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• Video rotating to left by 90 degree when converted using ffmpeg

  15 juillet 2017, par Herdesh Verma

  I developed a below code :

  extern "C"
  
  {
  
  #include <libavutil></libavutil>imgutils.h>
  
  #include <libavutil></libavutil>opt.h>
  
  #include <libavcodec></libavcodec>avcodec.h>
  
  #include <libavutil></libavutil>mathematics.h>
  
  #include <libavutil></libavutil>samplefmt.h>
  
  #include <libavutil></libavutil>timestamp.h>
  
  #include <libavformat></libavformat>avformat.h>
  
  #include <libavfilter></libavfilter>avfiltergraph.h>
  
  #include <libswscale></libswscale>swscale.h>
  
  }
  
  #include 
  
  static AVFormatContext *fmt_ctx = NULL;
  
  
  
  static int frame_index = 0;
  
  
  
  static int j = 0, nbytes=0;
  
  uint8_t *video_outbuf = NULL;
  
  static AVPacket *pAVPacket=NULL;
  
  static int value=0;
  
  static AVFrame *pAVFrame=NULL;
  
  static AVFrame *outFrame=NULL;
  
  static AVStream *video_st=NULL;
  
  static AVFormatContext *outAVFormatContext=NULL;
  
  static AVCodec *outAVCodec=NULL;
  
  static AVOutputFormat *output_format=NULL;
  
  static AVCodecContext *video_dec_ctx = NULL, *audio_dec_ctx;
  
  static AVCodecContext *outAVCodecContext=NULL;
  
  static int width, height;
  
  static enum AVPixelFormat pix_fmt;
  
  static AVStream *video_stream = NULL, *audio_stream = NULL;
  
  static const char *src_filename = NULL;
  
  static const char *video_dst_filename = NULL;
  
  static const char *audio_dst_filename = NULL;
  
  static FILE *video_dst_file = NULL;
  
  static FILE *audio_dst_file = NULL;
  
  static uint8_t *video_dst_data[4] = {NULL};
  
  static int      video_dst_linesize[4];
  
  static int video_dst_bufsize;
  
  static int video_stream_idx = -1, audio_stream_idx = -1;
  
  static AVPacket *pkt=NULL;
  
  static AVPacket *pkt1=NULL;
  
  static AVFrame *frame = NULL;
  
  //static AVPacket pkt;
  
  static int video_frame_count = 0;
  
  static int audio_frame_count = 0;
  
  static int refcount = 0;
  
  AVCodec *codec;
  
  static struct SwsContext *sws_ctx;
  
  AVCodecContext *c= NULL;
  
   int i, out_size, size, x, y, outbuf_size;
  
   AVFrame *picture;
  
   uint8_t *outbuf, *picture_buf;
  
  int video_outbuf_size;
  
  int w, h;
  
  AVPixelFormat pixFmt;
  
  uint8_t *data[4];
  
  int linesize[4];
  
  
  
  static int open_codec_context(int *stream_idx,
  
                            AVCodecContext **dec_ctx, AVFormatContext 
  
  *fmt_ctx, enum AVMediaType type)
  
  {
  
  int ret, stream_index;
  
  AVStream *st;
  
  AVCodec *dec = NULL;
  
  AVDictionary *opts = NULL;
  
  ret = av_find_best_stream(fmt_ctx, type, -1, -1, NULL, 0);
  
  if (ret &lt; 0) {
  
      printf("Could not find %s stream in input file '%s'\n",
  
              av_get_media_type_string(type), src_filename);
  
      return ret;
  
  } else {
  
      stream_index = ret;
  
      st = fmt_ctx->streams[stream_index];
  
      /* find decoder for the stream */
  
      dec = avcodec_find_decoder(st->codecpar->codec_id);
  
      if (!dec) {
  
          printf("Failed to find %s codec\n",
  
                  av_get_media_type_string(type));
  
          return AVERROR(EINVAL);
  
