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• C++/OpenCV - VideoCapture doesn't work but it worked before with exactly the same code

  5 mars 2015, par Damià Obrador

  I’m trying to write a shot boundary detection algorithm in C++ using OpenCV. After all, I have to say that I have no experience working with OpenCV.

  I have been improving the following code (and I am still in it) during the last two weeks and everything seems the works correctly, not in terms of perfect shot detection, but every line of code did what was expected from it.

  #include <cstdlib>
  
  #include <opencv2></opencv2>opencv.hpp>
  
  #include <opencv2></opencv2>core/core.hpp>
  
  #include <opencv2></opencv2>video/background_segm.hpp>
  
  #include <opencv2></opencv2>highgui/highgui.hpp>
  
  #include <iostream>
  
  #include <opencv2></opencv2>imgproc/imgproc.hpp>
  
  #include 
  
  #include <istream>
  
  #include <fstream>
  
  using namespace cv;
  
  
  
  
  
  
  
  int main(){
  
  
  
      VideoCapture capture("vdevendetta.mp4");
  
      if ( !capture.isOpened() )
  
       {
  
           std::cout &lt;&lt; "Cannot open the video file";
  
           return -1;
  
       }
  
      int numFrames=capture.get(CV_CAP_PROP_FRAME_COUNT);
  
      bool SB_counter=false;
  
      Mat currentFrame;
  
      Mat frame;
  
      Mat fore;
  
      Mat back;
  
      vector<mat> frames;
  
      FileStorage file;
  
      FileStorage file2;
  
      Mat prev_Y;
  
      Mat channels[3];
  
      for(int i=0;i>currentFrame;
  
              frame=currentFrame.clone();
  
              cvtColor(frame,frame,CV_BGR2YUV);
  
              split( frame, channels );
  
              prev_Y=channels[0];
  
              SB_counter=false;
  
          }
  
          else
  
          {
  
              capture>>currentFrame;
  
              frame=currentFrame.clone();
  
              Mat channels[3];
  
              cvtColor(frame,frame,CV_BGR2YUV);
  
              split( frame, channels );
  
              Mat curr_Y=channels[0];
  
              channels[0]=prev_Y;
  
              prev_Y=curr_Y;
  
              merge(channels,3,frame);
  
              cvtColor(frame,frame,CV_Luv2BGR);
  
              cvtColor(frame,frame,CV_BGR2GRAY);
  
              frames.push_back(frame);
  
          }
  
  
  
      }
  
  
  
      vector<double> MAFDs;
  
      vector<double> MAFD;
  
      vector<double> aux;
  
      double min;
  
      double min2;
  
  
  
      for(int j=1;j14)
  
          {
  
              std::cout&lt;&lt;"De"&lt;*
  
      std::ofstream fout("MAFD.txt");
  
      if(fout.is_open()==true)
  
      {
  
        //file opened successfully so we are here
  
        std::cout &lt;&lt; "File Opened successfully!!!. Writing data from array to file" &lt;&lt; std::endl;
  
  
  
          for(int i = 0; MAFD[i] != '\0'; i++)
  
          {
  
          fout &lt;&lt; MAFD[i]; //writing ith character of array in the file
  
          }
  
        std::cout &lt;&lt; "Array data successfully saved into the file test.txt" &lt;&lt; std::endl;
  
      }
  
      else //file could not be opened
  
      {
  
          std::cout &lt;&lt; "File could not be opened." &lt;&lt; std::endl;
  
      }*/
  
      return 0;
  
  }
  
  </double></double></double></mat></fstream></istream></iostream></cstdlib>

  Three days ago I had an strange problem. The line :

  VideoCapture capture("vdevendetta.mp4");

  stopped working. I spent many hours looking for the solution but nothing seems to repair it. After reading everything related with OpenCV, VideoCapture and ffmpeg that I found on internet I decided to reinstall everything taking care of each detail, but it still didn’t work. Finally I solved it changing the line with this other one :

  VideoCapture capture("/home/damia/Documentos/Universitat/ARA/PAEAV/workspace_cpp/SBD/src/vdevendetta.mp4");

  I did not know why this solved it because the video is in the same directory than the program, but I continued working because everything seemed correct.
  Today I had the same problem again on the new line.
  The terminal doesn’t show any error comment (exceptuating "Cannot open the video file", obviously) but the code doesn’t work again.

  I’m using Ubuntu 14.04 LTS, OpenCV 2.4.9 and Eclipse.

  I think if someone test the code it will run correctly, but I would like to know if there is something I have no taking into account.

  Thank you very match.

• Android FFMPEG - Low FPS & File Size is massive

  2 mai 2018, par Alexzander Flores

  I am new to Android app development and I have been asked to make a video splitter app. I am trying to use FFMPEG, but the library size is massive and makes the .APK file 140MB. How can I solve this ? Similar apps are around 15MBs in size.

