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• ffmpeg .bat script to change frame rate for multiple clips in a folder ?

  3 avril 2020, par Dan

  How do I write a .bat file in Windows 10 that changes the frame rate for multiple mp4 video clips in a folder ? For example ; change the frame rate from 50fps to 25fps (without re-encoding or dropping frames, so that footage is essentially slowed down.)

  



  At the moment these are the commands I've tried using in two separate .bat text files. (I'd like to combine them but don't know how yet).

  



  for %%A IN (*.mp4) DO ffmpeg -y -i "%%A" -c copy -f h264 "%%A.h264"

for %%A IN (*.h264) DO ffmpeg -y -r 25 -i "%%A" -c copy
    "%%A_25.mp4"


  



  Problem is these commands don't replace the file extension type, they append to the existing one, ie. '.mp4' becomes '.mp4.h264' then '.mp4.h264_25fps.mp4', and I can't get the second one to work for some reason.

  



  Any advice appreciated. How do I replace the existing file extensions for a group of clips and combine commands into a single .bat ?

  


• libkvazaar : Set frame rate as a rational number

  15 janvier 2016, par Arttu Ylä-Outinen

  libkvazaar : Set frame rate as a rational number
  Updates libkvazaar to pass the exact frame rate to Kvazaar by setting
  
  the numerator and denominator separately instead of a single floating
  
  point number. The exact frame rate is needed for writing timing info to
  
  the bitstream.
  Requires Kvazaar version 0.8.1.
  Signed-off-by : Arttu Ylä-Outinen <arttu.yla-outinen@tut.fi>
  
  Signed-off-by : Luca Barbato <lu_zero@gentoo.org>
  

  • [DBH] configure
  • [DBH] libavcodec/libkvazaar.c

• How to use libvlc for low-frame-rate rtsp stream decoding

  11 mai 2017, par user1547688

  I am using libvlc for RTSP h.264 bitstream decoding and display in PC. For the best experience (i.e. low latency), I uses the following options

  :file-caching=0
  
  :tcp-caching=0
  
  :rtsp-caching=0
  
  :network-caching=0
  
  :clock-jitter=0
  
  :avcodec-fast

  With these parameters, the latency is acceptable in comparison to the open-source project "ONVIF device manager"(ODM) where FFMPEG is used for decoding.

  When RTSP server deliver low frame-rate RTSP stream, (1 frame/second). These configuration will freeze after displaying a few frames (3-5 frames).

  I have tried 2 different approaches

  1. Disable synchronization by

     :clock-synchro=0

  This will enable the decoding process to go on, however, an accumulated period of time lagging could be observed.

  2. Use network-cache

  My experiments shows that

  :network-caching=1200

  Will make decoding go smoothly, however, the latency is over 1-2 second in comparison to ODM.

  Is there a way to handle the low frame rate issue in libvlc without providing such big latency ?