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• Spotlight : Alwaysdata.com the company behind Piwik.org web hosting [Interview]

  11 avril 2013, par matt — About, Community

  Piwik is the result of the work of many talented individuals and companies. Today we’d like to showcase Alwaysdata.com, the awesome web hosting company providing managed hosting for all Piwik.org websites and services.

  I recently met and asked a few questions to Cyril, co-founder of Alwaysdata.com and Piwik core developer. Learn more in the interview below !

  

  1. What is Alwaysdata ?
  2. Who are your customers and what kind of work do you do ?
  3. What sets Alwaysdata apart from the large web hosting competition ?
  4. Are you using Piwik internally or with customers ? If so, how are you using Piwik ?
  5. What is the next big thing for Alwaysdata ?
  6. Learn more

  What is Alwaysdata ?

  We are a French web hosting company created in 2006. If you need to host a website — a Piwik installation, for example — or even your domains/emails, we provide infrastructure and maintenance services.

  Who are your customers and what kind of work do you do ?

  We have several types of clients :

  • Individuals who need hosting for their personal site and who benefit from storage space with direct SSH access.
  • Web agencies who need hosting for their clients’ sites.
  • The largest customers, often on dedicated servers, for hosting their site/infrastructure.

  Our work falls into three categories :

  1. Support (via administration, telephone, Twitter, IRC, etc.)
  2. Development (in Python), primarily to add new features
  3. System administration, either for maintenance (e.g. adding servers), or for preparing new features

  What sets Alwaysdata apart from the large web hosting competition ?

  Two things :

  • Availability. We are a small team and often know our customers quite well. We are all on IRC, so you can contact us directly if you need any assistance.
  • Features. We are halfway between traditional web hosting and the cloud, combining the advantages of both.

  Are you using Piwik internally or with customers ? If so, how are you using Piwik ?

  All of our customers can view statistics for their sites via our global Piwik installation, without having to configure anything.

  To provide these analytics reports to our customers, we implemented import of the raw access logs in Piwik. The Log import toolkit is now a feature included in Piwik.

  What is the next big thing for Alwaysdata ?

  We are going to upgrade our pricing : instead of fixed costs, each of our clients will now pay exactly what they consume. This allows our clients the benefit of a very high quality service for the lowest possible price.

  We are also going to add native support for more technologies : Java, Node.js, ZeroMQ, etc.

  Thank you for your time and all the best to Alwaysdata for the future !

  —

  Note from Matt, Piwik founder : Cyril and the team at Alwaysdata.com have been consistently great in their system administration work for Piwik.org services, providing a fast and reliable web hosting experience with top notch support and security practises. They also handled the migration of all services from our old servers with total piece of mind.

  Alwaysdata contributed to Piwik the popular Log Analytics toolkit. They are great software developers and system administrators with a passion for their work. Since 2006, they have been maintaining optimized hosting services for the entire web infrastructure (websites, domains, emails, databases, etc.), from the simplest to the most exotic. We do recommend their managed hosting services.

  Learn more

  • Visit their website at Alwaysdata.com
  • Learn more about their Managed hosting on dedicated servers
  • Learn more about other companies and individuals who make a difference in Piwik.

• [Aug-Sept 2013] Piwik 2.0 Development Update !

  3 octobre 2013, par Fabian Becker — Development

  This Development Update is the first in a new series of posts we’ll be writing to keep you, our loyal users, informed of our efforts. We hope these updates keep you excited about Piwik’s future, and if you’re a developer, we hope they inspire and challenge you to accomplish more yourself !

  Despite this being our first update, it will probably be one of our biggest. We’ve gotten a lot done as we race towards the Piwik 2.0 release ! Just see for yourself :

  What we’ve accomplished

  Theming

  Piwik now supports theming, a feature that was requested often in the past. Because of our switch to the Twig template engine and other major code changes it is now possible to change the way Piwik looks. Additionally, developers can use the dynamic stylesheet language LESS, instead of CSS. Piwik will automatically transform the LESS code into CSS.

