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• Opening file with unknown extension (Mjpeg ?) in OpenCV python

  14 novembre 2013, par bw4sz

  I am trying to open a third party video file into OpenCV with python.
  My camera (plotwatcher camera trap) shoots in a silly proprietary format. The extension is unique (.tlv) but i can play the file in VLC, and using ffmpeg i can see the following encoding :

  C:\Users\Ben>ffmpeg -i C:/Users/Ben/Documents/OpenCV_HummingbirdsMotion/PlotwatcherTest.tlv
  
  
  
  ffmpeg version N-58037-g355cea8 Copyright (c) 2000-2013 the FFmpeg developers
  
  built on Nov 11 2013 18:01:42 with gcc 4.8.2 (GCC)
  
  configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-av
  
  isynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enab
  
  le-iconv --enable-libass --enable-libbluray --enable-libcaca --enable-libfreetyp
  
  e --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --ena
  
  ble-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-l
  
  ibopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libsp
  
  eex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-aa
  
  cenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavp
  
  ack --enable-libx264 --enable-libxavs --enable-libxvid --enable-zlib
  
  libavutil      52. 52.100 / 52. 52.100
  
  libavcodec     55. 41.100 / 55. 41.100
  
  libavformat    55. 21.100 / 55. 21.100
  
  libavdevice    55.  5.100 / 55.  5.100
  
  libavfilter     3. 90.102 /  3. 90.102
  
  libswscale      2.  5.101 /  2.  5.101
  
  libswresample   0. 17.104 /  0. 17.104
  
  libpostproc    52.  3.100 / 52.  3.100
  
  Input #0, avi, from 'C:/Users/Ben/Documents/OpenCV_HummingbirdsMotion/Plotwatche
  
  rTest.tlv':
  
  Duration: 00:00:05.00, start: 0.000000, bitrate: 14608 kb/s
  
  Stream #0:0: Video: mjpeg (MJPG / 0x47504A4D), yuvj420p(pc), 1280x720, 10 tb
  
  r, 10 tbn, 10 tbc

  From this i can see file is encoded into mjpeg format.

  How can i open this file in open cv ?

  import cv2
  
  #import cv2.cv as cv
  
  import numpy as np
  
  cap = cv2.VideoCapture("C:/Users/Ben/Documents/OpenCV_HummingbirdsMotion/PlotwatcherTest.mjpg")
  
  ret, frame = cap.read()
  
  #show first image
  
  cv2.imshow('my window',frame)
  
  cv2.waitKey(0)
  
  cv2.destroyWindow('my window')

  I can see nothing has been loaded. When i try to view the first frame i get the error :

  File "C:\Users\Ben\Documents\OpenCV_HummingbirdsMotion\Test.py", line 21, in <module>
  
  cv2.imshow(&#39;my window&#39;,frame)
  
  error: ..\..\..\..\opencv\modules\highgui\src\window.cpp:261: error: (-215)
  
  size.width>0        &amp;&amp; size.height>0
  
  </module>

  I've tried leaving the native .tlv, mjpeg and mjpg, and .MJPG endings following the conceptual idea found here : MJPEG stream fails to open in OpenCV 2.4

  i appreciate all help !

• x11grab : Drop a spurious space in the extension reporting message

  27 août 2014, par Luca Barbato

  x11grab : Drop a spurious space in the extension reporting message
  Signed-off-by : Diego Biurrun <diego@biurrun.de>
  

  • [DH] libavdevice/x11grab.c

• PHP extension writing

  19 octobre 2013, par Mikko Koppanen — Imagick

  I’ve written quite a few PHP extensions over the past years and thought that I could share some of the experience with larger community. PHP internals can be a bit scary at times and in the past I’ve scoured through a lot of extensions to find practical examples of things such as how to return objects from internal functions/methods, how to handle different types of parameters, class properties etc.

  To document some of the experiences I started a project called extsample, in which I plan to add practical examples related to extension writing. There won’t be extensive written documentation outside the code, but hopefully the code itself contains enough nuggets of information to be useful. As the README says, if you need a specific example or clarification on something just open an issue in Github.

  The project is still very fresh but hopefully soon it will contain more examples. Pull requests are also welcome if you have code that you want to share with others.