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• ffmpeg c++/cli wrapper for using in c# . AccessViolationException after call dll function by it's pointer

  4 octobre 2017, par skynet_v

  My target is to write a c++/cli wrap arount ffmpeg library, using by importing ffmpeg functions from dll-modules.
  Later I will use this interface in c#.
  This is my challenge, don’t ask me why))

  So i’ve implemented Wrap class, which is listed below :

  namespace FFMpegWrapLib 
  
  {
  
      public class Wrap
  
      {
  
      private:
  
  
  
      public:
  
          //wstring libavcodecDllName = "avcodec-56.dll";
  
          //wstring libavformatDllName = "avformat-56.dll";
  
          //wstring libswscaleDllName = "swscale-3.dll";
  
          //wstring libavutilDllName = "avutil-54.dll";
  
  
  
          HMODULE libavcodecDLL;
  
          HMODULE libavformatDLL; 
  
          HMODULE libswsscaleDLL;
  
          HMODULE libavutilDLL;
  
  
  
          AVFormatContext     **pFormatCtx = nullptr;
  
          AVCodecContext      *pCodecCtxOrig = nullptr;
  
          AVCodecContext      *pCodecCtx = nullptr;
  
          AVCodec             **pCodec = nullptr;
  
          AVFrame             **pFrame = nullptr;
  
          AVFrame             **pFrameRGB = nullptr;
  
          AVPacket            *packet = nullptr;
  
          int                 *frameFinished;
  
          int                 numBytes;
  
          uint8_t             *buffer = nullptr;
  
          struct SwsContext   *sws_ctx = nullptr;
  
  
  
          void                Init();
  
          void                AVRegisterAll();
  
          void                Release();
  
          bool                SaveFrame(const char *pFileName, AVFrame * frame, int w, int h);
  
          bool                GetStreamInfo();
  
          int                 FindVideoStream();
  
          bool                OpenInput(const char* file);
  
          AVCodec*            FindDecoder();
  
          AVCodecContext*     AllocContext3();
  
          bool                CopyContext();
  
          bool                OpenCodec2();
  
          AVFrame*            AllocFrame();
  
          int                 PictureGetSize();
  
          void*               Alloc(size_t size);
  
          int                 PictureFill(AVPicture *, const uint8_t *, enum AVPixelFormat, int, int);
  
          SwsContext*         GetSwsContext(int, int, enum AVPixelFormat, int, int, enum AVPixelFormat, int, SwsFilter *, SwsFilter *, const double *);
  
          int                 ReadFrame(AVFormatContext *s, AVPacket *pkt);
  
          int                 DecodeVideo2(AVCodecContext *avctx, AVFrame *picture, int *got_picture_ptr, const AVPacket *avpkt);
  
          int                 SwsScale(struct SwsContext *c, const uint8_t *const srcSlice[], const int srcStride[], int srcSliceY, int srcSliceH, uint8_t *const dst[], const int dstStride[]);
  
          void                PacketFree(AVPacket *pkt);
  
          void                BufferFree(void *ptr);
  
          void                FrameFree(AVFrame **frame);
  
          int                 CodecClose(AVCodecContext *);
  
          void                CloseInput(AVFormatContext **);
  
          bool                SeekFrame(AVFormatContext *s, int stream_index, int64_t timestamp, int flags);
  
  
  
          Wrap();
  
          ~Wrap();
  
  
  
          bool                GetVideoFrame(char* str_in_file, char* str_out_img, uint64_t time);
  
      };
  
  
  
      public ref class managedWrap
  
      {
  
      public:
  
  
  
          managedWrap(){}
  
          ~managedWrap(){ delete unmanagedWrap; }
  
  
  
          bool GetVideoFrameToFile(char* str_in_file, char* str_out_img, uint64_t time)
  
          {
  
              return unmanagedWrap->GetVideoFrame(str_in_file, str_out_img, time);
  
          }
  
  
  
          static Wrap* unmanagedWrap = new Wrap();
  
      };
  
  }

  So the imports to libavcodec and etc. are succesful.
  The problem is in AccessViolationException during calling dll func, for example, in OpenInput (i.e. av_open_input in native ffmpeg library)

  The OpenInput func code is below :

  bool FFMpegWrapLib::Wrap::OpenInput(const char* file)
  
  {
  
      typedef int avformat_open_input(AVFormatContext **, const char *, AVInputFormat *, AVDictionary **);
  
  
  
      avformat_open_input* pavformat_open_input = (avformat_open_input *)GetProcAddress(libavformatDLL, "avformat_open_input");
  
      if (pavformat_open_input == nullptr)
  
