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• Add a text/caption to the first few seconds of a cut video ?

  6 mai 2022, par JR Jr.

  I want to cut a video and at the same time add a caption during the first few seconds of the video using drawtext. I have tried lots of different google searches but all turned out to be totally unhelpful for this specific purpose (even the answers on the SS pages). Also, I am on Windows, I don't care for other OS's, such as Unix/ubuntu/Mac.

  


  Let's use the below cut syntax as an example. It's cutting and changing the format from mkv to mp4, and I want to add a simple title to be displayed in the first 5 seconds of the video, since this will be done to various files and then they will be concatenated together and it's good to let the viewer know which movie each excerpt belongs to (without doing that manually for each single video, the goal is to add these texts to each of the below commands).

  


  "C:\ffmpeg\bin\ffmpeg.exe" -y -i "D:\S01\SATC - S01E03 - Bay of Married Pigs.mkv" -ss 00:18:05 -to 00:19:15 -codec copy "002-SATC - S01E03 - Bay of Married Pigs-00_18_05-00_19_15.mp4"


  


  Let's say I want to add the title "S01E03 - Bay of Married Pigs" in the center of the screen, in white, with font size 12, displayed between 1 and 5 seconds. How do I do that ?

  


  And more importantly, since these syntaxes tend to make the command line insanely long and it needs to be a one liner, is there a smarter way to feed the settings/configuration of the drawtext clause into the command line, as to not make the code very messy, long and chaotic ?
Besides, do white spaces matter/would misplaced blank spaces make the command line crash ?

  


  Been trying this for hours now, so I really appreciate your help on this.

  


• Cannot stream webcam using ffserver because of malloc error [migrated]

  21 septembre 2012, par user1509326

  I was following this tutorial RaspBerry Pi webcam and when I run the following command from root :

  $ ffserver -f /root/ffserver.conf & ffmpeg -v 2 -r 5 -s 640x480 -f video4linux2 -i /dev/video1` http://localhost:8090/webcam.ffm

  The camera is turned on and everything is fine, except it does not stream. I checked the terminal. From video 1, I get the following error :

  bind(port 8090): Address already in use
  
  *** glibc detected *** ffmpeg: malloc(): smallbin double linked list corrupted: 0x0000000000e5ac00 **

  When I use another port like 5000, I get the same result :

  $ ffserver -f /root/ffserver.conf & ffmpeg -v 2 -r 5 -s 640x480 -f video4linux2 -i /dev/video1 http://localhost:8090/webcam.ffm
  
  [2] 3795
  
  avserver version 0.8.3-4:0.8.3-0ubuntu0.12.04.1, Copyright (c) 2000-2012 the Libav developers
  
    built on Jun 12 2012 16:52:09 with gcc 4.6.3
  
  *** glibc detected *** ffmpeg: malloc(): smallbin double linked list corrupted: 0x0000000000b77c00 ***

• OpenCV no longer opens video files VideoCapture

  15 février 2018, par gruffmeister

  I have a problem seemingly caused by OpenCV 3.xx - the problem does not manifest in OpenCV 2.xx

  The issue is reading video files. I’ve set my code up as follows :

  >#include 
  
  >#include 
  
  >#include 
  
  >#include 
  
  >#include 
  
  
  
  >int main()
  
  
  
  >    cv::VideoCapture cap;
  
  >    cv::Mat frame;
  
  >    if(!cap.open("Myfile.avi"))
  
  >        std::cout << "Open failed" << std::endl;
  
  >    else
  
  >        cap.read(frame);
  
  >
  
  >    cv::imshow("Frame", frame);
  
  >    cv::waitKey(5000);
  
  >    return 0;

  Now the problem is when the code gets to "cap.read(frame)" I get a "vector subscript is out of range" error with OpenCV 3.40 and this does not happen with my build of OpenCV 2.4.9. The format of the file is in avi, its not some weird codec, and clearly it works in previous versions of OpenCV.

  I’ve tried other OpenCV 3.xx builds and I get the same or similar problems with simply reading a file in.

  My question is twofold :
  How do I get OpenCV 3.xx to work with reading video files (or do I need to regress to 2.xx ?)

  Why has the major revision change completely screwed up video file reading ? That doesn’t make any sense for a computer vision API.

  As a guess it will be something to do with the FFMPEG implementation because various searches have turned up other people having issues with this.

  Any help is much appreciated.

  Thanks