      }
  
      /* Allocate a codec context for the decoder */
  
      *dec_ctx = avcodec_alloc_context3(dec);
  
      if (!*dec_ctx) {
  
          printf("Failed to allocate the %s codec context\n",
  
                  av_get_media_type_string(type));
  
          return AVERROR(ENOMEM);
  
      }
  
      /* Copy codec parameters from input stream to output codec context */
  
      if ((ret = avcodec_parameters_to_context(*dec_ctx, st->codecpar)) &lt; 0) {
  
          printf("Failed to copy %s codec parameters to decoder context\n",
  
                  av_get_media_type_string(type));
  
          return ret;
  
      }
  
      /* Init the decoders, with or without reference counting */
  
      av_dict_set(&amp;opts, "refcounted_frames", refcount ? "1" : "0", 0);
  
      if ((ret = avcodec_open2(*dec_ctx, dec, &amp;opts)) &lt; 0) {
  
          printf("Failed to open %s codec\n",
  
                  av_get_media_type_string(type));
  
          return ret;
  
      }
  
      *stream_idx = stream_index;
  
  }
  
  return 0;
  
  }
  
  
  
  
  
  
  
  int main (int argc, char **argv)
  
  {
  
   int ret = 0, got_frame;
  
  src_filename = argv[1];
  
  video_dst_filename = argv[2];
  
  audio_dst_filename = argv[3];
  
  av_register_all();
  
  avcodec_register_all();
  
  printf("Registered all\n");
  
  
  
  /* open input file, and allocate format context */
  
  if (avformat_open_input(&amp;fmt_ctx, src_filename, NULL, NULL) &lt; 0) {
  
      printf("Could not open source file %s\n", src_filename);
  
      exit(1);
  
  }
  
  
  
  /* retrieve stream information */
  
  if (avformat_find_stream_info(fmt_ctx, NULL) &lt; 0) {
  
      printf("Could not find stream information\n");
  
      exit(1);
  
  }
  
  
  
  if (open_codec_context(&amp;video_stream_idx, &amp;video_dec_ctx, fmt_ctx, 
  
  AVMEDIA_TYPE_VIDEO) >= 0) {
  
      video_stream = fmt_ctx->streams[video_stream_idx];
  
      avformat_alloc_output_context2(&amp;outAVFormatContext, NULL, NULL, 
  
  video_dst_filename);
  
      if (!outAVFormatContext)
  
      {
  
              printf("\n\nError : avformat_alloc_output_context2()");
  
              return -1;
  
      }
  
  }
  
  
  
  if (open_codec_context(&amp;audio_stream_idx, &amp;audio_dec_ctx, fmt_ctx, 
  
  AVMEDIA_TYPE_AUDIO) >= 0) {
  
      audio_stream = fmt_ctx->streams[audio_stream_idx];
  
      audio_dst_file = fopen(audio_dst_filename, "wb");
  
      if (!audio_dst_file) {
  
          printf("Could not open destination file %s\n", audio_dst_filename);
  
          ret = 1;
  
          goto end;
  
      }
  
  }
  
  /* dump input information to stderr */
  
  av_dump_format(fmt_ctx, 0, src_filename, 0);
  
  
  
  if (!audio_stream &amp;&amp; !video_stream) {
  
      printf("Could not find audio or video stream in the input, aborting\n");
  
      ret = 1;
  
      goto end;
  
  }
  
  
  
      output_format = av_guess_format(NULL, video_dst_filename, NULL);
  
      if( !output_format )
  
      {
  
       printf("\n\nError : av_guess_format()");
  
       return -1;
  
      }
  
  
  
      video_st = avformat_new_stream(outAVFormatContext ,NULL);
  
      if( !video_st )
  
      {
  
              printf("\n\nError : avformat_new_stream()");
  
        return -1;
  
      }
  
  
  
      outAVCodecContext = avcodec_alloc_context3(outAVCodec);
  
      if( !outAVCodecContext )
  
      {
  
        printf("\n\nError : avcodec_alloc_context3()");
  
        return -1;
  
      }
  
  
  
