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• Introducing WebM, an open web media project

  20 mai 2010, par noreply@blogger.com (christosap)

  A key factor in the web’s success is that its core technologies such as HTML, HTTP, TCP/IP, etc. are open and freely implementable. Though video is also now core to the web experience, there is unfortunately no open and free video format that is on par with the leading commercial choices. To that end, we are excited to introduce WebM, a broadly-backed community effort to develop a world-class media format for the open web.

  WebM includes :
  

  • VP8, a high-quality video codec we are releasing today under a BSD-style, royalty-free license
  • Vorbis, an already open source and broadly implemented audio codec
  • a container format based on a subset of the Matroska media container

  The team that created VP8 have been pioneers in video codec development for over a decade. VP8 delivers high quality video while efficiently adapting to the varying processing and bandwidth conditions found on today’s broad range of web-connected devices. VP8’s efficient bandwidth usage will mean lower serving costs for content publishers and high quality video for end-users. The codec’s relative simplicity makes it easy to integrate into existing environments and requires less manual tuning to produce high quality results. These existing attributes and the rapid innovation we expect through the open-development process make VP8 well suited for the unique requirements of video on the web.

  A developer preview of WebM and VP8, including source code, specs, and encoding tools is available today at www.webmproject.org.

  We want to thank the many industry leaders and web community members who are collaborating on the development of WebM and integrating it into their products. Check out what Mozilla, Opera, Google Chrome, Adobe, and many others below have to say about the importance of WebM to the future of web video.

  
  

  AMD

  ARM

  Brightcove

  Broadcom

  Collabora

  Digital Rapids

  Encoding.com

  Grab Networks

  iLinc

  INLET

  Kaltura

  Logitech

  MIPS

  Nvidia

  Ooyala

  Qualcomm

  Skype

  Sorenson

  Telestream
  

  Texas Instruments

  Verisilicon

  ViewCast

  Wildform

  
  

  Posted by Jeremy Doig, Engineering Director of video and Mike Jazayeri, Group Product Manager, Google

  

• FFMPEG : How to keep UDP stream connection open even source drop some minute

  2 mars 2016, par ALiS

  i decode UDP stream (that genrate from DVB signal) using ffmpeg to HLS with this code :

  ffmpeg -i udp://239.1.2.1:60001?fifo_size=50000000 -acodec copy -vcodec copy -hls_time 2 -hls_wrap 5 -f hls /var/www/html/ts/1.m3u8

  Sometime DVB signal drop for some second or minute and that lead to ffmpeg stop encoding and show error :

  udp://239.1.2.1:60001: Connection timed out

  When i play udp in VLC player and input stream drop for some second VLC wait stop play and when stream start again play again.

  Now i want to know is there exist a way that ffmpeg either found that stream stop and dont show timeout error...it mean that FFMPEG keep connection open and wait for receive stream every time start from source. Thanks

• OpenCV VideoWriter will not open

  21 février 2015, par ChrisC

  I’m having trouble instantiating and opening an OpenCV VideoWriter for recording video on a Raspberry Pi (Raspbian Weezy).

  My project is written in C++, but I’ve written a minimal Python program that demonstrates the problem.

  https://gist.github.com/chriscollins/11ff2f43852e1c93dae8

  Both my C++ code and the Python code above run without problem on my Windows machine. Sometimes the writer does not open, but that’s to be expected - I don’t have all of the listed codecs installed (the list of codecs comes from the Open CV source), but a good number of them work correctly. However, on a Raspberry Pi, both the C++ code and the Python code fail with the VideoWriter never being opened. In the above Python code, writer.isOpened() returns false for every single codec, when run on a Raspberry Pi.

  I’ve chowned the destination directory to the user I’m running the Python script as, and chmodded it to 777 so I don’t believe that it is a permissions problem. I think it may be connected with how I’ve installed OpenCV or some of its dependencies, but I’m not sure how to rectify it.

  The install process I’ve used is as follows :

  1. Update firmware/packages via rpi-update, apt-get update and apt-get upgrade.

  2. Install the following dependencies via apt-get :

     libjpeg8
libjpeg8-dev
libjpeg8-dbg
libjpeg-progs
ffmpeg
libavcodec-dev
libavcodec53
libavformat53
libavformat-dev
libgstreamer0.10-0-dbg
libgstreamer0.10-0
libgstreamer0.10-dev
libxine1-ffmpeg
libxine-dev
libxine1-bin
libunicap2
libunicap2-dev
swig
libv4l-0
libv4l-dev
python-numpy
libpython2.6
python-dev
python2.6-dev
libgtk2.0-dev

  3. Download and unzip http://sourceforge.net/projects/opencvlibrary/files/opencv-unix/2.4.9/opencv-2.4.9.zip to /root/opencv-2.4.9.

  4. cd /root/opencv-2.4.9 and run cmake -DCMAKE_BUILD_TYPE=RELEASE -DCMAKE_INSTALL_PREFIX=/usr/local -DBUILD_PERF_TESTS=OFF -DBUILD_opencv_gpu=OFF -DBUILD_opencv_ocl=OFF. Output of cmake is available at https://gist.github.com/chriscollins/d8060e03a6acd6d4336c

  5. make and make install from the same directory.

  Various other OpenCV functionality works correctly on the Raspberry Pi (in C++ or in Python) - e.g. viewing a webcam via VideoCapture, but I can’t get the VideoWriter to work. I’m tempted to try installing FFMPEG from source instead of via apt-get, but as make takes 5+ hours to run on a Raspberry Pi, I was hoping I’d find the answer here, rather than proceeding with a trial and error approach !

  Any advice on how to solve (or debug) this is appreciated.

  EDIT : Added output of cmake command (https://gist.github.com/chriscollins/d8060e03a6acd6d4336c)