Recherche avancée

Sur d’autres sites (10172)

• Perf Script Erroneous Dwarf Stacktrace Output

  12 juin 2020, par TheAhmad

  I used the following command to sample backtraces for an ffmpeg benchmark :

  



  sudo perf record -d --call-graph dwarf,65528 -c 1000000 -e mem_load_uops_retired.l3_miss:u ffmpeg -i /media/ahmad/DATA/Videos/video.mp4 -threads 1 -vf spp out.mp4


  



  As can be seen, PEBS is not used, the stack size is set to the maximum and the sampling period is quite large. I also limited the thread count, but this is the first part of perf script --no-demangle output :

  



  ffmpeg 11750  6670.061261:    1000000 mem_load_uops_retired.l3_miss:u:                0         5080021 N/A|SNP N/A|TLB N/A|LCK N/A
        7fffeab68844 x264_pixel_avg_w16_avx2+0x4 (/usr/lib/x86_64-linux-gnu/libx264.so.152)

ffmpeg 11750  6670.274835:    1000000 mem_load_uops_retired.l3_miss:u:                0         5080021 N/A|SNP N/A|TLB N/A|LCK N/A
        7fffeab68844 x264_pixel_avg_w16_avx2+0x4 (/usr/lib/x86_64-linux-gnu/libx264.so.152)

ffmpeg 11750  6670.496159:    1000000 mem_load_uops_retired.l3_miss:u:                0         5080021 N/A|SNP N/A|TLB N/A|LCK N/A
        7fffeab8ef89 x264_pixel_sad_x4_16x16_avx2+0x49 (/usr/lib/x86_64-linux-gnu/libx264.so.152)

ffmpeg 11750  6670.852598:    1000000 mem_load_uops_retired.l3_miss:u:                0         5080021 N/A|SNP N/A|TLB N/A|LCK N/A
        7fffeaac97b3 pixel_memset+0x293 (inlined)
        7fffeaac97b3 plane_expand_border+0x293 (inlined)
        7fffeaac97b3 x264_frame_expand_border_filtered+0x293 (/usr/lib/x86_64-linux-gnu/libx264.so.152)
        7fffeab463bc x264_fdec_filter_row+0x69c (/usr/lib/x86_64-linux-gnu/libx264.so.152)
        7fffeab49523 x264_slice_write+0x1873 (/usr/lib/x86_64-linux-gnu/libx264.so.152)
        7fffeab85285 x264_stack_align+0x15 (/usr/lib/x86_64-linux-gnu/libx264.so.152)
        7fffeab45bdb x264_slices_write+0xfb (/usr/lib/x86_64-linux-gnu/libx264.so.152)
        5555561e3d87 [unknown] ([heap])

ffmpeg 11750  6671.110007:    1000000 mem_load_uops_retired.l3_miss:u:                0         5080021 N/A|SNP N/A|TLB N/A|LCK N/A
        7fffeab6cdde x264_frame_init_lowres_core_avx2+0x8e (/usr/lib/x86_64-linux-gnu/libx264.so.152)

ffmpeg 11750  6671.463562:    1000000 mem_load_uops_retired.l3_miss:u:                0         5080021 N/A|SNP N/A|TLB N/A|LCK N/A
        7fffeaabf806 x264_macroblock_load_pic_pointers+0x886 (inlined)
        7fffeaabf806 x264_macroblock_cache_load+0x886 (inlined)
        7fffeaabf806 x264_macroblock_cache_load_progressive+0x886 (/usr/lib/x86_64-linux-gnu/libx264.so.152)
        7fffeab49204 x264_slice_write+0x1554 (/usr/lib/x86_64-linux-gnu/libx264.so.152)
        7fffeab85285 x264_stack_align+0x15 (/usr/lib/x86_64-linux-gnu/libx264.so.152)
        7fffeab45bdb x264_slices_write+0xfb (/usr/lib/x86_64-linux-gnu/libx264.so.152)
                  1c [unknown] ([unknown])


  



  None of the backtraces are correct. Because none of them begin with _start or __GI___clone. I also used LBR, instead. But it has more size constraints and, therefore, not suitable. Any suggestions on how to get around the problem ?

