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• loop ffmpeg command through sets of subfolders and process one folder at a time

  23 octobre 2022, par Ashraf El-Madhoun

  I have this script on .bat file that will process any .mp4 file and create a new one with same name but adds -no-logo after the name for each video file

  


  The problem is that I have 150 folder each has video files that I want to run this script on, is there a way to run it on each folders one by one, and do the same task

  


  script

  


  for %%a in (".mp4") do ffmpeg -i "%%a" -filter:v "crop=1280:700:0:0" -c:a copy "%% na-old.mp4"
for %%a in (".mp4") do ffmpeg -i "%% na-old.mp4" -vf scale=1280:720,setsar=1:1 "%% na-no-Logo.mp4"
for %%a in ("*.mp4") do del "%% na-old.mp4"

  


  I don't want it to run 150 time at once, this will kill my PC, I want it to go one folder at a time

  


• How make audio to start from the specified point in the video and last specified amount of time

  5 avril 2022, par Vuqar Samed

  Lets say I have sample video named "samplevideo" and sample audio named "sampleaudio". I want to replace the audio of the samplevideo with the sampleaudio starting from 5 sec to 12 sec. Until 5 sec mark the video audio won't change, then sampleaudio starts and lasts for 7 sec.

  


  I tried to come up with ffmpeg command that solves this problem :

  


  ffmpeg -i samplevideo.mp4  -i sampleaudio.aac -ss 20 -map 0:v  -map 1:a -c:v copy output.mp4


  


  Problem :
  
It cuts video starting from 20 sec time mark. What I want is to persist the video and the original audio stream until it hits desired time mark and then use sampleaudio until desired end time.

  


  I would appreciate any help.

  


• lavu/timer : use time for AV_READ_TIME on RISC-V

  15 août 2023, par Rémi Denis-Courmont

  lavu/timer : use time for AV_READ_TIME on RISC-V
  So far, AV_READ_TIME would return the cycle counter. This posed two
  
  problems :
  
  1) On recent systems, it would just raise an illegal instruction
  
     exception. Indeed RDCYCLE is blocked in user space to ward off some
  
     side channel attacks. In particular, this would cause the random
  
     number generator to crash.
  
  2) It does not match the x86 behaviour and the apparent original intent
  
     of AV_READ_TIME in the functional code base (outside test cases).
  So this replaces the cycle counter with the time counter. The unit is
  
  a platform-dependent constant fraction of time, and the value should be
  
  stable across harts (RISC-V lingo for physical CPU thread).
  

  • [DH] libavutil/riscv/timer.h