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• Revision 9d771f948f : Merge "Motion vectors code cleanup." into experimental

  27 février 2013, par Dmitry Kovalev

  Merge "Motion vectors code cleanup." into experimental

• Recommendations for real-time pixel-level analysis of television (TV) video

  6 décembre 2011, par Randall Cook

  [Note : This is a rewrite of an earlier question that was considered inappropriate and closed.]

  I need to do some pixel-level analysis of television (TV) video. The exact nature of this analysis is not pertinent, but it basically involves looking at every pixel of every frame of TV video, starting from an MPEG-2 transport stream. The host platform will be server-class, multiprocessor 64-bit Linux machines.

  I need a library that can handle the decoding of the transport stream and present me with the image data in real-time. OpenCV and ffmpeg are two libraries that I am considering for this work. OpenCV is appealing because I have heard it has easy to use APIs and rich image analysis support, but I have no experience using it. I have used ffmpeg in the past for extracting video frame data from files for analysis, but it lacks image analysis support (though Intel's IPP can supplement).

  In addition to general recommendations for approaches to this problem (excluding the actual image analysis), I have some more specific questions that would help me get started :

  1. Are ffmpeg or OpenCV commonly used in industry as a foundation for real-time
     video analysis, or is there something else I should be looking at ?
  2. Can OpenCV decode video frames in real time, and still leave enough
     CPU left over to do nontrivial image analysis, also in real-time ?
  3. Is sufficient to use ffpmeg for MPEG-2 transport stream decoding, or
     is it preferable to just use an MPEG-2 decoding library directly (and if so, which one) ?
  4. Are there particular pixel formats for the output frames that ffmpeg
     or OpenCV is particularly efficient at producing (like RGB, YUV, or YUV422, etc) ?

• "Droplet" batch script - filenames containing ampersands

  16 août 2014, par stephenwade

  I’m trying to create a batch file that can have other files dropped onto it. Specifically, I’m using ffmpeg to edit audio files produced by a handheld voice recorder. The problem is when using filenames with ampersands (&). Even when quoting the input, anything after the & is dropped off, but only when files are dropped onto it ; if the filename input is typed on the command line, the script works fine. Before the cmd window closes, I briefly see the rest of the filename with an error saying it is not recognized as a valid command.

  Here’s my script :

  rem Change to drive and directory of input file
  % d1
  cd % p1
  rem ffmpeg : mix to one channel, double the volume
  
  %HOMEDRIVE%%HOMEPATH%\ffmpeg.exe -i "% nx1" -ac 1 -vol 1024 "% n1 fixed% x1"
  pause
  

  Here’s what appears on the command line, after dropping "ch17&18.mp3" :

  C :\Users\computergeeksjw\Desktop>C :\Users\computergeeksjw\ffmpeg.exe -i "ch17" -ac 1 -vol 1024 "ch17 fixed"
  [...]
  ch17 : No such file or directory
  

  In case it matters : I’m using the Windows 8 Developer Preview. Is this causing my problem ? Does the same error occur on Windows 7 or earlier ?