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• recording yuv data which is converted from a bitmap and images are changed constantly on this bitmap

  3 février 2016, par UserAx

  I am trying to record images which are changed at a set time interval. These are displayed on an imageview. (something like a movie maker)

  For this I am :

  1. Drawing these images on a bitmap, this method is repeated over a 50ms interval

     private void BitmapUpdate() {
     
            timer = new Timer();
     
     timer.scheduleAtFixedRate(new TimerTask() {
     
         public void run() {
     
             try {
     
                 new Task1().execute();
     
             } catch (Exception e) {
     
                 // TODO: handle exception
     
             }
     
         }
     
     }, 0, 50);
     
     }
     
     
     
     class Task1 extends AsyncTask {
     
     
     
     @Override
     
     protected void onPreExecute() {
     
         super.onPreExecute();
     
         clearBitmap();
     
     
     
     }
     
     
     
     @Override
     
     protected String doInBackground(Void... arg0) {
     
     
     
         onImageDisplayed();
     
         return null;
     
     }
     
     
     
     @Override
     
     protected void onPostExecute(String result) {
     
         super.onPostExecute(result);
     
     
     
     }
     
     }
     
     
     
     public void clearBitmap(){
     
     if (imageview != null){
     
     //All the 3 methods below give same error - can't call getpixels() on recycled bitmap
     
     imageview.setDrawingCacheEnabled(false);
     
     //OR
     
     imageview.destroyDrawingCache();
     
     //OR
     
     bitmap.recycle();
     
     
     
     }
     
        }
     
     
     
     
     
     
     
      public void onImageDisplayed(){
     
     
     
     if (imageview != null) {
     
         imageview.setDrawingCacheEnabled(true);
     
         imageview.buildDrawingCache();
     
         bitmap = imageview.getDrawingCache();
     
         System.out.println(bitmap.getByteCount() + " is bitmap size ");
     
         }
     
        }

  2. Using the bitmap data to convert it to yuv data
     By using getNV21 method :

  Convert bitmap array to YUV (YCbCr NV21)

  3. Finally this yuv data is passed FFmpeg recorder, through a method similar to onPreviewFrame, except that the data is from getNV21 method. This method is started by a button click.

  What I have achieved :

  1. If i dont use clearBitmap() ; i get only the first image recorded in the video, even on changing to next image only first image is present throughout the video.

  2. So After research on stack overflow many developers suggested clearing the previous imageCache for the next Image. But in my case if i use any of these methods, anywhere,

     imageview.setDrawingCacheEnabled(false);
     
     //OR
     
     imageview.destroyDrawingCache();
     
     //OR
     
     bitmap.recycle();

  I get the error ; mostly because the getNV21 method is running non stop, and always is expecting pixels flow from the Bitmap.

  3. If i try running the methods one after another, by stopping getpixels for a moment by a boolean, i only get a black screen.

  Kindly help...!

  THANKS.

• x11grab : fixed next frame capture time calculation

  3 février 2016, par Trevor \\\\ Higgins

  x11grab : fixed next frame capture time calculation
  The next frame time could slip, causing the frame rate to drop until
  
   frames were dropped. Now will capture at the next correct moment instead.
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavdevice/x11grab.c

• How to get accurate time information from ffmpeg audio outputs ?

  11 février 2016, par user2192778

  I want to figure out the best way to have accurate (down to millisecond) time information encoded into a web stream audio recording. So, if I wanted to know what was streaming at exactly 07:57:25 yesterday, I could retrieve that information using my program code. How can I do this in my ffmpeg function ?

  So far I have a python script that calls the following ffmpeg function every hour :

  ffmpeg -i http://webstreamurl.mp3 -t 01:30:00 outputname.mp3

  It will record 1.5 hours of my stream every hour. This leaves me with many 1.5 hour-long clips which together (due to some overlap) will give me audio at every moment.

  I don’t know how I will sync these clips with their stream times, however. Is there a way to put timestamps in the audio and have python read it ? Or is there a way to name these output files such that python could calculate the times itself ? Any other way ?