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• How to open .mp4 file using JavaCV's FFmpegGrabber in Android ?

  20 août 2015, par 7bitex

  I’m using JavaCV’s FFmpegFrameGrabber to open an mp4 file and grab frames for processing later. The mp4 file is chosen with an ACTION_GET_CONTENT intent which returns a file URI. Here is my code :

  FFmpegFrameGrabber grabber = new FFmpegFrameGrabber(mFileUri.getPath());
  
  grabber.setFormat("mp4");
  
  
  
  AndroidFrameConverter converter = new AndroidFrameConverter();
  
  try {
  
      grabber.start();
  
      Frame frame;
  
      while ((frame = grabber.grabFrame()) != null) {
  
          mImageResult.setImageBitmap(converter.convert(frame));
  
      }
  
  
  
      grabber.stop();
  
  } catch (FrameGrabber.Exception ex) {
  
      Log.e("Detector", ex.getLocalizedMessage());
  
  }

  But an error occurs saying avformat_open_input() error -13: Could not open input "/storage/emulated/0/DCIM/Camera/VID_20150820_152542.mp4". (Has setFormat() been called?). So where is wrong with my code ?

• How to set a timeout for FFmpegFrameGrabber grab() method in JavaCV

  18 janvier 2019, par Null Pointer

  I’m trying to create a player in Java using JavaCV. But .grab() method takes different amounts of time for each grab. How can I discard a grab() operation when it takes too much time ?

  In detail : I’m working on a project to display rtsp streams. To do this, I use JavaCV and its FFmpegFrameGrabber class. Inside a loop I call its .grab() method to grab frames and then I print them on a panel.
  (Not knowing the reason) grab() method takes much more time in some calls. For example :

  1. grab : 15ms,
  2. grab : 13ms,
  3. grab : 14ms,
  4. grab : 95ms,
  5. grab : 12ms, ...

  I wish not to wait for a grab, in case it is taking too long like in this fourth call.

  (Sorry for not providing a working code, it’s all over different huge classes)

  I use the following grabber options (selected by some other colleague) :

  grabber.setImageHeight(480);
  
  grabber.setImageWidth(640);
  
  grabber.setOption("reconnect", "1");
  
  grabber.setOption("reconnect_at_eof", "1");
  
  grabber.setOption("reconnect_streamed", "1");
  
  grabber.setOption("reconnect_delay_max", "2");
  
  grabber.setOption("preset", "veryfast");
  
  grabber.setOption("probesize", "192");
  
  grabber.setOption("tune", "zerolatency");
  
  grabber.setFrameRate(30.0);
  
  grabber.setOption("buffer_size", "" + this.bufferSize);
  
  grabber.setOption("max_delay", "500000");
  
  grabber.setOption("stimeout", String.valueOf(6000000));
  
  grabber.setOption("loglevel", "quiet");
  
  grabber.start();

  Also I tried to do the grab() in another thread and not wait for that to end in case it takes too long. But this time I get an EXCEPTION_ACCESS_VIOLATION when I call .grab() method before the previous one did not end yet. "Calling .release() ; and .restart() ; methods before trying to grab again" also did not solve the access violation.

  Is there a setting option to cancel unordinarily long grabs ? (Or wouldn’t it work without these frames (because of a reason that I don’t know))

  Thanks

• Trim video length in Android with javacv and ffmpeg

  11 juillet 2017, par Morya Yaroslav

  I’m trying to trim video length with ffmpeg implementation of FrameGrabber and FrameRecorder, but getting corrupted file of smaller size then it’s going to be. Maybe there is other way to trim video from start time to end time, also updating trim progress. Seems like it’s not recording changes between frames. Maybe there are some other ways to trim videos of different formats like mp4, flv and others. Here is code snippet :

          FrameGrabber grabber = new FFmpegFrameGrabber(mClip.getPath());
  
          grabber.start();
  
          grabber.setTimestamp(mClip.getClipStartMs()); // Write from specific moment
  
  
  
          File out = new File(mClip.getOutPutPath(params[0])); // Set destination to write
  
          FrameRecorder recorder = new FFmpegFrameRecorder(out, grabber.getImageWidth(), grabber.getImageHeight());
  
  
  
  
  
          recorder.setFormat(grabber.getFormat());
  
          recorder.setFrameRate(grabber.getFrameRate());
  
          recorder.setSampleRate(grabber.getSampleRate());
  
          recorder.setAspectRatio(grabber.getAspectRatio());
  
          recorder.setSampleFormat(grabber.getSampleFormat());
  
  
  
          recorder.setAudioCodec(grabber.getAudioCodec());
  
          recorder.setAudioBitrate(grabber.getAudioBitrate());
  
          recorder.setAudioChannels(grabber.getAudioChannels());
  
  
  
          recorder.setVideoCodec(grabber.getVideoCodec());
  
          recorder.setVideoBitrate(grabber.getVideoBitrate());
  
  
  
          recorder.start();
  
  
  
          Frame frame;
  
          Long timestamp;
  
          Long fullLength = mClip.getClipEndMs() - mClip.getClipStartMs();
  
          double percent = 0d, oldPercent = 0d;
  
  
  
          while ((frame = grabber.grabFrame()) != null && (timestamp = grabber.getTimestamp()) <= mClip.getClipEndMs()) {
  
              Log.d(ASYNC_SAVE_TAG, "Started command : ffmpeg " + mClip.toString());
  
  
  
              if (timestamp != 0d) {
  
                  oldPercent = percent;
  
                  percent = timestamp.doubleValue() / fullLength.doubleValue();
  
                  if (MathUtil.compare(percent, oldPercent) != 0) {
  
                      publishProgress(percent);
  
                  }
  
              }
  
  
  
              recorder.setTimestamp(grabber.getTimestamp() - mClip.getClipStartMs());
  
              recorder.record(frame);
  
          }
  
  
  
          grabber.close();
  
          recorder.close();