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• How to speed up video conversion

  3 février 2021, par Arheisel

  I'm currently working in a project that involves converting large series of .jpg (>6000) into video format. These frames (320x240) are stored in folders at a rate of 2.5fps. Generating a couple of folders every hour that need to be converted ASAP.

  


  For now I've tried copying the folder to a ram disk and using avconv which takes about a minute.

  


  Here is my command :

  


  avconv -threads auto -y -r 2.51 -i %03d-capture.jpg -s 320x240 -r 25 video.mpeg


  


  

  • Could ffmpeg work faster ?

  


  • Is there a way to speed it up ?

  


  • Which video format takes less time to convert to ?

  


  


• FFmpeg accurate speed for x11grab

  21 mars 2017, par Peter Shaw

  Hi I am trying to make a screencast in realtime with ffmpeg on Linux.

  This is my call :

  ffmpeg \
  
  -f x11grab \
  
  -s 1920x1080 \
  
  -r 24 -framerate 24 \
  
  -i $DISPLAY \
  
  -preset ultrafast \
  
  -tune zerolatency \
  
  -pix_fmt yuv420p \
  
  -acodec copy \
  
  -vcodec libx264 \
  
  -b:v 500k \
  
  -crf 0 \
  
  -threads 0 \
  
  -y /data/production/out.mkv \
  
  -an \
  
  -t $LEN

  As far as i can tell this is near accurate and has a decent quality. Maybe there is a better settling, than let me please know.

  As the screen will be captured the timing is not correct. I get a message with something like this :

  frame=  901 fps= 22 q=0.0 size=   66553kB time=00:00:37.50 bitrate=14538.3kbits/s speed=0.905x   

  The Speed will turn around from 0.600x to 1.200x and is never stable to 1x.
  I wonder if it’s possible to get a accurate timing.
  I have to do a 60sec movie that is in speed exactly 100% like the frame-buffer is. Is it possible ?

• Is there a way to speed up audio processing (amix and adelay) in FFMPEG ?

  30 mars 2017, par Nadir

  I’m using, in android application, many ffmpeg amix and adelay filter commands over very small mp3 files (not longer than 3 seconds).
  Unfortunately each adelay or amix command takes between 2 and 4 seconds to execute, which is a lot considering that I should run the same operation for a lot of files.
  Here are two example of commands I’m running :

  amix :

  [-i, input1.mp3, -i, input2.mp3, -filter_complex, amix=inputs=2:duration=longest:dropout_transition=0,dynaudnorm=f=100[aout], -map, [aout], -ac, 2, -c:a, libmp3lame, -q:a, 4, output.mp3]

  adelay :

  [-i, input3.mp3, -filter_complex, [0:a]adelay=1|1, -c:a, libmp3lame, output1.mp3]

  I know in video there is an option (-preset ultrafast) to make the execution faster, is there a way to do the same for audio ?