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• How can I reencode a video to match another's codec exactly ?

  24 janvier 2020, par Stephen Schrauger

  When I’m on vacation, I usually use our camcorder to record videos. Since they’re all the same format, I can use ffmpeg to concat them into one large, smooth video without re-encoding.

  However, sometimes I will use a phone or other camera to record a video (if the camcorder ran out of space/battery or was left at a hotel).

  I’d like to determine the codec, framerate, etc used by my camcorder and use those parameters to convert the phone vidoes into the same format. That way, I will be able to concatonate all the videos without re-encoding the camcorder videos.

  Using ffprobe, I found my camcorder has this encoding :

    Input #0, mpegts, from 'camcorderfile.MTS':
  
    Duration: 00:00:09.54, start: 1.936367, bitrate: 24761 kb/s
  
    Program 1 
  
      Stream #0:0[0x1011]: Video: h264 (High) (HDPR / 0x52504448), yuv420p(progressive), 1920x1080 [SAR 1:1 DAR 16:9], 59.94 fps, 59.94 tbr, 90k tbn, 119.88 tbc
  
      Stream #0:1[0x1100]: Audio: ac3 (AC-3 / 0x332D4341), 48000 Hz, stereo, fltp, 256 kb/s
  
      Stream #0:2[0x1200]: Subtitle: hdmv_pgs_subtitle ([144][0][0][0] / 0x0090), 1920x1080

  The phone (iPhone 5s) encoding is :

    Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'mov.MOV':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 0
  
      compatible_brands: qt  
  
      creation_time   : 2017-01-02T03:04:05.000000Z
  
      com.apple.quicktime.location.ISO6709: +12.3456-789.0123+456.789/
  
      com.apple.quicktime.make: Apple
  
      com.apple.quicktime.model: iPhone 5s
  
      com.apple.quicktime.software: 10.2.1
  
      com.apple.quicktime.creationdate: 2017-01-02T03:04:05-0700
  
    Duration: 00:00:14.38, start: 0.000000, bitrate: 11940 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 1920x1080, 11865 kb/s, 29.98 fps, 29.97 tbr, 600 tbn, 1200 tbc (default)
  
      Metadata:
  
        creation_time   : 2017-01-02T03:04:05.000000Z
  
        handler_name    : Core Media Data Handler
  
        encoder         : H.264
  
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 63 kb/s (default)
  
      Metadata:
  
        creation_time   : 2017-01-02T03:04:05.000000Z
  
        handler_name    : Core Media Data Handler
  
      Stream #0:2(und): Data: none (mebx / 0x7862656D), 0 kb/s (default)
  
      Metadata:
  
        creation_time   : 2017-01-02T03:04:05.000000Z
  
        handler_name    : Core Media Data Handler
  
      Stream #0:3(und): Data: none (mebx / 0x7862656D), 0 kb/s (default)
  
      Metadata:
  
        creation_time   : 2017-01-02T03:04:05.000000Z
  
        handler_name    : Core Media Data Handler

  I’m presuming that ffmpeg will automatically take any acceptable video format, and that I only need to figure out the output settings. I think I need to use -s 1920x1080 and -pix_fmt yuv420p for the output, but what other flags do I need in order to make the phone video into the same encoding as the camcorder video ?

  Can I get some pointers as to how I can translate the ffprobe output into the flags I need to give to ffmpeg ?

  Edit : Added the entire Input #0 for both media files.

• AV_PIX_FMT_YUVJ422P to jpeg conversion

  4 mars 2019, par user3743908

  i am able to convert image from AV_PIX_FMT_YUVJ422P to jpeg format (below Code) but the resultant image having green shade on complete bottom half plz suggest where i am doing wrong.
  Following step i have taken

  1. Initially i have AV_PIX_FMT_UYVY422 image from camera, i have convert it in AV_PIX_FMT_YUVJ422P format and able to see this image on http://rawpixels.net/ the parameters shown by website is size 2448X2050, Bpp1= 8,Bpp2 = 8 and Bpp3 = 8,alignment 1, SubSampling H =2, and SubSampling V = 1, format : YUV422P
     so input image is Correct AV_PIX_FMT_YUVJ422P format. & also able to see on "YUV image viewer Software" using YUV422 format.

