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• Recording real-time video from images with FFmpeg

  17 juillet 2015, par Solarnum

  I am really not sure what else I could be doing to achieve this. I’m trying to record the actions in one of the views in my Android app so that it can be played back later and show the previous actions in real time. The major problem (among others, because there is no way I’m doing this optimally) is that the video takes at least 4 times longer to make than it does to playback. If I ask FFmpeg to create a 5 second video the process will run in the background for 20 seconds and output a greatly accelerated 5 second video.

  My current strategy is to use the -loop 1 parameter on a single image file and continuously write a jpeg to that image file. (If someone has a better idea than this for feeding continuously updated image information to FFmpeg let me know)

  encodingThread = new Thread(new Runnable() {
  
              private boolean running = true;
  
              @Override
  
              public void run() {
  
                  while (running) {
  
                      try {
  
  
  
                          Bitmap bitmap = makeBitmapFromView();
  
  
  
                          String filepath = Environment.getExternalStorageDirectory().getAbsolutePath() + "/test.jpg";
  
                          File file = new File(filepath);
  
                          FileOutputStream fout = new FileOutputStream(file);
  
                          bitmap.compress(Bitmap.CompressFormat.JPEG, 100, fout);
  
                          fout.flush();
  
                          fout.close();
  
                          Thread.sleep(50);
  
                      } catch (IOException e) {
  
                          e.printStackTrace();
  
                      } catch (InterruptedException e) {
  
                          running = false;
  
                      }
  
                  }
  
              }
  
          });
  
          startVideoMaking();
  
          encodingThread.start();

  The startVideoMaking method is as follows :

  private void startVideoMaking(){
  
      ffmpeg.killRunningProcesses();
  
              File outputFile = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + "/testout.mp4");
  
              String path = Environment.getExternalStorageDirectory().getAbsolutePath() + "/test.jpg";
  
              String output = Environment.getExternalStorageDirectory().getAbsolutePath() + "/testout.mp4";
  
  
  
              String command = "-loop 1 -t 5 -re -i " + path + " -c:v libx264 -loglevel verbose -vsync 0 -threads 0 -preset ultrafast -tune zerolatency -y -pix_fmt yuv420p " + output;
  
              executeFFM(command);
  
  }

  Just to make it clear, the FFmpeg command that I am executing is

  ffmpeg -loop 1 -re -i /storage/emulated/0/test.jpg -t 5 -c:v libx264 -loglevel verbose -vsync 0 -threads 0 -preset ultrafast -tune zerolatency -y -pix_fmt yuv420p /storage/emulated/0/testout.mp4

  The makeBitmapFromView() method takes about 50ms to process and writing the bitmap to the sd card takes around 200ms, which is not great.

  I’m pretty lost as to what other solutions there would be to creating a video of a single view in Android. I know there is the MediaCodec class, but I couldn’t get that to work and also it would raise my minimum sdk, which is not ideal. I’m also not sure that the MediaCodec class would even solve my problem.

  Is there some way that I can get FFmpeg to create a 5 second video that is equivalent to 5 seconds of real time ? I have also tried converting a single image, without updating it’s content continuously and had the same results.

  If my question isn’t clear enough let me know.

• How does CMP pass comparison value to the next line in a bash script ?

  22 août 2015, par Tandy Freeman

  I want to compare the output of two framemd5 (decoded md5 of every video frame) digests.
  http://stackoverflow.com/a/12736416/2188572

  The cmp script works perfectly for me.
  I know next to nothing about coding, so I want to educate myself on what’s happening, and I can’t figure out from SO or googling.

  It seems like the script should require more input from me, like I should have to stipulate(apologies for awful pseudo code)

  cmp file1 file 2
  
  if cmp produces a difference;then
  
  else 

  It seems that just entering "if cmp file1 file 2" automatically produced the equivalent of a YES or NO and stores that info for the then, else etc ?

• avcodec/libopenh264enc : Use av_log() to log messages

  9 septembre 2015, par Gregory J. Wolfe

  avcodec/libopenh264enc : Use av_log() to log messages
  File libopenh264enc.c has been modified so that the encoder uses av_log()
  
  to log messages (error, warning, info, etc.) instead of logging them
  
  directly to stderr.  At the time the encoder is created, the current
  
  ffmpeg log level is mapped to an equivalent libopenh264 log level.  This
  
  log level, and a message logging function that invokes av_log() to
  
  actually log messages, are then set on the encoder.
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/libopenh264enc.c