title: Add transparency to overlaid gif on a video using ffmpeg
body: <p>I am trying to add a vintage kind of effect on the selected video. For the effect, I used a vintage effect gif file and I successfully added it as an overlay on my video using the below method.</p>
  
  <pre><code>ffmpeg.execute(new String[]{"-i",uri,"-ignore_loop", "1","-i",overlayUri ,"-filter_complex","[0:v]scale="+width+":"+height+"[v1];[1:v]scale="+width+":"+height+"[v2];[v1][v2]overlay",outputPath}, new ExecuteBinaryResponseHandler() {
                  @Override
                  public void onStart() {
                      Log.d("success", "process complete");
                  }
  
                  @Override
                  public void onProgress(String message) {
                      Log.d("progress", message);
                  }
  
                  @Override
                  public void onFailure(String message) {
                      Log.d("failure", message);
                  }
  
                  @Override
                  public void onSuccess(String message) {
                      Log.d("success", "process complete");
                  }
  
                  @Override
                  public void onFinish() {
                  }
              });
              break;
  </code></pre>
  
  <p>But now as the overlay is not transparent, I can't see the video behind the overlay image. So how to do that.</p>