytestream -5
[h264 @ 0x7f813c84bc00] concealing 142 DC, 142 AC, 142 MV errors in P frame
[h264 @ 0x7f813c831800] error while decoding MB 23 20, bytestream -7
[h264 @ 0x7f813c831800] concealing 426 DC, 426 AC, 426 MV errors in P frame
[h264 @ 0x7f813c858e00] error while decoding MB 29 26, bytestream -5184320.0kbits/s dup=31 drop=0 speed=1.43x
[h264 @ 0x7f813c858e00] concealing 180 DC, 180 AC, 180 MV errors in P frame
[h264 @ 0x7f813c821600] error while decoding MB 26 26, bytestream -5
[h264 @ 0x7f813c821600] concealing 183 DC, 183 AC, 183 MV errors in P frame
[h264 @ 0x7f813c858e00] error while decoding MB 27 27, bytestream -9
[h264 @ 0x7f813c858e00] concealing 142 DC, 142 AC, 142 MV errors in P frame
[h264 @ 0x7f813c824600] error while decoding MB 30 4, bytestream -8
[h264 @ 0x7f813c824600] concealing 1059 DC, 1059 AC, 1059 MV errors in P frame
[h264 @ 0x7f813c858e00] error while decoding MB 9 22, bytestream -5=184320.0kbits/s dup=33 drop=0 speed=1.42x
[h264 @ 0x7f813c858e00] concealing 360 DC, 360 AC, 360 MV errors in P frame
[h264 @ 0x7f813c873200] error while decoding MB 25 13, bytestream -12
[h264 @ 0x7f813c873200] concealing 704 DC, 704 AC, 704 MV errors in P frame
[h264 @ 0x7f813c880400] error while decoding MB 14 1, bytestream -9
[h264 @ 0x7f813c880400] concealing 1195 DC, 1195 AC, 1195 MV errors in P frame
[h264 @ 0x7f813c821600] error while decoding MB 29 23, bytestream -9
[h264 @ 0x7f813c821600] concealing 300 DC, 300 AC, 300 MV errors in P frame
[h264 @ 0x7f813c824600] error while decoding MB 30 25, bytestream -10
[h264 @ 0x7f813c824600] concealing 219 DC, 219 AC, 219 MV errors in P frame
[h264 @ 0x7f813c831800] error while decoding MB 27 27, bytestream -8
[h264 @ 0x7f813c831800] concealing 142 DC, 142 AC, 142 MV errors in P frame
[h264 @ 0x7f813c83ea00] error while decoding MB 13 23, bytestream -6184320.0kbits/s dup=34 drop=0 speed=1.42x
[h264 @ 0x7f813c83ea00] concealing 316 DC, 316 AC, 316 MV errors in P frame
[h264 @ 0x7f813c84bc00] error while decoding MB 37 12, bytestream -5
[h264 @ 0x7f813c84bc00] concealing 732 DC, 732 AC, 732 MV errors in P frame
[h264 @ 0x7f813c866000] error while decoding MB 27 2, bytestream -6
[h264 @ 0x7f813c866000] concealing 1142 DC, 1142 AC, 1142 MV errors in P frame
[h264 @ 0x7f813c873200] error while decoding MB 22 25, bytestream -10
[h264 @ 0x7f813c873200] concealing 227 DC, 227 AC, 227 MV errors in P frame
[h264 @ 0x7f813c880400] error while decoding MB 5 15, bytestream -6
[h264 @ 0x7f813c880400] concealing 644 DC, 644 AC, 644 MV errors in P frame
[h264 @ 0x7f813c84bc00] error while decoding MB 27 13, bytestream -8
[h264 @ 0x7f813c84bc00] concealing 702 DC, 702 AC, 702 MV errors in P frame
[h264 @ 0x7f813c858e00] error while decoding MB 33 15, bytestream -12
[h264 @ 0x7f813c858e00] concealing 616 DC, 616 AC, 616 MV errors in P frame
[h264 @ 0x7f813c866000] error while decoding MB 39 16, bytestream -5
[h264 @ 0x7f813c866000] concealing 570 DC, 570 AC, 570 MV errors in P frame
[h264 @ 0x7f813c831800] error while decoding MB 27 29, bytestream -8
[h264 @ 0x7f813c831800] concealing 62 DC, 62 AC, 62 MV errors in P frame
[h264 @ 0x7f813c873200] error while decoding MB 35 29, bytestream -5184320.0kbits/s dup=38 drop=0 speed=1.42x
[h264 @ 0x7f813c873200] concealing 54 DC, 54 AC, 54 MV errors in P frame
[h264 @ 0x7f813c821600] error while decoding MB 32 14, bytestream -14
[h264 @ 0x7f813c821600] concealing 657 DC, 657 AC, 657 MV errors in P frame
[h264 @ 0x7f813c824600] error while decoding MB 29 22, bytestream -7
[h264 @ 0x7f813c824600] concealing 340 DC, 340 AC, 340 MV errors in P frame
[h264 @ 0x7f813c831800] error while decoding MB 8 13, bytestream -7
[h264 @ 0x7f813c831800] concealing 721 DC, 721 AC, 721 MV errors in P frame
[NULL @ 0x7f813c808000] missing picture in access unit with size 1448
[h264 @ 0x7f813c83ea00] no frame!
