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• How to set pts, dts and duration in ffmpeg library ?

  24 mars, par hslee

  I want to pack some compressed video packets(h.264) to ".mp4" container.
One word, Muxing, no decoding and no encoding.
And I have no idea how to set pts, dts and duration.

  



  

  1. I get the packets with "pcap" library.

  


  2. I removed headers before compressed video data show up. e.g. Ethernet, VLAN.

  


  3. I collected data until one frame and decoded it for getting information of data. e.g. width, height. (I am not sure that it is necessary)

  


  4. I initialized output context, stream and codec context.

  


  5. I started to receive packets with "pcap" library again. (now for muxing)

  


  6. I made one frame and put that data in AVPacket structure.

  


  7. I try to set PTS, DTS and duration. (I think here is wrong part, not sure though)

  


  



  *7-1. At the first frame, I saved time(msec) with packet header structure.

  



  *7-2. whenever I made one frame, I set parameters like this : PTS(current time - start time), DTS(same PTS value), duration(current PTS - before PTS)

  



  I think it has some error because :

  



  


  1. I don't know how far is suitable long for dts from pts.

  


  2. At least, I think duration means how long time show this frame from now to next frame, so It should have value(next PTS - current PTS), but I can not know the value next PTS at that time.

  


  



  It has I-frame only.

  



  // make input context for decoding

AVFormatContext *&ic = gInputContext;

ic = avformat_alloc_context();

AVCodec *cd = avcodec_find_decoder(AV_CODEC_ID_H264);

AVStream *st = avformat_new_stream(ic, cd);

AVCodecContext *cc = st->codec;

avcodec_open2(cc, cd, NULL);

// make packet and decode it after collect packets is be one frame

gPacket.stream_index = 0;

gPacket.size    = gPacketLength[0];

gPacket.data    = gPacketData[0];

gPacket.pts     = AV_NOPTS_VALUE;

gPacket.dts     = AV_NOPTS_VALUE;

gPacket.flags   = AV_PKT_FLAG_KEY;

avcodec_decode_video2(cc, gFrame, &got_picture, &gPacket);

// I checked automatically it initialized after "avcodec_decode_video2"

// put some info that I know that not initialized

cc->time_base.den   = 90000;

cc->time_base.num   = 1;

cc->bit_rate    = 2500000;

cc->gop_size    = 1;

// make output context with input context

AVFormatContext *&oc = gOutputContext;

avformat_alloc_output_context2(&oc, NULL, NULL, filename);

AVFormatContext *&ic = gInputContext;

AVStream *ist = ic->streams[0];

AVCodecContext *&icc = ist->codec;

AVStream *ost = avformat_new_stream(oc, icc->codec);

AVCodecContext *occ = ost->codec;

avcodec_copy_context(occ, icc);

occ->flags |= CODEC_FLAG_GLOBAL_HEADER;

avio_open(&(oc->pb), filename, AVIO_FLAG_WRITE);

// repeated part for muxing

AVRational Millisecond = { 1, 1000 };

gPacket.stream_index = 0;

gPacket.data = gPacketData[0];

gPacket.size = gPacketLength[0];

gPacket.pts = av_rescale_rnd(pkthdr->ts.tv_sec * 1000 /

    + pkthdr->ts.tv_usec / 1000 /

    - gStartTime, Millisecond.den, ost->time_base.den, /

    (AVRounding)(AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));

gPacket.dts = gPacket.pts;

gPacket.duration = gPacket.pts - gPrev;

gPacket.flags = AV_PKT_FLAG_KEY;

gPrev = gPacket.pts;

av_interleaved_write_frame(gOutputContext, &gPacket);


  



  Expected and actual results is a .mp4 video file that can play.

  


• FFmpeg : undefined references to av_frame_alloc()

  6 août 2014, par dontrythisathome

  I want to get into FFmpeg developing and i started following these samples tutorial here : here

  I started with the first tutorial - tutorial01.c - but i run into this problem ’undefined references to av_frame_alloc()’.

  I’m on Ubuntu 12.04 LTS.

