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• ffmpeg_kit_flutter operation not permitted for audio operations

  25 août 2023, par Black Eyed Beans

  I'm trying to trim an audio file using ffmpeg_kit_flutter but I keep getting the error :

  


  audio/path/output.mp3: Operation not permitted.


  


  This is the ffmpeg command that I'm using :

  


  final cmd="-y -i \"$audioPath\" -ss $audioStartTime -to $audioEndTime -c:a libmp3lame $outPutName";


  


  And I've also tried :

  


  final cmd="-y -i \"$audioPath\" -ss $audioStartTime -to $audioEndTime -c copy $outPutName";


  


  But the error is still the same.
I'm using the ffmpeg_kit_flutter_full_gpl package.

  


• How to stack several videos using ffmpeg ?

  13 juillet 2019, par John

  I have four cameras that are recording videos and wand to stack all videos into one video file. The final video must be a 2x2 grid.

  

  THE HARD PART is that sometimes cameras are not recording simultaneously.

  Here you can see one situation of how cameras are recording :

  Camera 1 timeline: |recording....................................|
  
  Camera 2 timeline: |stopped....|recording........................|
  
  Camera 3 timeline: |recording.........|stopped....|recording.....|
  
  Camera 4 timeline: |recording..................|stopped..........|

  Explanation :

  • Camera 1 is recording all time.
  • Camera 2 is starting recording later.
  • Camera 3 is recording, then stopped a period of time, then again recording.
  • Camera 4 is recording a period of time, then stopped.

  In the final video I want to synchronize each video by timestamps.

  If a camera is stopped a period of time then at its position must be a black portion.

  How can I do this ?

• Memory Leak in c++/cli application

  10 décembre 2013, par Ankush

  I am passing bitmap from my c# app to c++/cli dll that add it to video.
  The problem is program slowly leaking memory. I tried _CrtDumpMemoryLeaks() shows me leak of bitmap & another 40 byte leak but i am disposing bitmap.
  Can anyone see memory leak, Here is code..

  Flow :

  1) Capture screenshot by takescreenshot()

  2) pass it to c++/cli function

  3) dispose bitmap

  lines from my c# app

  Bitmap snap = takescreeshot();
  
  vencoder.AddBitmap(snap);
  
  snap.Dispose();
  
  vencoder.printleak();
  
  
  
  private static Bitmap takescreeshot()
  
      {
  
          System.Drawing.Bitmap bitmap = null;
  
          System.Drawing.Graphics graphics = null;
  
  
  
          bitmap = new Bitmap
  
          (
  
              System.Windows.Forms.Screen.PrimaryScreen.Bounds.Width,
  
              System.Windows.Forms.Screen.PrimaryScreen.Bounds.Height,
  
              System.Drawing.Imaging.PixelFormat.Format24bppRgb
  
          );
  
  
  
          graphics = System.Drawing.Graphics.FromImage(bitmap);
  
  
  
          graphics.CopyFromScreen(Screen.PrimaryScreen.Bounds.X, Screen.PrimaryScreen.Bounds.Y, 0, 0, Screen.PrimaryScreen.Bounds.Size);
  
  
  
          //Write TimeSpamp
  
          Rectangle rect = new Rectangle(1166, 738, 200, 20);
  
          String datetime= System.String.Format("{0:dd:MM:yy  hh:mm:ss}",DateTime.Now);
  
          System.Drawing.Font sysfont = new System.Drawing.Font("Times New Roman", 14, FontStyle.Bold);
  
          graphics.DrawString(datetime, sysfont, Brushes.Red,rect);
  
          //
  
  
  
          Grayscale filter = new Grayscale(0.2125, 0.7154, 0.0721);
  
          Bitmap grayImage = filter.Apply(bitmap);
  
  
  
          //Dispose
  
          bitmap.Dispose();
  
          graphics.Dispose();
  
  
  
          return grayImage;
  
      }

  now in c++/cli dll

  bool VideoEncoder::AddBitmap(Bitmap^ bitmap)
  
