Recherche avancée

Sur d’autres sites (7543)

• How to send time stamps to ffmpeg when encoding uncompressed video frames via stdin ?

  7 août 2023, par Spacy

  I'm writing a C# application, but this question applies to any programming language.
I know it is possible to pass uncompressed video frames (in yuv420p format) via stdin to ffmpeg.exe, but I recorded these frames to RAM from a webcam that has a variable frame rate. I have the exact time stamps for each frame. How do I send the time stamps to ffmpeg.exe together with the uncompressed frame data ?

  


  I would prefer if it was possible to send them within the stdin byte stream, but I could also provide them up front when invoking ffmpeg.exe (this might become a very long argument list though). I could also write them to a text file on disk if nothing else works.

  


• python simple web app stack [on hold]

  8 septembre 2013, par Shonu93

  I am currently learning python and have written an app that I would like to put out on the web and/or Facebook platform. My script for the app is around 50-100 lines. The things I would like to implement are :

  1.HTML5 and CSS3

  • I'm good with this and would like to make the front end really appealing.

  2.Database

  • A simple database that keeps some basic info of the users who have used this app. (Either
    through their Facebook account or something else ! )
  • I would also like to have the option of storing 30 second mp3 clips. Say around 50 of
    these clips which the user can select and download.

  3.Python Backend

  • My python script should process user input on the server and send the output to the user.
  • My server should also have ffmpeg and lame libraries installed. (As my app requires this !)

  NOTE ** I would like to develop the complete web app locally first, before deploying it on the web **

  I really have no idea how to go about this. My app works like a charm on my Mac OSX and I really want to deploy this app on the web to make others happy too ! Do help me out guys !

• Issue with image rotation using JavaCV library

  26 février 2015, par intrepidkarthi

  I am writing an Android application which records video for a specified amount of time. Everything works fine if I record using the smartphone’s back camera. The app has a feature to pause/record feature like in Vine app. The issue comes when recording using the device’s front camera. The video surface frame looks fine when storing/playing the video the video is upside down. There is a lot of things discussed about this issue everywhere. But I didn’t find any solution that WORKS.

  Have a look at the code and image mentioned below.

  Here is the original image taken from front camera. I have turned it upside down for a better view.

  

  Here is what I actually get after rotation :

  

  Method :

       IplImage copy = cvCloneImage(image);
  
       IplImage rotatedImage = cvCreateImage(cvGetSize(copy), copy.depth(), copy.nChannels());
  
       //Define Rotational Matrix
  
       CvMat mapMatrix = cvCreateMat(2, 3, CV_32FC1);
  
  
  
       //Define Mid Point
  
       CvPoint2D32f centerPoint = new CvPoint2D32f();
  
       centerPoint.x(copy.width() / 2);
  
       centerPoint.y(copy.height() / 2);
  
  
  
       //Get Rotational Matrix
  
       cv2DRotationMatrix(centerPoint, angle, 1.0, mapMatrix);
  
  
  
       //Rotate the Image
  
       cvWarpAffine(copy, rotatedImage, mapMatrix, CV_INTER_CUBIC + CV_WARP_FILL_OUTLIERS, cvScalarAll(170));
  
       cvReleaseImage(copy);
  
       cvReleaseMat(mapMatrix);

  I have tried doing

       double angleTemp = angle;
  
  
  
       angleTemp= ((angleTemp / 90)%4)*90;       
  
       final int number = (int) Math.abs(angleTemp/90);
  
  
  
       for(int i = 0; i != number; ++i){            
  
           cvTranspose(rotatedImage, rotatedImage);
  
           cvFlip(rotatedImage, rotatedImage, 0);           
  
       }

  Ends up in throwing exception saying that source and destination doesn’t match with number of columns and rows.

  Update :

  Video is recorded in this way.

  IplImage newImage = null;
  
  if(cameraSelection == CameraInfo.CAMERA_FACING_FRONT){
  
      newImage = videoRecorder.rotate(yuvIplImage, 180);
  
      videoRecorder.record(newImage);
  
  }
  
  else
  
      videoRecorder.record(yuvIplImage);  

  Rotation is done in this way :

      IplImage img = IplImage.create(image.height(), image.width(),
  
              image.depth(), image.nChannels());
  
  
  
      for (int i = 0; i < 180; i++) {
  
          cvTranspose(image, img);
  
          cvFlip(img, img, 0);
  
      }

  Can anyone point out what is wrong here if you have experienced this before ?