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• FFMpeg : h.264 to h.264 with the same quality and bitrate

  6 octobre 2018, par Vasya

  I have a some mp4 video file with 1 video stream, encoded in h.264 and with bitrate XYZ kb/s, for example, let’s have a name xxx.mp4 (not a home video, just a film). Its frames looks like some video data and two horizontal black strips on top and bottom side. On one of those strips there is some text, like "Our XXX super videos". I want to draw a black box on those text with dratext filter. Obviously, that processed video must be with almost same bitrate and same file size. But which options I must put in ffmpeg.exe to do so ? CRF 0 ? CRF 18 ? b:v XYZ ? Two-pass ? VBV with crf 23 -maxrate XYZ -bufsize 2M ?
  I want get video data without any losses in comprasion with original mp4 file.

• When I run `ffmpeg` in the background, how do I prevent `suspended (tty output)` ?

  4 novembre 2017, par Jim DeLaHunt

  I have a sh script which calls ffmpeg on several files. When I try to run this script in the background, redirecting output to a file, the job starts but then immediately suspends :

  % bin/mp3convert.sh path/a/b &> ~/tmp/log.txt &
  
  [1] 93352
  
  % 
  
  [1]  + suspended (tty output)  bin/mp3convert.sh path/a/b &> 

  If I try making the script continue in the background, it immediately suspends again :

  % jobs
  
  [1]  + suspended (tty output)  bin/mp3convert.sh path/a/b &> 
  
  % bg %1
  
  [1]  + continued  bin/mp3convert.sh path/a/b &> 
  
  % jobs
  
  [1]  + suspended (tty output)  bin/mp3convert.sh path/a/b &> 
  
  %

  I can make the script continue, by making it the foreground, but then my terminal is occupied until the script finishes. That means I don’t get the benefit of running the script in the background.

  % 
  
  [1]  + suspended (tty output)  bin/mp3convert.sh path/a/b &> 
  
  % fg %1
  
  [1]  + continued  bin/mp3convert.sh path/a/b &> 
  
  % # much time passes with no activity on terminal, then script finishes
  
  %

  How can I make the script run cleanly in the background ?

  A simplified version of my script is :

  #!/bin/sh
  
  # mp3convert.sh
  
  for f in "$1"/*.flac; do
  
      ffmpeg -i "$f" -c:v copy path/to/dest/"$(basename -s .flac "$f")".mp3
  
  done

  I am running on Mac OS X 10.11.6, with ffmpeg version 3.4 supplied by MacPorts.

  An apparently related question is why do I get “Suspended (tty output)” in one terminal but not in others ?. The answer there is to set the terminal state with stty -tostop. That didn’t help me ; I already had that state set.

• Possible to change progress output interval in ffmpeg ?

  12 septembre 2021, par Thorts

  Example output :

  


  frame= 1234 fps= 25 q= 0.0 size= 10321 time = 00:02:12:31 bitrate= 301.1kbits/s speed=7.21x


  


  This output is updated around 4-5 times per second in the terminal.

  


  Is it possible to to change the interval for this status update ? Like once per second or once every 10 seconds.

  


  Reason being better overview when queueing several ffmpeg-jobs in a row.
Searched for 'interval' in the documentation but didn't find anything relevant.