  Also, the framerate starts at 30FPS and drops to around 2.2FPS over time when trying to split a 30 second long video into two parts. How can I solve this ? This is my code currently :

  package splicer.com.splicer;
  
  
  
  import android.Manifest;
  
  import android.content.Context;
  
  import android.content.Intent;
  
  import android.content.pm.PackageManager;
  
  import android.database.Cursor;
  
  import android.media.MediaMetadataRetriever;
  
  import android.media.MediaScannerConnection;
  
  import android.net.Uri;
  
  import android.provider.MediaStore;
  
  import android.support.v4.app.ActivityCompat;
  
  import android.support.v4.content.ContextCompat;
  
  import android.support.v7.app.AppCompatActivity;
  
  import android.os.Bundle;
  
  import android.text.method.ScrollingMovementMethod;
  
  import android.view.View;
  
  import android.widget.Button;
  
  import android.widget.TextView;
  
  
  
  import com.github.hiteshsondhi88.libffmpeg.ExecuteBinaryResponseHandler;
  
  import com.github.hiteshsondhi88.libffmpeg.FFmpeg;
  
  import com.github.hiteshsondhi88.libffmpeg.LoadBinaryResponseHandler;
  
  import com.github.hiteshsondhi88.libffmpeg.exceptions.FFmpegNotSupportedException;
  
  
  
  public class MainActivity extends AppCompatActivity {
  
  
  
      private Button button;
  
      private TextView textView;
  
      private FFmpeg ffmpeg;
  
  
  
      static {
  
          System.loadLibrary("native-lib");
  
      }
  
  
  
      @Override
  
      protected void onCreate(Bundle savedInstanceState) {
  
          super.onCreate(savedInstanceState);
  
          setContentView(R.layout.activity_main);
  
  
  
          ffmpeg = FFmpeg.getInstance(getApplicationContext());
  
          try {
  
              ffmpeg.loadBinary(new LoadBinaryResponseHandler() {
  
  
  
                  @Override
  
                  public void onStart() {}
  
  
  
                  @Override
  
                  public void onFailure() {}
  
  
  
                  @Override
  
                  public void onSuccess() {}
  
  
  
                  @Override
  
                  public void onFinish() {}
  
              });
  
          } catch(FFmpegNotSupportedException e) {
  
              e.printStackTrace();
  
          }
  
  
  
          textView = (TextView) findViewById(R.id.textView);
  
          textView.setY(200);
  
          textView.setHeight(700);
  
          textView.setMovementMethod(new ScrollingMovementMethod());
  
  
  
          button = (Button) findViewById(R.id.button);
  
          button.setOnClickListener(new View.OnClickListener() {
  
              @Override
  
              public void onClick(View view) {
  
                  openGallery();
  
              }
  
          });
  
      }
  
  
  
      /**
  
       * A native method that is implemented by the 'native-lib' native library,
  
       * which is packaged with this application.
  
       */
  
      public native String stringFromJNI();
  
  
  
      public void openGallery() {
  
          if(ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
  
              ActivityCompat.requestPermissions(this, new String [] {Manifest.permission.READ_EXTERNAL_STORAGE}, 0);
  
          }
  
  
  
          if(ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
  
              ActivityCompat.requestPermissions(this, new String [] {Manifest.permission.WRITE_EXTERNAL_STORAGE}, 0);
  
          }
  
  
  
          Intent gallery = new Intent(Intent.ACTION_PICK, MediaStore.Video.Media.EXTERNAL_CONTENT_URI);
  
          startActivityForResult(gallery, 100);
  
      }
  
  
  
      public String getRealPathFromURI(Context context, Uri contentUri) {
  
          Cursor cursor = null;
  
          try {
  
              String[] proj = { MediaStore.Images.Media.DATA };
  
              cursor = context.getContentResolver().query(contentUri,  proj, null, null, null);
  
              int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
  
              cursor.moveToFirst();
  
              return cursor.getString(column_index);
  
          } finally {
  
              if (cursor != null) {
  
                  cursor.close();
  
              }
  
          }
  
      }
  
  
  
      @Override
  
      protected void onActivityResult(int requestCode, int resultCode, final Intent intent) {
  
          super.onActivityResult(requestCode, resultCode, intent);
  
          if(resultCode == RESULT_OK && requestCode == 100) {
  
              MediaMetadataRetriever retriever = new MediaMetadataRetriever();
  
              try {
  
                  retriever.setDataSource(getBaseContext(), intent.getData());
  
                  String time = retriever.extractMetadata(MediaMetadataRetriever.METADATA_KEY_DURATION);
  
                  long splitCount = Long.valueOf(time) / 1000 / 15;
  
                  if(splitCount > 1) {
  
                      final String path = getRealPathFromURI(getBaseContext(), Uri.parse(intent.getData().toString()));
  
