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• FFmpeg vs Libav vs libVLC vs Gstreamer as of 2018 [on hold]

  25 avril 2018, par Dharma

  I am trying to do some video processing on real time. I was beginning to try the FFmpeg, but I saw this question :

  Why would I choose Libav over FFmpeg, or is there even a difference ?

  Which further links to this question :

  What are the differences and similarities between ffmpeg, libav, and avconv ?

  and this blog post :

  http://blog.pkh.me/p/13-the-ffmpeg-libav-situation.html

  After reading this I came to know that Libav is a fork from FFmpeg and is being developed separately. I am need of developing C++ application using either Libav or FFmpeg or libVLC or Gstreamer. I think there has been a lot of changes after these questions are answered. It would be great to have some benchmark on these tools.

  Do you guys have any preference of one over another, any benchmark results for video and audio processing ? I need to process frames fast and stream a video to multiple C++ applications, what would be the best way to solve this problem and what will be the best tool to choose ?

  So as of 2018 what is the current status of these tools on video processing.
  It would be nice to know some results from the people working on video processing who are familiar with these tools.

• Opencv cv2.VideoCapture('file.avi') shows first frame then throws exception

  3 novembre 2014, par holografix

  I’m trying to read a .avi included in the OpenCV original package, it’s called 768x576.avi and shows a few people walking around a street.

  The code below shows what seems to be the 1st frame and runs for a few seconds before returning an Exception.

  import cv2
  
  cap = cv2.VideoCapture('768x576.avi')
  
  cap.isOpened() # returns True
  
  cap.get(3); cap.get(4) # returns 768 and 576
  
  
  
  while (True):
  
      ret, frame = cap.read()
  
      cv2.imshow('frame', frame)

  Hands me this error after a few secs on the cv2.imshow line, I think it means the returned frame had no data associated it in.

  error: /tmp/opencv-7y6HHt/opencv-2.4.9/modules/highgui/src/window.cpp:261: error: (-215) size.width>0 && size.height>0 in function imshow

  I have no idea why this is happening, I’m running Yosemite, brew installed Python, OpenCv and Ffmpeg.

  opencv: stable 2.4.9, HEAD
  
  http://opencv.org/
  
  /usr/local/Cellar/opencv/2.4.9 (219 files, 38M) *
  
  
  
  ffmpeg: stable 2.4.2 (bottled), HEAD
  
  https://ffmpeg.org/
  
  /usr/local/Cellar/ffmpeg/2.4.2 (199 files, 40M) *
  
    Poured from bottle
  
  From: https://github.com/Homebrew/homebrew/blob/master/Library/Formula/ffmpeg.rb
  
  ==> Dependencies
  
  Build: pkg-config ✔, texi2html ✘, yasm ✘
  
  Recommended: x264 ✔, faac ✔, lame ✔, xvid ✔

• FFMPEG conversion from .H264 to MP4 playing too fast

  28 juin 2017, par NickR

  I accidentally deleted a video file but managed to save it with a recovery tool. The video was however corrupted, but I managed to repair that and now have a .h264 file.

  The file plays ok in the VLC player. There are a few glitches but on the whole its 98% perfect. However I now need to convert that into a more useable format (mp4 say).

  Ive downloaded the FFMPEG tool and have managed to pretty easily copy into mp4 with the following command line instruction :

  ffmpeg -i repairedVid.h264 -c copy repairedVid.mp4

  The problem is that the video is playing much too fast. I’ve done some research tried some tweaks that seem to have worked for other people (like forcing frame rate and changing the -vsync) :

  ffmpeg -i repairedVid.h264 -c copy repairedVid.mp4 -vsync 2 -r 23.976

  Ive also tried the crude approach of slowing the video down like this, but this was more of a long shot and I don’t think is the right way to go about it

  ffmpeg -i repairedVid.mp4 -filter:v "setpts=1.5*PTS" repairedVid.mp4

  This is the output when the video copies to MP4. Looks like it might have a clue to the problem (the video should be much longer than 4:40 minutes) :

  frame=13459 fps=1118 q=-1.0 size= 4102773kB time=00:04:40.65 bitrate=119756.4kbiframe=13459 fps=1117 q=-1.0 Lsize= 4102928kB time=00:04:40.65 bitrate=119761.0kbits/s speed=23.3x
  video:4102773kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead : 0.003784%

  I’m totally new to FFMPEG and not having much luck. Any advice would be great.

  Thanks in advance