  
  
      outAVCodecContext = video_st->codec;
  
      outAVCodecContext->codec_id = AV_CODEC_ID_MPEG4;// AV_CODEC_ID_MPEG4; // 
  
   AV_CODEC_ID_H264 // AV_CODEC_ID_MPEG1VIDEO
  
      outAVCodecContext->codec_type = AVMEDIA_TYPE_VIDEO;
  
      outAVCodecContext->pix_fmt  = AV_PIX_FMT_YUV420P;
  
      outAVCodecContext->bit_rate = 400000; // 2500000
  
      outAVCodecContext->width = 1920;
  
      //outAVCodecContext->width = 500;
  
      outAVCodecContext->height = 1080;
  
      //outAVCodecContext->height = 500;
  
      outAVCodecContext->gop_size = 3;
  
      outAVCodecContext->max_b_frames = 2;
  
      outAVCodecContext->time_base.num = 1;
  
      outAVCodecContext->time_base.den = 30; // 15fps
  
  
  
      if (outAVCodecContext->codec_id == AV_CODEC_ID_H264)
  
      {
  
       av_opt_set(outAVCodecContext->priv_data, "preset", "slow", 0);
  
      }
  
  
  
      outAVCodec = avcodec_find_encoder(AV_CODEC_ID_MPEG4);
  
      if( !outAVCodec )
  
      {
  
       printf("\n\nError : avcodec_find_encoder()");
  
       return -1;
  
      }
  
  
  
      /* Some container formats (like MP4) require global headers to be 
  
   present
  
         Mark the encoder so that it behaves accordingly. */
  
  
  
      if ( outAVFormatContext->oformat->flags &amp; AVFMT_GLOBALHEADER)
  
      {
  
              outAVCodecContext->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
  
      }
  
  
  
      value = avcodec_open2(outAVCodecContext, outAVCodec, NULL);
  
      if( value &lt; 0)
  
      {
  
              printf("\n\nError : avcodec_open2()");
  
              return -1;
  
      }
  
  
  
  /* create empty video file */
  
      if ( !(outAVFormatContext->flags &amp; AVFMT_NOFILE) )
  
      {
  
       if( avio_open2(&amp;outAVFormatContext->pb , video_dst_filename, 
  
  AVIO_FLAG_WRITE ,NULL, NULL) &lt; 0 )
  
       {
  
        printf("\n\nError : avio_open2()");
  
       }
  
      }
  
  
  
      if(!outAVFormatContext->nb_streams)
  
      {
  
              printf("\n\nError : Output file dose not contain any stream");
  
        return -1;
  
      }
  
  
  
      /* imp: mp4 container or some advanced container file required header 
  
   information*/
  
      value = avformat_write_header(outAVFormatContext , NULL);
  
      if(value &lt; 0)
  
      {
  
              printf("\n\nError : avformat_write_header()");
  
              return -1;
  
      }
  
  
  
      printf("\n\nOutput file information :\n\n");
  
      av_dump_format(outAVFormatContext , 0 ,video_dst_filename ,1);
  
  
  
  
  
      int flag;
  
      int frameFinished;
  
  
  
  
  
      value = 0;
  
  
  
      pAVPacket = (AVPacket *)av_malloc(sizeof(AVPacket));
  
      av_init_packet(pAVPacket);
  
  
  
      pAVFrame = av_frame_alloc();
  
      if( !pAVFrame )
  
      {
  
       printf("\n\nError : av_frame_alloc()");
  
       return -1;
  
      }
  
  
  
      outFrame = av_frame_alloc();//Allocate an AVFrame and set its fields to 
  
   default values.
  
      if( !outFrame )
  
      {
  
       printf("\n\nError : av_frame_alloc()");
  
       return -1;
  
      }
  
  
  
      nbytes = av_image_get_buffer_size(outAVCodecContext-
  
   >pix_fmt,outAVCodecContext->width,outAVCodecContext->height,32);
  
      video_outbuf = (uint8_t*)av_malloc(nbytes);
  
      if( video_outbuf == NULL )
  
      {
  
      printf("\n\nError : av_malloc()");
  
      }
  
  
  
  
  
      value = av_image_fill_arrays( outFrame->data, outFrame->linesize, 
  
   video_outbuf , AV_PIX_FMT_YUV420P, outAVCodecContext-
  
   >width,outAVCodecContext->height,1 ); // returns : the size in bytes 
  
   required for src
  
      if(value &lt; 0)
  
      {
  
      printf("\n\nError : av_image_fill_arrays()");
  
      }
  
  
  
      SwsContext* swsCtx_ ;
  
  
  
      // Allocate and return swsContext.
  
