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• Merge commit ’1481d24c3a0abf81e1d7a514547bd5305232be30’

  17 mars 2014, par Michael Niedermayer

  Merge commit ’1481d24c3a0abf81e1d7a514547bd5305232be30’
  * commit ’1481d24c3a0abf81e1d7a514547bd5305232be30’ :
  
    RGBA64 pixel formats
  Conflicts :
  
  	doc/APIchanges
  
  	libavutil/pixdesc.c
  
  	libavutil/pixfmt.h
  
  	libavutil/version.h
  
  	libswscale/utils.c
  See : 9569a3c9f41387a8c7d1ce97d8693520477a66c3
  
  See : 92afb431621c79155fcb7171d26f137eb1bee028, as well as others
  
  Note : the enum values added in libav are incompatible/different to what ffmpeg used since 3 years
  
  Merged-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] doc/APIchanges
  • [DH] libavutil/pixdesc.c
  • [DH] libavutil/pixfmt.h
  • [DH] libavutil/version.h
  • [DH] libswscale/swscale_internal.h

• Trouble with the ffmpeg -ss flag when capturing one frame from a Macbook iSight webcam

  1er mars 2014, par Andy

  For about five years I've used ffmpeg in a shell script to grab one frame from my linux'd-up Macbook's iSight :

  ffmpeg -f video4linux2 -s 640x480 -r 15 -i /dev/video0 -an -vframes 1 -vcodec mjpeg -y -sameq -ss 1.5 snapshot.jpg

  I just upgraded my Ubuntu distro from Lucid to Natty (ffmpeg ver. 0.6.2-4:0.6.2-1ubuntu1).
  Now that syntax turns the iSight on but hangs indefinitely.

  [output snipped, ending with:]
  
  frame=    0 fps=  0 q=0.0 Lsize=      -0kB time=10000000000.00 bitrate=  -0.0kbits/s    
  
  video:0kB audio:0kB global headers:0kB muxing overhead -inf%

  Without the '-ss' flag it seems to successfully grab the first frame and exit immediately - the only difference in output being :

  frame=    1 fps=  0 q=0.0 Lsize=      -0kB time=0.07 bitrate=  -2.6kbits/s    
  
  video:16kB audio:0kB global headers:0kB muxing overhead -100.132730%

  However, the '-ss 1.5' was necessary to delay the frame capture by 1.5 seconds to allow the cam sufficient time to adjust the exposure.

  The -itsoffset flag seemed promising, but doesn't seem to change ffmpeg's behavior (ie doesn't hang, but no delay).

  Any ideas ?

• Recommendataions for robust and invisible video watermarking software / library [on hold]

  1er mars 2014, par id128

  I am doing a research project in search of a robust and invisible video watermarking software / library (preferably in C++). It needs to meet the following requirements :

  • Robust - that is the watermark needs to survive common transformations such as re-encoding, A/D / D/A conversion, luminance/color change, shift, and crop (both in size and length)'

  • Invisible - to the human eye

  The watermark does not need to carry too much data - maybe a 64-bit UUID - and can be temporal or spatial. But I will need the ability to determine the existence (or not) of the watermark with only a few seconds of the video

  Some research I have done so far :

  • JAWS research paper (http://pdf.aminer.org/000/316/002/the_viva_project_digital_watermarking_for_broadcast_monitoring.pdf) but cannot find any implementations on the web and the authors are not responding to emails. Plus, that research is over 10 years old and I am hoping for something more modern.

  • OpenPuff - does not satisfy the robustness requirement in that the resulting video does not survive transformations.

  • ffmpeg software - I have figured out how to overlay a visible watermark, but that does not satisfy the invisibility requirement.

  Any ideas / suggestions / pointers will be awesome. Thanks.