[h264 @ 0x7f813c84bc00] error while decoding MB 9 16, bytestream -19
[h264 @ 0x7f813c84bc00] concealing 600 DC, 600 AC, 600 MV errors in P frame
[h264 @ 0x7f813c858e00] error while decoding MB 24 18, bytestream -16
[h264 @ 0x7f813c858e00] concealing 505 DC, 505 AC, 505 MV errors in P frame
Error while decoding stream #0:0: Invalid data found when processing input
[h264 @ 0x7f813c866000] error while decoding MB 22 13, bytestream -5
[h264 @ 0x7f813c866000] concealing 707 DC, 707 AC, 707 MV errors in P frame
[h264 @ 0x7f813c880400] error while decoding MB 11 29, bytestream -6
[h264 @ 0x7f813c880400] concealing 78 DC, 78 AC, 78 MV errors in P frame
[h264 @ 0x7f813c821600] error while decoding MB 38 14, bytestream -6
[h264 @ 0x7f813c821600] concealing 651 DC, 651 AC, 651 MV errors in P frame
[h264 @ 0x7f813c824600] error while decoding MB 6 17, bytestream -6
[h264 @ 0x7f813c824600] concealing 563 DC, 563 AC, 563 MV errors in P frame
[h264 @ 0x7f813c83ea00] error while decoding MB 19 27, bytestream -5
[h264 @ 0x7f813c83ea00] concealing 150 DC, 150 AC, 150 MV errors in P frame
[h264 @ 0x7f813c84bc00] error while decoding MB 18 17, bytestream -9
[h264 @ 0x7f813c84bc00] concealing 551 DC, 551 AC, 551 MV errors in P frame
[h264 @ 0x7f813c858e00] error while decoding MB 38 9, bytestream -16
[h264 @ 0x7f813c858e00] concealing 851 DC, 851 AC, 851 MV errors in P frame
[h264 @ 0x7f813c880400] error while decoding MB 8 19, bytestream -7=184320.0kbits/s dup=41 drop=0 speed=1.42x
[h264 @ 0x7f813c880400] concealing 481 DC, 481 AC, 481 MV errors in P frame
[h264 @ 0x7f813c821600] error while decoding MB 24 21, bytestream -14
[h264 @ 0x7f813c821600] concealing 385 DC, 385 AC, 385 MV errors in P frame
[h264 @ 0x7f813c873200] error while decoding MB 26 23, bytestream -5
[h264 @ 0x7f813c873200] concealing 303 DC, 303 AC, 303 MV errors in P frame
[h264 @ 0x7f813c83ea00] error while decoding MB 31 26, bytestream -25
[h264 @ 0x7f813c83ea00] concealing 178 DC, 178 AC, 178 MV errors in P frame
[h264 @ 0x7f813c866000] error while decoding MB 25 28, bytestream -6
[h264 @ 0x7f813c866000] concealing 104 DC, 104 AC, 104 MV errors in P frame
[h264 @ 0x7f813c821600] error while decoding MB 23 29, bytestream -1284320.0kbits/s dup=44 drop=0 speed=1.42x
[h264 @ 0x7f813c821600] concealing 66 DC, 66 AC, 66 MV errors in P frame
[h264 @ 0x7f813c831800] error while decoding MB 23 20, bytestream -19
[h264 @ 0x7f813c831800] concealing 426 DC, 426 AC, 426 MV errors in P frame
[h264 @ 0x7f813c84bc00] error while decoding MB 27 26, bytestream -10
[h264 @ 0x7f813c84bc00] concealing 182 DC, 182 AC, 182 MV errors in P frame
[h264 @ 0x7f813c858e00] error while decoding MB 31 26, bytestream -10
[h264 @ 0x7f813c858e00] concealing 178 DC, 178 AC, 178 MV errors in P frame
[h264 @ 0x7f813c866000] error while decoding MB 8 25, bytestream -8
[h264 @ 0x7f813c866000] concealing 241 DC, 241 AC, 241 MV errors in P frame
[h264 @ 0x7f813c873200] error while decoding MB 39 27, bytestream -8
[h264 @ 0x7f813c873200] concealing 130 DC, 130 AC, 130 MV errors in P frame
[h264 @ 0x7f813c83ea00] error while decoding MB 26 13, bytestream -10
[h264 @ 0x7f813c83ea00] concealing 703 DC, 703 AC, 703 MV errors in P frame
[h264 @ 0x7f813c866000] error while decoding MB 5 23, bytestream -6
[h264 @ 0x7f813c866000] concealing 324 DC, 324 AC, 324 MV errors in P frame
[h264 @ 0x7f813c880400] error while decoding MB 39 4, bytestream -9=184320.0kbits/s dup=47 drop=0 speed=1.41x
[h264 @ 0x7f813c880400] concealing 1050 DC, 1050 AC, 1050 MV errors in P frame
[h264 @ 0x7f813c821600] error while decoding MB 27 27, bytestream -5
[h264 @ 0x7f813c821600] concealing 142 DC, 142 AC, 142 MV errors in P frame
[h264 @ 0x7f813c84bc00] error while decoding MB 18 3, bytestream -7
