I am a newbie to this forum and am hoping I can get some insight and assistance with an issue I am having. I wrote a script that takes all of my captured videos (.avi) and converts them to mp4 using ffmpeg. When I run the script by double clicking the file, it runs good at about 45 FPS using about 85% of my CPU. I created a task in Windows 10 Task Scheduler and when I run the file from there, it only converts between 1.5-2 FPS utilizing only 3% of my CPU and I have no idea why. Obviously, that conversion rate is not acceptable. Here is the script file which also shows all the ffmpeg parameters I have passed in:

@echo off
for %%a in ("D:\Aaron Cirlin\Videos\Captured Movies\*.avi") do 
"C:\Program Files\WinFF\ffmpeg" -y -i "%%a" -itsoffset 0.765 -i "%%a" -map 1:0 -map 0:1 -crf 20.0 -vcodec libx264 -filter:v scale=1280:720 -preset slow -acodec libvo_aacenc -ar 48000 -b:a 128k -coder 1 -flags +loop -cmp chroma -partitions +parti4x4+partp8x8+partb8x8 -me_method hex -subq 6 -me_range 16 -g 250 -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71 -b_strategy 1 -threads 0 "D:\Aaron Cirlin\Videos\Movies\%%~na.mp4" & del "%%a"

Does anyone know why it would that much slower via the Task Scheduler?

Any help would be greatly appreciated.

  • 3
    I think this is related to Windows process management rather than FFmpeg. Better suited to Super User.
    – Gyan
    Aug 29, 2016 at 5:48
  • What's your reason for including everything from -coder to -threads? All of these are default or already covered by your preset and are therefore unecessary or even suboptimal.
    – llogan
    Nov 30, 2016 at 0:35

1 Answer 1


I was able to change the priority level by exporting the task and editing the XML file, then deleting the initial task and re-creating task by importing the edited XML file. Worked like a charm.

  • Be careful with task priorities. You can crash your system.
    – user3643
    Jan 28, 2017 at 20:30

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