  Piwik 2.0 will ship with a new dark theme called PleineLune (french for Full Moon) that makes use of the new theming feature. Another theme with a left-aligned menu was created during the Piwik Meetup in Paris. Both of these themes were created by Thomas Zilliox, a very talented designer and CSS expert.

  

  PHP 5.3 Namespaces

  For Piwik 2.0 we decided to make use of namespaces, a feature introduced in PHP 5.3. The usage of namespaces makes our code more readable and allows us to better modularize the platform. This is in part why we are raising the required minimum PHP version to 5.3 for Piwik 2.0. (Remember to update your server !)

  Translations in JSON

  All translations are now stored in JSON files which makes storing translations in Piwik a lot cleaner that the giant PHP array we previously used.

  Side note : if you’d like to make Piwik available to more languages, please sign up at translations.piwik.org. We’d love to have your help !

  UI Tests

  We now use UI tests to make sure that changes to the code don’t break the UI. UI tests use PhantomJS and CutyCapt and are automatically executed on Travis CI. Whenever an integration test fails the script produces a screenshot diff that shows the difference. Learn more.

  

  AnonymizeIP supports IPv6

  The AnonymizeIP plugin now masks IPv6 addresses. The concept of the config option ‘ip_address_mask_length’ has now changed to reflect the level of masking that should be applied to the IP. With a masking level of 1 Piwik will mask the last octet of an IPv4 address and the last 80 bits of an IPv6 address.

  All Websites Dashboard usable with 20,000+ Websites

  The All Websites Dashboard is now usable even if you track many thousands of websites in your Piwik instance. We rewrote parts of the archiving process in order to make this possible. Making Piwik fast and memory efficient is a constant concern for core developers.

  Plugins can now add new Visualizations

  Piwik Plugins and Themes can now create new visualizations for your report data. They can also specify their own ViewDataTable footer icons or modify existing ones. This will allow plugin developers to create new ways for you to view your data, customize existing reports so they look great in new visualizations and provide extra analytics functionality accessible in each of your reports.

  The new TreemapVisualization plugin makes use of this feature to let you view your reports as treemaps. It serves as an example of this new functionality.

  Piwik Marketplace

  The Piwik Marketplace is a new platform developers can use to publish their plugins and themes so all Piwik users can easily access them. The marketplace is hosted at plugins.piwik.org and is currently in an early development state, but we’re already able to host plugins !

  Developers can easily publish their plugins by adding a commit hook to their Github repositories. Every time you push a new tag, the marketplace will make a new version of your plugin available. The marketplace will provide a centralized platform to search for plugins and also provide statistics on plugin usage.

  Install Plugins and Themes in one click from within Piwik

  Piwik has offered since the beginning the much-loved “one click update” feature. We are bringing the same functionnality to the Marketplace : you will be able to install Plugins and Themes in one click directly within the Piwik interface ! Similarly to WordPress or Firefox, Piwik will let you extend the functionnality of your analytics platform.

  Conclusion

  In Piwik 2.0 you will be able to install plugins and themes from the marketplace. And, if you’re so inclined, you will be able to create and host your own plugins/themes on the marketplace so everyone can use them. This is by far the accomplishment we are most excited by… the possibilities it opens up for Piwik’s future are truly unlimited. We hope you share our excitement !

  Au revoir, until next time !

  PS : our mission is to liberate web analytics ; thank you for sharing the word about Piwik 2.0 !

• FFmpeg : Parallel encoding with custom thread pool

  13 novembre 2017, par ZeroDefect

  One of the things I’m trying to achieve is parallel encoding via FFmpeg’s c API. This looks to work out of the box quite nicely ; however, I’ve changed the goal posts slightly :

  In an existing application, I already have a thread pool at hand. Instead of using another thread pool via FFmpeg, I would like reuse the existing thread pool in my application. Having studied the latest FFmpeg trunk docs, it very much looks possible.

  Using some FFmpeg sample code, I’ve created a sample application to demonstrate what I’m trying to achieve (see below). The sample app generates a video-only mpeg2 ts using the mp2v codec.

