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• 11 ways Piwik Analytics helps you to protect your visitors privacy

  11 janvier 2017, par InnoCraft — Community

  At Piwik and at InnoCraft, we think Privacy matters. From the beginning, Piwik has had a strong focus on privacy and ensures the privacy of your visitors and analytics data. As a result, Piwik has been recommended as a privacy-compliant analytics tool for example by the Independent Center for Privacy Protection in Germany (ULD) and by the Center for Data Privacy Protection in France (CNIL). In France, Piwik is the only web analytics tool that does not require Cookie Consent.

  Here are some ways how you can ensure your users and visitors privacy by using Piwik.

  1. You own the data

  Whether you host Piwik on premise yourself, managed on premise by InnoCraft, or whether you use our Piwik cloud, when you use Piwik, YOU keep control of your data and nobody else. This also means you can decide where your data should be located physically.

  2. Anonymized IP addresses

  For better privacy by default, Piwik will not record the full IP address of your visitors because otherwise the browsing history could be easily tracked across several days and even across websites within the same Piwik server. Some countries even require to anonymize the IP address, considered Personally Identifiable Information (PII).

  To change the IP anonymization settings go to “Administration > Privacy”. Optionally, you can use the full IP to still get for example accurate location data.

  

  3. Delete old visitor logs

  The visitor logs contain information all the collected raw data about every visitor and every action. You can configure Piwik to automatically delete logs from the database. When you delete old logs, only the real time and visitor log reports will no longer work for this old time period, all other aggregated reports will still work.

  For privacy reasons, we highly recommend that you keep the detailed Piwik logs for only 3 to 6 months and delete older log data. This has one other nice side effect : it will free significant database space, which will, in turn, slightly increase performance !

  

  4. Support Do Not Track preference

  Do Not Track enables users to opt out of any tracking by websites they do not visit, including analytics services, advertising networks, and social platforms. By default, Piwik respects users preference and will not track visitors which have specified “I do not want to be tracked” in their web browsers. Get more information about DoNotTrack.

  To make sure Do Not Track is respected, go to “Administration => Privacy”.

  5. Include an Opt-Out Feature on your website or app

  By embedding the Opt-Out feature in your website, you give your visitors the possibility to opt-out of the tracking. When you go to “Administration > Privacy”, you will be able to copy and paste an HTML Iframe code to embed the opt-out feature for example into your privacy policy page or in your ‘Legal’ page. Your users can then click on a link to opt-out.

  On the Piwik Marketplace there are also some plugins available to customize the Opt-Out experience. For example AjaxOptOut and CustomOptOut.

  

  6. Disable Live features

  The Real-Time, Visitor Log and Visitor Profile features give you insights into the tracked raw data by showing you details about every visitor and every action they performed. To protect the privacy of your visitors you may decide to prevent access to such features by disabling the “Live” plugin in “Administration => Plugins”. This way only aggregated reports will be shown in your Piwik.

  7. Disable fingerprinting across websites

  By default, when one of your visitors visits several of your websites, Piwik will create a fingerprint for this user that will be different across the websites to increase the visitors’ privacy. You can make sure that this feature is disabled by going to “Administration => Config file” and verifying that the value of “enable_fingerprinting_across_websites” is set to zero.

  8. Disable tracking cookies

  Piwik uses cookies to store some information about visitors between visits. In some countries, the legislation requires websites to provide a way for users to opt-out of all tracking, in particular tracking cookies. You can disable cookies by adding one line in the Piwik Javascript code.

  9. Custom development

  Piwik is an open platform that lets you extend and customize the tracking, the reporting and the Piwik user interface to your needs and to protect your visitors’ privacy the way you want or need it. Learn more in the Piwik Developer Zone. You may also have a look at our Piwik Marketplace where you can find several free and premium features to extend your Piwik.

  10. Transparency

  By default, all information and all collected data in your Piwik server are protected and nobody can access it. However, Piwik allows you to optionally make your collected data public and you can export any Piwik report including the whole dashboard to embed it into your website. This way you can show your users exactly which information you track. When you decide to make reports public, we do our best to protect privacy and automatically hide any Personally Identifiable Information such as the Visitor Profile and we make sure to not show any Visitor IP address and the Visitor ID.

  11. Privacy policy

  When you use Piwik to track your visitors, we recommend to update your Privacy Policy to explain how Piwik is used and what data it gathers. We provide a Privacy Policy template for Piwik users that you can copy on your site.

  Continuous privacy improvements

  We are always interested in improving the privacy. If you miss any feature or have an idea on how to improve the privacy, please let us know.

