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• ffmpeg webm vs mp4 quality issue

  17 juillet 2014, par Benjamin

  I have a series of .jpg files in a directory that I want to turn into the movie with ffmpeg. When I make a .mp4 file of all the jpegs, the video quality is pretty much the same as the original images. When I make a .webm file though, it looks very blocky. These are the two commands I’m using :

  $ ffmpeg -i %10d.jpg -s 640x480 -r 16 test.mp4
  
  
  
  $ ffmpeg -i %10d.jpg -s 640x480 -r 16 test.webm

  I know next to nothing about video encoding so any help would be appreciated.

• Revision 44eb577cf7 : invalid_file_test : convert test param from tuple to struct fixes visual studio

  12 juillet 2014, par James Zern

  Changed Paths :
   Modify /test/invalid_file_test.cc

  
  
  invalid_file_test : convert test param from tuple to struct

  fixes visual studio 9 + apple clang builds where the template type is
  interpreted as char[] rather than const char* :

  ::f1_’ : cannot specify explicit initializer for arrays
  error : array initializer must be an initializer list or string literal

  Change-Id : I27286ce341b2f7a09b6202caffd6b72f64fd2234

• My crazy linux.conf.au week

  9 février 2012, par silvia

  In January I attended the annual Australian Linux and Open Source conference (LCA). But since I was sick all of January and had a lot to catch up on, I never got around to sharing all the talks that I gave during that time.

  Drupal Down Under

  It started with a talk at Drupal Down Under, which happened the weekend before LCA. I gave a talk titled “HTML5 video specifications” (video, slides).

  I spoke about the video and audio element in HTML5, how to provide fallback content, how to encode content, how to control them from JavaScript, and briefly about Drupal video modules, though the next presentation provided much more insight into those. I explained how to make the HTML5 media elements accessible, including accessible controls, captions, audio descriptions, and the new WebVTT file format. I ran out of time to introduce the last section of my slides which are on WebRTC.

  Linux.conf.au

  On the first day of LCA I gave a talk both in the Multimedia Miniconf and the Browser Miniconf.

  Browser Miniconf

  In the Browser Miniconf I talked about “Web Standardisation – how browser vendors collaborate, or not” (slides). Maybe the most interesting part about this was that I tried out a new slide “deck” tool called impress.js. I’m not yet sure if I like it but it worked well for this talk, in which I explained how the HTML5 spec is authored and who has input.

  I also sat on a panel of browser developers in the Browser Miniconf (more as a standards than as a browser developer, but that’s close enough). We were asked about all kinds of latest developments in HTML5, CSS3, and media standards in the browser.

  Multimedia Miniconf

  In the Multimedia Miniconf I gave a “HTML5 media accessibility update” (slides). I talked about the accessibility problems of Flash, how native HTML5 video players will be better, about accessible video controls, captions, navigation chapters, audio descriptions, and WebVTT. I also provided a demo of how to synchronize multiple video elements using a polyfill for the multitrack API.

  I also provided an update on HTTP adaptive streaming APIs as a lightning talk in the Multimedia Miniconf. I used an extract of the Drupal conference slides for it.

  Main conference

  Finally, and most importantly, Alice Boxhall and myself gave a talk in the main linux.conf.au titled “Developing Accessible Web Apps – how hard can it be ?” (video, slides). I spoke about a process that you can follow to make your Web applications accessible. I’m writing a separate blog post to explain this in more detail. In her part, Alice dug below the surface of browsers to explain how the accessibility markup that Web developers provide is transformed into data structures that are handed to accessibility technologies.