Recherche avancée

Sur d’autres sites (12539)

• Revision 1434f7695b : Skip ref frame mode search conditioned on predicted mv residuals This commit ma

  3 novembre 2014, par Jingning Han

  Changed Paths :
   Modify /vp9/encoder/vp9_pickmode.c

  
  
  Skip ref frame mode search conditioned on predicted mv residuals

  This commit makes the RTC coding mode to conditionally skip the
  reference frame mode search, when the predicted motion vector of
  the current reference frame gives more than two times sum of
  absolute difference compared to that of other reference frames.

  It reduces the runtim by 1% - 4% for speed -5 and -6. The average
  compression performance is improved by about 0.1% in both settings.

  It is of particular benefit to light change scenarios. The
  compression performance of test clip mmmovingvga.y4m is improved by
  6.39% and 15.69% at high bit rates for speed -5 and -6, respectively.

  Speed -5
  vidyo1 16555 b/f, 40.818 dB, 12422 ms ->
  16552 b/f, 40.804 dB, 12100 ms

  nik 33211 b/f, 39.138 dB, 11341 ms ->
  33228 b/f, 39.139 dB, 11023 ms

  mmmoving 33263 b/f, 40.935 dB, 13508 ms ->
  33256 b/f, 41.068 dB, 12861 ms

  Speed -6
  vidyo1 16541 b/f, 40.227 dB, 8437 ms ->
  16540 b/f, 40.220 dB, 8216 ms

  nik 33272 b/f, 38.399 dB, 7610 ms ->
  33267 b/f, 38.414 dB, 7490 ms

  mmmoving 33255 b/f, 40.555 dB, 7523 ms ->
  33257 b/f, 40.975 dB, 7493 ms

  Change-Id : Id2aef76ef74a3cba5e9a82a83b792144948c6a91

• Pre- and postrecording using ffmpeg

  29 juillet 2020, par Sander

  I want to to be able to add a 1-2 second "prerecording" to an output file, like usually is the case on a cctv camera. (a few seconds video from before the alarm is triggered)

  



  I have an idea on how to have it work in a hacky way, but I'm sure there's already a better solution for it.
1 ffmpeg instance records on a 5 second loop outputting a video every 5 seconds
every 5 seconds the oldest file is removed to keep some space available via cron/script/loop/...
When the event is triggered a second ffmpeg instance starts recording for 5 seconds and prepends the last 5-second video from the other process to it's own video and outputs the final video to be prerecording+recording.mp4

  



  This script will run on a sd-powered device, so the less writes the better (but this could be done in a ramdisk)

  



  Is there a better way to do this ?

  


• Revision 139ac07ae7 : Changes quantization tables to improve quality Changes quantization tables so t

  9 juillet 2014, par Deb Mukherjee

  Changed Paths :
   Modify /vp9/common/vp9_quant_common.c

  
  
  Changes quantization tables to improve quality

  Changes quantization tables so that the scale factor diff against
  8-bt version is 1 at the low q end and increases to 4 (16) at the
  high q end for 10 (12) bit versions, using a logarithmic like
  function.

  This change improves the quality gap aginst the no-high-quant version,
  for both 10-bit and 12-bit. 10-bit is virtually similar in performance
  to the no-high-quant version, while the gap for 12-bit is reduced to
  the 0.3% range.

  Change-Id : I08cc329a77aeb19cc232f8e4458f188c6ae65363