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• avcodec/h264pred : Remove dead > 8 pixels checks for 8bit codecs

  10 janvier 2022, par Andreas Rheinhardt

  avcodec/h264pred : Remove dead > 8 pixels checks for 8bit codecs
  RV40, SVQ3 and VP7/VP8 are eight-bit only, so it makes no sense
  
  to check for them in the codepath initializing > eight bit contexts.
  
  Move the codec-specific code to a switch located after the eight-bit
  
  init code where this is easily possible ; and add checks to the macro
  
  to enable the compiler to remove the remaining checks when initializing
  
  bitdepths > 8 at compile-time.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/h264pred.c

• Add a sample "CAMM" data to specific PTS in a MP4 file

  11 janvier 2023, par Cheloute

  For testing purpose, I need to add programatically some samples to an existing MP4 video file but I can't understand how.
My goal is to add some CAMM1 records (exposure data) associated to each PTS multiple of 33366, that's to say : PTS=0, PTS=33366, PTS=66732, ...

  


  I already have an existing camm track atom in my file, so the idea is to duplicate all the existing CAMM samples (CAMM2 and CAMM3 data), add my CAMM1 samples to the existing CAMM data, and write all the samples again at the end of the mdat atom (moov atom is located after mdat atom in my case). Next I'll update the CAMM track atom (stts, stsc, stsz and stco) to index all the samples correctly.

  


  But I have 1 question I can't understand. STSC and STCO are dealing with offsets and STTS with time and delta, how can I do to link my CAMM1 records to PTS multiple of 33366 ?

  


  Thanks

  


• Revision eca93642e2 : Add a speed feature to give the tighter search range Add a speed feature to giv

  14 août 2014, par Pengchong Jin

  Changed Paths :
   Modify /vp9/encoder/vp9_encodeframe.c

  
   Modify /vp9/encoder/vp9_speed_features.c

  
   Modify /vp9/encoder/vp9_speed_features.h

  
  
  Add a speed feature to give the tighter search range

  Add a speed feature to give the tighter partition search
  range. Before partition search, calculate the histogram
  of the partition sizes of the left, above and previous
  co-located blocks of the current block. If the variance of
  observed partition sizes is small enough, adjust the search
  range around the mean partition size, which will be tigher.

  The feature is currently turned on at speed 2. Experiments on
  sample youtube clips show on average the runtime is reduced
  by 3-7%.

  For hard stdhd clips :
  park_joy_1080p @ 15000kbps : 509251 ms -> 491953 ms (3.3%)
  pedestrian_area_1080p @ 2000kbps : 223941 ms -> 214226 ms (4.3%)

  The PSNR performance is changed :
  derf : -0.112%
  yt : -0.099%
  hd : -0.090%
  stdhd :-0.102%

  Change-Id : Ie205ec5325bf92ec5676c243e30ba9d0adca10f2