  2. Now i am trying to convert it in jpeg format using below Code and attached is the resultant Image having green shade on complete bottom half.

         AVFormatContext*    pFormatCtx;
     
         AVOutputFormat*     fmt;
     
         AVStream*           video_st;
     
         AVCodecContext*     pCodecCtx;
     
         AVCodec*            pCodec;
     
     
     
         uint8_t*            picture_buf;
     
         AVFrame*            picture;
     
         AVPacket            pkt;
     
         int                 y_size;
     
         int                 size;
     
         int                 got_picture=0;  
     
         int                 ret=0;
     
     
     
     int main( int argc, char* argv[] )
     
     {
     
     
     
         FILE *in_file                       =   NULL;   
     
         unsigned int        in_width        =   2448;    
     
         unsigned int        in_height       =   2050;   
     
         const char* out_file                =   "encoded_pic.jpg";    
     
     
     
     
     
             in_file =   fopen("c:\\test_Planar.yuv","rb");
     
             if(in_file == NULL) { printf("\n\tFile Opening error...!!"); exit(1); }
     
             else printf("\n\tYUV File Open Sucessfully...!!\n\n");
     
     
     
             av_register_all();  // Loads the whole database of available codecs and formats.
     
     
     
             pFormatCtx          =   avformat_alloc_context();           
     
             fmt             =   NULL;
     
             fmt             =   av_guess_format("mjpeg",NULL,NULL);
     
             pFormatCtx->oformat     =   fmt;
     
     
     
     //------Output URL-------------------------
     
     if (avio_open(&pFormatCtx->pb,out_file, AVIO_FLAG_READ_WRITE) < 0)
     
     {
     
         printf("Couldn't open output file.");
     
         return -1;
     
     }
     
     
     
     video_st = avformat_new_stream(pFormatCtx, 0);    
     
     if (video_st==NULL)        return -1;
     
     
     
     
     
     pCodecCtx               =   video_st->codec;
     
     pCodecCtx->codec_id     =   fmt->video_codec;
     
     pCodecCtx->codec_type   =   AVMEDIA_TYPE_VIDEO;
     
     pCodecCtx->pix_fmt      =   AV_PIX_FMT_YUVJ422P;
     
     
     
     //--------------------------MY SOURCE PIXEL FORMAT--------------
     
     
     
     pCodecCtx->width        =   in_width;
     
     pCodecCtx->height       =   in_height;
     
     
     
     pCodecCtx->time_base.num = 1;
     
     pCodecCtx->time_base.den = 1;//25;
     
     
     
     //Output some information
     
     av_dump_format(pFormatCtx, 0, out_file, 1);
     
     
     
     // Determine if desired video encoder is installed 
     
     pCodec = avcodec_find_encoder(pCodecCtx->codec_id);
     
     
     
     if (!pCodec)
     
     {
     
         printf("Codec not found.");
     
         return -1;
     
     }
     
     
     
     printf("\nCodec Identified done\n");
     
     
     
     if (avcodec_open2(pCodecCtx, pCodec,NULL) < 0){
     
         printf("Could not open codec.\n");
     
         return -1;
     
     }
     
     picture     =   av_frame_alloc();
     
     size            =   avpicture_get_size(pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height);
     
     picture_buf     =   (uint8_t *)av_malloc(size);
     
     if (!picture_buf)    return -1;
     
     
     
     avpicture_fill((AVPicture *)picture, picture_buf, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height);
     
     
     
     printf("\t\nWrite Header..");
     
     avformat_write_header(pFormatCtx,NULL);
     
     y_size = pCodecCtx->width * pCodecCtx->height;
     
     av_new_packet(&pkt,y_size*3);
     
     
     
     
     
     //Read YUV
     
     if (fread(picture_buf, 1, y_size*3/2, in_file) <=0)
     
     {
     
         printf("Could not read input file.");
     
         return -1;
     
