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• Audio tracks while merging multiple videos using FFMPEG in Android ?

  23 avril 2016, par Leonti

  I have problem in video processing in Android.

  To merging multiple videos, I’m now using ffmpeg c++ library and JavaCV.

  Here is my code :

  protected Void doInBackground(String... params) {
  
      String firstVideo = params[0];
  
      String secondVideo = params[1];
  
      String outPutVideo = params[2];
  
  
  
      try {
  
          FrameGrabber grabber1 = new FFmpegFrameGrabber(firstVideo);
  
          grabber1.start();
  
          FrameGrabber grabber2 = new FFmpegFrameGrabber(secondVideo);
  
          grabber2.start();
  
          FrameRecorder recorder2 = new FFmpegFrameRecorder(outPutVideo, grabber2.getImageWidth(),
  
                  grabber2.getImageHeight(), grabber1.getAudioChannels());
  
  
  
          recorder2.setVideoCodec(grabber2.getVideoCodec());
  
          recorder2.setFrameRate(grabber2.getFrameRate());
  
          recorder2.setSampleFormat(grabber2.getSampleFormat());
  
          recorder2.setSampleRate(grabber2.getSampleRate());
  
          recorder2.setAudioChannels(2);
  
          recorder2.start();
  
          Frame frame;
  
          int j = 0;
  
  
  
          while ((frame = grabber1.grabFrame()) != null) {
  
              j++;
  
              recorder2.record(frame);
  
          }
  
          while ((frame = grabber2.grabFrame()) != null) {
  
              recorder2.record(frame);
  
          }
  
          recorder2.stop();
  
          grabber2.stop();
  
          grabber1.stop();
  
      } catch (Exception e) {
  
          e.printStackTrace();
  
          success = false;
  
      }
  
      return null;
  
  } 

  First video has no sound, and second video has audio tack.

  Audio of second video starts from start of result video.

  I tried and had search many hours, but cannot find solution. Please give me advise if you have experience !!!

• Add image overlay for each millisecond the video using ffmpeg and php

  21 octobre 2016, par Domenike

  I need to add an image and different position for each millisecond the video frame, using php and ffmpeg.
  For example :
  In the first second I add an image in the X position, the next second another image in the position X.
  If you use the command directly on the terminal, the conversion is successful. But in PHP I have difficulties.
  In php, use the following command :

  <?php
  
  shell_exec('C:\\ffmpeg\\bin\\ffmpeg.exe -i C:\\ffmpeg\\bin\\vid.mp4 -i C:\\ffmpeg\\bin\\1.png -filter_complex "[0:v][1:v] overlay=100:25:enable=\'between(t,1,1.5)\'"  C:\\ffmpeg\\bin\\output1.mp4');
  
  sleep(20);
  
  echo "1";
  
  shell_exec('C:\\ffmpeg\\bin\\ffmpeg.exe -i C:\\ffmpeg\\bin\\output1.mp4 -i C:\\ffmpeg\\bin\\2.png -filter_complex "[0:v][1:v] overlay=10:25:enable=\'between(t,1.5,2)\'"  C:\\ffmpeg\\bin\\output2.mp4');
  
  sleep(50);
  
  echo "2";
  
  shell_exec('C:\\ffmpeg\\bin\\ffmpeg.exe -i C:\\ffmpeg\\bin\\output2.mp4 -i C:\\ffmpeg\\bin\\3.png -filter_complex "[0:v][1:v] overlay=250:25:enable=\'between(t,2,2.5)\'"  C:\\ffmpeg\\bin\\output1.mp4');
  
  sleep(20);
  
  echo "3";
  
  shell_exec('C:\\ffmpeg\\bin\\ffmpeg.exe -i C:\\ffmpeg\\bin\\output1.mp4 -i C:\\ffmpeg\\bin\\4.png -filter_complex "[0:v][1:v] overlay=300:25:enable=\'between(t,3,3.5)\'"  C:\\ffmpeg\\bin\\output2.mp4');
  
  sleep(20);
  
  echo "4";
  
  shell_exec('C:\\ffmpeg\\bin\\ffmpeg.exe -i C:\\ffmpeg\\bin\\output2.mp4 -i C:\\ffmpeg\\bin\\5.png -filter_complex "[0:v][1:v] overlay=350:25:enable=\'between(t,4,4.5)\'"  C:\\ffmpeg\\bin\\output1.mp4');
  
  sleep(70000);
  
  shell_exec('C:\\ffmpeg\\bin\\ffmpeg.exe -i C:\\ffmpeg\\bin\\output1.mp4 -i C:\\ffmpeg\\bin\\1.png -filter_complex "[0:v][1:v] overlay=400:25:enable=\'between(t,5,5.5)\'"  C:\\ffmpeg\\bin\\output2.mp4');

  I used the sleep function (PHP), but it did not work.
  Please, as I have not much experience with ffmpeg and php, you can help me.

  Thank you very much.

• Improving Google Cloud Speech-to-Text accuracy

  6 juillet 2020, par lr_optim

  I'm working on a project where I need to perform these steps :

  


  

  1. Record a voice call (.webm -file)

  


  2. Split the webm -file into chunks with ffmpeg and convert the file into wav

  


  3. Transcribe the chunks using SpeechRecognition -library and Google Cloud API

  


  


  I've faced problems with the transcription accuracy and wondering if there is something I could do to improve it. At the time I'm splitting the original file into 30s chunks. I thought there might be one problem, that I might be missing words because of splitting so I've tried also with longer chunks under 60s but didn't notice any improve in accuracy.
Reading trough the speechRecognition docs I decided to set r.energy_threshold = 4000, I also tried to set the energy_treshold dynamically like this :

  


  with sr.AudioFile(name) as source:
    r.dynamic_energy_threshold = True
    r.adjust_for_ambient_noise(source, duration = 1)
    audio = r.record(source)


  


  I've also tested en-US and en-GB to see if there's some difference but there isn't as much as I'd want. The program is supposed to work with english language spoken by nordic people. If someone has experience about choosing a right language model for people speaking with accent, please let me know.

  


  This is the ffmpeg command is use to split the webm file into chunks : command = ['ffmpeg', '-i', filename, '-f', 'segment', '-segment_time', '30', parts_dir + outputname + '%09d.wav']

  


  Is there somethig I could do better ? I'm wondering if the quality is not good enough an Google is having hard time because of that ?

  


  The main problem is I'm getting bad results (lots of wrong words) from Google and wondering if there is something I could do about it.