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• FFmpeg Video Library Quick Review

  3 juillet 2019, par Rich_F

  I’m in need of reducing 18 videos so I can review them daily. I’d like to script some kind of compression or sampling using FFmpeg to not have to sit through 6 hours of video every day.

  What is the best way to review 6 hours of videos captured every day on SD cards ? The videos come in two cards, a 32 GB card ( 4 hours) and a 16 GB card ( 2 hours).

  Currently, I’m concatenating all videos and creating a screenshot every 3 seconds, which seems the longest I can go without missing something in the field of view (a vehicle will enter/leave). Still, this is thousands of images per card, and I select all, then preview and scroll down using page up/down. Any vehicle quickly appears in the thumbnails. This system isn’t bad, but I’m always inquisitive. I’m looking for more ways of sampling or seeing if any motion detection or frame analysis might register where I should be looking in my library of original captured videos.

  Options :

  1. Motion capture by analysis of frame by frame through trial and error on sensitivity to not measure wind on the bushes. This could be output to filename and time within the video (videos are captured 10 minutes long).

  2. Take my exported list of png files and string them together somehow into a slide show.

  3. Version 1 here, plus some retroactive capture of clips inside master clips.

  4. Some kind of compression. Again, I have to respect the 3-second max jump.

  Any other options that would be relatively easy to achieve without moving into any other software ? I’m trying to put the heavy lifting on the computer, as staring at videos is not something I’m finding I’ll be able to do for many days.

• ffmpeg only records 6 seconds of video

  2 novembre 2017, par purzel

  I’m trying to record a video from a capture card. As I want my program to control ffmpeg, I started a process within Java, let ffmpeg run for 30 seconds and then shut it down by sending "q" to the process. The video however is only 6 seconds long. I couldn’t find anything wrong in my code and would appreciate some help

  My code :

  import java.io.*;
  
  
  
  public class FfmpegTest {
  
      public static void main(String[] args) throws Exception {
  
          Process process = Runtime.getRuntime().exec("E:\\ffmpeg\\bin\\ffmpeg.exe -y -f dshow -i video=\"The video card\" bla.mp4");
  
          PrintWriter pw = new PrintWriter(process.getOutputStream(),true);
  
  
  
          Thread.sleep(30000);
  
          System.out.println("recording done");
  
          pw.println("q");
  
          Thread.sleep(2000);
  
      }
  
  }

• Can FFMPEG output like if it was a WDM / directshow webcam ?

  22 septembre 2015, par Jeffcurious

  I am using a 3D scanning program that uses a Directshow input from a camera / webcam.

  To increase the quality of the scan, I purchased a Blackmagic HDMI acquisition card that appears as a "webcam" in Windows. I am capturing the live HDMI output from a Canon DSLR (60D) into the Blackmagic card and then into the scanning program. But the output of the live Canon HDMI is interlaced (1080i). This is causing problems during the scan process.

  I would like to deinterlace the signal coming from the Blackmagic with FFmpeg and then output it "as if it was a windows WDM/directshow".

  Can FFMPEG output a stream that appears to other application as if it was a regular webcam ?
  Thanks,
  Jeff