  More information about all the Piwik features

  If you want to learn more about all the features in Piwik, have a look at our User Guides and FAQ entries.

• Merge commit '8dfba25ce89b62c80ba83e2116d549176c376144'

  26 avril 2017, par Clément Bœsch

  Merge commit '8dfba25ce89b62c80ba83e2116d549176c376144'
  * commit '8dfba25ce89b62c80ba83e2116d549176c376144' :
  
    pthread_frame : ensure the threads don't run simultaneously with hwaccel
  This commit is a noop, see 14bb15bfd56d6e907fabe4620206c1ee152b7a20
  Merged-by : Clément Bœsch <u@pkh.me>
  

• FFmpeg filtergraph memory leak

  5 juillet 2017, par Leif Andersen

  I have an FFmpeg program that :

  1. Demuxes and decodes a video file.
  2. Passes it through a filtergraph
  3. encodes and muxes the new video.

  The filtergraph itself is rather complex, and can be run directly from the command line as such :

  ffmpeg -i demo.mp4 -filter_complex \
  
   "[audio3]atrim=end=30:start=10[audio2];\
  
    [video5]trim=end=30:start=10[video4];[audio2]anull[audio6];\
  
    [video4]scale=width=1920:height=1080[video7];[audio6]anull[audio8];\
  
    [video7]fps=fps=30[video9];[audio8]anull[audio10];\
  
    [video9]format=pix_fmts=yuv420p[video11];\
  
    [audio10]asetpts=expr=PTS-STARTPTS[audio12];\
  
    [video11]setpts=expr=PTS-STARTPTS[video13];\
  
    [audio15]concat=v=0:a=1:n=1[audio14];\
  
    [video17]concat=v=1:a=0:n=1[video16];\
  
    [audio12]afifo[audio15];[video13]fifo[video17];\
  
    [audio14]afifo[audio18];[video16]fifo[video19];\
  
    [audio18]anull[audio20];\
  
    [video19]pad=width=1920:height=1080[video21];\
  
    [audio20]anull[audio22];[video21]fps=fps=25[video23];\
  
    [audio22]aformat=sample_fmts=fltp:sample_rates=44100:channel_layouts=stereo[fa];\
  
    [video23]format=pix_fmts=yuv420p[fv];[0:a]afifo[audio3];\
  
    [0:v]fifo[video5]" \
  
  -map "[fv]" -map "[fa]" out.mp4

  I realize this is a massive filtergraph with a lot of no-op filters, it was autogenerated rather than being hand written. Here is a more cleaner version of the graph. (Its a graphviz file, you can run it in the command line or here.)

  Anyway, when I run the program that uses this filtergraph my memory usage spikes. I end up using about 7 GB of RAM for a 30 second clip. However, when I run the program using the ffmpeg command above, it peaks out at about 600 MB of RAM. This causes me to believe that the problem is not the ungodly size of the filtergraph, but a problem with how my program is using it.

  The program sets up the filtergraph (using av_filter_parse_ptr, giving the filtergraph string shown above), encoder, muxer, decoder, and demuxer, then spawns two threads, one that sends frames into the filtergraph, and one that receives them. The frame that sends them looks something like :

  void decode () {
  
      while(... more_frames ...) {
  
          AVFrame *frame = av_frame_alloc();
  
          ... fill next frame of stream ...
  
          av_buffersrc_write_frame(ctx, frame);
  
          av_frame_free(&frame);
  
      }
  
  }

  (I have elided the av_send_packet/av_receive_frame functions as they don’t seem to be leaking memory. I have also elided the process of flushing the buffersrc as that won’t happen until the end, and the memory spikes long before that.)

  And the encoder thread looks similar :

  void encode() {
  
      while(... nodes_in_graph ...) {
  
          AVFrame *frame = av_frame_alloc();
  
          av_buffersink_get_frame(ctx, frame);
  
          ... ensure frame actually was filled ...
  
          ... send frame to encoder ...
  
          av_frame_free(&frame);
  
      }
  
  }

  As with the decoder, I have elided the send_frame/receive_packet combo as they don’t seem to be leaking memory. Additionally I have elided the details of ensuring that the frame actually was filled. The code loops until the frame eventually does get filled.

  Every frame I allocate I fairly quickly deallocate. I additionally handled all of the error cases that the ffmpeg can give (Elided in the example).

  I have also tried having only one frame for the encoder and one for the decoder (and calling av_frame_unref in each iteration of the loop).

