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• avcodec/vaapi : mask unused bits in bitplane_present.value

  25 février 2018, par Jerome Borsboom

  avcodec/vaapi : mask unused bits in bitplane_present.value
  Due to the union construct, unused bits in bitplane_present.value might
  
  be uninitialized even when the used bits are all set to a value.
  
  Masking the unused bits prevents spurious true values when all used
  
  bits are unset, e.g. skipped pictures.
  Signed-off-by : Jerome Borsboom <jerome.borsboom@carpalis.nl>
  

  • [DH] libavcodec/vaapi_vc1.c

• Revision 75d77e36db : Fix the all intra modes mask constant. The new constant expands to 0x3fc00808.

  28 mai 2014, par Alex Converse

  Changed Paths :
   Modify /vp9/encoder/vp9_rdopt.c

  
  
  Fix the all intra modes mask constant.

  The new constant expands to 0x3fc00808.

  Change-Id : Ib5109e4faf035fe0402b59f8a8d2e412628b9276

• Using ffmpeg alphamerge to mask two images before calculating similarity index [closed]

  12 août 2024, par user2814357

  I'm working on a script that removes duplicate frames from images stored on disk. I need to ignore certain irrelevant parts of the images.

  


  The following ffmpeg command line should work, but it returns the same SSIM statistics as without mask.

  


  ffmpeg -i 1.webp -i 2.webp -i mask.png -filter_complex \
"[0][2]alphamerge[img1]; \
 [1][2]alphamerge[img2]; \
 [img1]format=yuva420p[masked1]; \
 [img2]format=yuva420p[masked2]; \
 [masked1][masked2]ssim=stats_file=-" -f null -


  


  Example output :

  


  [Parsed_ssim_4 @ 0x7fb76b70ff00] SSIM Y:0.829392 (7.680003) U:0.987882 (19.165656) V:0.993201 (21.675403) All:0.883108 (9.322165)
[out#0/null @ 0x7fb76c604700] video:0KiB audio:0KiB subtitle:0KiB other streams:0KiB global headers:0KiB muxing overhead: unknown
frame=    1 fps=0.0 q=-0.0 Lsize=N/A time=00:00:00.04 bitrate=N/A speed=0.602x    



  


  Result is the same with ffmpeg -i 1.webp -i 2.webp  -lavfi ssim=stats_file=- -f null -.

  


  [Parsed_ssim_0 @ 0x7f9c0cf06d80] SSIM Y:0.829392 (7.680003) U:0.987882 (19.165656) V:0.993201 (21.675403) All:0.883108 (9.322165)
[out#0/null @ 0x7f9c0da08e80] video:0KiB audio:0KiB subtitle:0KiB other streams:0KiB global headers:0KiB muxing overhead: unknown


  


  This is weird because the masked output files look as expected if I output them with :

  


  ffmpeg -i 1.webp -i 2.webp -i mask.png -filter_complex \
"[0][2]alphamerge[img1]; \
 [1][2]alphamerge[img2]; \
 [img1]format=yuva420p[masked1]; \
 [img2]format=yuva420p[masked2]" \
-map "[masked1]" masked_1.webp \
-map "[masked2]" masked_2.webp


  


  Does anyone know what the right syntax would be for getting the SSIM values from a single command using a mask ?

  


  Side note : If I use -map "[masked1]" masked_1.jpg it outputs the original picture, not the masked one. Could there be a problem in the ffmpeg pipeline ?

  


  Thank you very much !