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• ffmpeg encoder (h264) example yields invalid video

  18 mai 2017, par Jason M

  I am trying to implement the h264 encoder (no audio) for my c++ program with ffmpeg (3.24). I started out with running the supposed official example but got a unplayable video. When I probed it with my ffmpeg decoder, which works nicely on other h264 videos, it shows that the video has a time_base = 1/1200000, nb_frames = 0, avg_frame_rate = 25 and duration and start_time of large negative numbers.

  What may have caused the problem ? Is there other up-to-date encoder examples out there ?

• how to pass custom values into this Android ffmpeg method

  28 août 2014, par kc ochibili

  i am trying to call this method. but i dont know how to pass my own values into it
  Like : the output length, or FrameRate.

  The code uses some letters like "-y" "-i" which they explained without really explaining what the letters meant

  here is the method from https://github.com/guardianproject/android-ffmpeg-java/blob/master/src/org/ffmpeg/android/FfmpegController.java#L488

    /*
  
       * ffmpeg -y -loop 0 -f image2 -r 0.5 -i image-%03d.jpg -s:v 1280x720 -b:v 1M \
  
     -i soundtrack.mp3 -t 01:05:00 -map 0:0 -map 1:0 out.avi
  
  
  
     -loop_input – loops the images. Disable this if you want to stop the encoding when all images are used or the soundtrack is finished.
  
  
  
  -r 0.5 – sets the framerate to 0.5, which means that each image will be shown for 2 seconds. Just take the inverse, for example if you want each image to last for 3 seconds, set it to 0.33.
  
  
  
  -i image-%03d.jpg – use these input files. %03d means that there will be three digit numbers for the images.
  
  
  
  -s 1280x720 – sets the output frame size.
  
  
  
  -b 1M – sets the bitrate. You want 500MB for one hour, which equals to 4000MBit in 3600 seconds, thus a bitrate of approximately 1MBit/s should be sufficient.
  
  
  
  -i soundtrack.mp3 – use this soundtrack file. Can be any format.
  
  
  
  -t 01:05:00 – set the output length in hh:mm:ss format.
  
  
  
  out.avi – create this output file. Change it as you like, for example using another container like MP4.
  
       */
  
  
  
  public Clip createSlideshowFromImagesAndAudio (ArrayList<clip> images, Clip audio,  Clip out, int durationPerSlide, ShellCallback sc) throws Exception
  
      {
  
  
  
          final String imageBasePath = new File(mFileTemp,"image-").getCanonicalPath();
  
          final String imageBaseVariablePath = imageBasePath + "%03d.jpg";
  
  
  
  
  
          ArrayList<string> cmd = new ArrayList<string>();
  
  
  
  
  
          String newImagePath = null;
  
          int imageCounter = 0;
  
  
  
          Clip imageCover = images.get(0); //add the first image twice
  
  
  
          cmd = new ArrayList<string>();
  
          cmd.add(mFfmpegBin);
  
          cmd.add("-y");
  
  
  
          cmd.add("-i");
  
          cmd.add(new File(imageCover.path).getCanonicalPath());
  
  
  
          if (out.width != -1 &amp;&amp; out.height != -1)
  
          {
  
              cmd.add("-s");
  
              cmd.add(out.width + "x" + out.height);
  
          }
  
  
  
          newImagePath = imageBasePath + String.format(Locale.US, "%03d", imageCounter++) + ".jpg";
  
          cmd.add(newImagePath);
  
  
  
          execFFMPEG(cmd, sc);
  
  
  
          for (Clip image : images)
  
          {
  
              cmd = new ArrayList<string>();
  
              cmd.add(mFfmpegBin);
  
              cmd.add("-y");
  
  
  
              cmd.add("-i");
  
              cmd.add(new File(image.path).getCanonicalPath());
  
  
  
              if (out.width != -1 &amp;&amp; out.height != -1)
  
              {
  
                  cmd.add("-s");
  
                  cmd.add(out.width + "x" + out.height);
  
              }
  
  
  
              newImagePath = imageBasePath + String.format(Locale.US, "%03d", imageCounter++) + ".jpg";
  
              cmd.add(newImagePath);
  
  
  
              execFFMPEG(cmd, sc);
  
  
  
  
  
          }
  
  
  
          //then combine them
  
          cmd = new ArrayList<string>();
  
  
  
          cmd.add(mFfmpegBin);
  
          cmd.add("-y");
  
  
  
          cmd.add("-loop");
  
          cmd.add("0");
  
  
  
          cmd.add("-f");
  
          cmd.add("image2");
  
  
  
          cmd.add("-r");
  
          cmd.add("1/" + durationPerSlide);
  
  
  
          cmd.add("-i");
  
          cmd.add(imageBaseVariablePath);
  
  
  
          cmd.add("-strict");
  
          cmd.add("-2");//experimental
  
  
  
          String fileTempMpg = new File(mFileTemp,"tmp.mpg").getCanonicalPath();
  
  
  
          cmd.add(fileTempMpg);
  
  
  
          execFFMPEG(cmd, sc);
  
  
  
          //now combine and encode
  
          cmd = new ArrayList<string>();
  
  
  
          cmd.add(mFfmpegBin);
  
          cmd.add("-y");
  
  
  
          cmd.add("-i");
  
          cmd.add(fileTempMpg);
  
  
  
          if (audio != null &amp;&amp; audio.path != null)
  
          {
  
              cmd.add("-i");
  
              cmd.add(new File(audio.path).getCanonicalPath());
  
  
  
              cmd.add("-map");
  
              cmd.add("0:0");
  
  
  
              cmd.add("-map");
  
              cmd.add("1:0");
  
  
  
              cmd.add(Argument.AUDIOCODEC);
  
              cmd.add("aac");
  
  
  
              cmd.add(Argument.BITRATE_AUDIO);
  
              cmd.add("128k");
  
  
  
          }
  
  
  
          cmd.add("-strict");
  
          cmd.add("-2");//experimental
  
  
  
          cmd.add(Argument.VIDEOCODEC);
  
  
  
  
  
          if (out.videoCodec != null)
  
              cmd.add(out.videoCodec);
  
          else
  
              cmd.add("mpeg4");
  
  
  
          if (out.videoBitrate != -1)
  
          {
  
              cmd.add(Argument.BITRATE_VIDEO);
  
              cmd.add(out.videoBitrate + "k");
  
          }
  
  
  
          cmd.add(new File(out.path).getCanonicalPath());
  
  
  
  
  
          execFFMPEG(cmd, sc);
  
  
  
          return out;
  
      }
  
  </string></string></string></string></string></string></clip>

  so, say i want an out put video that has a

  framerate -->           2sec
  
  output frame size -->   480 x 480
  
  output lenght of-->     02:08:00
  
  and output file type --> .mp4

  How can i do call this method with these values ?
  and how do they relate to the letters used above.

• Audio not working with FFMPEG conversion

  17 juillet 2017, par mikelbring

  I am trying to convert an avi file to flv with an fairly simple ffmpeg command :

  ffmpeg -i dbkai12.avi -ab 96k -b 700k -ar 44100 -s 640x480 -acodec mp3 video.flv

  The video does exactly what I want, just no audio. I didnt come up with these numbers, just pulled them from different sources.

  Also tried :

  ffmpeg -i video.avi -ar 22050 -ab 32 -f flv -s 320x240 video.flv

  Same result.