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• Video transcoding

  12 mai 2020, par avanjv

  I have successfully implemented video compression commands for android using FFmpeg with following command :

  



  ffmpeg -i input.mp4 -vf "scale=-1:height" -vcodec h264 -b:v 1000k -acodec mp3 output.mp4


  



  It reduces video file size substantially, though after compression video was not playing on some android devices, the issue was resolved by removing codec from the command

  



  ffmpeg -i input.mp4 -vf "scale=-1:height" -b:v 1000k output.mp4


  



  But the processing time is way too longer than expected.
I have found this official linkedin library for video transcoding
https://github.com/linkedin/LiTr

  



  Which can be used for changing resolution and/or bitrate of a video track(s). Has anyone used it ? I am new in this field, I couldn't figure out the methods to be used for scaling and adjusting bitrate of a video file for this lib (Litr). Any help with these methods ?

  


• EmguCV capture rtsp ip camera stream ffmpeg

  2 février 2018, par Mr Neo

  I am working with IP camera and EmguCV to detect person in an area.
  Everything is work normally with Highgui capture source.
  But with Arlo camera which use FFMPEG format, I am unable to get stream without any exception.
  Here is the code I have tried :

  if (capture == null)
  
          {
  
              try
  
              {
  
                  capture = new Capture("rtsp://<ip>:8554/live"); 
  
                  capture.ImageGrabbed += Capture_ImageGrabbed;
  
                  capture.Grab();
  
                  capture.Start();
  
              }
  
  
  
  
  
              catch (NullReferenceException exception)
  
              {
  
                  MessageBox.Show(exception.Message);
  
              }
  
              catch (TypeInitializationException exc)
  
              {
  
                  MessageBox.Show(
  
                     "Attention: You have to copy all the assemblies and native libraries from an official release of EmguCV to the directory of the demo." +
  
                     Environment.NewLine + Environment.NewLine + exc);
  
              }
  
  }
  
  </ip>

  and here is Capture_ImageGrabbed event which is not fired.

  private void Capture_ImageGrabbed(object sender, EventArgs e)
  
      {
  
          Mat image = new Mat();
  
          capture.Retrieve(image);
  
          picCAM.Image = image.Bitmap;
  
      }

  Thanks so much for your help !

• SharedArrayBuffer for ffmpeg not working with React-Native

  31 août 2022, par Peter Garcia

  I am currently working on a React Native App using ffmpeg.wasm

  


  but for some reason, SharedArrayBuffer is still not working. My React version is "react" : "17.0.2", and React-dom is "17.0.2",. My Chrome version is Version 104.0.5112.101 (Official Build) (arm64)

  


  I've been racking my brain about why this isn't working on my React Native app since I did a test app and it works there but on this app, it doesn't.

  


  I am getting this error whenever I run ffmpeg.wasm :

  


  Uncaught (in promise) ReferenceError: SharedArrayBuffer is not defined
at aa35944d-451a-411f-bf18-4e42f7bbceb0:22:175
at Object.load (createFFmpeg.js:64:1)


  


  I cannot use Cross-Origin Opener headers :

  


  Cross-Origin-Opener-Policy: same-origin
Cross-Origin-Embedder-Policy: require-corp


  


  because our app calls from a lot of outside APIs and it breaks them.

  


  Any help would be greatly appreciated.