  The problem I’m experiencing is that the custom ’thread_execute’ or ’thread_execute2’ are never invoked. This is despite the fact that the codec appears to indicate that threading is supported. Please be aware that I have not yet plumbed in the thread pool just yet. My first goal is for it to call the custom function pointer.

  I’ve tried to get assistance on the FFmpeg mailing lists but to no avail.

  #include <iostream>
  
  #include <thread>
  
  #include 
  
  #include 
  
  #include 
  
  #include <cstring>
  
  #include <future>
  
  
  
  extern "C"
  
  {
  
  #include <libavutil></libavutil>avassert.h>
  
  #include <libavutil></libavutil>channel_layout.h>
  
  #include <libavutil></libavutil>opt.h>
  
  #include <libavutil></libavutil>timestamp.h>
  
  #include <libavformat></libavformat>avformat.h>
  
  //#include <libswscale></libswscale>swscale.h>
  
  #include <libswresample></libswresample>swresample.h>
  
  }
  
  
  
  #define STREAM_DURATION   1000.0
  
  #define STREAM_FRAME_RATE 25 /* 25 images/s */
  
  #define STREAM_PIX_FMT    AV_PIX_FMT_YUV420P /* default pix_fmt */
  
  
  
  #define SCALE_FLAGS SWS_BICUBIC
  
  
  
  // a wrapper around a single output AVStream
  
  typedef struct OutputStream {
  
      AVStream *st;
  
      AVCodecContext *enc;
  
  
  
      /* pts of the next frame that will be generated */
  
      int64_t next_pts;
  
      int samples_count;
  
  
  
      AVFrame *frame;
  
      AVFrame *tmp_frame;
  
  
  
      float t, tincr, tincr2;
  
  
  
      struct SwsContext *sws_ctx;
  
      struct SwrContext *swr_ctx;
  
  } OutputStream;
  
  
  
  /////////////////////////////////////////////////////////////////////////////
  
  //  The ffmpeg variation raises compiler warnings.
  
  char *cb_av_ts2str(char *buf, int64_t ts)
  
  {
  
      std::memset(buf,0,AV_TS_MAX_STRING_SIZE);
  
      return av_ts_make_string(buf,ts);
  
  }
  
  
  
  /////////////////////////////////////////////////////////////////////////////
  
  //  The ffmpeg variation raises compiler warnings.
  
  char *cb_av_ts2timestr(char *buf, int64_t ts, AVRational *tb)
  
  {
  
      std::memset(buf,0,sizeof(AV_TS_MAX_STRING_SIZE));
  
      return av_ts_make_time_string(buf,ts,tb);
  
  }
  
  
  
  /////////////////////////////////////////////////////////////////////////////
  
  //  The ffmpeg variation raises compiler warnings.
  
  char *cb_av_err2str(char *errbuf, size_t errbuf_size, int errnum)
  
  {
  
      std::memset(errbuf,0,errbuf_size);
  
      return av_make_error_string(errbuf,errbuf_size,errnum);
  
  }
  
  
  
  int thread_execute(AVCodecContext* s, int (*func)(AVCodecContext *c2, void *arg2), void* arg, int* ret, int count, int size)
  
  {
  
      // Do it all serially for now
  
      std::cout &lt;&lt; "thread_execute" &lt;&lt; std::endl;
  
  
  
      for (int k = 0; k &lt; count; ++k)
  
      {
  
          ret[k] = func(s, arg);
  
      }
  
  
  
      return 0;
  
  }
  
  
  
  int thread_execute2(AVCodecContext* s, int (*func)(AVCodecContext* c2, void* arg2, int, int), void* arg, int* ret, int count)
  
  {
  
      // Do it all serially for now
  
      std::cout &lt;&lt; "thread_execute2" &lt;&lt; std::endl;
  
  
  
      for (int k = 0; k &lt; count; ++k)
  
      {
  
          ret[k] = func(s, arg, k, count);
  