      {
  
          throw exception("Unable to find avformat_open_input function address in libavformat module");
  
          return false;
  
      }
  
  
  
      //pin_ptr<avformatcontext> pinFormatContext = &amp;(new interior_ptr<avformatcontext>(pCodecCtx));
  
      pFormatCtx = new AVFormatContext*;
  
      //*pFormatCtx = new AVFormatContext;
  
  
  
  
  
      int ret = pavformat_open_input(pFormatCtx, file, NULL, NULL); // here it fails
  
  
  
      return ret == 0;
  
  }
  
  </avformatcontext></avformatcontext>

  So the problem, i think, is that class-fields of Wrap class are in secure memory. And ffmpeg works with native memory, initialising pFormatCtx variable by it’s address.
  Can I avoid this, or it is impossible ?

• Android : Select from images extracted with FFMPEG

  21 juillet 2017, par Tix

  I’m currently able to extract images(frames) from a video, and display all the extracted images using the code below, how do i make it so that the displayed images could be selected by user and passed as a bitmap to another activity ?

  FFMPEG Compiled using

  compile ’com.writingminds:FFmpegAndroid:0.3.2’

  Complex Command used to get the frames/images

  String[] complexCommand = "-y", "-i", yourRealPath, "-an", "-framerate", "60", "-vf", "select=’gte(n,45)’", "-vsync", "0", dest.getAbsolutePath() ;

  Main Activity

          /**
  
           * Command for extracting images from video
  
           */
  
          private void extractImagesVideo(int startMs, int endMs) {
  
              File moviesDir = Environment.getExternalStoragePublicDirectory(
  
                      Environment.DIRECTORY_PICTURES
  
              );
  
  
  
              String filePrefix = "extract_picture";
  
              String fileExtn = ".jpg";
  
              String yourRealPath = getPath(MainActivity.this, selectedVideoUri);
  
  
  
              File dir = new File(moviesDir, "VideoEditor");
  
              int fileNo = 0;
  
              while (dir.exists()) {
  
                  fileNo++;
  
                  dir = new File(moviesDir, "VideoEditor" + fileNo);
  
  
  
              }
  
              dir.mkdir();
  
              filePath = dir.getAbsolutePath();
  
              File dest = new File(dir, filePrefix + "%03d" + fileExtn);
  
  
  
  
  
              Log.d(TAG, "startTrim: src: " + yourRealPath);
  
              Log.d(TAG, "startTrim: dest: " + dest.getAbsolutePath());
  
  
  
              String[] complexCommand = {"-y", "-i", yourRealPath, "-an", "-r", "1/2", "-ss", "" + startMs / 1000, "-t", "" + (endMs - startMs) / 1000, dest.getAbsolutePath()};
  
  
  
              execFFmpegBinary(complexCommand);
  
  
  
          }
  
  
  
       /**
  
           * Executing ffmpeg binary
  
           */
  
          private void execFFmpegBinary(final String[] command) {
  
              try {
  
                  ffmpeg.execute(command, new ExecuteBinaryResponseHandler() {
  
                      @Override
  
                      public void onFailure(String s) {
  
                          Log.d(TAG, "FAILED with output : " + s);
  
                      }
  
  
  
                      @Override
  
                      public void onSuccess(String s) {
  
                          Log.d(TAG, "SUCCESS with output : " + s);
  
                          if (choice == 1 || choice == 2 || choice == 5 || choice == 6 || choice == 7) {
  
                              Intent intent = new Intent(MainActivity.this, PreviewActivity.class);
  
                              intent.putExtra(FILEPATH, filePath);
  
                              startActivity(intent);
  
                          } else if (choice == 3) {
  
                              Intent intent = new Intent(MainActivity.this, PreviewImageActivity.class);
  
                              intent.putExtra(FILEPATH, filePath);
  
                              startActivity(intent);
  
                          } else if (choice == 4) {
  
                              Intent intent = new Intent(MainActivity.this, AudioPreviewActivity.class);
  
                              intent.putExtra(FILEPATH, filePath);
  
                              startActivity(intent);
  
                          } else if (choice == 8) {
  
                              choice = 9;
  
                              reverseVideoCommand();
  
                          } else if (Arrays.equals(command, lastReverseCommand)) {
  
                              choice = 10;
  
                              concatVideoCommand();
  
                          } else if (choice == 10) {
  
                              File moviesDir = Environment.getExternalStoragePublicDirectory(
  
                                      Environment.DIRECTORY_MOVIES
  
                              );
  
                              File destDir = new File(moviesDir, ".VideoPartsReverse");
  
