title: ffmpeg extracting frames from video
body: <p>I am using <a href="http://writingminds.github.io/ffmpeg-android-java/" rel="nofollow noreferrer">Writingminds FFmpeg</a> to use FFmpeg with Android. I am currently trying to extract frames from a video.</p>
  
  <p>I would like to extract 8 frames from the video evenly distributed throughout the video. I found this <a href="http://muzso.hu/2008/12/28/extracting-thumbnails-still-images-frames-from-a-video-with-ffmpeg" rel="nofollow noreferrer">tutorial</a> here is my implementation of it.</p>
  
  <pre><code>MediaMetadataRetriever retriever = new MediaMetadataRetriever();
      retriever.setDataSource(videoCroppedFile.getAbsolutePath());
      String time = retriever.extractMetadata(MediaMetadataRetriever.METADATA_KEY_DURATION);
      Long videoLength = Long.parseLong(time);
  
  
  final String cmd[] = {
  
              "-i",
              videoCroppedFile.getAbsolutePath(),
              "-f",
              "image2",
              "-ss",
              String.valueOf(videoLength.intValue() / ((8 + 1) * 10)),
              "-r",
              String.valueOf((8 + 1) / videoLength.intValue()),
              mediaStorageDir.getAbsolutePath() + "/%d.jpg"
      };
  </code></pre>
  
  <p>However, when i go to the folder where the frames should be saved there isn't anything there. Also there are no error messages.</p>
  
  <p>I feel like its a way this library takes the String parameters. I've been stuck on this for sometime I have tried lots of different versions of the <code>cmd</code>. I was hoping someone could help.</p>
  
  <p>Here is my output from ffmpeg:</p>
  
  <pre><code>1-22 19:33:14.904 30981-30981/com.firebase.android D/videoFrames:  failure reason ffmpeg version n3.0.1 Copyright (c) 2000-2016 the FFmpeg developers
           built with gcc 4.8 (GCC)
           configuration: --target-os=linux --cross-prefix=/home/vagrant/SourceCode/ffmpeg-android/toolchain-android/bin/arm-linux-androideabi- --arch=arm --cpu=cortex-a8 --enable-runtime-cpudetect --sysroot=/home/vagrant/SourceCode/ffmpeg-android/toolchain-android/sysroot --enable-pic --enable-libx264 --enable-libass --enable-libfreetype --enable-libfribidi --enable-libmp3lame --enable-fontconfig --enable-pthreads --disable-debug --disable-ffserver --enable-version3 --enable-hardcoded-tables --disable-ffplay --disable-ffprobe --enable-gpl --enable-yasm --disable-doc --disable-shared --enable-static --pkg-config=/home/vagrant/SourceCode/ffmpeg-android/ffmpeg-pkg-config --prefix=/home/vagrant/SourceCode/ffmpeg-android/build/armeabi-v7a --extra-cflags='-I/home/vagrant/SourceCode/ffmpeg-android/toolchain-android/include -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -fno-strict-overflow -fstack-protector-all' --extra-ldflags='-L/home/vagrant/SourceCode/ffmpeg-android/toolchain-android/lib -Wl,-z,relro -Wl,-z,now -pie' --extra-libs='-lpng -lexpat -lm' --extra-cxxflags=
           libavutil      55. 17.103 / 55. 17.103
           libavcodec     57. 24.102 / 57. 24.102
           libavformat    57. 25.100 / 57. 25.100
           libavdevice    57.  0.101 / 57.  0.101
           libavfilter     6. 31.100 /  6. 31.100
           libswscale      4.  0.100 /  4.  0.100
           libswresample   2.  0.101 /  2.  0.101
           libpostproc    54.  0.100 / 54.  0.100
         Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/data/user/0/com.firebase.android/cache/videovgntp6q5ar4dglkaflaoobfpcv945824159.mp4':
           Metadata:
             major_brand     : isom
             minor_version   : 512
             compatible_brands: isomiso2avc1mp41
             encoder         : Lavf57.25.100
           Duration: 00:00:08.28, start: 0.000000, bitrate: 391 kb/s
             Stream #0:0(eng): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 720x764 [SAR 1:1 DAR 180:191], 132 kb/s, 16.67 fps, 16.67 tbr, 12800 tbn, 33.33 tbc (default)
             Metadata:
               handler_name    : VideoHandler
             Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 256 kb/s (default)
             Metadata:
               handler_name    : SoundHandler
         Invalid framerate value: 0
  </code></pre>
  
  <p><strong>Update 2</strong></p>
  
  <p>Here is my Android code:</p>
  
  <pre><code>      try {
          ffmpeg.loadBinary(new LoadBinaryResponseHandler() {
  
              @Override
              public void onStart() {
                  Log.d("videoFrames", "starting to load binary");
              }
  
              @Override
              public void onFailure() {
                  Log.d("videoFrames", "failed to load binary");
              }
  
              @Override
              public void onSuccess() {
                  Log.d("videoFrames", "loaded binary");
                  try {
                      ffmpeg.execute(cmd, new ExecuteBinaryResponseHandler() {
  
                          @Override
                          public void onStart() {
                              Log.d("videoFrames", " starting to get frames from video");
                              if (mediaStorageDir.isDirectory() &amp;&amp; mediaStorageDir.list().length &gt; 0) {
                                  String[] children = mediaStorageDir.list();
                                  for (int i = 0; i &lt; children.length; i++) {
                                      new File(mediaStorageDir, children[i]).delete();
                                  }
                              }
                          }
  
                          @Override
                          public void onProgress(String message) {
                              Log.d("videoFrames", " progress getting frames from video");
                          }
  
                          @Override
                          public void onFailure(String message) {
                              Log.d("videoFrames", " failed to get frames from video");
                              Log.d("videoFrames", " failure reason " + message);
                              Log.d("videoFrames", " ----------------------------------------------- ");
                          }
  
                          @Override
                          public void onSuccess(String message) {
                              Log.d("videoFrames", " success getting frames from video");
                          }
  
                          @Override
                          public void onFinish() {
                              Log.d("videoFrames", " finished getting frames from video");
                          }
                      });
                  } catch (FFmpegCommandAlreadyRunningException e) {
                      Log.d("videoFrames", " command already running in fmpeg");
                      e.printStackTrace();
                  }
              }
  
              @Override
              public void onFinish() {}
          });
      } catch (FFmpegNotSupportedException e) {
          // Handle if FFmpeg is not supported by device
      }
  </code></pre>
  
  <p><strong>Update 3</strong></p>
  
  <p>I fixed my code by doing:</p>
  
  <pre><code> final String cmd[] = {
  
              "-i",
              videoCroppedFile.getAbsolutePath(),
              "-f",
              "image2",
              "-ss",
              String.valueOf(videoLength.floatValue() / (8.0  * 10.0)),
              "-r",
              String.valueOf(8.0 / videoLength.floatValue()),
              mediaStorageDir.getAbsolutePath() + "/%d.jpg"
      };
  </code></pre>