      }
  
  
  
      return 0;
  
  }
  
  
  
  
  
  static void log_packet(const AVFormatContext *fmt_ctx, const AVPacket *pkt)
  
  {
  
      char s[AV_TS_MAX_STRING_SIZE];
  
  
  
      AVRational *time_base = &amp;fmt_ctx->streams[pkt->stream_index]->time_base;
  
  
  
      printf("pts:%s pts_time:%s dts:%s dts_time:%s duration:%s duration_time:%s stream_index:%d\n",
  
             cb_av_ts2str(s,pkt->pts), cb_av_ts2timestr(s,pkt->pts, time_base),
  
             cb_av_ts2str(s,pkt->dts), cb_av_ts2timestr(s,pkt->dts, time_base),
  
             cb_av_ts2str(s,pkt->duration), cb_av_ts2timestr(s,pkt->duration, time_base),
  
             pkt->stream_index);
  
  }
  
  
  
  static int write_frame(AVFormatContext *fmt_ctx, const AVRational *time_base, AVStream *st, AVPacket *pkt)
  
  {
  
      /* rescale output packet timestamp values from codec to stream timebase */
  
      av_packet_rescale_ts(pkt, *time_base, st->time_base);
  
      pkt->stream_index = st->index;
  
  
  
      /* Write the compressed frame to the media file. */
  
      log_packet(fmt_ctx, pkt);
  
      return av_interleaved_write_frame(fmt_ctx, pkt);
  
  }
  
  
  
  /* Add an output stream. */
  
  static void add_stream(OutputStream *ost, AVFormatContext *oc,
  
                         AVCodec **codec,
  
                         enum AVCodecID codec_id)
  
  {
  
      AVCodecContext *c;
  
      int i;
  
  
  
      /* find the encoder */
  
      *codec = avcodec_find_encoder(codec_id);
  
      if (!(*codec)) {
  
          fprintf(stderr, "Could not find encoder for '%s'\n",
  
                  avcodec_get_name(codec_id));
  
          exit(1);
  
      }
  
  
  
      ost->st = avformat_new_stream(oc, NULL);
  
      if (!ost->st) {
  
          fprintf(stderr, "Could not allocate stream\n");
  
          exit(1);
  
      }
  
      ost->st->id = oc->nb_streams-1;
  
      c = avcodec_alloc_context3(*codec);
  
      if (!c) {
  
          fprintf(stderr, "Could not alloc an encoding context\n");
  
          exit(1);
  
      }
  
      ost->enc = c;
  
  
  
      switch ((*codec)->type)
  
      {
  
          case AVMEDIA_TYPE_AUDIO:
  
              c->sample_fmt  = (*codec)->sample_fmts ?
  
                               (*codec)->sample_fmts[0] : AV_SAMPLE_FMT_FLTP;
  
              c->bit_rate    = 64000;
  
              c->sample_rate = 44100;
  
              if ((*codec)->supported_samplerates) {
  
                  c->sample_rate = (*codec)->supported_samplerates[0];
  
                  for (i = 0; (*codec)->supported_samplerates[i]; i++) {
  
                      if ((*codec)->supported_samplerates[i] == 44100)
  
                          c->sample_rate = 44100;
  
                  }
  
              }
  
              c->channels        = av_get_channel_layout_nb_channels(c->channel_layout);
  
              c->channel_layout = AV_CH_LAYOUT_STEREO;
  
              if ((*codec)->channel_layouts) {
  
                  c->channel_layout = (*codec)->channel_layouts[0];
  
                  for (i = 0; (*codec)->channel_layouts[i]; i++) {
  
                      if ((*codec)->channel_layouts[i] == AV_CH_LAYOUT_STEREO)
  
                          c->channel_layout = AV_CH_LAYOUT_STEREO;
  
                  }
  
              }
  
              c->channels        = av_get_channel_layout_nb_channels(c->channel_layout);
  
              ost->st->time_base = (AVRational){ 1, c->sample_rate };
  
              break;
  