      // a pointer to an allocated context, or NULL in case of error
  
      // Deprecated : Use sws_getCachedContext() instead.
  
      swsCtx_ = sws_getContext(video_dec_ctx->width,
  
                              video_dec_ctx->height,
  
                              video_dec_ctx->pix_fmt,
  
                              video_dec_ctx->width,
  
                              video_dec_ctx->height,
  
                              video_dec_ctx->pix_fmt,
  
                              SWS_BICUBIC, NULL, NULL, NULL);
  
  
  
  
  
      AVPacket outPacket;
  
  
  
      int got_picture;
  
  
  
      while( av_read_frame( fmt_ctx , pAVPacket ) >= 0 )
  
      {
  
              if(pAVPacket->stream_index == video_stream_idx)
  
              {
  
                      value = avcodec_decode_video2(video_dec_ctx , pAVFrame , 
  
    &amp;frameFinished , pAVPacket );
  
                      if( value &lt; 0)
  
                      {
  
                              printf("Error : avcodec_decode_video2()");
  
                      }
  
  
  
                      if(frameFinished)// Frame successfully decoded :)
  
                      {
  
                              sws_scale(swsCtx_, pAVFrame->data, pAVFrame-
  
   >linesize,0, video_dec_ctx->height, outFrame->data,outFrame->linesize);
  
  //                              sws_scale(swsCtx_, pAVFrame->data, pAVFrame-
  
  >linesize,0, video_dec_ctx->height, outFrame->data,outFrame->linesize);
  
                              av_init_packet(&amp;outPacket);
  
                              outPacket.data = NULL;    // packet data will be 
  
   allocated by the encoder
  
                              outPacket.size = 0;
  
  
  
                              avcodec_encode_video2(outAVCodecContext , 
  
   &amp;outPacket ,outFrame , &amp;got_picture);
  
  
  
                              if(got_picture)
  
                              {
  
                                      if(outPacket.pts != AV_NOPTS_VALUE)
  
                                              outPacket.pts = 
  
   av_rescale_q(outPacket.pts, video_st->codec->time_base, video_st-
  
   >time_base);
  
                                      if(outPacket.dts != AV_NOPTS_VALUE)
  
                                              outPacket.dts = 
  
   av_rescale_q(outPacket.dts, video_st->codec->time_base, video_st-
  
   >time_base);
  
  
  
                                      printf("Write frame %3d (size= %2d)\n", 
  
   j++, outPacket.size/1000);
  
                                      if(av_write_frame(outAVFormatContext , 
  
   &amp;outPacket) != 0)
  
                                      {
  
                                              printf("\n\nError : 
  
   av_write_frame()");
  
                                      }
  
  
  
                              av_packet_unref(&amp;outPacket);
  
                              } // got_picture
  
  
  
                      av_packet_unref(&amp;outPacket);
  
                      } // frameFinished
  
  
  
              }
  
      }// End of while-loop
  
  
  
      value = av_write_trailer(outAVFormatContext);
  
      if( value &lt; 0)
  
      {
  
              printf("\n\nError : av_write_trailer()");
  
      }
  
  
  
  
  
      //THIS WAS ADDED LATER
  
      av_free(video_outbuf);
  
  
  
  end:
  
      avcodec_free_context(&amp;video_dec_ctx);
  
      avcodec_free_context(&amp;audio_dec_ctx);
  
      avformat_close_input(&amp;fmt_ctx);
  
      if (video_dst_file)
  
          fclose(video_dst_file);
  
     if (audio_dst_file)
  
         fclose(audio_dst_file);
  
     //av_frame_free(&amp;frame);
  
     av_free(video_dst_data[0]);
  
     return ret &lt; 0;
  
  }

  Problem with above code is that it rotates a video to left by 90 degree.