[h264 @ 0x7f813c84bc00] concealing 1111 DC, 1111 AC, 1111 MV errors in P frame
[h264 @ 0x7f813c873200] error while decoding MB 39 19, bytestream -8
[h264 @ 0x7f813c873200] concealing 450 DC, 450 AC, 450 MV errors in P frame
[h264 @ 0x7f813c866000] error while decoding MB 28 23, bytestream -6
[h264 @ 0x7f813c866000] concealing 301 DC, 301 AC, 301 MV errors in P frame
[h264 @ 0x7f813c824600] error while decoding MB 35 7, bytestream -5=184320.0kbits/s dup=51 drop=0 speed=1.41x
[h264 @ 0x7f813c824600] concealing 934 DC, 934 AC, 934 MV errors in P frame
[h264 @ 0x7f813c83ea00] error while decoding MB 19 29, bytestream -7
[h264 @ 0x7f813c83ea00] concealing 70 DC, 70 AC, 70 MV errors in P frame
[h264 @ 0x7f813c873200] error while decoding MB 37 16, bytestream -6
[h264 @ 0x7f813c873200] concealing 572 DC, 572 AC, 572 MV errors in P frame
[h264 @ 0x7f813c831800] error while decoding MB 16 12, bytestream -5
[h264 @ 0x7f813c831800] concealing 753 DC, 753 AC, 753 MV errors in P frame
[h264 @ 0x7f813c866000] error while decoding MB 29 13, bytestream -6
[h264 @ 0x7f813c866000] concealing 700 DC, 700 AC, 700 MV errors in P frame
[h264 @ 0x7f813c821600] error while decoding MB 31 8, bytestream -6=184320.0kbits/s dup=55 drop=0 speed=1.42x
[h264 @ 0x7f813c821600] concealing 898 DC, 898 AC, 898 MV errors in P frame
[h264 @ 0x7f813c84bc00] error while decoding MB 11 22, bytestream -6
[h264 @ 0x7f813c84bc00] concealing 358 DC, 358 AC, 358 MV errors in P frame
frame= 400 fps= 35 q=-0.0 Lsize= 360000kB time=00:00:16.00 bitrate=184320.0kbits/s dup=56 drop=0 speed=1.41x
video:360000kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000000%
Traceback (most recent call last):
File "videoFeed.py", line 19, in <module>
image = image.reshape((480,640,3)) # Notice how height is specified first and then width
ValueError: cannot reshape array of size 0 into shape (480,640,3)
我在某处读到，如果您在管道开始接收数据后不立即开始读取数据，则可能会出现问题，但如果有人能指出潜在的问题，那将会有所帮助。
Update
我可以使用 netcat 获得高质量的摄像机源，同时将输出传输到 mplayer：
sudo nc -l 777 | mplayer -fps 200 -demuxer h264es -
所以我只能假设这与我处理饲料的方式有关，而不是与管道的构造方式有关。
更多测试
使用以下脚本我可以从 fifo264 管道读取视频，但它也会终止。
import cv2
import sys
video_capture = cv2.VideoCapture(r'fifo264')
video_capture.set(cv2.CAP_PROP_FRAME_WIDTH, 640);
video_capture.set(cv2.CAP_PROP_FRAME_HEIGHT, 480);
while True:
# Capture frame-by-frame
ret, frame = video_capture.read()
if ret == False:
pass
cv2.imshow('Video', frame)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
# When everything is done, release the capture
video_capture.release()
cv2.destroyAllWindows()
从 Raspberry PI 进行流式传输：
#!/bin/bash
raspivid -ih -vs -vf -n -w 640 -h 480 -o - -t 0 -b 2000000 | nc -v 10.0.0.3 777
错误和产生的输出：
[h264 @ 0x7fb25005d400] error while decoding MB 22 28, bytestream -8
[h264 @ 0x7fb250068c00] error while decoding MB 8 24, bytestream -9
[h264 @ 0x7fb25005d400] error while decoding MB 2 18, bytestream -5
[h264 @ 0x7fb250060400] error while decoding MB 23 11, bytestream -7
[h264 @ 0x7fb250073000] error while decoding MB 22 18, bytestream -11
[h264 @ 0x7fb250073600] error while decoding MB 36 9, bytestream -5
[h264 @ 0x7fb250067a00] error while decoding MB 29 23, bytestream -8
[NULL @ 0x7fb251155a00] missing picture in access unit with size 1448
[h264 @ 0x7fb251155400] Got unexpected packet size after a partial decode
[h264 @ 0x7fb251155400] Got unexpected packet size after a partial decode
[h264 @ 0x7fb251155400] Got unexpected packet size after a partial decode
[NULL @ 0x7fb251155a00] missing picture in access unit with size 1448
[h264 @ 0x7fb251155400] Got unexpected packet size after a partial decode
[h264 @ 0x7fb25005d400] error while decoding MB 35 2, bytestream -6
[NULL @ 0x7fb251155a00] missing picture in access unit with size 1200
[h264 @ 0x7fb25005d400] No start code is found.
