Recherche avancée

Sur d’autres sites (13495)

• On WebP and Academic Exercises

  2 octobre 2010, par Multimedia Mike — General

  Yesterday, Google released a new still image format called WebP. To those skilled in the art, this new format will be recognizable as a single VP8 golden frame with a 20-byte header slapped on the front (and maybe a little metadata thrown in for good measure). We have a MultimediaWiki page and a sample ready to go.

  Further, I submitted a patch to ffmpeg-devel for FFmpeg’s img2 handling system to decode these files. FFmpeg should support processing these files soon… if anyone cares. This leads into…

  The Point, or Lack Thereof
  Since yesterday’s release, I have read a whirlwind of commentary about this format, much of it critical and of the “what’s the point ?” variety. For my part, I can respect academic exercises, a.k.a., just trying random stuff to see if you can make it work. That’s pretty much this blog’s entire raison d’être. But WebP transcends mere academic exercise ; Google seems to be trying to push it as a new web standard. I don’t see how the format can go anywhere based on criticisms raised elsewhere — e.g., see Dark Shikari’s thoughtful write-up — which basically boil down to WebP not solving any real problems, technical, legal, or otherwise.

  How did WebP come to be ? I strongly suspect some engineers noticed that JPEG is roughly the same as an MPEG-1 intraframe, so why not create a new still frame format based on VP8 intraframes ? Again, I can respect that thinking– I have pondered how a still image format would perform if based on VP3/Theora or Sorenson Video 1.

  Technically
  Google claims a significant size savings for WebP vs. standard JPEG. Assuming that’s true (and there will be no shortage of blog posts to the contrary), it will still be some time before WebP support will find its way into the majority of the web browser population.

  But this got me thinking about possible interim solutions. A website could store images compressed in both formats if it so chose. Then it could serve up a WebM image if the browser could support it, as indicated by the ‘Accept’ header in the HTTP request. It seems that a website might have to reference a generic image name such as <img src="some-picture.image"> ; the web server would have to recognize the .image extension and map it to either a .jpg or a .webp image depending on what the browser claims it is capable of displaying.

  Leftovers
  I appreciate that Dark Shikari has once again stuck his neck out and made a valiant — though often futile — effort to educate the internet’s masses. I long ago resigned myself to the fact that many people aren’t going to understand many of the most basic issues surrounding multimedia technology (i.e., moving pictures synchronized with audio). But apparently, this extends to still image formats as well. It was simultaneously humorous and disheartening to see commenters who don’t even understand the application of, e.g., PNG vs. JPEG : Ahem, “We already have a great replacement for jpg : .PNG”. Coupled with the typical accusations of MPEG tribalism, I remain impressed D. Shikari finds the will to bother.

  Still, I appreciate that the discussion has introduced me to some new image formats of which I was previously unaware, such as PGF and JPEG XR.

• Failed to build gem native extension while installing rmovie gem

  12 janvier 2013, par Dmitry

  I am trying to install rmovie gem on Ubuntu Desktop 12.04 LTS. ffmpeg is installed but I'm getting this error :

  $ gem install rmovie
  
  Building native extensions.  This could take a while...
  
  ERROR:  Error installing rmovie:
  
      ERROR: Failed to build gem native extension.
  
  
  
          /home/ror_dev/.rvm/rubies/ruby-1.9.3-p362/bin/ruby extconf.rb
  
  gcc -c -fpic -g  qp_movie.c -o qp_movie.o
  
  In file included from qp_movie.c:4:0:
  
  qp_util.h:4:28: fatal error: ffmpeg/avcodec.h: No such file or directory
  
  compilation terminated.
  
  make: *** [qp_movie.o] Error 1
  
  checking for avcodec_init() in -lavcodec... yes
  
  checking for av_register_all() in -lavformat... yes
  
  checking for quadrupel_init() in -lquadrupel... no
  
  *** extconf.rb failed ***
  
  Could not create Makefile due to some reason, probably lack of
  
  necessary libraries and/or headers.  Check the mkmf.log file for more
  
  details.  You may need configuration options.
  
  
  
  Provided configuration options:
  
      --with-opt-dir
  
      --with-opt-include
  
      --without-opt-include=${opt-dir}/include
  
      --with-opt-lib
  
      --without-opt-lib=${opt-dir}/lib
  
      --with-make-prog
  
      --without-make-prog
  
      --srcdir=.
  
      --curdir
  
      --ruby=/home/ror_dev/.rvm/rubies/ruby-1.9.3-p362/bin/ruby
  
      --with-ffmpeg-dir
  
      --without-ffmpeg-dir
  
      --with-ffmpeg-include
  
      --without-ffmpeg-include=${ffmpeg-dir}/include
  
      --with-ffmpeg-lib
  
      --without-ffmpeg-lib=${ffmpeg-dir}/lib
  
      --with-quadrupel-dir
  
      --without-quadrupel-dir
  
      --with-quadrupel-include
  
      --without-quadrupel-include=${quadrupel-dir}/include
  
      --with-quadrupel-lib
  
      --without-quadrupel-lib=${quadrupel-dir}/lib
  
      --with-avcodeclib
  
      --without-avcodeclib
  
      --with-avformatlib
  
      --without-avformatlib
  
      --with-quadrupellib
  
      --without-quadrupellib
  
   extconf failed: need quadrupel library

  First attempt was to relocate avcodec to where installer is searching for it. No success. Next - correcting paths in quadrupel files to point it to where avcodec is located. No success.

  What is this quadrupel thing and how to force it to work ?

  Or maybe there is some replacement for rmovie ?

• Remove avserver.

  9 juin 2014, par Anton Khirnov

  Remove avserver.
  It has not been properly maintained for years and there is little hope
  
  of that changing in the future.
  
  It appears simpler to write a new replacement from scratch than
  
  unbreaking it.
  

  • [DBH] .gitignore
  • [DBH] Changelog
  • [DBH] Makefile
  • [DBH] avserver.c
  • [DBH] configure
  • [DBH] doc/avserver.conf
  • [DBH] doc/avserver.texi
  • [DBH] doc/general.texi
  • [DBH] libavformat/Makefile
  • [DBH] libavformat/allformats.c
  • [DBH] libavformat/ffm.h
  • [DBH] libavformat/ffmdec.c
  • [DBH] libavformat/ffmenc.c
  • [DBH] tests/fate/avformat.mak
  • [DBH] tests/fate/seek.mak
  • [DBH] tests/lavf-regression.sh
  • [DBH] tests/ref/lavf/ffm
  • [DBH] tests/ref/seek/lavf-ffm