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• How to specify the GPU to be used by nvenc in ffmpeg [closed]

  25 septembre 2022, par Gio

  I'm using compiled ffmpeg executable for transcoding mpegts stream from h264 to h265 with nvenc. I have two nvidia Graphics Cards installed on my motherboard : GeForce GTX 690 and Tesla k-10. Is there any codec specific parameters for nvenc to choose the GPU I want to encode with ?

  


• ffmpeg encode single input to multiple outputs simultaneously

  23 août 2019, par jippyjoe4

  Suppose I have a single input file that I would like to transcode into two different formats (ProRes and Mp4). Individually, the two commands I would use look like this :

  To convert it to mp4, I would use :

  ffmpeg -i in.mov -c:v libx264 -x264-params "nal-hrd=cbr" -b:v 30M -minrate 30M -maxrate 30M -bufsize 60M "out.mp4"

  And to convert it to ProRes, I would use :

  ffmpeg -i in.mov -c:v prores_ks -profile:v 2 -bits_per_mb 540 -vendor apl0 -pix_fmt yuv422p10le "out.mov"

  Rather than running these two commands sequentially to do the conversion, I think ffmpeg can encode to both formats simultaneously and save time. I’ve read this page (https://trac.ffmpeg.org/wiki/Creating%20multiple%20outputs), but I find it confusing. I tried something along the lines of :

  ffmpeg -i "in.mov" \
  
   -c:v libx264 -x264-params "nal-hrd=cbr" -b:v 30M -minrate 30M -maxrate 30M -bufsize 60M "out.mp4" \
  
   -c:v prores_ks -profile:v 2 -bits_per_mb 540 -vendor apl0 -pix_fmt yuv422p10le "out.mov"

  But attempting to run this just gives me the error :

  Unable to find a suitable output format for '\

  I don’t quite understand what’s going wrong. How can I encode my single input to both outputs simultaneously ?

• FFmpeg : How do i use this script to concatenate incoming segments

  5 juillet 2017, par NGage

  I’d like to use this script but i don’t know how it should be applied. I was going to use it for encoding tv-shows and be able to start encoding as i had cut out the first segment.

  According to the ffmpeg-wiki (where i found the script) it says : "Concatenation becomes troublesome, if next clip for concatenation does not exist at the moment, because decoding won’t start until the whole list is read. However, it is possible to refer another list at the end of the current list :"

  Bear in mind that i dont know to much about bash

  #!/bin/bash
  
  
  
  fn_concat_init() {
  
  echo "fn_concat_init"
  
  concat_pls=`mktemp -u -p . concat.XXXXXXXXXX.txt`
  
  concat_pls="${concat_pls#./}"
  
  echo "concat_pls=${concat_pls:?}"
  
  mkfifo "${concat_pls:?}"
  
  echo
  
  }
  
  
  
  fn_concat_feed() {
  
  echo "fn_concat_feed ${1:?}"
  
  {
  
      >&2 echo "removing ${concat_pls:?}"
  
      rm "${concat_pls:?}"
  
      concat_pls=
  
      >&2 fn_concat_init
  
      echo 'ffconcat version 1.0'
  
      echo "file '${1:?}'"
  
      echo "file '${concat_pls:?}'"
  
  } >"${concat_pls:?}"
  
  echo
  
  }
  
  
  
  fn_concat_end() {
  
  echo "fn_concat_end"
  
  {
  
      >&2 echo "removing ${concat_pls:?}"
  
      rm "${concat_pls:?}"
  
      # not writing header.
  
  } >"${concat_pls:?}"
  
  echo
  
  }
  
  
  
  fn_concat_init
  
  
  
  echo "launching ffmpeg ... all.mkv"
  
  timeout 60s ffmpeg -y -re -loglevel warning -i "${concat_pls:?}" -pix_fmt 
  
  yuv422p all.mkv &
  
  
  
  ffplaypid=$!
  
  
  
  
  
  echo "generating some test data..."
  
  i=0; for c in red yellow green blue; do
  
  ffmpeg -loglevel warning -y -f lavfi -i testsrc=s=720x576:r=12:d=4 -pix_fmt 
  
  yuv422p -vf "drawbox=w=50:h=w:t=w:c=${c:?}" test$i.mkv
  
  fn_concat_feed test$i.mkv
  
  ((i++));
  
  echo
  
  done
  
  echo "done"
  
  
  
  fn_concat_end
  
  
  
  wait "${ffplaypid:?}"
  
  
  
  echo "done encoding all.mkv"