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• Revision faff6ed0fb : Skip duplicate block encoding in the rd loop This speed feature allows the enco

  9 juillet 2013, par Jingning Han

  Changed Paths :
   Modify /vp9/encoder/vp9_block.h

  
   Modify /vp9/encoder/vp9_encodeframe.c

  
   Modify /vp9/encoder/vp9_encodeintra.c

  
   Modify /vp9/encoder/vp9_encodemb.c

  
   Modify /vp9/encoder/vp9_onyx_if.c

  
   Modify /vp9/encoder/vp9_onyx_int.h

  
   Modify /vp9/encoder/vp9_rdopt.c

  
   Modify /vp9/encoder/vp9_rdopt.h

  
  
  Skip duplicate block encoding in the rd loop

  This speed feature allows the encoder to largely remove the spatial
  dependency between blocks inside a 64x64 superblock, thereby removing
  the need to repeatedly encode superblocks per partition type in the
  rate-distortion optimization loop.

  A major challenge lies in the intra modes tested in the rate-distortion
  optimization loop. The subsequent blocks do not have access to the
  reconstructed boundary pixels without the intermediate coding steps.
  This was resolved by using the original pixels for intra prediction
  in the rd loop, followed by an appropriately designed distortion
  modeling on the quantization parameters. Experiments also suggested
  that the performance impact is more discernible at lower bit-rate/psnr
  settings. Hence a quantizer dependent threshold is applied to deactivate
  skip of block coding.

  For bus_cif at 2000 kbps,
  speed 0 : runtime 269854ms -> 237774ms (12% speed-up) at 0.05dB
  performance loss.

  speed 1 : runtime 65312ms -> 61536ms, (7% speed-up) at 0.04dB
  performance loss.

  This operation is currently turned on in settings of speed 1.

  Change-Id : Ib689741dfff8dd38365d8c1b92860a3e176f56ec

• Revision 336ca9a43a : Merge "keyframe_test : use a fixed speed step for realtime"

  8 août 2012, par John Koleszar

  Changed Paths : Modify /test/encode_test_driver.h Merge "keyframe_test : use a fixed speed step for realtime"

• How to get FFmpeg to consistently apply speed effect to first few frames ?

  16 janvier 2021, par melody_florum

  I am using FFmpeg to apply speed effects to short gifs and videos and I noticed strange stuttering on looping gifs when sped up. I manually tested and found what was going on. FFmpeg failed to apply the speed filter to the first few frames of the video.

  


  I started with this file, which loops between the numbers "1 2 3 4" every frame.

  


  123410fps.mp4

  


  I then ran the command ffmpeg -i 123410fps.mp4 -vf setpts=0.5*PTS 123410fpsout.mp4

  


  That left me with this file : 123410fpsout.mp4

  


  On close analysis, I discovered that the output file didn't show a repeating 1 3 1 3 or 2 4 2 4 pattern, but shows 1 2 3 4 1 3 1 3 1 3... the speed effect didn't apply for the first few frames

  


  I apologize if it sounds like i'm being super nitpicky, but my usage for this is on very short gifs and videos where this effect is very apparent. How can I prevent this effect from happening and have a 100% consistent speed effect applied to the video ? I don't mind using other non-ffmpeg software but a CLI solution that works easily for most videos is ideal.

  


  In case anyone is wondering, I don't use ffmpeg to encode gifs, i use gifski from ffmpeg exported image sequences. The problem shows up even when no gifs are used, so it's not a gifski problem.