      {
  
          BitmapData^ bitmapData = bitmap->LockBits( System::Drawing::Rectangle( 0, 0,bitmap->Width, bitmap->Height ),ImageLockMode::ReadOnly,PixelFormat::Format8bppIndexed);
  
          uint8_t* ptr = reinterpret_cast( static_cast( bitmapData->Scan0 ) );
  
          uint8_t* srcData[4] = { ptr, NULL, NULL, NULL };
  
          int srcLinesize[4] = { bitmapData->Stride, 0, 0, 0 };
  
  
  
          pCurrentPicture = CreateFFmpegPicture(pVideoStream->codec->pix_fmt, pVideoStream->codec->width, pVideoStream->codec->height);
  
  
  
          sws_scale(pImgConvertCtx, srcData, srcLinesize, 0, bitmap->Height, pCurrentPicture->data, pCurrentPicture->linesize );
  
  
  
          bitmap->UnlockBits( bitmapData );
  
  
  
          write_video_frame();
  
  
  
          bitmapData=nullptr;
  
          ptr=NULL;
  
  
  
          return true;
  
      }
  
  
  
  AVFrame * VideoEncoder::CreateFFmpegPicture(int pix_fmt, int nWidth, int nHeight)
  
      {
  
  
  
        AVFrame *picture     = NULL;
  
        uint8_t *picture_buf = NULL;
  
        int size;
  
  
  
        picture = avcodec_alloc_frame();
  
        if ( !picture)
  
        {
  
          printf("Cannot create frame\n");
  
          return NULL;
  
        }
  
  
  
        size = avpicture_get_size((AVPixelFormat)pix_fmt, nWidth, nHeight);
  
  
  
        picture_buf = (uint8_t *) av_malloc(size);
  
  
  
        if (!picture_buf) 
  
        {
  
          av_free(picture);
  
          printf("Cannot allocate buffer\n");
  
          return NULL;
  
        }
  
  
  
        avpicture_fill((AVPicture *)picture, picture_buf,
  
          (AVPixelFormat)pix_fmt, nWidth, nHeight);
  
  
  
        return picture;
  
      }
  
  
  
      void VideoEncoder::write_video_frame()
  
      {
  
          AVCodecContext* codecContext = pVideoStream->codec;
  
  
  
          int out_size, ret = 0;
  
  
  
          if ( pFormatContext->oformat->flags & AVFMT_RAWPICTURE )
  
          {
  
              printf( "raw picture must be written" );
  
          }
  
          else
  
          {
  
              out_size = avcodec_encode_video( codecContext, pVideoEncodeBuffer,nSizeVideoEncodeBuffer, pCurrentPicture );
  
  
  
              if ( out_size > 0 )
  
              {
  
                  AVPacket packet;
  
                  av_init_packet( &packet );
  
  
  
                  if ( codecContext->coded_frame->pts != AV_NOPTS_VALUE )
  
                  {
  
                      packet.pts = av_rescale_q( packet.pts, codecContext->time_base, pVideoStream->time_base );
  
                  }
  
  
  
                  if ( codecContext->coded_frame->pkt_dts != AV_NOPTS_VALUE )
  
                  {
  
                      packet.dts = av_rescale_q( packet.dts, codecContext->time_base, pVideoStream->time_base );
  
                  }
  
  
  
                  if ( codecContext->coded_frame->key_frame )
  
                  {
  
                      packet.flags |= AV_PKT_FLAG_KEY;
  
                  }
  
  
  
                  packet.stream_index = pVideoStream->index;
  
                  packet.data = pVideoEncodeBuffer;
  
                  packet.size = out_size;
  
  
  
                  ret = av_interleaved_write_frame( pFormatContext, &packet );
  
  
  
                  av_free_packet(&packet);
  
                  av_freep(pCurrentPicture);
  
              }
  
              else
  
              {
  
                  // image was buffered
  
              }
  
          }
  
  
  
          if ( ret != 0 )
  
          {
  
              throw gcnew Exception( "Error while writing video frame." );
  
          }
  
      }
  
  
  
  
  
      void VideoEncoder::printleak()
  
      {
  
          printf("No of leaks: %d",_CrtDumpMemoryLeaks());
  
          printf("\n");
  
      }