                              File dir = new File(moviesDir, ".VideoSplit");
  
                              if (dir.exists())
  
                                  deleteDir(dir);
  
                              if (destDir.exists())
  
                                  deleteDir(destDir);
  
                              choice = 11;
  
                              Intent intent = new Intent(MainActivity.this, PreviewActivity.class);
  
                              intent.putExtra(FILEPATH, filePath);
  
                              startActivity(intent);
  
                          }
  
                      }

  PreviewImageActivity

      public class PreviewImageActivity extends AppCompatActivity {
  
  
  
          private static final String FILEPATH = "filepath";
  
              @Override
  
              protected void onCreate(@Nullable Bundle savedInstanceState) {
  
                  super.onCreate(savedInstanceState);
  
                  setContentView(R.layout.activity_gallery);
  
                  getSupportActionBar().setDisplayHomeAsUpEnabled(true);
  
                  getSupportActionBar().setDisplayShowHomeEnabled(true);
  
                  TextView tvInstruction=(TextView)findViewById(R.id.tvInstruction) ;
  
  
  
                  GridLayoutManager lLayoutlLayout = new GridLayoutManager(PreviewImageActivity.this, 4);
  
                  RecyclerView rView = (RecyclerView)findViewById(R.id.recycler_view);
  
                  rView.setHasFixedSize(true);
  
                  rView.setLayoutManager(lLayoutlLayout);
  
                  String filePath = getIntent().getStringExtra(FILEPATH);
  
                  ArrayList<string> f = new ArrayList<string>();
  
  
  
  
  
  
  
     File dir = new File(filePath);
  
              tvInstruction.setText("Images stored at path "+filePath);
  
              File[] listFile;
  
  
  
                  listFile = dir.listFiles();
  
  
  
  
  
  
  
              for(File e:listFile)
  
              {
  
                  f.add(e.getAbsolutePath());
  
              }
  
  
  
              PreviewImageAdapter rcAdapter = new PreviewImageAdapter( f);
  
              rView.setAdapter(rcAdapter);
  
  
  
  
  
          }
  
      @Override
  
      public boolean onOptionsItemSelected(MenuItem item) {
  
          // handle arrow click here
  
          if (item.getItemId() == android.R.id.home) {
  
              finish(); // close this activity and return to preview activity (if there is any)
  
          }
  
  
  
          return super.onOptionsItemSelected(item);
  
      }
  
  }
  
  </string></string>

  PreviewImageAdapter

  public class PreviewImageAdapter extends RecyclerView.Adapter {
  
  
  
      private ArrayList<string> paths;
  
  
  
      public PreviewImageAdapter( ArrayList<string> paths) {
  
          this.paths = paths;
  
      }
  
  
  
      @Override
  
      public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
  
          View itemView = LayoutInflater.from(parent.getContext())
  
                  .inflate(R.layout.item_gallery, parent, false);
  
  
  
          return new MyViewHolder(itemView);
  
      }
  
  
  
      @Override
  
      public void onBindViewHolder(MyViewHolder holder, int position) {
  
          Bitmap bmp = BitmapFactory.decodeFile(paths.get(position));
  
          holder.ivPhoto.setImageBitmap(bmp);
  
      }
  
  
  
      @Override
  
      public int getItemCount() {
  
          return paths.size();
  
      }
  
  
  
      public class MyViewHolder extends RecyclerView.ViewHolder {
  
          private ImageView ivPhoto;
  
  
  
          public MyViewHolder(View itemView) {
  
              super(itemView);
  
  
  
              ivPhoto = (ImageView) itemView.findViewById(R.id.ivPhoto);
  
          }
  
      }
  
  
  
  }
  
  </string></string>

• A ffmpeg comman canwork in cmd but not in Python using subprocess.call() or os.system()

  6 juin 2018, par Starrysky

  I wanna transfer a .mp3 to .wav. This is my command :
  ffmpeg -i a.mp3 -ar 16000 -ac 1 -acodec pcm_s16le a.wav