  
  
          case AVMEDIA_TYPE_VIDEO:
  
              c->codec_id = codec_id;
  
  
  
              c->bit_rate = 400000;
  
              /* Resolution must be a multiple of two. */
  
              c->width    = 352;
  
              c->height   = 288;
  
              /* timebase: This is the fundamental unit of time (in seconds) in terms
  
               * of which frame timestamps are represented. For fixed-fps content,
  
               * timebase should be 1/framerate and timestamp increments should be
  
               * identical to 1. */
  
              ost->st->time_base = (AVRational){ 1, STREAM_FRAME_RATE };
  
              c->time_base       = ost->st->time_base;
  
  
  
              c->gop_size      = 12; /* emit one intra frame every twelve frames at most */
  
              c->pix_fmt       = STREAM_PIX_FMT;
  
              if (c->codec_id == AV_CODEC_ID_MPEG2VIDEO) {
  
                  /* just for testing, we also add B-frames */
  
                  c->max_b_frames = 2;
  
              }
  
              if (c->codec_id == AV_CODEC_ID_MPEG1VIDEO) {
  
                  /* Needed to avoid using macroblocks in which some coeffs overflow.
  
                   * This does not happen with normal video, it just happens here as
  
                   * the motion of the chroma plane does not match the luma plane. */
  
                  c->mb_decision = 2;
  
              }
  
              break;
  
  
  
          default:
  
              break;
  
      }
  
  
  
      if (c->codec->capabilities &amp; AV_CODEC_CAP_FRAME_THREADS ||
  
          c->codec->capabilities &amp; AV_CODEC_CAP_SLICE_THREADS)
  
      {
  
          if (c->codec->capabilities &amp; AV_CODEC_CAP_FRAME_THREADS)
  
          {
  
              c->thread_type = FF_THREAD_FRAME;
  
          }
  
          if (c->codec->capabilities &amp; AV_CODEC_CAP_SLICE_THREADS)
  
          {
  
              c->thread_type = FF_THREAD_SLICE;
  
          }
  
  
  
          c->execute = &amp;thread_execute;
  
          c->execute2 = &amp;thread_execute2;
  
          c->thread_count = 4;
  
  
  
          // NOTE: Testing opaque.
  
          c->opaque = (void*)0xff;
  
      }
  
  
  
      /* Some formats want stream headers to be separate. */
  
      if (oc->oformat->flags &amp; AVFMT_GLOBALHEADER)
  
          c->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
  
  }
  
  
  
  /**************************************************************/
  
  /* video output */
  
  
  
  static AVFrame *alloc_picture(enum AVPixelFormat pix_fmt, int width, int height)
  
  {
  
      AVFrame *picture;
  
      int ret;
  
  
  
      picture = av_frame_alloc();
  
      if (!picture)
  
          return NULL;
  
  
  
      picture->format = pix_fmt;
  
      picture->width  = width;
  
      picture->height = height;
  
  
  
      /* allocate the buffers for the frame data */
  
      ret = av_frame_get_buffer(picture, 32);
  
      if (ret &lt; 0) {
  
          fprintf(stderr, "Could not allocate frame data.\n");
  
          exit(1);
  
      }
  
  
  
      return picture;
  
  }
  
  
  
  static void open_video(AVFormatContext *oc, AVCodec *codec, OutputStream *ost, AVDictionary *opt_arg)
  
  {
  
      int ret;
  
      AVCodecContext *c = ost->enc;
  
      //AVDictionary *opt = NULL;
  
  
  
      //av_dict_copy(&amp;opt, opt_arg, 0);
  
  
  
      /* open the codec */
  
      ret = avcodec_open2(c, codec, NULL);
  
      //av_dict_free(&amp;opt);
  
      if (ret &lt; 0) {
  
          char s[AV_ERROR_MAX_STRING_SIZE];
  
          fprintf(stderr, "Could not open video codec: %s\n", cb_av_err2str(s,AV_ERROR_MAX_STRING_SIZE,ret));
  
          exit(1);
  
      }
  
  
  
