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• value of got_picture_ptr is always 0. when use avcodec_decode_video2()

  4 septembre 2014, par user3867261

  I’m using visual studio 2013 professional.

  below code is simple decode tutorial using ffmpeg.

  ///> Include FFMpeg
  
  extern "C" {
  
  #include <libavformat></libavformat>avformat.h>
  
  }
  
  
  
  ///> Library Link On Windows System
  
  #pragma comment( lib, "avformat.lib" )  
  
  #pragma comment( lib, "avutil.lib" )
  
  #pragma comment( lib, "avcodec.lib" )
  
  
  
  static void write_ascii_frame(const char *szFileName, const AVFrame *pVframe);
  
  
  
  int main(void)
  
  {
  
      const char *szFilePath = "C:\\singlo\\example.avi";
  
  
  
      ///> Initialize libavformat and register all the muxers, demuxers and protocols.
  
      av_register_all();
  
  
  
      ///> Do global initialization of network components.
  
      avformat_network_init();
  
  
  
      int ret;
  
      AVFormatContext *pFmtCtx = NULL;
  
  
  
      ///> Open an input stream and read the header. 
  
      ret = avformat_open_input( &amp;pFmtCtx, szFilePath, NULL, NULL );
  
      if( ret != 0 ) {
  
          av_log( NULL, AV_LOG_ERROR, "File [%s] Open Fail (ret: %d)\n", ret );
  
          exit( -1 );
  
      }
  
      av_log( NULL, AV_LOG_INFO, "File [%s] Open Success\n", szFilePath );
  
      av_log( NULL, AV_LOG_INFO, "Format: %s\n", pFmtCtx->iformat->name );
  
  
  
      ///> Read packets of a media file to get stream information. 
  
      ret = avformat_find_stream_info( pFmtCtx, NULL );
  
      if( ret &lt; 0 ) {
  
          av_log( NULL, AV_LOG_ERROR, "Fail to get Stream Information\n" );
  
          exit( -1 );
  
      }
  
      av_log( NULL, AV_LOG_INFO, "Get Stream Information Success\n" );
  
  
  
      ///> Find Video Stream
  
      int nVSI = -1;
  
      int nASI = -1;
  
      int i;
  
      for( i = 0 ; i &lt; pFmtCtx->nb_streams ; i++ ) {
  
          if( nVSI &lt; 0 &amp;&amp; pFmtCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO ) {
  
              nVSI = i;
  
          }
  
          else if( nASI &lt; 0 &amp;&amp; pFmtCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO ) {
  
              nASI = i;
  
          }
  
      }
  
  
  
      if( nVSI &lt; 0 &amp;&amp; nASI &lt; 0 ) {
  
          av_log( NULL, AV_LOG_ERROR, "No Video &amp; Audio Streams were Found\n");
  
          exit( -1 );
  
      }
  
  
  
      ///> Find Video Decoder
  
      AVCodec *pVideoCodec = avcodec_find_decoder( pFmtCtx->streams[nVSI]->codec->codec_id );
  
      if( pVideoCodec == NULL ) {
  
          av_log( NULL, AV_LOG_ERROR, "No Video Decoder was Found\n" );
  
          exit( -1 );
  
      }
  
  
  
      ///> Initialize Codec Context as Decoder
  
      if( avcodec_open2( pFmtCtx->streams[nVSI]->codec, pVideoCodec, NULL ) &lt; 0 ) {
  
          av_log( NULL, AV_LOG_ERROR, "Fail to Initialize Decoder\n" );
  
          exit( -1 );
  
      }
  
  
  
      ///> Find Audio Decoder
  
      AVCodec *pAudioCodec = avcodec_find_decoder( pFmtCtx->streams[nASI]->codec->codec_id );
  
      if( pAudioCodec == NULL ) {
  
          av_log( NULL, AV_LOG_ERROR, "No Audio Decoder was Found\n" );
  
          exit( -1 );
  
      }
  
  
  
      ///> Initialize Codec Context as Decoder
  
      if( avcodec_open2( pFmtCtx->streams[nASI]->codec, pAudioCodec, NULL ) &lt; 0 ) {
  
          av_log( NULL, AV_LOG_ERROR, "Fail to Initialize Decoder\n" );
  
          exit( -1 );
  
      }
  
  
  
      AVCodecContext *pVCtx = pFmtCtx->streams[nVSI]->codec;
  
      AVCodecContext *pACtx = pFmtCtx->streams[nASI]->codec;
  
  
  
      AVPacket pkt;
  
      AVFrame* pVFrame, *pAFrame;
  
      int bGotPicture = 0;    // flag for video decoding
  
      int bGotSound = 0;      // flag for audio decoding
  
  
  
      int bPrint = 0; // ë¹ëì¤ ì²« ì¥ë©´ë§ íì¼ë¡ ë¨ê¸°ê¸° ìí ìì flag ìëë¤
  
  
  
      pVFrame = avcodec_alloc_frame();
  
      pAFrame = avcodec_alloc_frame();
  
  
  
      while( av_read_frame( pFmtCtx, &amp;pkt ) >= 0 ) {
  
          ///> Decoding
  
          if( pkt.stream_index == nVSI ) {
  
              if( avcodec_decode_video2( pVCtx, pVFrame, &amp;bGotPicture, &amp;pkt ) >= 0 ) {
  
         ///////////////////////problem here/////////////////////////////////////////////
  
                  if( bGotPicture ) {
  
                      ///> Ready to Render Image
  
                      av_log( NULL, AV_LOG_INFO, "Got Picture\n" );
  
                      if( !bPrint ) {
  
                          write_ascii_frame( "output.txt", pVFrame );
  
