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• avutil/mathematics : speed up av_gcd by using Stein’s binary GCD algorithm

  11 octobre 2015, par Ganesh Ajjanagadde

  avutil/mathematics : speed up av_gcd by using Stein’s binary GCD algorithm
  This uses Stein’s binary GCD algorithm :
  
  https://en.wikipedia.org/wiki/Binary_GCD_algorithm
  
  to get a roughly 4x speedup over Euclidean GCD on standard architectures
  
  with a compiler intrinsic for ctzll, and a roughly 2x speedup otherwise.
  
  At the moment, the compiler intrinsic is used on GCC and Clang due to
  
  its easy availability.
  Quick note regarding overflow : yes, subtractions on int64_t can, but the
  
  llabs takes care of that. The llabs is also guaranteed to be safe, with
  
  no annoying INT64_MIN business since INT64_MIN being a power of 2, is
  
  shifted down before being sent to llabs.
  The binary GCD needs ff_ctzll, an extension of ff_ctz for long long (int64_t). On
  
  GCC, this is provided by a built-in. On Microsoft, there is a
  
  BitScanForward64 analog of BitScanForward that should work ; but I can’t confirm.
  
  Apparently it is not available on 32 bit builds ; so this may or may not
  
  work correctly. On Intel, per the documentation there is only an
  
  intrinsic for _bit_scan_forward and people have posted on forums
  
  regarding _bit_scan_forward64, but often their documentation is
  
  woeful. Again, I don’t have it, so I can’t test.
  As such, to be safe, for now only the GCC/Clang intrinsic is added, the rest
  
  use a compiled version based on the De-Bruijn method of Leiserson et al :
  
  http://supertech.csail.mit.edu/papers/debruijn.pdf.
  Tested with FATE, sample benchmark (x86-64, GCC 5.2.0, Haswell)
  
  with a START_TIMER and STOP_TIMER in libavutil/rationsl.c, followed by a
  
  make fate.
  aac-am00_88.err :
  
  builtin :
  
  714 decicycles in av_gcd,    4095 runs,      1 skips
  de-bruijn :
  
  1440 decicycles in av_gcd,    4096 runs,      0 skips
  previous :
  
  2889 decicycles in av_gcd,    4096 runs,      0 skips
  Signed-off-by : Ganesh Ajjanagadde <gajjanagadde@gmail.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavutil/intmath.h
  • [DH] libavutil/mathematics.c

• FFMPEG with VP9 + RTSP

  4 janvier 2021, par Jim Jin

  When we use HEVC + RTSP, ffmpeg works fine. The stream is captured by webcam.

  


  ffmpeg -f dshow -rtbufsize 100M  -f vfwcap -i "0" -strict experimental -c:v hevc_qsv -f rtsp -rtsp_transport tcp rtsp://127.0.0.1/live/test


  


  The output is like :

  


  frame=  355 fps= 37 q=-0.0 size=N/A time=00:00:11.27 bitrate=N/A dup=159 drop=0 speed=1.18x


  


  Then we switch to VP9 + RTSP.

  


  ffmpeg -f dshow -rtbufsize 100M  -f vfwcap -i "0" -strict experimental -c:v libvpx-vp9 -f rtsp -rtsp_transport tcp rtsp://127.0.0.1/live/test


  


  The fps and speed looks too slow :

  


  frame=  263 fps=9.5 q=0.0 size=N/A time=00:00:07.94 bitrate=N/A dup=119 drop=0 speed=0.288x


  


  Then we use ffplay to play the stream. There are a lot of error messages and the video seems frozen.