     }
     
      //--------------------------------------------input image format UYVY
     
     picture->data[0] = picture_buf;             // Y
     
     picture->data[1] = picture_buf+ y_size;         // U
     
     picture->data[2] = picture_buf+ y_size*5/4;     // V
     
     //-----------------------------------------------
     
     
     
     printf("\t\n Encode the image..\n");
     
     ret = avcodec_encode_video2(pCodecCtx, &pkt,picture, &got_picture);
     
     if(ret < 0)
     
     {
     
         printf("Encode Error.\n");
     
         return -1;
     
     }
     
     
     
     if (got_picture==1)
     
     {
     
         pkt.stream_index = video_st->index;
     
         ret = av_write_frame(pFormatCtx, &pkt);
     
     }
     
     
     
     av_free_packet(&pkt);
     
     //Write Trailer
     
     av_write_trailer(pFormatCtx);    
     
     printf("Encode Successful.\n");
     
     
     
     if (video_st)
     
     {
     
         avcodec_close(video_st->codec);
     
         av_free(picture);
     
         av_free(picture_buf);
     
     }
     
     
     
     avio_close(pFormatCtx->pb);
     
     avformat_free_context(pFormatCtx);    
     
     
     
         fclose(in_file);
     
         printf("\n\tYUV File Close Sucessfully...!!");    
     
     }

  Resultant output jpeg encoded image from yuvj422p image having green shade

• FFmpeg : Jpeg file to AVFrame

  1er janvier 2020, par darja

  I need to join several jpg files into video using FFmpeg library. But I have a problem with reading this files. Here is a function which reads image file and makes AVFrame :

  AVFrame* OpenImage(const char* imageFileName)
  
  {
  
      AVFormatContext *pFormatCtx;
  
  
  
      if(av_open_input_file(&pFormatCtx, imageFileName, NULL, 0, NULL)!=0)
  
      {
  
          printf("Can't open image file '%s'\n", imageFileName);
  
          return NULL;
  
      }       
  
  
  
      dump_format(pFormatCtx, 0, imageFileName, false);
  
  
  
      AVCodecContext *pCodecCtx;
  
  
  
      pCodecCtx = pFormatCtx->streams[0]->codec;
  
      pCodecCtx->width = W_VIDEO;
  
      pCodecCtx->height = H_VIDEO;
  
      pCodecCtx->pix_fmt = PIX_FMT_YUV420P;
  
  
  
      // Find the decoder for the video stream
  
      AVCodec *pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
  
      if (!pCodec)
  
      {
  
          printf("Codec not found\n");
  
          return NULL;
  
      }
  
  
  
      // Open codec
  
      if(avcodec_open(pCodecCtx, pCodec)<0)
  
      {
  
          printf("Could not open codec\n");
  
          return NULL;
  
      }
  
  
  
      // 
  
      AVFrame *pFrame;
  
  
  
      pFrame = avcodec_alloc_frame();
  
  
  
      if (!pFrame)
  
      {
  
          printf("Can't allocate memory for AVFrame\n");
  
          return NULL;
  
      }
  
  
  
      int frameFinished;
  
      int numBytes;
  
  
  
      // Determine required buffer size and allocate buffer
  
      numBytes = avpicture_get_size(PIX_FMT_YUVJ420P, pCodecCtx->width, pCodecCtx->height);
  
      uint8_t *buffer = (uint8_t *) av_malloc(numBytes * sizeof(uint8_t));
  
  
  
      avpicture_fill((AVPicture *) pFrame, buffer, PIX_FMT_YUVJ420P, pCodecCtx->width, pCodecCtx->height);
  
  
  
      // Read frame
  
  
  
      AVPacket packet;
  
  
  
      int framesNumber = 0;
  
      while (av_read_frame(pFormatCtx, &packet) >= 0)
  
      {
  
          if(packet.stream_index != 0)
  
              continue;
  
  
  
          int ret = avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
  
          if (ret > 0)
  
          {
  
              printf("Frame is decoded, size %d\n", ret);
  
              pFrame->quality = 4;
  
              return pFrame;
  
          }
  
          else
  
              printf("Error [%d] while decoding frame: %s\n", ret, strerror(AVERROR(ret)));
  
      }
  
  }

  This causes no error but creates only black frame, no image. What is wrong ?