  Am I forgetting to free something, or am I just using the calls to libavfilter incorrectly such that it has to buffer all of the data ? I don’t think the leak is caused by the memory graph because running it from the command line doesn’t seem to cause the same memory explosion.

  FWIW, the actual code is here, although its written in Racket. I do have a minimal example that also seems to duplicate this behavior (modified from the doc/example/filtering_video.c file from the ffmpeg code :

  #include 
  
  
  
  #include <libavcodec></libavcodec>avcodec.h>
  
  #include <libavformat></libavformat>avformat.h>
  
  #include <libavfilter></libavfilter>avfiltergraph.h>
  
  #include <libavfilter></libavfilter>buffersink.h>
  
  #include <libavfilter></libavfilter>buffersrc.h>
  
  #include <libavutil></libavutil>opt.h>
  
  
  
  const char *filter_descr = "trim=start=10:end=30,scale=78:24,transpose=cclock";
  
  
  
  static AVFormatContext *fmt_ctx;
  
  static AVCodecContext *dec_ctx;
  
  AVFilterContext *buffersink_ctx;
  
  AVFilterContext *buffersrc_ctx;
  
  AVFilterGraph *filter_graph;
  
  static int video_stream_index = -1;
  
  static int64_t last_pts = AV_NOPTS_VALUE;
  
  
  
  static int open_input_file(const char *filename)
  
  {
  
      int ret;
  
      AVCodec *dec;
  
  
  
      if ((ret = avformat_open_input(&amp;fmt_ctx, filename, NULL, NULL)) &lt; 0) {
  
          av_log(NULL, AV_LOG_ERROR, "Cannot open input file\n");
  
          return ret;
  
      }
  
  
  
      if ((ret = avformat_find_stream_info(fmt_ctx, NULL)) &lt; 0) {
  
          av_log(NULL, AV_LOG_ERROR, "Cannot find stream information\n");
  
          return ret;
  
      }
  
  
  
      /* select the video stream */
  
      ret = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, &amp;dec, 0);
  
      if (ret &lt; 0) {
  
          av_log(NULL, AV_LOG_ERROR, "Cannot find a video stream in the input file\n");
  
          return ret;
  
      }
  
      video_stream_index = ret;
  
  
  
      /* create decoding context */
  
      dec_ctx = avcodec_alloc_context3(dec);
  
      if (!dec_ctx)
  
          return AVERROR(ENOMEM);
  
      avcodec_parameters_to_context(dec_ctx, fmt_ctx->streams[video_stream_index]->codecpar);
  
      av_opt_set_int(dec_ctx, "refcounted_frames", 1, 0);
  
  
  
      /* init the video decoder */
  
      if ((ret = avcodec_open2(dec_ctx, dec, NULL)) &lt; 0) {
  
          av_log(NULL, AV_LOG_ERROR, "Cannot open video decoder\n");
  
          return ret;
  
      }
  
  
  
      return 0;
  
  }
  
  
  
  static int init_filters(const char *filters_descr)
  
  {
  
      char args[512];
  
      int ret = 0;
  
      AVFilter *buffersrc  = avfilter_get_by_name("buffer");
  
      AVFilter *buffersink = avfilter_get_by_name("buffersink");
  
      AVFilterInOut *outputs = avfilter_inout_alloc();
  
      AVFilterInOut *inputs  = avfilter_inout_alloc();
  
      AVRational time_base = fmt_ctx->streams[video_stream_index]->time_base;
  
      enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE };
  
  
  
      filter_graph = avfilter_graph_alloc();
  
      if (!outputs || !inputs || !filter_graph) {
  
          ret = AVERROR(ENOMEM);
  
          goto end;
  
      }
  
  
  
      /* buffer video source: the decoded frames from the decoder will be inserted here. */
  
      snprintf(args, sizeof(args),
  
              "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",
  
              dec_ctx->width, dec_ctx->height, dec_ctx->pix_fmt,
  
              time_base.num, time_base.den,
  
              dec_ctx->sample_aspect_ratio.num, dec_ctx->sample_aspect_ratio.den);
  
  
  
      ret = avfilter_graph_create_filter(&amp;buffersrc_ctx, buffersrc, "in",
  
                                     args, NULL, filter_graph);
  
      if (ret &lt; 0) {
  
          av_log(NULL, AV_LOG_ERROR, "Cannot create buffer source\n");
  
          goto end;
  
      }
  
  
  