                          bPrint = 1;
  
                      }
  
                  }
  
              }
  
              // else ( &lt; 0 ) : Decoding Error
  
          }
  
          else if( pkt.stream_index == nASI ) {
  
              if( avcodec_decode_audio4( pACtx, pAFrame, &amp;bGotSound, &amp;pkt ) >= 0 ) {
  
                  if( bGotSound ) {
  
                      ///> Ready to Render Sound
  
                      av_log( NULL, AV_LOG_INFO, "Got Sound\n" );
  
                  }
  
              }
  
              // else ( &lt; 0 ) : Decoding Error
  
          }
  
  
  
          ///> Free the packet that was allocated by av_read_frame
  
          av_free_packet( &amp;pkt );
  
      }
  
  
  
      av_free( pVFrame );
  
      av_free( pAFrame );
  
  
  
      ///> Close an opened input AVFormatContext. 
  
      avformat_close_input( &amp;pFmtCtx );
  
  
  
      ///> Undo the initialization done by avformat_network_init.
  
      avformat_network_deinit();
  
  
  
      return 0;
  
  }
  
  
  
  static void write_ascii_frame(const char *szFileName, const AVFrame *frame)
  
  {
  
      int x, y;
  
      uint8_t *p0, *p;
  
      const char arrAsciis[] = " .-+#";
  
  
  
      FILE* fp = fopen( szFileName, "w" );
  
      if( fp ) {
  
          /* Trivial ASCII grayscale display. */
  
          p0 = frame->data[0];        
  
          for (y = 0; y &lt; frame->height; y++) {
  
              p = p0;
  
              for (x = 0; x &lt; frame->width; x++)
  
                  putc( arrAsciis[*(p++) / 52], fp );
  
              putc( '\n', fp );
  
              p0 += frame->linesize[0];
  
          }
  
          fflush(fp);
  
          fclose(fp);
  
      }
  
  }

  there is a problem in below part

  if( avcodec_decode_video2( pVCtx, pVFrame, &bGotPicture, &pkt ) >= 0 ) {
  
         ///////////////////////problem here/////////////////////////////////////////////
  
         if( bGotPicture ) {
  
               ///> Ready to Render Image
  
              av_log( NULL, AV_LOG_INFO, "Got Picture\n" );
  
              if( !bPrint ) {
  
                   write_ascii_frame( "output.txt", pVFrame );
  
                   bPrint = 1;
  
               }
  
          }
  
   }

  the value of bGotPicture is always 0.. So i can’t decode video
  plz help me.
  where do problem occurs from ? in video ? in my code ?

• function and variable "chicken or the egg" scenario

  17 mars 2014, par user3426923

  I'm making a simple program to run in C++ to do ffmpeg for me, but I have the problem of needing certain variables defined in the "main", but the function needs to be above main to be ready to be used. what can I do ?

  #include <iostream>
  
  #include <cstdlib>
  
  
  
  using namespace std;
  
  
  
  int convert()
  
  {
  
      int operation;
  
      switch(operation){
  
          case &#39;1&#39;:
  
  
  
          case &#39;2&#39;:
  
  
  
          case &#39;3&#39;:
  
  
  
          case &#39;4&#39;:
  
              ;
  
      }
  
      return 0;
  
  }
  
  int main()
  
  {
  
      std::string formatIn;
  
      std::string FormatOut;
  
      std::string confirm;
  
      cout &lt;&lt; "select format that file is currently in: mp3, gp3, mp4, flv" &lt;&lt; endl;
  
      cin >> formatIn;
  
      cout &lt;&lt; "original format = " &lt;&lt; formatIn &lt;&lt; endl;
  
      cout &lt;&lt; "choose your target format: mp3, gp3, mp4, flv" &lt;&lt; endl;
  
      cin >> FormatOut;
  
      cout &lt;&lt; "selected format = " &lt;&lt; FormatOut &lt;&lt; endl;
  
      cout &lt;&lt; "proceed? ";
  
      cin >> confirm;
  
      if(confirm == "yes"){
  
      cout &lt;&lt; "proceeding with operation:" &lt;&lt; endl;
  
      convert();
  
      }
  
      else{
  
              if(confirm == "no"){
  
              cout &lt;&lt; "canceling,,," &lt;&lt; endl;
  
              }
  
      }
  
  }
  
  </cstdlib></iostream>

• HTML5 audio conversion using NodeJS on Heroku

  14 mars 2015, par nvd_ai

  I have a HTML5 app that allows users to upload and play their audio files. The server is Node running on Heroku.

  To allow cross-browser audio play, what I understand is that I have to at least maintain two formats of each audio file, let’s say .mp3 and .ogg. So, I need to transcode the files automatically on the server side.

  The problem is that Heroku does not run ffmpeg. I found this project that creates a custom buildpack for heroku that supports ffmpeg but it seems to be for Rails apps : https://github.com/dzello/ffmpeg-heroku.

  I was thinking to run an external server for transcoding, which my nodejs app sends the file to, it does the transcoding, and reuploads the new file on my nodejs server. But I don’t know how to set up such a server, and whether there is already a ready solution which does this kind of work ?

  So, here are my questions :

  1- Is there a solution to run ffmpeg on heroku+nodejs?
  
  
  
  2- How can I set up a transcoding server that communicates with my nodejs+heroku server?

  Thanks !