[h264 @ 0x7fb25005d400] Error splitting the input into NAL units.
OpenCV(3.4.0-dev) Error: Assertion failed (size.width>0 && size.height>0) in imshow, file /Users/jamie/opencv/modules/highgui/src/window.cpp, line 356
Traceback (most recent call last):
File "video3.py", line 14, in <module>
cv2.imshow('Video', frame)
cv2.error: OpenCV(3.4.0-dev) /Users/jamie/opencv/modules/highgui/src/window.cpp:356: error: (-215) size.width>0 && size.height>0 in function imshow
归根结底，这不是管道、平台或权限的结果。在 Raspberry Pi 上生成并通过管道传输到 python 脚本的视频未得到正确处理。
我最终适应了这个picamera蟒蛇食谱
在 Raspberry Pi 上：(createStream.py)
import io
import socket
import struct
import time
import picamera
# Connect a client socket to my_server:8000 (change my_server to the
# hostname of your server)
client_socket = socket.socket()
client_socket.connect(('10.0.0.3', 777))
# Make a file-like object out of the connection
connection = client_socket.makefile('wb')
try:
with picamera.PiCamera() as camera:
camera.resolution = (1024, 768)
# Start a preview and let the camera warm up for 2 seconds
camera.start_preview()
time.sleep(2)
# Note the start time and construct a stream to hold image data
# temporarily (we could write it directly to connection but in this
# case we want to find out the size of each capture first to keep
# our protocol simple)
start = time.time()
stream = io.BytesIO()
for foo in camera.capture_continuous(stream, 'jpeg', use_video_port=True):
# Write the length of the capture to the stream and flush to
# ensure it actually gets sent
connection.write(struct.pack('<L', stream.tell()))
connection.flush()
# Rewind the stream and send the image data over the wire
stream.seek(0)
connection.write(stream.read())
# Reset the stream for the next capture
stream.seek(0)
stream.truncate()
# Write a length of zero to the stream to signal we're done
connection.write(struct.pack('<L', 0))
finally:
connection.close()
client_socket.close()
在处理流的机器上：(processStream.py)
import io
import socket
import struct
import cv2
import numpy as np
# Start a socket listening for connections on 0.0.0.0:8000 (0.0.0.0 means
# all interfaces)
server_socket = socket.socket()
server_socket.bind(('0.0.0.0', 777))
server_socket.listen(0)
# Accept a single connection and make a file-like object out of it
connection = server_socket.accept()[0].makefile('rb')
try:
while True:
# Read the length of the image as a 32-bit unsigned int. If the
# length is zero, quit the loop
image_len = struct.unpack('<L', connection.read(struct.calcsize('<L')))[0]
if not image_len:
break
# Construct a stream to hold the image data and read the image
# data from the connection
image_stream = io.BytesIO()
image_stream.write(connection.read(image_len))
# Rewind the stream, open it as an image with opencv and do some
# processing on it
image_stream.seek(0)
image = Image.open(image_stream)
data = np.fromstring(image_stream.getvalue(), dtype=np.uint8)
imagedisp = cv2.imdecode(data, 1)
cv2.imshow("Frame",imagedisp)
cv2.waitKey(1) #imshow will not output an image if you do not use waitKey
cv2.destroyAllWindows() #cleanup windows
finally:
connection.close()
server_socket.close()
该解决方案与我在原始问题中引用的视频具有相似的结果。较大的分辨率帧会增加提要的延迟，但这对于我的应用程序来说是可以容忍的。
首先需要运行processStream.py，然后在Raspberry Pi上执行createStream.py