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• Thinking about switching to GeoIP2 for better location detection ? Here’s what you should know

  5 juin 2018, par Matomo Core Team

  In Matomo 3.5.0 we added a new feature to improve the location detection (country, region, city) of your visitors. Especially when it comes to IPv6 addresses, you will see less “Unknown” locations and more accurate results in general. This feature is now enabled for all new installations but needs to be manually enabled for existing Matomo self-hosted users.

  

  Why is the Matomo plugin not enabled for existing users ?

  When you enable the GeoIP2 plugin, a database update will need to be executed on two datatable tables (“log_visit” and “log_conversion”) which stores some of the raw data. Please be aware that this update could take several hours depending on the size of your database.

  If you store many visits in your database, it is recommended to execute the update through the command line by executing the command ./console core:update to avoid the update from timing out. You may also have to put your Matomo into maintenance mode during this time and replay the missed traffic from logs afterwards as explained in the FAQ article.

  GeoIP2 may slow down your tracking

  In the past we have seen that a few Matomo databases with high traffic volumes struggle to handle all the tracking requests after enabling GeoIP2. The reason for this is the location database now contains many more entries because it has to store all the IPv6 addresses and the database itself has a different format. Hence, the location lookup takes longer.

  It is hard to say how much slower the location lookup gets, but we found GeoIP2-PHP is about 20 times slower than GeoIP1-PHP. On a fast CPU the lookup time for an IP with GeoIP2 takes about 1ms, but can also take much longer depending on the server.

  Making location lookups fast again

  There is a PHP extension available that makes lookups very fast, even faster than the old GeoIP1-PHP provider. If you can install additional PHP extensions on your server and have a high traffic website, you may want to install the GeoIP2 extension.

  There is also an Nginx module and an Apache module. Unfortunately, we don’t have any performance metrics for these providers.

  How do I activate the GeoIP2 location provider ?

  As a Super User, log in to your Matomo and go to “Administration => Plugins”. There you can activate the “GeoIP2” plugin. As mentioned, this will trigger a database update which can take a while and you may want to perform this update through the command line.

  Now you can go to “Administration => Geolocation”. Here you will first need to install the GeoIP2 databases at the bottom of the page before you can activate the GeoIP2-PHP provider. To activate any of the other GeoIP2 providers, you will need to install the required modules.

  You will be able to check if the detection works on the right next to location provider. Once you selected one of the available providers, you’re all good to go.

  The post Thinking about switching to GeoIP2 for better location detection ? Here’s what you should know appeared first on Analytics Platform - Matomo.

• avcodec/mpeg2dec : Fix motion vector rounding for chroma components

  11 février 2018, par Nekopanda

  avcodec/mpeg2dec : Fix motion vector rounding for chroma components
  In 16x8 motion compensation, for lower 16x8 region, the input to mpeg_motion() for motion_y was "motion_y + 16", which causes wrong rounding. For 4:2:0, chroma scaling for y is dividing by two and rounding toward zero. When motion_y < 0 and motion_y + 16 > 0, the rounding direction of "motion_y" and "motion_y + 16" is different and rounding "motion_y + 16" would be incorrect.
  We should input "motion_y" as is to round correctly. I add "is_16x8" flag to do that.
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/mpegvideo_motion.c
  • [DH] tests/ref/fate/filter-mcdeint-fast
  • [DH] tests/ref/fate/filter-mcdeint-medium
  • [DH] tests/ref/fate/filter-w3fdif-complex
  • [DH] tests/ref/fate/filter-w3fdif-simple
  • [DH] tests/ref/fate/filter-yadif-mode0
  • [DH] tests/ref/fate/filter-yadif-mode1
  • [DH] tests/ref/fate/filter-yadif10
  • [DH] tests/ref/fate/filter-yadif16
  • [DH] tests/ref/fate/mpeg2-field-enc
  • [DH] tests/ref/fate/mpeg2-ticket6677

• How to Simply Remove Duplicate Frames from a Video using ffmpeg

  29 janvier 2017, par Skeeve

  First of all, I’d preface this by saying I’m NO EXPERT with video manipulation,
  although I’ve been fiddling with ffmpeg for years (in a fairly limited way). Hence, I’m not too flash with all the language folk often use... and how it affects what I’m trying to do in my manipulations... but I’ll have a go with this anyway...