      /* allocate and init a re-usable frame */
  
      ost->frame = alloc_picture(c->pix_fmt, c->width, c->height);
  
      if (!ost->frame) {
  
          fprintf(stderr, "Could not allocate video frame\n");
  
          exit(1);
  
      }
  
  
  
      /* If the output format is not YUV420P, then a temporary YUV420P
  
       * picture is needed too. It is then converted to the required
  
       * output format. */
  
      ost->tmp_frame = NULL;
  
      if (c->pix_fmt != AV_PIX_FMT_YUV420P) {
  
          ost->tmp_frame = alloc_picture(AV_PIX_FMT_YUV420P, c->width, c->height);
  
          if (!ost->tmp_frame) {
  
              fprintf(stderr, "Could not allocate temporary picture\n");
  
              exit(1);
  
          }
  
      }
  
  
  
      /* copy the stream parameters to the muxer */
  
      ret = avcodec_parameters_from_context(ost->st->codecpar, c);
  
      if (ret &lt; 0) {
  
          fprintf(stderr, "Could not copy the stream parameters\n");
  
          exit(1);
  
      }
  
  }
  
  
  
  /* Prepare a dummy image. */
  
  static void fill_yuv_image(AVFrame *pict, int frame_index,
  
                             int width, int height)
  
  {
  
      int x, y, i;
  
  
  
      i = frame_index;
  
  
  
      /* Y */
  
      for (y = 0; y &lt; height; y++)
  
          for (x = 0; x &lt; width; x++)
  
              pict->data[0][y * pict->linesize[0] + x] = x + y + i * 3;
  
  
  
      /* Cb and Cr */
  
      for (y = 0; y &lt; height / 2; y++) {
  
          for (x = 0; x &lt; width / 2; x++) {
  
              pict->data[1][y * pict->linesize[1] + x] = 128 + y + i * 2;
  
              pict->data[2][y * pict->linesize[2] + x] = 64 + x + i * 5;
  
          }
  
      }
  
  }
  
  
  
  static AVFrame *get_video_frame(OutputStream *ost)
  
  {
  
      AVCodecContext *c = ost->enc;
  
  
  
      /* check if we want to generate more frames */
  
      if (av_compare_ts(ost->next_pts, c->time_base,
  
                        STREAM_DURATION, (AVRational){ 1, 1 }) >= 0)
  
          return NULL;
  
  
  
      /* when we pass a frame to the encoder, it may keep a reference to it
  
       * internally; make sure we do not overwrite it here */
  
      if (av_frame_make_writable(ost->frame) &lt; 0)
  
          exit(1);
  
  
  
      if (c->pix_fmt != AV_PIX_FMT_YUV420P) {
  
          /* as we only generate a YUV420P picture, we must convert it
  
           * to the codec pixel format if needed */
  
          /*if (!ost->sws_ctx) {
  
              ost->sws_ctx = sws_getContext(c->width, c->height,
  
                                            AV_PIX_FMT_YUV420P,
  
                                            c->width, c->height,
  
                                            c->pix_fmt,
  
                                            SCALE_FLAGS, NULL, NULL, NULL);
  
              if (!ost->sws_ctx) {
  
                  fprintf(stderr,
  
                          "Could not initialize the conversion context\n");
  
                  exit(1);
  
              }
  
          }
  
          fill_yuv_image(ost->tmp_frame, ost->next_pts, c->width, c->height);
  
          sws_scale(ost->sws_ctx,
  
                    (const uint8_t * const *)ost->tmp_frame->data, ost->tmp_frame->linesize,
  
                    0, c->height, ost->frame->data, ost->frame->linesize);*/
  
      } else {
  
          fill_yuv_image(ost->frame, ost->next_pts, c->width, c->height);
  
      }
  
  
  
      ost->frame->pts = ost->next_pts++;
  
  
  
      return ost->frame;
  
  }
  
  
  
  /*
  
   * encode one video frame and send it to the muxer
  
   * return 1 when encoding is finished, 0 otherwise
  
   */
  
  static int write_video_frame(AVFormatContext *oc, OutputStream *ost)
  
