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• Issue in recording video

  16 novembre 2015, par human123

  I am trying to record video in 480*480 resolution like in vine using javacv. As a starting point I used the sample provided in https://github.com/bytedeco/javacv/blob/master/samples/RecordActivity.java Video is getting recorded (but not in the desired resolution) and saved.

  But the issue is that 480*480 resolution is not supported natively in android. So some pre processing needs to be done to get the video in desired resolution.

  So once I was able to record video using code sample provided by javacv, next challenge was on how to pre process the video. On research it was found that efficient cropping is possible when final image width required is same as recorded image width. Such a solution was provided in the SO question,Recording video on Android using JavaCV (Updated 2014 02 17). I changed onPreviewFrame method as suggested in that answer.

      @Override
  
      public void onPreviewFrame(byte[] data, Camera camera) {
  
          if (audioRecord == null || audioRecord.getRecordingState() != AudioRecord.RECORDSTATE_RECORDING) {
  
              startTime = System.currentTimeMillis();
  
              return;
  
          }
  
          if (RECORD_LENGTH > 0) {
  
              int i = imagesIndex++ % images.length;
  
              yuvImage = images[i];
  
              timestamps[i] = 1000 * (System.currentTimeMillis() - startTime);
  
          }
  
          /* get video data */
  
          imageWidth = 640;
  
          imageHeight = 480    
  
          int finalImageHeight = 360;
  
          if (yuvImage != null && recording) {
  
              ByteBuffer bb = (ByteBuffer)yuvImage.image[0].position(0); // resets the buffer
  
              final int startY = imageWidth*(imageHeight-finalImageHeight)/2;
  
              final int lenY = imageWidth*finalImageHeight;
  
              bb.put(data, startY, lenY);
  
              final int startVU = imageWidth*imageHeight + imageWidth*(imageHeight-finalImageHeight)/4;
  
              final int lenVU = imageWidth* finalImageHeight/2;
  
              bb.put(data, startVU, lenVU);
  
              try {
  
                  long t = 1000 * (System.currentTimeMillis() - startTime);
  
                  if (t > recorder.getTimestamp()) {
  
                      recorder.setTimestamp(t);
  
                  }
  
                  recorder.record(yuvImage);
  
              } catch (FFmpegFrameRecorder.Exception e) {
  
                  Log.e(LOG_TAG, "problem with recorder():", e);
  
              }
  
          }
  
  
  
  
  
      }
  
  }

  Please also note that this solution was provided for an older version of javacv. The resulting video had a yellowish overlay covering 2/3rd part. Also there was empty section on left side as the video was not cropped correctly.

  So my question is what is the most appropriate solution for cropping videos using latest version of javacv ?

  Code after making change as suggested by Alex Cohn

      @Override
  
      public void onPreviewFrame(byte[] data, Camera camera) {
  
          if (audioRecord == null || audioRecord.getRecordingState() != AudioRecord.RECORDSTATE_RECORDING) {
  
              startTime = System.currentTimeMillis();
  
              return;
  
          }
  
          if (RECORD_LENGTH > 0) {
  
              int i = imagesIndex++ % images.length;
  
              yuvImage = images[i];
  
              timestamps[i] = 1000 * (System.currentTimeMillis() - startTime);
  
          }
  
          /* get video data */
  
          imageWidth = 640;
  
          imageHeight = 480;       
  
          destWidth = 480;
  
  
  
          if (yuvImage != null && recording) {
  
              ByteBuffer bb = (ByteBuffer)yuvImage.image[0].position(0); // resets the buffer
  
              int start = 2*((imageWidth-destWidth)/4); // this must be even
  
              for (int row=0; row2; row++) {
  
                  bb.put(data, start, destWidth);
  
                  start += imageWidth;
  
              }
  
              try {
  
                  long t = 1000 * (System.currentTimeMillis() - startTime);
  
                  if (t > recorder.getTimestamp()) {
  
                      recorder.setTimestamp(t);
  
                  }
  
                  recorder.record(yuvImage);
  
              } catch (FFmpegFrameRecorder.Exception e) {
  
                  Log.e(LOG_TAG, "problem with recorder():", e);
  
              }
  
          }
  
  
  
  
  
      }

  Screen shot from video generated with this code (destWidth 480) is

  

  Next I tried capturing a video with destWidth speciified as 639. The result is

  

  When destWidth is 639 video is repeating contents twice. When it is 480, contents are repeated 5 times and the green overlay and distortion is more.