  
  
                      for(int a = 0, start = 0; a < splitCount; ++a, start += 15) {
  
                          // I am only testing with .mp4s atm, this will change before production
  
                          final String targetPath = path.replace(".mp4", "_" + (a + 1) + ".mp4");
  
  
  
                          ffmpeg.execute(new String [] {
  
                                  "-r",
  
                                  "1",
  
                                  "-i",
  
                                  path,
  
                                  "-ss",
  
                                  String.valueOf(start),
  
                                  "-t",
  
                                  String.valueOf(start + 15),
  
                                  "-r",
  
                                  "24",
  
                                  targetPath
  
                          }, new ExecuteBinaryResponseHandler() {
  
                              @Override
  
                              public void onStart() {}
  
  
  
                              @Override
  
                              public void onProgress(String message) {
  
                                  textView.setText("onProcess: " + message);
  
                              }
  
  
  
                              @Override
  
                              public void onFailure(String message) {
  
                                  textView.setText("onFailure: " + message + " --- " + path);
  
                              }
  
  
  
                              @Override
  
                              public void onSuccess(String message) {
  
                                  textView.setText("onSuccess:" + message);
  
                                  MediaScannerConnection.scanFile(getBaseContext(),
  
                                  new String [] { targetPath }, null,
  
                                  new MediaScannerConnection.OnScanCompletedListener() {
  
                                      public void onScanCompleted(String path, Uri uri) {}
  
                                  });
  
                              }
  
  
  
                              @Override
  
                              public void onFinish() {}
  
                          });
  
                      }
  
                  }
  
              } catch(Exception e) {
  
                  e.printStackTrace();
  
              } finally {
  
                  retriever.release();
  
              }
  
          }
  
      }
  
  }

  I don’t believe everything here is as optimal as it could be, but I’m just trying to prove the concept at the moment. Any help in the right direction would be amazing, thank you !

• Can I Config FFMEG-2.4.3 to use in android windows 64 ?

  13 novembre 2014, par Ngo Ky

  I want to build ffmpeg-2.4.3 (lastest c lib) to use it on android for managing video.
  my OS is windows 7 Utimate x64
  cywin64 in directory : C :/cywin64/ have make installed.
  NDK in directory : D :\solfware\Programming\android-ndk-r10c

  i follow toturial form : http://www.roman10.net/how-to-build-ffmpeg-for-android/comment-page-1/
  my project struture like :

  

  i create build_android.sh like roman10 as following code :

  # ARMv7+Neon (Cortex-A8)
  
  # Customizing:
  
  # 1. Feel free to change ./configure parameters for more features
  
  # 2. To adapt other ARM variants
  
  # set $CPU and $OPTIMIZE_CFLAGS 
  
  # call build_one
  
  ######################################################
  
  NDK=D:\solfware\Programming\android-ndk-r10c
  
  PLATFORM=$NDK/platforms/android-8/arch-arm/
  
  PREBUILT=$NDK/prebuilt/windows-x86_64
  
  function build_one
  
  {
  
  ./configure --target-os=linux \
  
      --prefix=$PREFIX \
  
      --enable-cross-compile \
  
      --extra-libs="-lgcc" \
  
      --arch=arm \
  
      --cc=$PREBUILT/bin/arm-linux-androideabi-gcc \
  
      --cross-prefix=$PREBUILT/bin/arm-linux-androideabi- \
  
      --nm=$PREBUILT/bin/arm-linux-androideabi-nm \
  
      --sysroot=$PLATFORM \
  
      --extra-cflags=" -O3 -fpic -DANDROID -DHAVE_SYS_UIO_H=1 -Dipv6mr_interface=ipv6mr_ifindex -fasm -Wno-psabi -fno-short-enums -fno-strict-aliasing -finline-limit=300 $OPTIMIZE_CFLAGS " \
  
      --disable-shared \
  
      --enable-static \
  
      --extra-ldflags="-Wl,-rpath-link=$PLATFORM/usr/lib -L$PLATFORM/usr/lib -nostdlib -lc -lm -ldl -llog" \
  