  



  ---

  



  UPDATE :

  



  The problem happens for all events that I checked. When I used mem_load_uops_retired.l3_miss or LLC-load-misses the problem was visible from the beginning. I also checked the output with the cycles event and everything worked fine, at the beginning. But after that, the same problem was seen.

  



  Also, note that, the problem disappears when I sample only kernel mem_load_uops_retired.l3_miss events.

  


• Tracking User Acquisition and Social Media Activity with Piwik

  25 avril 2017, par Florian Hieß — Community

  Being able to monitor user acquisition and social media activity is essential for determining whether the outcome of your campaigns is in line with the business objectives. Determining the source of each website visit that gets you closer to your business goals enables you to focus your efforts in the directions that are worth it. In this article you will learn why it is important to identify your traffic sources and how you can track user acquisition with Piwik Analytics.

  Why Is It Important to Identify Traffic Sources on Your Website ?

  Since brands nowadays use multiple channels for promotion and advertising, identifying the touch points and traffic sources of a lead or customer seems to become more and more difficult. And yet, this channel multiplication is what makes the source of a purchase more important. Once you identify the traffic origin and how each source is performing you are able to increase your efforts on the best performers, both in terms of human resources and monetary investments, to attract more leads or customers in these marketing channels.

  The default referrer types are defined by :

  • Search engine
  • Direct traffic
  • Websites and
  • Campaigns

  But consider that within the “Campaigns” type, each of the following referrers is a possible traffic source for your website and can be tracked with the Piwik URL builder :

  • Google AdWords
  • Display Ads, Banners
  • Links in Newsletters, Emailing
  • Affiliate links
  • Tweets
  • Facebook Ads

  Measure your performance and conversion

  With so many options, wouldn’t you like to know which one of them worked best ? To rate channels based on their performance, you first need to establish conversion goals and attribution.

  A conversion can be anything from sign-ups or downloads to leads, registered users and even paying customers. Define conversions based on what you want people to do once they’ve landed on your website.

  

  You need to define each conversion type in the Piwik dashboard, so that the analytics platform knows what to track. As far as attribution goes, Piwik by default links the conversion and attributes to the last seen (non-direct) referrer. You are able to change that to the first referrer in the attribution line by following the instructions in this conversion attribution FAQ.

  Track Your User Acquisition Right with Piwik

  Using the Piwik URL Builder tool, you can tag each URL you promote in your campaigns using relevant keywords. Provided that your URLs are tagged, whenever someone clicks on them, the campaign will be listed as the referrer in the Piwik dashboard. Once you’ve generated trackable URLs, you can include them in your social media posts which could be planned and scheduled using a social media management tool such as Swat.io.

  

  Campaign URLs work wonders for telling which campaign helped you reach your goals faster, more efficiently and so on but they do have a downside. They only work for URLs that you’ve shared. If someone decides to share a link of yours on social media they won’t be tagged beforehands. This is where the Referrers section of Piwik comes in handy, as it acts as a backup for tracking traffic sources. The overview tab features a graph that can help you identify when spikes occurred.

  

  As well as a numerical representation of the main referrer categories for the selected time period.

  

  Switching from Overview to Websites & Social, you can see a graphical representation of the social networks acting as referrers. The visualization can be changed to bar graphs or table, and can be easily exported in various formats for reports.

  

  The websites list features not only the social referrers, but all of the websites generating visits to your website. With Piwik you should not have issues with referrer spam, as the Piwik core team has tackled this problem early on, as detailed in how to stop referrer spam. Our analytics spam blacklist is a public project on GitHub.

  

  Assuming that you’re relying only on Facebook and VK.com for your campaigns, as the above screenshot would suggest, you might want to give paid advertising a try on these two social networks. Paid ads can increase reach and engagement, can get more relevant visitors to your website and can have a snowball effect in a short period of time.

  What Social Networks Can Piwik Track ?

  Piwik’s built-in social network list is quite extensive, as it currently features 70 platforms. The entries range from popular social networks such as Facebook, Twitter and LinkedIn to more obscure ones such as Renren. However, this list is not available by default, and to see it or alter it, you would need a third-party plugin.

  How Does the Referrers Manager Plugin for Piwik Work ?

