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• Converting png images series to webm with transparent white background from Daz3d

  25 août 2015, par James

  I’m trying to make a webm video with a transparent background from a Daz3D model.
  My process is export png image series with transparent background from Daz3D, use ffmpeg to convert png series to webm video.
  This was working well in Daz3D 4.6.

  But in Daz3D 4.8 the exported background is black instead of white, so when converted to webm is ok on Chrome as has the transparency, but on Firefox is black and has a halo (as Firefox does not support transparency so displays background).

  So I’m looking for a solution with Daz3D, or tools like ImageMagik.
  I almost got it with ImageMagik,

  convert -alpha extract *.png mask.png
  
  mogrify -flatten talk*.png
  
  for /f %x in ('dir /s /b blink*.png') do @composite -compose CopyOpacity mask-0.png %x %x

  But for some reason the final webm has a white background not transparent ...
  Some more info here,

  http://www.daz3d.com/forums/discussion/61237/daz3d-4-8-png-background-is-black

  and here,

  http://www.imagemagick.org/discourse-server/viewtopic.php?f=1&t=28214

  >
  Doh, okay I figured it out. My images were good, but I somehow have two different versions of ffmpeg on my computer and was using the wrong one that doesn’t seem to support transparency.

  Now it is working.

  My only issue is the last shell line,

  for /f %x in (’dir /s /b blink*.png’) do @composite -compose CopyOpacity mask-0.png %x %x

  This only uses mask-0.png, instead of mask-1 for blink01.png, mask-2 for blink02.png etc.

• Piwik analytics database : migrating from MySQL to MariaDB

  11 novembre 2015, par Piwik Core Team — Meta

  This short blog post is an announcement regarding the Piwik technology stack.

  Piwik compatible with MySQL and MariaDB

  Since our first public release Piwik uses the open source database server MySQL to store the analytics data.

  Piwik is also compatible with MariaDB. MariaDB is an enhanced, drop-in replacement for MySQL.

  Upgrading to MariaDB

  Many users from our community as well as Piwik PRO have confirmed that using MariaDB for Piwik has several advantages. MariaDB has in some cases significantly improved query performance and reliability of Piwik. Because MariaDB 5.5 is a complete drop-in-replacement for MySQL 5.5, upgrading can be as easy as running apt-get install mariadb-server (or equivalent for your platform). Existing third party techologies such as TokuDB (FAQ) and Galera are fully compatible with MariaDB.

  Learn more about upgrading to MariaDB : Upgrading from MySQL to MariaDB

  In the future, Piwik will stay compatible with both MySQL and MariaDB.

• avconv audio and video out of sync

  28 juillet 2015, par bram_aerts

  I have a problem synchronizing audio and video using avconv.
  My goal is to process the video stream with opencv and later put the original audio back on the soundless video.
  The processed video stream will be at the same period of time as the original video, but will have a starting offset of a few minutes.

  I tried to simplify the problem with the following code :

  filename="inputvideo.mp4"
  
  avconv -i $filename -an -ss 30 test.mp4
  
  avconv -i test.mp4 -vn -ss 30 -i $filename -async 1 testmerged.mp4

  The second line removing the audio of the original video and shifting it 30 seconds (emulating what the opencv-code will do).
  The last line putting the video and original audio (shifted 30 seconds) back together.

  I assumed if I’d both shift them the same amount of seconds, they would be neatly synchronized, but curiously the video and audio in the resulting movie are out of sync. It is a static delay of about about 3 seconds (audio is behind).
  The same problem appears when making an interim mp3 file and using this as audio track for the resulting movie.

  When searching for a solution I found none that resolve this.
  I tried to overcome this issue by using the -vsync/-async options. But since there is no timestamp information in the video this doesn’t solve the problem.
  Even with the latest static build of ffmpeg the audio and video are still out of sync.

  Is there anything I overlooked or is it just impossible to sync audio and video in ffmpeg ?
  And if so, What would be a decent and simple replacement for the funcionality I’m looking for ?