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• FFmpeg - Turn a 1280x720 video into 720x1280 video and add blur

  6 janvier 2021, par offish

  I've searched around and found multiple solutions. I've found one that works well, but the final video ends up being too big which makes the rendering slow.

  


  I'm giving it a 1280x720 video and want it to turn out like shown here with 720x1280 as the resolution.

  


  -lavfi "[0:v]scale=256/81*iw:256/81*ih,boxblur=luma_radius=min(h\,w)/40:luma_power=3:chroma_radius=min(cw\,ch)/40:chroma_power=1[bg];[bg][0:v]overlay=(W-w)/2:(H-h)/2,setsar=1,crop=w=iw*81/256"


  


  This video ends up being 1280x2274 instead of 720x1280, everything else is fine except the speed and resolution.

  


  -lavfi [0:v]scale=16/9*iw:16/9*ih,boxblur=luma_radius=min(h\,w)/40:luma_power=3:chroma_radius=min(cw\,ch)/40:chroma_power=1[bg];[bg][0:v]overlay=(W-w)/2:(H-h)/2,setsar=1,crop=w=720:h=1280


  


  This cuts the original video, but ends up being 720x1280, faster than the first solution.

  


  -lavfi "[0:v]scale=256/81*iw:256/81*ih,boxblur=luma_radius=min(h\,w)/40:luma_power=3:chroma_radius=min(cw\,ch)/40:chroma_power=1[bg];[bg][0:v]overlay=(W-w)/2:(H-h)/2,setsar=1,crop=w=iw*81/256,scale=720:1280"


  


  This is the same as the first one, but it gets scaled again. It has the correct resolution, but is way to slow for my liking (only about 3.6 it/s, when I've tried other solutions which fluctuates around 35 it/s).

  


  I guess my scaling is wrong, but I don't understand what I should multiply and divide by, to get the result I'm looking for.

  


  Thanks.

  


• Revision 810b612c23 : Enable bit-stream support to 8x4 and 4x8 partition The recursive partition type

  16 mai 2013, par Jingning Han

  Changed Paths :
   Modify /vp9/common/vp9_blockd.h

  
   Modify /vp9/common/vp9_entropymode.c

  
   Modify /vp9/decoder/vp9_decodemv.c

  
   Modify /vp9/decoder/vp9_decodframe.c

  
   Modify /vp9/decoder/vp9_onyxd_if.c

  
   Modify /vp9/encoder/vp9_bitstream.c

  
   Modify /vp9/encoder/vp9_encodeframe.c

  
   Modify /vp9/encoder/vp9_encodemv.c

  
   Modify /vp9/encoder/vp9_rdopt.c

  
  
  Enable bit-stream support to 8x4 and 4x8 partition

  The recursive partition type search is enabled down to 4x4, 4x8 and
  8x4, followed by the corresponding rate-distortion optimization for
  the per-partition encoding mode decisions.

  The bit-stream writing/reading synchronized in supporting the
  rectangular partition of 8x8 block.

  This provides above 1% coding performance gains on derf.

  To do next :
  1. re-design the rate-distortion loop for inter prediction below 8x8.
  2. re-design the rate-distortion loop for intra prediction below 4x4.
  3. make the loop-filter aware of rectangular partition of 8x8 block.
  4. clean the unused probability models.
  5. update default probability values.

  Change-Id : Idd41a315b16879db08f045a322241f46f1d53f20

• ffmpeg chromakey filter : blend parameter does not what it should

  5 mai 2017, par Mat

  I want to remove greenscreen background and am not completely satisfied with what I have achieved because I still have green borders (especially on semi-transparent areas like hair, when I move my head).

  The documentation for the blend-parameter of chromakey filter says

  blend

  Blend percentage.

  0.0 makes pixels either fully transparent, or not transparent at all.

  Higher values result in semi-transparent pixels, with a higher transparency the more similar the pixels color is to the key color.

  So I reckoned, I could use this to minimise greenscreen bleeding (is this the term ?) when removing the background with a command like this :

  ffmpeg -i DSCN0015.MOV -vf "[in] hqdn3d=4:4:8:8 [dn]; [dn] scale=iw*3:-1 [sc]; [sc] chromakey=0x005d0b:0.125:0.0 [out]" -r 24 -an -c:v ffvhuff 4.mov

  But when I use anything else than 0.0 for blend, it seems to determine some kind of MINIMUM transparency and the entire frame is affected.

  Here are some pics to visualize : the first is the raw material from the camera. the 2nd shows what I get with blend=0.0 and the last one shows the problem : blend=0.5, but the whole frame is almost completely transparent.

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