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• How to convert video with ffmpeg with few almost static images

  10 juillet 2015, par user1696947

  I have 8GB of video which have only 1 hour. I am trying to convert it to some format which reduce video size. Video contains few static images with dialogs in background. What is best way and format to convert it ?

  thanks a lot !

• Displaying Bitmaps sequentially, "like a video"

  15 juillet 2015, par Wamasa

  I’m trying to reproduce a video that is not android supported (like a .wmv video) in my app, and actually I’m able to grab every frame and create a Bitmap of it.

  So, now, I’m trying to show those bitmaps in a VideoView (or any other view), sequencially, something like a video.

  Some code :

  while (true) {
  
                  frame = frameGrabber.grab();
  
                  if (frame == null)
  
                      break;
  
                  frame2 =
  
                          IplImage.create(frame.width(), frame.height(),
  
                                  opencv_core.IPL_DEPTH_8U, 4);
  
                  opencv_imgproc.cvCvtColor(frame, frame2,
  
                          opencv_imgproc.CV_BGR2RGBA);
  
  
  
                  bm =
  
                          Bitmap.createBitmap(frame2.width(),
  
                                  frame2.height(), Bitmap.Config.ARGB_8888);
  
                  bm.copyPixelsFromBuffer(frame2.getByteBuffer());
  
                  canvas = new Canvas(bm);
  
                  mVideoView.draw(canvas);
  
                  canvas.save();

  It looks like I can grab every frame of the video (using ffmpeg), but I just don’t know how to display them.

  By the way, I’ve already tried encoding this video to a .mp4 file and playing it on the VideoView, but it takes much time to process the whole video (1 hour), so, now, I’m trying to display it right away, without encoding it do .mp4 (or any other android supported video)

  Any advices ?

• Programatically get non-overlapping images from MP4

  15 février 2013, par Carlos F

  My ultimate goal is to get meaningful snapshots from MP4 videos that are either 30 min or 1 hour long. "Meaningful" is a bit ambitious, so I have simplified my requirements.

  The image should be crisp - non-overlapping, and ideally not blurry. Initially, I thought getting a keyframe would work, but I had no idea that keyframes could have overlapping images embedded in them like this :

  Of course, some keyframe images look like this and those are much better :

  

  I was wondering if someone might have source code to :

  Take a sequence of say 10-15 continuous keyframes (jpg or png) and identify the best keyframe from all of them.

  This must happen entirely programaticaly. I found this paper : http://research.microsoft.com/pubs/68802/blur_determination_compressed.pdf

  and felt that I could "rank" a few images based on the above paper, but then I was dissuaded by this link : Extracting DCT coefficients from encoded images and video given that my source video is an MP4. Of course, this confuses me because the input into the system is just a sequence of jpg images.

  Another link that is interesting is :

  Detection of Blur in Images/Video sequences

  However, I am not sure if this will work for "overlapping" images.

  Any ideas ?