  I’ve checked a few links here, for example :
  ffmpeg - remove sequentially duplicate frames

  ...but the content didn’t really help me.

  I have some hundreds of video clips that have been created under both Windows and Linux using both ffmpeg and other similar applications. However, they have some problems with times in the video where the display is ’motionless’.

  As an example, let’s say we have some web site that streams a live video into, say, a Flash video player/plugin in a web browser. In this case, we’re talking about a traffic camera video stream, for example.

  There’s an instance of ffmpeg running that is capturing a region of the (Windows) desktop into a video file, viz :-

  ffmpeg -hide_banner -y -f dshow ^
  
        -i video="screen-capture-recorder" ^
  
        -vf "setpts=1.00*PTS,crop=448:336:620:360" ^
  
        -an -r 25 -vcodec libx264 -crf 0 -qp 0 ^
  
        -preset ultrafast SAMPLE.flv

  Let’s say the actual ’display’ that is being captured looks like this :-

  123456789 XXXXX 1234567 XXXXXXXXXXX 123456789 XXXXXXX
  
  ^---a---^ ^-P-^ ^--b--^ ^----Q----^ ^---c---^ ^--R--^ 

  ...where each character position represents a (sequence of) frame(s). Owing to a poor internet connection, a "single frame" can be displayed for an extended period (the ’X’ characters being an (almost) exact copy of the immediately previous frame). So this means we have segments of the captured video where the image doesn’t change at all (to the naked eye, anyway).

  How can we deal with the duplicate frames ?... and how does our approach change if the ’duplicates’ are NOT the same to ffmpeg but LOOK more-or-less the same to the viewer ?

  If we simply remove the duplicate frames, the ’pacing’ of the video is lost, and what used to take, maybe, 5 seconds to display, now takes a fraction of a second, giving a very jerky, unnatural motion, although there are no duplicate images in the video. This seems to be achievable using ffmpeg with an ’mp_decimate’ option, viz :-

       ffmpeg -i SAMPLE.flv ^                      ... (i)
  
          -r 25 ^
  
          -vf mpdecimate,setpts=N/FRAME_RATE/TB DEC_SAMPLE.mp4

  That reference I quoted uses a command that shows which frames ’mp_decimate’ will remove when it considers them to be ’the same’, viz :-

       ffmpeg -i SAMPLE.flv ^                      ... (ii)
  
          -vf mpdecimate ^
  
          -loglevel debug -f null -

  ...but knowing that (complicated formatted) information, how can we re-organize the video without executing multiple runs of ffmpeg to extract ’slices’ of video for re-combining later ?

  In that case, I’m guessing we’d have to run something like :-

  • user specifies a ’threshold duration’ for the duplicates
    (maybe run for 1 sec only)
  • determine & save main video information (fps, etc - assuming
    constant frame rate)
  • map the (frame/time where duplicates start)->no. of
    frames/duration of duplicates
  • if the duration of duplicates is less than the user threshold,
    don’t consider this period as a ’series of duplicate frames’
    and move on
  • extract the ’non-duplicate’ video segments (a, b & c in the
    diagram above)
  • create ’new video’ (empty) with original video’s specs
  • for each video segment
    extract the last frame of the segment
    create a short video clip with repeated frames of the frame
    just extracted (duration = user spec. = 1 sec)
    append (current video segment+short clip) to ’new video’
    and repeat

  ...but in my case, a lot of the captured videos might be 30 minutes long and have hundreds of 10 sec long pauses, so the ’rebuilding’ of the videos will take a long time using this method.

  This is why I’m hoping there’s some "reliable" and "more intelligent" way to use
  ffmepg (with/without the ’mp_decimate’ filter) to do the ’decimate’ function in only a couple of passes or so... Maybe there’s a way that the required segments could even be specified (in a text file, for example) and as ffmpeg runs it will
  stop/restart it’s transcoding at specified times/frame numbers ?

  Short of this, is there another application (for use on Windows or Linux) that could do what I’m looking for, without having to manually set start/stop points,
  extracting/combining video segments manually...?

  I’ve been trying to do all this with ffmpeg N-79824-gcaee88d under Win7-SP1 and (a different version I don’t currently remember) under Puppy Linux Slacko 5.6.4.

  Thanks a heap for any clues.