  {
  
      int ret;
  
      AVCodecContext *c;
  
      AVFrame *frame;
  
      int got_packet = 0;
  
      AVPacket pkt = { 0 };
  
  
  
      c = ost->enc;
  
  
  
      frame = get_video_frame(ost);
  
  
  
      if (frame)
  
      {
  
          ret = avcodec_send_frame(ost->enc, frame);
  
          if (ret &lt; 0)
  
          {
  
              char s[AV_ERROR_MAX_STRING_SIZE];
  
              fprintf(stderr, "Error encoding video frame: %s\n", cb_av_err2str(s, AV_ERROR_MAX_STRING_SIZE, ret));
  
              exit(1);
  
          }
  
      }
  
  
  
      av_init_packet(&amp;pkt);
  
  
  
      ret = avcodec_receive_packet(ost->enc,&amp;pkt);
  
      if (ret &lt; 0)
  
      {
  
          if (ret == AVERROR(EAGAIN)) { ret = 0; }
  
          else
  
          {
  
              char s[AV_ERROR_MAX_STRING_SIZE];
  
              fprintf(stderr, "Error receiving packet: %s\n", cb_av_err2str(s,AV_ERROR_MAX_STRING_SIZE,ret));
  
              exit(1);
  
          }
  
      }
  
      else
  
      {
  
          got_packet = 1;
  
          ret = write_frame(oc, &amp;c->time_base, ost->st, &amp;pkt);
  
      }
  
  
  
      if (ret &lt; 0) {
  
          char s[AV_ERROR_MAX_STRING_SIZE];
  
          fprintf(stderr, "Error while writing video frame: %s\n", cb_av_err2str(s,AV_ERROR_MAX_STRING_SIZE,ret));
  
          exit(1);
  
      }
  
  
  
      return (frame || got_packet) ? 0 : 1;
  
  }
  
  
  
  static void close_stream(AVFormatContext *oc, OutputStream *ost)
  
  {
  
      avcodec_free_context(&amp;ost->enc);
  
      av_frame_free(&amp;ost->frame);
  
      av_frame_free(&amp;ost->tmp_frame);
  
      //sws_freeContext(ost->sws_ctx);
  
      //swr_free(&amp;ost->swr_ctx);
  
  }
  
  
  
  /**************************************************************/
  
  /* media file output */
  
  
  
  int main(int argc, char **argv)
  
  {
  
      OutputStream video_st = { 0 }, audio_st = { 0 };
  
      const char *filename;
  
      AVOutputFormat *fmt;
  
      AVFormatContext *oc;
  
      AVCodec /**audio_codec,*/ *video_codec;
  
      int ret;
  
      int have_video = 0, have_audio = 0;
  
      int encode_video = 0, encode_audio = 0;
  
      AVDictionary *opt = NULL;
  
      int i;
  
  
  
      /* Initialize libavcodec, and register all codecs and formats. */
  
      av_register_all();
  
      avformat_network_init();
  
  
  
      if (argc &lt; 2) {
  
          printf("usage: %s output_file\n"
  
                     "API example program to output a media file with libavformat.\n"
  
                     "This program generates a synthetic audio and video stream, encodes and\n"
  
                     "muxes them into a file named output_file.\n"
  
                     "The output format is automatically guessed according to the file extension.\n"
  
                     "Raw images can also be output by using '%%d' in the filename.\n"
  
                     "\n", argv[0]);
  
          return 1;
  
      }
  
  
  
      filename = argv[1];
  
      for (i = 2; i+1 &lt; argc; i+=2) {
  
          if (!strcmp(argv[i], "-flags") || !strcmp(argv[i], "-fflags"))
  
              av_dict_set(&amp;opt, argv[i]+1, argv[i+1], 0);
  
      }
  
  
  
      const char *pfilename = filename;
  
  
  
