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• Macroblock decoding in CUDA video decoding

  22 octobre 2016, par mkreddy

  I am new to video processing. I am trying to analyze Cuda video Decoder.

  Can anyone explain the decoding process in CUVID. The NVIDIA CUVID documentation has very little information regarding the decoding of slice and macro blocks.

  • Is cuvidDecodePicture will split the picture into macro blocks/slices to decode the picture ?
  • How entropy used in H.264 was handled in CUVID ?
  • Why are the CUVIDPICPARAMS has two separate structures for mpeg4 and H.264 ?
  • How to compare the process of video decoding in ffmpeg and CUVID ?

  Thanks in advance.

• how to ignore or fix false 'unmet dependencies' error ?

  31 août 2014, par yy502

  OS: LMDE 201403

  I previously installed OpenShot (a video editing software), which depends on libmlt6, and libmlt6 depends on ffmpeg. The chain of dependencies auto-installed just fine.

  Today I compiled and installed the latest ffmpeg v2.3.3 and apt-get starts to complain :

  You might want to run 'apt-get -f install' to correct these:
  
  The following packages have unmet dependencies:
  
   libmlt6 : Depends: ffmpeg (>= 5:0.6.2~) but 2.3.3-1 is to be installed
  
  E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).

  Well, I’m sure my compiled version of ffmpeg is newer than whatever version libmlt6 requires, but the package manager does not seem to understand the new version number. How can I ignore or fix false ’unmet dependencies’ error, please ?

  Thanks for your time !

  Edit :

  Executing apt-get -f install would install the ffmpeg from repository to /usr/bin/ and uninstall/overwrite my compiled version of ffmpeg in /usr/local/bin/... not really the solution I’m after...

  Edit2 :

  the auto fix of apt-get will remove my compiled version of ffmpeg as prompted below :

  sudo apt-get install -f
  
  Reading package lists... Done
  
  Building dependency tree       
  
  Reading state information... Done
  
  Correcting dependencies... Done
  
  The following extra packages will be installed:
  
    ffmpeg
  
  Suggested packages:
  
    nvidia-libvdpau1
  
  The following packages will be upgraded:
  
    ffmpeg
  
  1 upgraded, 0 newly installed, 0 to remove and 2 not upgraded.
  
  Need to get 0 B/1,307 kB of archives.
  
  After this operation, 242 MB disk space will be freed.
  
  Do you want to continue? [Y/n] n
  
  Abort.

• ffmpeg fails to capture video running on screen

  21 septembre 2014, par Ralf

  I’m trying to capture a slide presentation as video. I’m using the following command to capture my screen

  ffmpeg \
  
     -f x11grab -s 1024x768 -r 25 -i $DISPLAY \
  
     -f alsa -i pulse \
  
     -vcodec libx264 -preset ultrafast -vb 1000k \
  
     -acodec libmp3lame -ab 128k \
  
     test.avi

  This works (application windows on the screen are visible and sound is recorded in test.avi), but the problem is : Any video shown on the screen (e.g. a youtube video running in a browser window, but also e.g. a video played by mplayer) only appears as an empty (e.g. green) box when I play the captured video (test.avi).

  I’m using ffmpeg version 0.8.16-4:0.8.16-0ubuntu0.12.04.1 on Ubuntu 12.04.5 LTS with the nvidia-331 driver (effect is the same with older nvidia-304).

  I would really appreciate any suggestions, thanks a lot !