      /* buffer video sink: to terminate the filter chain. */
  
      ret = avfilter_graph_create_filter(&amp;buffersink_ctx, buffersink, "out",
  
                                         NULL, NULL, filter_graph);
  
      if (ret &lt; 0) {
  
          av_log(NULL, AV_LOG_ERROR, "Cannot create buffer sink\n");
  
          goto end;
  
      }
  
  
  
      ret = av_opt_set_int_list(buffersink_ctx, "pix_fmts", pix_fmts,
  
                                AV_PIX_FMT_NONE, AV_OPT_SEARCH_CHILDREN);
  
      if (ret &lt; 0) {
  
          av_log(NULL, AV_LOG_ERROR, "Cannot set output pixel format\n");
  
          goto end;
  
      }
  
  
  
      outputs->name       = av_strdup("in");
  
      outputs->filter_ctx = buffersrc_ctx;
  
      outputs->pad_idx    = 0;
  
      outputs->next       = NULL;
  
      inputs->name       = av_strdup("out");
  
      inputs->filter_ctx = buffersink_ctx;
  
      inputs->pad_idx    = 0;
  
      inputs->next       = NULL;
  
  
  
      if ((ret = avfilter_graph_parse_ptr(filter_graph, filters_descr,
  
                                      &amp;inputs, &amp;outputs, NULL)) &lt; 0)
  
          goto end;
  
  
  
      if ((ret = avfilter_graph_config(filter_graph, NULL)) &lt; 0)
  
          goto end;
  
  
  
  end:
  
      avfilter_inout_free(&amp;inputs);
  
      avfilter_inout_free(&amp;outputs);
  
  
  
      return ret;
  
  }
  
  
  
  int main(int argc, char **argv)
  
  {
  
      int ret;
  
      AVPacket packet;
  
      AVFrame *frame = av_frame_alloc();
  
      AVFrame *filt_frame = av_frame_alloc();
  
  
  
      if (!frame || !filt_frame) {
  
          perror("Could not allocate frame");
  
          exit(1);
  
      }
  
      if (argc != 2) {
  
          fprintf(stderr, "Usage: %s file\n", argv[0]);
  
          exit(1);
  
      }
  
  
  
      av_register_all();
  
      avfilter_register_all();
  
  
  
      if ((ret = open_input_file(argv[1])) &lt; 0)
  
          goto end;
  
      if ((ret = init_filters(filter_descr)) &lt; 0)
  
          goto end;
  
  
  
      /* read all packets */
  
      while (1) {
  
          if ((ret = av_read_frame(fmt_ctx, &amp;packet)) &lt; 0)
  
              break;
  
  
  
          if (packet.stream_index == video_stream_index) {
  
              ret = avcodec_send_packet(dec_ctx, &amp;packet);
  
              if (ret &lt; 0) {
  
                  av_log(NULL, AV_LOG_ERROR, "Error while sending a packet to the decoder\n");
  
                  break;
  
              }
  
  
  
              while (ret >= 0) {
  
                  ret = avcodec_receive_frame(dec_ctx, frame);
  
                  if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
  
                      break;
  
                  } else if (ret &lt; 0) {
  
                      av_log(NULL, AV_LOG_ERROR, "Error while receiving a frame from the decoder\n");
  
                      goto end;
  
                  }
  
  
  
                  if (ret >= 0) {
  
                       frame->pts = av_frame_get_best_effort_timestamp(frame);
  
  
  
                      /* push the decoded frame into the filtergraph */
  
                      if (av_buffersrc_add_frame_flags(buffersrc_ctx, frame, AV_BUFFERSRC_FLAG_KEEP_REF) &lt; 0) {
  
                          av_log(NULL, AV_LOG_ERROR, "Error while feeding the filtergraph\n");
  
                          break;
  
                      }
  
  
  
                      /* pull filtered frames from the filtergraph */
  
                      while (1) {
  
                          ret = av_buffersink_get_frame(buffersink_ctx, filt_frame);
  
                          if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
  
                              break;
  
                          if (ret &lt; 0)
  
                              goto end;
  
                          av_frame_unref(filt_frame);
  
                      }
  
                      av_frame_unref(frame);
  
                  }
  
              }
  
          }
  
          av_packet_unref(&amp;packet);
  
      }
  
  end:
  
      avfilter_graph_free(&amp;filter_graph);
  
      avcodec_free_context(&amp;dec_ctx);
  
      avformat_close_input(&amp;fmt_ctx);
  
      av_frame_free(&amp;frame);
  
      av_frame_free(&amp;filt_frame);
  
  
  
      return ret;
  
  }