  Also When the destWidth = imageWidth, video is captured properly. ie, for 640*480 there is no repetition of video contents and no green overlay.

  Converting frame to IplImage

  When this question was asked first, I missed to mention that the record method in FFmpegFrameRecorder is now accepting object of type Frame whereas earlier it was IplImage object. So I tried to apply Alex Cohn’s solution by converting Frame to IplImage.

  //---------------------------------------
  
  // initialize ffmpeg_recorder
  
  //---------------------------------------
  
  private void initRecorder() {
  
  
  
      Log.w(LOG_TAG,"init recorder");
  
  
  
      imageWidth = 640;
  
      imageHeight = 480; 
  
  
  
      if (RECORD_LENGTH > 0) {
  
          imagesIndex = 0;
  
          images = new Frame[RECORD_LENGTH * frameRate];
  
          timestamps = new long[images.length];
  
          for (int i = 0; i < images.length; i++) {
  
              images[i] = new Frame(imageWidth, imageHeight, Frame.DEPTH_UBYTE, 2);
  
              timestamps[i] = -1;
  
          }
  
      } else if (yuvImage == null) {
  
          yuvImage = new Frame(imageWidth, imageHeight, Frame.DEPTH_UBYTE, 2);
  
          Log.i(LOG_TAG, "create yuvImage");
  
          OpenCVFrameConverter.ToIplImage converter = new OpenCVFrameConverter.ToIplImage();
  
          yuvIplimage = converter.convert(yuvImage);
  
  
  
      }
  
  
  
      Log.i(LOG_TAG, "ffmpeg_url: " + ffmpeg_link);
  
      recorder = new FFmpegFrameRecorder(ffmpeg_link, imageWidth, imageHeight, 1);
  
      recorder.setFormat("flv");
  
      recorder.setSampleRate(sampleAudioRateInHz);
  
      // Set in the surface changed method
  
      recorder.setFrameRate(frameRate);
  
  
  
      Log.i(LOG_TAG, "recorder initialize success");
  
  
  
      audioRecordRunnable = new AudioRecordRunnable();
  
      audioThread = new Thread(audioRecordRunnable);
  
      runAudioThread = true;
  
  }
  
  
  
  
  
  
  
  @Override
  
      public void onPreviewFrame(byte[] data, Camera camera) {
  
          if (audioRecord == null || audioRecord.getRecordingState() != AudioRecord.RECORDSTATE_RECORDING) {
  
              startTime = System.currentTimeMillis();
  
              return;
  
          }
  
          if (RECORD_LENGTH > 0) {
  
              int i = imagesIndex++ % images.length;
  
              yuvImage = images[i];
  
              timestamps[i] = 1000 * (System.currentTimeMillis() - startTime);
  
          }
  
          /* get video data */
  
          int destWidth = 640;
  
  
  
          if (yuvIplimage != null && recording) {
  
              ByteBuffer bb = yuvIplimage.getByteBuffer(); // resets the buffer
  
              int start = 2*((imageWidth-destWidth)/4); // this must be even
  
              for (int row=0; row2; row++) {
  
                  bb.put(data, start, destWidth);
  
                  start += imageWidth;
  
              }
  
              try {
  
                  long t = 1000 * (System.currentTimeMillis() - startTime);
  
                  if (t > recorder.getTimestamp()) {
  
                      recorder.setTimestamp(t);
  
                  }
  
                  recorder.record(yuvImage);
  
              } catch (FFmpegFrameRecorder.Exception e) {
  
                  Log.e(LOG_TAG, "problem with recorder():", e);
  
              }
  
          }
  
  
  
  
  
      }

  But the videos generated with this method contained only green frames.