  Snapshot of video given as input to above program

  Snapshot of output video. It is rotated by 90 degree to left.

  I compiled program using below command :

  g++ -D__STDC_CONSTANT_MACROS -Wall -g ScreenRecorder.cpp -I/home/harry/Documents/compressor/ffmpeg-3.3/ -I/root/android-ndk-r14b/platforms/android-21/arch-x86_64/usr/include/ -c -o ScreenRecorder.o -w

  And linked it using below command :

  g++ -Wall -g ScreenRecorder.o -I/home/harry/Documents/compressor/ffmpeg-3.3/ -I/root/android-ndk-r14b/platforms/android-21/arch-x86_64/usr/include/ -L/usr/lib64 -L/lib64 -L/usr/lib/gcc/x86_64-redhat-linux/4.4.7/ -L/home/harry/Documents/compressor/ffmpeg-3.3/ffmpeg-build -L/root/android-ndk-r14b/platforms/android-21/arch-x86_64/usr/lib64 -o ScreenRecorder.exe -lavformat -lavcodec -lavutil -lavdevice -lavfilter -lswscale -lx264 -lswresample -lm -lpthread -ldl -lstdc++ -lc -lrt

  Program is being run using below command :

  ./ScreenRecorder.exe vertical.MOV videoH.mp4 audioH.mp3

  Note :
  - Source video is taken from iphone and is of .mov format.
  - Output video is being stored in .mp4 file.

  Can anyone please tell me why it is rotating video by 90 degree ?

  One thing i noticed in dump is shown below :

    Duration: 00:00:06.04, start: 0.000000, bitrate: 17087 kb/s
  
  Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 1920x1080, 17014 kb/s, 29.98 fps, 29.97 tbr, 600 tbn, 1200 tbc (default)
  
  Metadata:
  
    rotate          : 90
  
    creation_time   : 2017-07-09T10:56:42.000000Z
  
    handler_name    : Core Media Data Handler
  
    encoder         : H.264
  
  Side data:
  
    displaymatrix: rotation of -90.00 degrees

  it says displaymatrix: rotation of -90.00 degrees. Is it responsible for rotating video by 90 degree ?

• Piwik Analytics and becoming a Piwik Certified Professional

  10 juillet 2017, par Piwik Core Team — About

  Digital Analytics software

  Piwik Analytics is the leading open source digital analytics software, offering users around the world an opportunity to liberate their analytics. Most recently, they have introduced the Piwik Certified Professional certification exam which now allows users to become qualified in Piwik Analytics software on an individual level to gain a deeper understanding of Piwik. In this blog post I will guide you through the topics that are covered during the exam and provide you with advice on taking the official Piwik Certified Professional exam.

  

  Piwik certification exam

  Taking the exam will cost you a maximum investment of 60 minutes of your time, besides learning all materials of course. The exam consists of 55 multiple choice questions with four answers to choose from. The score needed to pass is 80% (44 questions answered correctly) and the cost is 50 USD total. An earned certificate is valid for 18 months, before these eighteen months are over a person should pass the exam again in order to retain the certified status.

  Learning topics

  The exam consists of two sections. The main section is focused on the Piwik Analytics software itself while the second part relates to digital analytics in general. All topics and content covered about Piwik Analytics is available through the official Piwik user guides. The second section tests your experience as a digital analyst, online marketer or any other function title in which you work with Piwik Analytics. In this case, the general digital analytics questions should be quite straightforward and easy to answer, and cover only a fraction of the total questions in the exam (around 10% with 5-7 general questions). An outline of all exam topics are listed below :

