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• Is it possible to encode one yuv file to 3 h.264 files with different bitrates with one command ?

  24 juillet 2012, par Richard Knop

  I have a YUV file. I need to encode it to H.264 but using three different bitrates. Is it possible to do it with one command so the yuv file does not need to be processed muttiple times ?

  Here's what I do right now :

  x264 -B 600 -o /path/to/output_first.264 /path/to/input.yuv
  
  x264 -B 800 -o /path/to/output_second.264 /path/to/input.yuv
  
  x264 -B 1000 -o /path/to/output_second.264 /path/to/input.yuv

  Is it possible to do it in one command to make it faster ? YUV file can be quite big so I don't want to extract it three times in a row. And all three encoding processes use the same input YUV file so I guess it should be possible.

• huffyuvdec : implement trick

  3 juin 2014, par Christophe Gisquet

  huffyuvdec : implement trick
  When the joint table does not contain a valid entry, the decoding restarts
  
  from scratch. By implementing the trick of jumping to the 2nd level of the
  
  individual table (and inlining the whole), a speed improvement of 5-10%
  
  is possible.
  On a 1000-frames YUV4:2:0 video, before :
  
  362851 decicycles in 422, 262094 runs, 50 skips
  
  182488 decicycles in gray, 262087 runs, 57 skips
  
  Object size : 23584
  
  Overall time : 8.377
  After :
  
  346800 decicycles in 422, 262079 runs, 65 skips
  
  168197 decicycles in gray, 262077 runs, 67 skips
  
  Object size : 23188
  
  Overall time : 7.878
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavcodec/huffyuvdec.c

• FATE’s New Look

  4 août 2010, par Multimedia Mike — FATE Server

  The FATE main page exposes a lot of data. The manner in which it is presented has always been bounded by my extremely limited web development abilities. I wrestled with whether I should learn better web development skills first and allow that to inform any improved design, or focus on the more useful design and invest my web development learning time towards realizing that design.

  Fortunately, Mans solved this conundrum with an elegantly simple solution :

  
  
  

  The top of the page displays a status bar that illustrates — at a glance — how functional the codebase is. The web page source code identifies this as the failometer. It took me a few seconds to recognize what information that status bar was attempting to convey ; maybe it could use a succinct explanation.

  Mini-Book Review
  
  Before Mans took over, I thought about this problem quite a bit. I needed inspiration for creating a better FATE main page and aggregating a large amount of data in a useful, easily-digested form. Looking around the web, I see no shortage of methods for visualizing data. I could start shoehorning FATE data into available methods and see what works. But I thought it would be better to take a step back and think about the best way to organize the data. My first clue came awhile ago in the form of an xkcd comic : Blogofractal. Actually, the clue came from the mouseover text which recommended Edward Tufte’s "The Visual Display of Quantitative Information".

  
  
  

  I ordered this up and plowed through it. It’s an interesting read, to be sure. However, I think it illustrates what a book on multimedia and compression technology would look like if authored by yours truly— a book of technical curiosities from epochs past that discusses little in the way of modern practical application. Tufte’s book showed me lots of examples of infographics from decades and even centuries past, but I never concisely learned exactly how to present data such as FATE’s main page in a more useful form.

  Visualization Blog
  More recently, I discovered a blog called Flowing Data, authored by a statistics Ph.D. candidate who purportedly eats, sleeps, and breathes infographics. The post 11 Ways to Visualize Changes Over Time : A Guide offers a good starting point for creating useful data presentations.

  I still subscribe to and eagerly read Flowing Data. But I might not have as much use for data visualization now that Mans is on FATE duty.