  The Referrers Manager plugin for Piwik provides access to the list of search engines and social networks that this analytics platform can handle by default. The simple plugin can come in handy when sorting out referrers. First of all, it displays a list of all search engines and social networks that Piwik can handle by default. Secondly, it enables users to disable/enable the platform’s default social network list. And using Referrers Manager, you can add custom engines or social networks to the referrers list in case they’re not already available.

  

  Conclusions

  Piwik is a very capable analytics platform as it is, but combined with third-party plugins such as Referrers Manager, it can provide even better insights on where your visitors are coming from. Remember to correlate the referrers with goals in order to determine which website or social network performs best in your context. And don’t forget to assign a monetary revenue value to each goal, in order to determine your social media ROI with greater accuracy.

• How to embed subtitles into an mp4 file using gstreamer

  27 août 2021, par Stephen

  My Goal

  


  I'm trying to embed subtitles into an mp4 file using the mp4mux gstreamer element.

  


  What I've tried

  


  The pipeline I would like to use is :

  


  GST_DEBUG=3 gst-launch-1.0 filesrc location=sample-nosub-avc.mp4 ! qtdemux ! queue ! video/x-h264 ! mp4mux name=mux reserved-moov-update-period=1000 ! filesink location=output.mp4 filesrc location=english.srt ! subparse ! queue ! text/x-raw,format=utf8 ! mux.subtitle_0


  


  It just demuxes a sample mp4 file for the h.264 stream and then muxes it together with an srt subtitle file.

  


  The error I get is :

  


  Setting pipeline to PAUSED ...&#xA;0:00:00.009958915 1324869 0x5624a8c7a0a0 WARN                 basesrc gstbasesrc.c:3600:gst_base_src_start_complete:<filesrc0> pad not activated yet&#xA;Pipeline is PREROLLING ...&#xA;0:00:00.010128080 1324869 0x5624a8c53de0 WARN                 basesrc gstbasesrc.c:3072:gst_base_src_loop:<filesrc1> error: Internal data stream error.&#xA;0:00:00.010129102 1324869 0x5624a8c53e40 WARN                 qtdemux qtdemux_types.c:239:qtdemux_type_get: unknown QuickTime node type pasp&#xA;0:00:00.010140810 1324869 0x5624a8c53de0 WARN                 basesrc gstbasesrc.c:3072:gst_base_src_loop:<filesrc1> error: streaming stopped, reason not-negotiated (-4)&#xA;0:00:00.010172990 1324869 0x5624a8c53e40 WARN                 qtdemux qtdemux.c:3237:qtdemux_parse_trex:<qtdemux0> failed to find fragment defaults for stream 1&#xA;ERROR: from element /GstPipeline:pipeline0/GstFileSrc:filesrc1: Internal data stream error.&#xA;Additional debug info:&#xA;gstbasesrc.c(3072): gst_base_src_loop (): /GstPipeline:pipeline0/GstFileSrc:filesrc1:&#xA;streaming stopped, reason not-negotiated (-4)&#xA;ERROR: pipeline doesn&#x27;t want to preroll.&#xA;Setting pipeline to NULL ...&#xA;Freeing pipeline ...&#xA;</qtdemux0></filesrc1></filesrc1></filesrc0>

  


  My Thoughts

  


  I believe the issue is not related to the above warning but rather mp4mux's incompatibility with srt subtitles.

  


  The reason I belive this is because, other debug logs hint at it, but also stealing the subititles from another mp4 file and muxing it back together does work.

  


  gst-launch-1.0  filesrc location=sample-nosub-avc.mp4 ! qtdemux ! mp4mux name=mux ! filesink location=output.mp4 filesrc location=sample-with-subs.mp4 ! qtdemux name=demux demux.subtitle_1 ! text/x-raw,format=utf8 ! queue ! mux.subtitle_0


  


  A major catch 22 I am having is that mp4 files don't typically support srt subtitles, but gstreamer's subparse element doesn't support parsing mp4 subtitle formats (tx3g, ttxt, etc.) so I'm not sure how I'm meant to put it all together.

  


  I'm very sorry for the lengthy question but I've tried many things so it was difficult to condense it. Any hints or help is appreciated. Thank you.