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• OpenCV in Python on Windows does not report correct video properties from VideoReader

  24 décembre 2015, par Mircea Davidescu

  I am running into a problem with using VideoReader in OpenCV with Python. Many of the properties that I should be able to get from the video reader are either somehow invalid (returning 0), or return the wrong number. For instance.

  vidFile = cv2.VideoCapture('movie.avi')
  
  vidFile.get(cv2.CAP_PROP_FRAME_COUNT)
  
  vidFile.get(cv2.CAP_PROP_FPS)

  The first get command returns a wrong value, while the second get command returns 0. The output of the ffprobe command is given below :

  built with gcc 5.2.0 (GCC)
  
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls 
  
  --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libdcadec --enable-libfreetype --enable-libgme --enable-libgsm 
  
  --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus 
  
  --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab 
  
  --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 
  
  --enable-libxavs --enable-libxvid --enable-lzma --enable-decklink --enable-zlib
  
    libavutil      55.  5.100 / 55.  5.100
  
    libavcodec     57. 12.100 / 57. 12.100
  
    libavformat    57. 11.100 / 57. 11.100
  
    libavdevice    57.  0.100 / 57.  0.100
  
    libavfilter     6. 14.101 /  6. 14.101
  
    libswscale      4.  0.100 /  4.  0.100
  
    libswresample   2.  0.100 /  2.  0.100
  
    libpostproc    54.  0.100 / 54.  0.100
  
  Input #0, avi, from 'movie.avi':
  
    Metadata:
  
      encoder         : Lavf55.0.100
  
    Duration: 00:31:59.97, start: 0.000000, bitrate: 24321 kb/s
  
      Stream #0:0: Video: mjpeg (MJPG / 0x47504A4D), yuvj420p(pc, bt470bg/unknown/unknown), 1392x1040 [SAR 1:1 DAR 87:65], 24316 kb/s, 30 fps, 30 tbr, 30 tbn, 
  
  30 tbc

  I am running a Windows 10 machine with Python 2.7.11 (Anaconda 2.4.1 64-bit). I have installed OpenCV 3.0.0 according the instructions provided here. Because I am using the VideoReader feature I also added C :\opencv\sources\3rdparty\ffmpeg to the system PATH and renamed both opencv_ffmpeg300.dll and opencv_ffmpeg_x64.dll to opencv_ffmpeg300.dll and opencv_ffmpeg300_64.dll respectively, as specified here.

  Thank you for your help with this problem !

• FFmpeg4 android Applying Overlay (watermark) taking too long

  13 janvier 2019, par Web Developer

  I’m using ffmpeg4 on android (Java) to apply overlay/watermark on the bottom left corner of the recorded video that is saved in the SD CARD.

  The video recording has maximum duration of 59 seconds. The problem that I’m facing is that I’m applying water through this command of ffmpeg4

  String[] complexCommand1 = new String[]"ffmpeg", "-y", "-i",
  "input.mp4", "-strict", "experimental", "-c:v", "libx264", "-preset",
  "ultrafast", "-vf", "movie=/water.png [watermark] ; [in][watermark] overlay=main_w-overlay_w-", "10:10", " [out]", "-s", "320x480", "-aspect",
  "2:3", "-r", "30", "-b:v", "500k",
  "output.mp4"  ;

  I’ve reduced the video resolution to 320x480 after the conversion and 480p to recorded video that is provided as input to this command but still the processing time is around 40 seconds.

  Can someone provide me workaround this to reduce this processing time.

  or what should I do to reduce this processing time. I’ve researched a lot on this and found some GitHub issues link and tried their solutions but none of them seemed to work for me.

• ffmpeg settings or alternatives to ffmpeg on raspberry pi for video streaming

  14 octobre 2016, par andrei

  I have a Raspberry Pi (model B) running raspbian wheezy on a 16gb SD card. I also have a 32gb flash storage attached on the usb. I’m trying to stream a video (h264 encoded mp4 file 1280x720) over the ethernet from that flash storage.
  I’m using ffmpeg+ffserver. Here is ffserver.conf (relevant parts) :

  ...
  
  MaxBandwidth 10000
  
  <feed>
  
  ...
  
  FileMaxSize 100M
  
  ACL allow 127.0.0.1
  
  </feed>
  
  ...
  
  <stream>
  
  Feed feed1.ffm
  
  Format flv
  
  VideoSize 288x176 #made small just for testing
  
  NoAudio
  
  </stream>
  
  ....

  I start the ffserver, then call ffmpeg with this command :

  ffmpeg -re -an -i /mnt/u32/main.mp4 -r 25 -bit_rate 300k http://localhost:8090/feed1.ffm

  And I’m getting fps 3-5 at most. Naturally when I try to view the stream on another computer it’s very choppy and virtually unusable.

  Am I missing some settings ? Or perhaps there is another streaming solution that leverages the GPU instead of just the CPU as ffmpeg does ? I’m even open to suggestions about other boards (e.g. a pandaboard ? or clustering several RPi’s ?) Also, I’m flexible about the output format.