• How to encode jpeg images to H264 very fast (transform images to video)

  17 juillet 2013, par Paul

  I have 30 JPEG images (.jpg) at a resolution of 480 x 640.
  Each image takes aboout 20KB (all of them takes about 600KB).

  I am using FFmpeg command to encode these images into a video in H264 format.

  I need this to be done very fast - about 1 second.

  Using the classic command :

  ffmpeg -y  -f  image2   -r 1/5   -i image_%d.jpg   -c:v libx264   -r 30   video.mp4

  takes about 90 seconds.

  After adding -preset ultrafast :

  ffmpeg -y  -f  image2   -r 1/5   -i image_%d.jpg   -c:v libx264   -preset ultrafast    -r 30   video.mp4

  the encoding takes about 15 seconds which is much better, but still not enough

  I've tried others parameters also, like :

  -profile:v baseline
  
  
  
  -qscale:v
  
  
  
  -b:v 1000k
  
  
  
  -crf 24

  but the encoding time does not fall below 10 seconds.

  I'm not familiar with FFmpeg commands nor with the parameters I need to use, and this is the reason I post here this question.

  The video quality needs to be ok, doesn't need to be perfect.

  As a note : I am running these commands in an Android application where I have the ffmpeg executable, using an ProcessBuilder.

  Reply1 (to Robert Rowntree) :

  ArrayList<string> l2 = new ArrayList<string>();
  
  
  
          //l2.add("ffmpeg");
  
          l2.add("/data/data/" + packageName + "/ffmpeg");
  
          l2.add("-y");
  
          l2.add("-loop");
  
          l2.add("1");
  
  
  
          l2.add("-i");
  
          l2.add("frame_%d.jpg");
  
  
  
  //            l2.add("-t");
  
  //            l2.add(strngs[3]);
  
  
  
          l2.add("-r");
  
          l2.add("1/2");
  
          l2.add("-preset");
  
          l2.add("superfast");
  
          l2.add("-tune");
  
          l2.add("zerolatency");
  
  
  
  //            l2.add("-pass");
  
  //            l2.add(Integer.valueOf(pass).toString());
  
  
  
          l2.add("-vcodec");
  
          l2.add("libx264");
  
          l2.add("-b:v");
  
          l2.add("200k");
  
          l2.add("-bt");
  
          l2.add("50k");
  
          l2.add("-threads");
  
          l2.add("0");
  
          l2.add("-b_strategy");
  
          l2.add("1");
  
  
  
  //            if(pass ==1){
  
  //                l2.add("-an");
  
  //            } else {
  
  //                l2.add("-acodec");
  
  //                l2.add("copy");
  
  //            }
  
  
  
          l2.add("-f");
  
          l2.add("mp4");
  
          l2.add("-strict");
  
          l2.add("-2");
  
  //            l2.add("-passlogfile");
  
  //            l2.add(strngs[4]);
  
  
  
  //            if(pass ==1){
  
  //                l2.add("/dev/null");
  
  //            } else {
  
  //                l2.add(strngs[5]);
  
  //            }
  
  
  
          l2.add("video.mp4");
  
          //return l2;
  
  </string></string>

• Live downscaling of video to memory

  4 juin 2013, par Paul Knopf

  I have some very large videos in 1080p with high bitrates. Needless to say, streaming these files (using HTTP partial content streaming) will require a great deal of buffering on the client.

  I need a way to compress/download/de-grade the quality on demand, starting from a certain byte (for range requests). I know I can use FFMpeg to shrink the video for low-resolution playback, but I can't wait for the entire video to be done downscaling before the client can playback. I need to downscale to an in-memory buffer so that I can output straight to the HTTP requests.

  How would I do this ? Any libraries out there ? Is this even possible ?

  Note : I am using c#/.net, however, I could use some c++/c libraries if any are available and marshal them into c#/.net.