title: ffmpeg error while adding text on video
body: <p>I have used 'com.writingminds:FFmpegAndroid:0.3.2' library for using ffmpeg in my app.I want to add text in video.I have added the library and used the methods specified there .Then I'm passing the ffmpeg command as an argument to the execute method .But it shows an error as output file not specified but i have added an output file in the commands.Don't know what is going wrong.</p>
  
  <p>My code is as follows:</p>
  
  <pre><code> `FFmpeg fFmpeg = FFmpeg.getInstance (MainActivity.this);
              try {
                  fFmpeg.loadBinary (new LoadBinaryResponseHandler () {
  
                      @Override
                      public void onStart() {
                          Log.e ("onStart", "onStart load");
                      }
  
                      @Override
                      public void onFailure() {
                          Log.e ("onFailure", "onFailure load");
                      }
  
                      @Override
                      public void onSuccess() {
                          Log.e ("onSuccess", "onSuccess load");
                      }
  
                      @Override
                      public void onFinish() {
                          Log.e ("onFinish", "onFinish load");
                      }
                  });
              } catch (FFmpegNotSupportedException e) {
                  e.printStackTrace ();
                  // Handle if FFmpeg is not supported by device
              }
  
              String[] cmd = {"-y",
                      "-i",
                      "/storage/emulated/0/DCIM/Camera/VID_20171212_120337.mp4",
                      "-vf",
                      "format=yuv444p",
                      "-codec:v",
                      "drawtext=text='Title of this Video': fontcolor=white: fontsize=24: x=(w-tw)/2: y=(h/PHI)+th  box=1: boxcolor=black@0.5",
                      "-c:v copy",
                      "outVideo.mp4"
              };
  
              try {
                  fFmpeg.execute (cmd, new ExecuteBinaryResponseHandler () {
  
                      @Override
                      public void onStart() {
                          Log.e ("onStart", "onStart execute");
                      }
  
                      @Override
                      public void onProgress(String message) {
                          Log.e ("onProgress execute", message);
                      }
  
                      @Override
                      public void onFailure(String message) {
                          Log.e ("onFailure execute", message);
                      }
  
                      @Override
                      public void onSuccess(String message) {
                          Log.e ("onSuccess execute", message);
                      }
  
                      @Override
                      public void onFinish() {
                          Log.e ("onFinish execute", "onFinish execute");
                      }
                  });
              } catch (FFmpegCommandAlreadyRunningException e) {
                  e.printStackTrace ();
                  // Handle if FFmpeg is already running
              }`
  </code></pre>
  
  <p>It shows the following error :</p>
  
  <pre><code>`onFailure execute: ffmpeg version n3.0.1 Copyright (c) 2000-2016 the FFmpeg developers built with gcc 4.8 (GCC)
  </code></pre>
  
  <p>Trailing options were found on the commandline.</p>
  
  <pre><code>                                                            Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/storage/emulated/0/DCIM/Camera/VID_20171212_120337.mp4':
                                                                 Metadata:
                                                                   major_brand     : mp42
                                                                   minor_version   : 0
                                                                   compatible_brands: isommp42
                                                                   creation_time   : 2017-12-12 06:33:43
                                                                 Duration: 00:00:04.84, start: 0.000000, bitrate: 8552 kb/s
                                                                   Stream #0:0(eng): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p, 1280x720, 7842 kb/s, SAR 1:1 DAR 16:9, 16.84 fps, 16.67 tbr, 90k tbn, 180k tbc (default)
                                                                   Metadata:
                                                                     rotate          : 90
                                                                     creation_time   : 2017-12-12 06:33:43
                                                                     handler_name    : VideoHandle
                                                                   Side data:
                                                                     displaymatrix: rotation of -90.00 degrees
                                                                   Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 96 kb/s (default)
                                                                   Metadata:
                                                                     creation_time   : 2017-12-12 06:33:43
                                                                     handler_name    : SoundHandle
                                                            **At least one output file must be specified**`
  </code></pre>