  


  [vp9 @ 000001c3da86c200] Not all references are available
[vp9 @ 000001c3dffd5700] Not all references are available
[vp9 @ 000001c3da8477c0] Not all references are available
[vp9 @ 000001c3da848240] Not all references are available
[vp9 @ 000001c3da848e40] Not all references are available
[vp9 @ 000001c3e01d2fc0] Not all references are available
[vp9 @ 000001c3e01dd280] Not all references are available
[vp9 @ 000001c3e01e8980] Not all references are available
[vp9 @ 000001c3e01f1880] Not all references are available
[vp9 @ 000001c3da86c200] Not all references are available
[vp9 @ 000001c3dffd5700] Not all references are available
[vp9 @ 000001c3da8477c0] Not all references are available
[vp9 @ 000001c3da848240] Not all references are available
[vp9 @ 000001c3da848e40] Not all references are available
[vp9 @ 000001c3e01d2fc0] Not all references are available
[vp9 @ 000001c3e01dd280] Not all references are available0B f=0/0
[vp9 @ 000001c3e01e8980] Not all references are available
[vp9 @ 000001c3e01f1880] Not all references are available
[vp9 @ 000001c3da86c200] Not all references are available
[vp9 @ 000001c3dffd5700] Not all references are available
[vp9 @ 000001c3da8477c0] Not all references are available
[vp9 @ 000001c3da848240] Not all references are available
[vp9 @ 000001c3da848e40] Not all references are available
[vp9 @ 000001c3e01d2fc0] Not all references are available
[vp9 @ 000001c3e01dd280] Not all references are available
[vp9 @ 000001c3e01e8980] Not all references are available
[vp9 @ 000001c3e01f1880] Not all references are available


  


  Finally, we try hardware VP9 encoder.

  


  ffmpeg -f dshow -rtbufsize 100M  -f vfwcap -i "0" -strict experimental -c:v vp9_qsv -f rtsp -rtsp_transport tcp rtsp://127.0.0.1/live/test


  


  It can't work.

  


  [swscaler @ 0000021e88df9fc0] deprecated pixel format used, make sure you did set range correctly
[vp9_qsv @ 0000021e8687df80] Selected ratecontrol mode is unsupported
[vp9_qsv @ 0000021e8687df80] Low power mode is unsupported
[vp9_qsv @ 0000021e8687df80] Current frame rate is unsupported
[vp9_qsv @ 0000021e8687df80] Current picture structure is unsupported
[vp9_qsv @ 0000021e8687df80] Current resolution is unsupported
[vp9_qsv @ 0000021e8687df80] Current pixel format is unsupported
[vp9_qsv @ 0000021e8687df80] some encoding parameters are not supported by the QSV runtime. Please double check the input parameters.
Error initializing output stream 0:0 -- Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height
Conversion failed!


  


  So, how can we deal with VP9 + RTSP successfully ?

  


• How to get your Piwik plugin translated in many languages ?

  8 septembre 2015, par Stefan Giehl — Community, Development, Plugins

  About a year ago we introduced the Piwik Marketplace to make it easy for developers to share their plugins with all Piwik users.

  As Piwik is currently available in 54 languages we would love to have as many plugins as possible available in at least a few of those languages.

  Currently most plugins on the Marketplace are only available in English and sometimes some other languages. To improve this situation, we offer plugin developers the possibility to use the power of our translators community to get their plugins translated.

  Some plugin developers are already using this service and some very popular plugins like BotTracker or CustomOptOut have already been translated in more than 10 languages !

  Getting translations for your plugin

  As long as you are developing an open source plugin hosted on Github, you may get in touch with us (translations@piwik.org) in order to get your plugin translated by the Piwik translators community.

  You will need an account on Transifex.com. If you use Transifex with a social login, please ensure to set a password in your account settings. This will be required for fetching new translations into your plugin repository.

  Importing your plugin’s strings in the translation platform

  While doing the initial setup for your plugin, we will import your english translation file (en.json) in your Github plugin repository and we will configure an auto-update for this file. Source strings on Transifex will automatically synchronise with your plugin repository. When you change any string in your en.json translation file, the updated English strings will automatically be imported in Transifex.

  How to fetch your plugins translations into your repository

  As soon as we have set up your plugin within our Piwik project on Transifex and there are new translations available, you will be able to update your plugin translations using the Piwik console. You will need a locally installed Piwik with development mode enabled, and your plugin installed. To update the translations go to the Piwik directory on your development box and execute the following command :

  ./console translations:update -u {YourTransifexUserName} -p {YourTransifexPassword} -P {YourPluginName}

  We are looking forward to seeing your Piwik plugins available in more languages ! For more information, check out our Translations plugin developer guide.

  Happy hacking,