  This is my program :

  /* 
  
   * File:   main.c
  
   * Author: dontrythisathome
  
   *
  
   * Created on 3 giugno 2014, 23.02
  
   */
  
  
  
  #include 
  
  #include <libavcodec></libavcodec>avcodec.h>
  
  #include <libavformat></libavformat>avformat.h>
  
  #include <libavutil></libavutil>frame.h>
  
  #include <libswscale></libswscale>swscale.h>
  
  /*
  
   *
  
   */
  
  void SaveFrame(AVFrame *pFrame, int width, int height, int iFrame)
  
      {
  
          FILE   *pFile;
  
          char  szFilename[32];
  
          int       y;
  
  
  
          //Apre il file
  
          sprintf(szFilename, "frame%d.ppm", iFrame);
  
          pFile=fopen(szFilename, "wb");
  
          if(pFile==NULL)
  
          {return; }
  
  
  
          //Scrive l'intestazione del file ( Larghezza x Altezza su video)
  
          fprintf(pFile, "P6\n%d %d\n255\n", width, height);
  
  
  
          //Scrive i data pixel
  
          for(y=0; ydata[0]+y*pFrame->linesize[0], 1, width*3, pFile);
  
          }
  
  
  
          //Chiude il file
  
          fclose(pFile);
  
        }
  
  /*
  
   * 
  
   */
  
  /*Main Function*/
  
  int main(int argc, char *argv[])
  
  {
  
      AVFormatContext *pFormatCtx;
  
      int                                     i, videoStreamIdx;
  
      AVCodecContext   *pCodecCtx;
  
      AVCodec                      *pCodec;
  
      AVFrame                      *pFrame;
  
      AVFrame                      *pFrameRGB;
  
      AVPacket                     packet;
  
      int                                     frameFinished;
  
      int                                     numBytes;
  
      uint8_t                           *buffer;
  
      static struct SwsContext  *img_convert_ctx;
  
  
  
      if(argc &lt; 2){
  
          printf("Inserisci un file video\n");
  
          return -1;
  
      }
  
  
  
      //Registra tutti i formati e i codec
  
      av_register_all();
  
  
  
      //Apre il file video
  
      if(avformat_open_input(&amp;pFormatCtx, argv[1], NULL, NULL) != 0)
  
      {return -1;} //Impossibile aprire il file
  
  
  
      //Recupera le informazioni dello stream
  
      if(avformat_find_stream_info(pFormatCtx, NULL) &lt; 0)
  
      {return -1;} // Couldn't find stream information
  
  
  
      //Versa le informazioni del file sullo standard error
  
      av_dump_format(pFormatCtx, 0, argv[1], 0);
  
  
  
      //Trova il primo stream video
  
      videoStreamIdx=-1;
  
      for(i=0; inb_streams; i++)
  
      {
  
          if(pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
  
          { videoStreamIdx=i;
  
              break;}
  
      }
  
  
  
      if(videoStreamIdx==-1)
  
          return -1; // Impossibile trovare lo stream video
  
  
  
      // Punta al contenuto del codec per lo stream video
  
      pCodecCtx = pFormatCtx->streams[videoStreamIdx]->codec;
  
  
  
      // Trova il decoder per lo stream video
  
      pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
  
      if(pCodec==NULL)
  
      {
  
          fprintf(stderr, "Codec Non Supportato!\n");
  
          return -1; //Impossibile trovare il codec
  
      }
  
  
  
      //Apre il codec
  
      if(avcodec_open2(pCodecCtx, pCodec, NULL) &lt; 0)
  
      {return -1;} //Impossibile aprire il codec
  
  
  
      //Alloca il frame video
  
      pFrame = av_frame_alloc();
  
  
  
      //Alloca una struct AVFrame
  
      pFrameRGB = av_frame_alloc();
  
      if(pFrameRGB==NULL)
  
      {return -1;}
  
  
  
      //Determina la grandezza necessaria per il buffer e lo alloca
  
      numBytes = avpicture_get_size(PIX_FMT_RGB24,
  
                                                                              pCodecCtx->width,
  
                                                                              pCodecCtx->height);
  
  
  
      buffer = (uint8_t *) av_malloc(numBytes*sizeof(uint8_t));
  
  
  
      //Assegna le parti appropriate del buffer sulla superficie dell'immagine in pFrameRGB
  
      //Tenere presente che pFrameRGB è un AVFrame, ma AVFrame è una superset di AVPicture
  
      avpicture_fill((AVPicture *)pFrameRGB, buffer, PIX_FMT_RGB24, pCodecCtx->width, pCodecCtx->height);
  
  
  
      int w = pCodecCtx->width;
  
      int h = pCodecCtx->height;
  
      img_convert_ctx = sws_getContext(w, h, pCodecCtx->pix_fmt,
  
                                                                                         w, h, PIX_FMT_RGB24,
  
                                                                                          SWS_LANCZOS, NULL, NULL, NULL);
  
  
  
      //Legge i frame e salva i primi 5 frame su disco
  
     i=0;
  
     while((av_read_frame(pFormatCtx, &amp;packet)>=0) &amp;&amp; (i&lt;5))
  