  It worked well in cmd

  C:\Users\starrysky\Documents\GitHub\bing_pic\html>ffmpeg -i a.mp3 -ar 16000 -ac 1 -acodec pcm_s16le a.wav
  
  ffmpeg version N-86482-gbc40674 Copyright (c) 2000-2017 the FFmpeg developers
  
    built with gcc 7.1.0 (GCC)
  
    configuration: --enable-gpl --enable-version3 --enable-cuda --enable-cuvid --enable-d3d11va --enable-dxva2 --enable-libmfx --enable-nvenc --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma --enable-zlib
  
    libavutil      55. 66.100 / 55. 66.100
  
    libavcodec     57. 99.100 / 57. 99.100
  
    libavformat    57. 73.100 / 57. 73.100
  
    libavdevice    57.  7.100 / 57.  7.100
  
    libavfilter     6. 92.100 /  6. 92.100
  
    libswscale      4.  7.101 /  4.  7.101
  
    libswresample   2.  8.100 /  2.  8.100
  
    libpostproc    54.  6.100 / 54.  6.100
  
  Input #0, mp3, from 'a.mp3':
  
    Metadata:
  
      encoder         : Lavf54.6.100
  
    Duration: 00:00:01.87, start: 0.000000, bitrate: 8 kb/s
  
      Stream #0:0: Audio: mp3, 8000 Hz, mono, s16p, 8 kb/s
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (mp3 (native) -> pcm_s16le (native))
  
  Press [q] to stop, [?] for help
  
  Output #0, wav, to 'a.wav':
  
    Metadata:
  
      ISFT            : Lavf57.73.100
  
      Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 16000 Hz, mono, s16, 256 kb/s
  
      Metadata:
  
        encoder         : Lavc57.99.100 pcm_s16le
  
  size=      59kB time=00:00:01.87 bitrate= 256.3kbits/s speed= 187x
  
  video:0kB audio:58kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.130208%

  but when I moved it into my python program, something strange happened.

  >>> C:\Users\starrysky\Documents\GitHub\bing_pic\html\
  
  'ffmpeg' �����ڲ����ⲿ���Ҳ���ǿ����еij���
  
  ���������ļ���
  
  1 Command 'ffmpeg -i a.mp3 -ar 16000 -ac 1 -acodec pcm_s16le a.wav' returned non-zero exit status 1.
  
  文件错误啊，亲
  
  [WinError 2] 系统找不到指定的文件。: 'a.wav'

  This is part of my python code :

  @bot.register(wife, RECORDING)
  
  def translate_sound(msg):
  
      msg.get_file(save_path='a.mp3')
  
      path = os.path.abspath('.')+'\\'
  
      print(path)
  
      try:
  
          subprocess.check_call('ffmpeg -i a.mp3 -ar 16000 -ac 1 -acodec pcm_s16le a.wav', shell=True)
  
          # ''
  
      except Exception as e:
  
          print(1, e)
  
      wav_to_text('a.wav')
  
      try:
  
          os.remove('a.wav')
  
      except Exception as e:
  
          print(e)

  ---

  # 调用百度语音识别API
  
  def get_token():
  
      URL = 'http://openapi.baidu.com/oauth/2.0/token'
  
      _params = urllib.parse.urlencode({'grant_type': b'client_credentials',
  
                                        'client_id': b''
  
                                        'client_secret': b''})
  
      _res = urllib.request.Request(URL, _params.encode())
  
      _response = urllib.request.urlopen(_res)
  
      _data = _response.read()
  
      _data = json.loads(_data)
  
      return _data['access_token']
  
  
  
  
  
  def wav_to_text(wav_file):
  
      try:
  
          wav_file = open(wav_file, 'rb')
  
      except IOError:
  
          print('文件错误啊，亲')
  
          return
  
      wav_file = wave.open(wav_file)
  
      n_frames = wav_file.getnframes()
  
      print('n_frames ', n_frames)
  
      frame_rate = wav_file.getframerate()
  
      print("frame_rate ", frame_rate)
  
      if n_frames == 1 or frame_rate not in (8000, 16000):
  
          print('不符合格式')
  
          return
  
      audio = wav_file.readframes(n_frames)
  
      seconds = n_frames/frame_rate+1
  
      minute = int(seconds/60 + 1)
  
      for i in range(0, minute):
  
          sub_audio = audio[i*60*frame_rate:(i+1)*60*frame_rate]
  
          base_data = base64.b64encode(sub_audio)
  
          data = {"format": "wav",
  
                  "token": get_token(),
  
                  "len": len(sub_audio),
  
                  "rate": frame_rate,
  
                  "speech": base_data.decode(),
  
                  "cuid": "B8-AC-6F-2D-7A-94",
  
                  "channel": 1}
  
          data = json.dumps(data)
  
          res = urllib.request.Request('http://vop.baidu.com/server_api',
  
                                data.encode(),
  
                                {'content-type': 'application/json'})
  
          response = urllib.request.urlopen(res)
  
          res_data = json.loads(response.read())
  
          try:
  
              print(res_data['result'][0])
  
          except Exception as e:
  
              print(e)

  What happened ?