  • A Tour of Piwik
  • Track Goals and Measure Conversions
  • Event Tracking
  • Content Tracking
  • Ecommerce Analytics
  • Row Evolution – View and compare historical data
  • Segmentation – Compare segments of visitors
  • Visitors Maps – World, region, city
  • Real Time Visitor World Map
  • Real Time Analytics
  • The Visitor Profile
  • Site speed and Page speed
  • Site Search Tracking and Reporting
    
  • Transitions – Analyze the previous and following actions of your visitors for each page
  • Page Overlay
  • Custom Variables Analytics
  • Custom Dimensions
  • User ID
  • Annotating your data
  • Tracking Campaigns
  • URL Builder for Marketing Campaign Tracking

  The best way to prepare for the exam is read the entire Piwik user guides. You should definitely read the “Analytics Features” section since most questions of the Piwik Certified Professional – Digital Analytics exam that will be asked come from these sections. Furthermore you should be able to find your way around in Piwik at a basic level which means you know what the reports mean and where to find certain information. In addition, some basic knowledge regarding the settings is useful too. The exam is definitely not a technical implementation exam so no coding knowledge or any other deeply technical knowledge regarding Piwik is required.

  Finally, some general questions will be asked regarding digital analytics covering topics about KPI’s and the role of the analyst within an organization. While Piwik provides some links to articles by Avinash Kaushik covering these topics, you will not be able to learn these topics just by reading. When you have some experience with digital analytics you should be able to answer these general digital analytics questions with common sense and (even basic) experience as a digital analyst, analytics consultant, online marketer or any other related job whereby you work with Piwik.

  Taking the exam

  With 55 questions to be answered in 60 minutes the key to passing the exam is to keep moving. You have about 1 minute and 5 seconds to answer each question. This means that you should focus on the easiest questions first and return later to the questions that are a bit more challenging to answer. Keep an eye on the timer that will be displayed in the exam window. When the time expires or you click ‘Finish test’ your exam will end and be automatically submitted for review. Remember to first check all questions and answers before you click on the ‘Finish test’ button. If you click too soon and you still haven’t answered all questions, all unanswered questions will be marked as incorrect.

  During the test, no hard copy or online materials may be referenced. As you can imagine, it is almost impossible to check if users reference these kind of materials. However, be aware of the penalty system that is in place during the test. When a user leaves from the active test screen to another screen (i.e. a different browser tab) the screen turns red and provides a warning count when the user returns to the test screen again. You will have three warnings, after this your test will be submitted and graded as false. Furthermore, keep in mind you will have to do the test in one go and cannot pause and come back another time.

  Practice makes perfect

  Below I have included some example questions that could be asked during the exam. These questions do not necessarily represent how Piwik will test you on these topics.

  • What is the default report date that is selected by Piwik ?
  • Why would someone flatten a report in Piwik ?
  • Why would a user especially use the Page Overlay report ?
  • What are the three main Ecommerce interactions tracked with Piwik ?
  • What is an example of an anonymized IP address in Piwik ?

  Passing the Piwik Certified Professional – Digital Analytics exam

  Directly after submitting the exam you will receive a notification telling you whether or not you have passed the exam. If you pass, you will be able to download your personal certification right away. A report of your exam performance will also be available. This report lists the amount of correct answers and total questions by topic. The report with your exam performance is also available if you did not pass the exam. The certificate is valid for 18 months from the date of successful completion.

  Sometimes the difference between passing and failing can be a matter of how you interpret some of Piwik’s questions. There are several tricky questions included, so be sure to pay attention to detail on every question. If you fail, you may take the exam again. You will have to pay the 50 USD fee for each try, so do your best to pass it the first time.

  → Register to become a Piwik Certified Professional.

  We wish you the best of luck and happy analytics !

• Is there a way to use external filters in ffmpeg ?

  26 octobre 2017, par Eduardo

  I want to write a filter that is saved to a shared object or independent executable that can be used as any other ffmpeg filter.

  I am using the architecture described here : http://nullprogram.com/blog/2017/07/02/ but it is not ideal as it is not integrated and I have to specify the framerate (even if I am not changing it) in the encoder after the filter has been aplied.