      --disable-everything \
  
      --enable-demuxer=mov \
  
      --enable-demuxer=h264 \
  
      --disable-ffplay \
  
      --enable-protocol=file \
  
      --enable-avformat \
  
      --enable-avcodec \
  
      --enable-decoder=rawvideo \
  
      --enable-decoder=mjpeg \
  
      --enable-decoder=h263 \
  
      --enable-decoder=mpeg4 \
  
      --enable-decoder=h264 \
  
      --enable-parser=h264 \
  
      --disable-network \
  
      --enable-zlib \
  
      --disable-avfilter \
  
      --disable-avdevice \
  
      $ADDITIONAL_CONFIGURE_FLAG
  
  
  
  make clean
  
  make  -j4 install
  
  $PREBUILT/bin/arm-linux-androideabi-ar d libavcodec/libavcodec.a inverse.o
  
  $PREBUILT/bin/arm-linux-androideabi-ld -rpath-link=$PLATFORM/usr/lib -L$PLATFORM/usr/lib  -soname libffmpeg.so -shared -nostdlib  -z,noexecstack -Bsymbolic --whole-archive --no-undefined -o $PREFIX/libffmpeg.so libavcodec/libavcodec.a libavformat/libavformat.a libavutil/libavutil.a libswscale/libswscale.a -lc -lm -lz -ldl -llog  --warn-once  --dynamic-linker=/system/bin/linker $PREBUILT/lib/gcc/arm-linux-androideabi/4.4.3/libgcc.a
  
  }
  
  
  
  #arm v6
  
  #CPU=armv6
  
  #OPTIMIZE_CFLAGS="-marm -march=$CPU"
  
  #PREFIX=./android/$CPU 
  
  #ADDITIONAL_CONFIGURE_FLAG=
  
  #build_one
  
  
  
  #arm v7vfpv3
  
  CPU=armv7-a
  
  OPTIMIZE_CFLAGS="-mfloat-abi=softfp -mfpu=vfpv3-d16 -marm -march=$CPU "
  
  PREFIX=./android/$CPU
  
  ADDITIONAL_CONFIGURE_FLAG=
  
  build_one
  
  
  
  #arm v7vfp
  
  #CPU=armv7-a
  
  #OPTIMIZE_CFLAGS="-mfloat-abi=softfp -mfpu=vfp -marm -march=$CPU "
  
  #PREFIX=./android/$CPU-vfp
  
  #ADDITIONAL_CONFIGURE_FLAG=
  
  #build_one
  
  
  
  #arm v7n
  
  #CPU=armv7-a
  
  #OPTIMIZE_CFLAGS="-mfloat-abi=softfp -mfpu=neon -marm -march=$CPU -mtune=cortex-a8"
  
  #PREFIX=./android/$CPU 
  
  #ADDITIONAL_CONFIGURE_FLAG=--enable-neon
  
  #build_one
  
  
  
  #arm v6+vfp
  
  #CPU=armv6
  
  #OPTIMIZE_CFLAGS="-DCMP_HAVE_VFP -mfloat-abi=softfp -mfpu=vfp -marm -march=$CPU"
  
  #PREFIX=./android/${CPU}_vfp 
  
  #ADDITIONAL_CONFIGURE_FLAG=
  
  #build_one

  i have set my path like above
  I built it in Eclipse Everything is ok. but when i ran it in Android it crashed Unfortunately.
  I found the errors in Logcat monitor :

  E/AndroidRuntime(1931) : java.lang.UnsatisfiedLinkError : Couldn’t load avcodec-55 from loader dalvik.system.PathClassLoader[DexPathList [1]] : findLibrary returned null

  E/AndroidRuntime(1931) : at java.lang.Runtime.loadLibrary(Runtime.java:358)

  In my activity i just call add Library from C preference like :

  static {
  
          //System.loadLibrary("avutil-52");
  
          System.loadLibrary("avcodec-55");
  
          System.loadLibrary("avformat-55");
  
          System.loadLibrary("swscale-2");
  
          System.loadLibrary("tutorial02");
  
      }

  i check in DDMS in app-lib there is no existing Library in there.

  The question is : Can i can compile the ffmpeg on windows ?
  if ok. how can i config build_android.sh to point to Android $PREBUILT

  PLATFORM=$NDK/platforms/android-8/arch-arm/
  
      PREBUILT=$NDK/prebuilt/windows-x86_64
  
      function build_one
  
      {
  
      ./configure --target-os=linux \
  
          --prefix=$PREFIX \
  
          --enable-cross-compile \
  
          --extra-libs="-lgcc" \
  
          --arch=arm \
  
          --cc=$PREBUILT/bin/arm-linux-androideabi-gcc \
  
          --cross-prefix=$PREBUILT/bin/arm-linux-androideabi- \
  
          --nm=$PREBUILT/bin/arm-linux-androideabi-nm \
  
          --sysroot=$PLATFORM \
  
          --extra-cflags=" -O3 -fpic -DANDROID -DHAVE_SYS_UIO_H=1 -Dipv6mr_interface=ipv6mr_ifindex -fasm -Wno-psabi -fno-short-enums -fno-strict-aliasing -finline-limit=300 $OPTIMIZE_CFLAGS " \
  
          --disable-shared \

  i found that in $NDK/prebuilt/windows-x86_64/bin did not exist arm-linux-androideabi-gcc\
  How can i config to be suitable to run on windows ?

  Thank in advanced