      /* allocate the output media context */
  
      avformat_alloc_output_context2(&amp;oc, NULL, "mpegts", pfilename);
  
      if (!oc) {
  
          printf("Could not deduce output format from file extension: using MPEG.\n");
  
          avformat_alloc_output_context2(&amp;oc, NULL, "mpeg", pfilename);
  
      }
  
      if (!oc)
  
          return 1;
  
  
  
      fmt = oc->oformat;
  
  
  
      /* Add the audio and video streams using the default format codecs
  
       * and initialize the codecs. */
  
      if (fmt->video_codec != AV_CODEC_ID_NONE) {
  
          add_stream(&amp;video_st, oc, &amp;video_codec, fmt->video_codec);
  
          have_video = 1;
  
          encode_video = 1;
  
      }
  
      /*if (fmt->audio_codec != AV_CODEC_ID_NONE) {
  
          add_stream(&amp;audio_st, oc, &amp;audio_codec, fmt->audio_codec);
  
          have_audio = 1;
  
          encode_audio = 1;
  
      }*/
  
  
  
      /* Now that all the parameters are set, we can open the audio and
  
       * video codecs and allocate the necessary encode buffers. */
  
      if (have_video)
  
          open_video(oc, video_codec, &amp;video_st, opt);
  
  
  
      //if (have_audio)
  
      //    open_audio(oc, audio_codec, &amp;audio_st, opt);
  
  
  
      av_dump_format(oc, 0, pfilename, 1);
  
  
  
      /* open the output file, if needed */
  
      if (!(fmt->flags &amp; AVFMT_NOFILE)) {
  
          ret = avio_open(&amp;oc->pb, pfilename, AVIO_FLAG_WRITE);
  
          if (ret &lt; 0) {
  
              char s[AV_ERROR_MAX_STRING_SIZE];
  
              fprintf(stderr, "Could not open '%s': %s\n", pfilename,
  
                      cb_av_err2str(s,AV_ERROR_MAX_STRING_SIZE,ret));
  
              return 1;
  
          }
  
      }
  
  
  
      /* Write the stream header, if any. */
  
      ret = avformat_write_header(oc, &amp;opt);
  
      if (ret &lt; 0) {
  
          char s[AV_ERROR_MAX_STRING_SIZE];
  
          fprintf(stderr, "Error occurred when opening output file: %s\n",
  
                  cb_av_err2str(s,AV_ERROR_MAX_STRING_SIZE,ret));
  
          return 1;
  
      }
  
  
  
      while (encode_video || encode_audio) {
  
          /* select the stream to encode */
  
          if (encode_video &amp;&amp;
  
              (!encode_audio || av_compare_ts(video_st.next_pts, video_st.enc->time_base,
  
                                              audio_st.next_pts, audio_st.enc->time_base) &lt;= 0)) {
  
              encode_video = !write_video_frame(oc, &amp;video_st);
  
          } else {
  
              //encode_audio = !write_audio_frame(oc, &amp;audio_st);
  
          }
  
  
  
          //std::this_thread::sleep_for(std::chrono::milliseconds(35));
  
      }
  
  
  
      /* Write the trailer, if any. The trailer must be written before you
  
       * close the CodecContexts open when you wrote the header; otherwise
  
       * av_write_trailer() may try to use memory that was freed on
  
       * av_codec_close(). */
  
      av_write_trailer(oc);
  
  
  
      /* Close each codec. */
  
      if (have_video)
  
          close_stream(oc, &amp;video_st);
  
      if (have_audio)
  
          close_stream(oc, &amp;audio_st);
  
  
  
      if (!(fmt->flags &amp; AVFMT_NOFILE))
  
          /* Close the output file. */
  
          avio_closep(&amp;oc->pb);
  
  
  
      /* free the stream */
  
      avformat_free_context(oc);
  
  
  
      return 0;
  
  }
  
  
  
                                                  //
  
  </future></cstring></thread></iostream>

  Environment :

  • Ubuntu Zesty (17.04)
  • FFmpeg version 3.2.4 (via package manager)
  • gcc 6.3 (C++)