     {
  
         //Questo è il packet dello stream video?
  
         if(packet.stream_index==videoStreamIdx)
  
         {
  
             //Decodifica il frame video
  
             avcodec_decode_video2(pCodecCtx, pFrame, &amp;frameFinished, &amp;packet);
  
  
  
             //Si è riusiciti ad ottenere il frame video?
  
             if(frameFinished)
  
             {
  
                 i++;
  
                 sws_scale(img_convert_ctx, (const uint8_t * const *)pFrame->data,
  
                                          pFrame->linesize, 0, pCodecCtx->height,
  
                                          pFrameRGB->data, pFrameRGB->linesize);
  
                 SaveFrame(pFrameRGB, pCodecCtx->width, pCodecCtx->height, i);
  
             }
  
         }
  
  
  
         //Libera il pacchetto che era allocato da av_read_frame
  
         av_free_packet(&amp;packet);
  
     }
  
  
  
     //Libera l'immagine RGB
  
     av_free(buffer);
  
     av_free(pFrameRGB);
  
  
  
     //Libera il frame YUV
  
     av_free(pFrame);
  
  
  
     //Chiude il codec
  
     avcodec_close(pCodecCtx);
  
  
  
     //Chiude il file video
  
     avformat_close_input(&amp;pFormatCtx);
  
  
  
     /*FINE PROGRAMMA*/ 
  
  
  
      return 0;
  
  }

  This is the build output :

  "/usr/bin/make" -f nbproject/Makefile-Debug.mk QMAKE= SUBPROJECTS= .build-conf
  
  make[1]: ingresso nella directory "/home/dontrythisathome/Programmazione/C-C++/SimpleMediaPlayerForAndroid"
  
  "/usr/bin/make"  -f nbproject/Makefile-Debug.mk dist/Debug/GNU-Linux-x86/simplemediaplayerforandroid
  
  make[2]: ingresso nella directory "/home/dontrythisathome/Programmazione/C-C++/SimpleMediaPlayerForAndroid"
  
  mkdir -p dist/Debug/GNU-Linux-x86
  
  gcc     -o dist/Debug/GNU-Linux-x86/simplemediaplayerforandroid build/Debug/GNU-Linux-x86/main.o -L/usr/lib/x86_64-linux-gnu -lavformat -lavcodec -lavutil -lswscale -lz -lbz2
  
  build/Debug/GNU-Linux-x86/main.o: In function `main':
  
  /home/dontrythisathome/Programmazione/C-C++/SimpleMediaPlayerForAndroid/main.c:105: undefined reference to `av_frame_alloc'
  
  /home/dontrythisathome/Programmazione/C-C++/SimpleMediaPlayerForAndroid/main.c:108: undefined reference to `av_frame_alloc'
  
  collect2: ld returned 1 exit status
  
  make[2]: *** [dist/Debug/GNU-Linux-x86/simplemediaplayerforandroid] Errore 1
  
  make[2]: uscita dalla directory "/home/dontrythisathome/Programmazione/C-C++/SimpleMediaPlayerForAndroid"
  
  make[1]: *** [.build-conf] Errore 2
  
  make[1]: uscita dalla directory "/home/dontrythisathome/Programmazione/C-C++/SimpleMediaPlayerForAndroid"
  
  make: *** [.build-impl] Errore 2
  
  
  
  BUILD FAILED (exit value 2, total time: 143ms)

  I also linked the correct library path and headers path because there is no error with that.

  But when i try to build the program from the terminal with these commands :

  gcc -o prog1 /home/dontrythisathome/Programmazione/C-C++/SimpleMediaPlayerForAndroid/main.c -lavformat -lavcodec -lavutil -lswscale -lz -lbz2

  And the output is different :

  /home/dontrythisathome/Programmazione/C-C++/SimpleMediaPlayerForAndroid/main.c:11:29: fatal error: libavutil/frame.h: File o directory non esistente
  
  compilation terminated.

  The output says that there is no file or directory existing.
  What is the problem ?

• FFMPEG - CONVERT VIDEO TO GREYSCALE EXCEPT ONE COLOR ? LEAVE ONE COLOR, THE REST BLACK & WHITE ? [closed]

  19 décembre 2023, par scm360

  I have been researching and cannot find anything on how to preserve just one color / color range ; while converting a video to greyscale / black & white using FFMPEG. For example ; all black and white, except the peoples Blue Jeans, etc.

  


  Anyone know how to do this in FFMPEG ?

  


  Thanks in advance.

  


  I haven't actually found anything that has promise to achieve this. Of course I know how to convert everything to greyscale / black & white. But, not just leave the color / color range.