Recherche avancée

Sur d’autres sites (7565)

• The Future of the VP8 Bitstream

  17 juin 2010, par noreply@blogger.com (John Luther) — vp8

  Recently we’ve seen software products such as VLC, FFmpeg, Logitech Vid, Flumotion and Tixeo adopting and using WebM and VP8 (the video codec in WebM) in exciting new ways.

  In addition to software developers, many hardware vendors have committed to shipping VP8-accelerated products based on our current bitstream in 2011 . Devices that use hardware acceleration for video are a very small percentage of overall web traffic today, but they are a rapidly growing segment of the market and our project must be mindful of these vendors’ needs. Given the longer lead times for changes in chipsets, hardware companies implementing the codec today need to be confident that it will be stable and supported as VP8 content proliferates.

  Like every codec, WebM is not immune to change ; the difference in our project is that the improvements are publicly visible, and compatibility and implementation issues can be worked through in an open forum.

  So, to maintain codec stability while also allowing for quality and performance improvements in VP8, we have added an experimental branch to the VP8 source tree. The WebM community can use this unstable branch to propose changes to VP8 that will produce the best video codec possible, but without the constraints of a frozen bitstream. At some point in the future, when the experimental branch proves significantly better than the stable branch, we will create a new version of the codec.

  Teams dedicated to improving WebM are actively investigating and evaluating new techniques, and are committed to do so for the long term. We encourage the WebM community to keep contributing as well. To learn more about the experimental branch and get involved, see our repository layout page.

  Jim Bankoski is Codec Engineering Manager at Google.

  

• Windows 2003 using php popen "start /b" because of executing ffmpeg.exe

  1er juillet 2013, par Oh Seung Kwon

  I have some problem.

  There is a php code that convert audio(wav) to mp3 file with using ffmpeg.exe.

  Here is some code.

  $cmd = "./inc/ffmpeg.exe -i ".$file_name." -acodec mp3 -y -ac 1 -ab 96k ".$mp3_file_name;
  
  
  
  echo $cmd;
  
  echo "Windows";
  
  $handle = popen("start /B ".$cmd, "r");
  
  while(!feof($handle)) {
  
      $read = fread($handle, 2096);
  
      echo $read;
  
  }
  
  pclose($handle);

  Problem is when I execute this code, ffmpeg.exe process isn't terminated. And not gonna die when I stop process with using Windows task manager.

  Do you have a solution for this situation ?

• Easy Tricks for Finding WebM Videos in YouTube

  9 août 2010, par noreply@blogger.com (John Luther)

  Since the WebM project launch, YouTube has been encoding videos uploaded at 720p or higher resolution in the WebM format. Today, the one million most popular videos of any size on YouTube are also available in the WebM format.

  We have instructions on our project site for finding these videos but they require adding a special parameter onto the end of each search query. All of the browsers that support WebM can create search shortcuts with custom parameters, however, so we’ve compiled instructions for making it very simple to search for WebM videos in YouTube.

  Important : First, make sure you have a supported browser and are enrolled in the YouTube HTML5 beta by going to http://youtube.com/html5 and clicking Enter the HTML5 Beta.

  Creating a WebM Search Shortcut

  Firefox 4 Beta :
  

  1. Select Bookmarks > Organize Bookmarks. A bookmark manager dialog opens.
  2. In the left column, choose a location for the new bookmark you’re creating. Next, choose Organize > New Bookmark (on MacOS click the gear icon). The new bookmark dialog opens.
  3. In the Name box, type WebM.
  4. In the Location box, type http://youtube.com/results?search_query=%s&webm=1.
  5. In the Keyword box, type webm.
  6. Click Add.

  Google Chrome Early Release Channel :
  

  1. On Windows and Linux, click the Chrome wrench icon in the toolbar and select Options. On MacOS, select Chrome > Preferences.
  2. On the Basics tab, click the Manage button in the Default Search section.
  3. On Windows and Linux, click Add. On MacOS X, click the plus (+) button.
  4. In the Name box, type WebM.
  5. In the Keyword box, type webm.
  6. In the URL box, type http://youtube.com/results?search_query=%s&webm=1.
  7. Click OK.

  Opera 10.60 and later :
  

  1. Go to http://youtube.com.
  2. Right-click in the YouTube search box at the top of the page and select Create Search. On MacOS, use Ctrl+click if you don’t a secondary mouse button enabled.
  3. In the Name box, type WebM.
  4. In the Keyword box, type webm.
  5. In the Address box, type http://youtube.com/results?search_query=%s&webm=1.
  6. Click OK.

  
  

  
  Now you’re ready to search. In the location box of the browser, type webm monster trucks. The YouTube search results page will open with a selection of monster truck videos encoded in the WebM format. When watching a video, look for the HTML5 WebM indicator in the player control bar.

  If you can’t find WebM videos it is most likely a browser cookie problem. Your enrollment in the YouTube HTML5 beta test is stored in a browser cookie (not in your YouTube or Google account), and that cookie can expire. Visit http://youtube.com/html5 and opt-in again to re-set the cookie.

  Directly Accessing WebM Videos by URL

  To find out if any YouTube video is available in WebM, simply add &html5=True (make sure True is capitalized) to the end of the video URL. If there is a WebM version of the video, it will open instead of the Flash version. For example :
  

  • Flash version : http://www.youtube.com/watch?v=Dz6gFokvOr0
  • WebM version : http://www.youtube.com/watch?v=Dz6gFokvOr0&html5=True