anchor.diff:  
   set /a "keyint=keysecs*framerate"
   
  -echo frame rate: %framerate% fps
  -echo size: %sizereport%
  -echo position: %left% x %top%
  -echo input: %input%
  -echo writing to %FILENAME%
  +:: codec "qtrle" (default)
  +
  +:setcodec
  +set encoptsset=0
  +set encopts=
  +
  +if "%codec%"=="qtrle" (
  +	set encopts=-c:v qtrle
  +	set encoptsset=1
  +	echo Encoder: Quicktime Animation (qtrle)
  +)
  +if "%codec%"=="x264" (
  +	set encopts=-c:v libx264 -preset:v fast -tune:v stillimage -tune:v zerolatency -crf 0
  +	set encoptsset=1
  +	echo Encoder: H.264 (libx264)
  +)
  +
  +if %encoptsset%==0 (
  +	echo WARNING: unknown codec %codec% specified!
  +	set codec=qtrle
  +	goto setcodec
  +)
  +
  +
  +echo Frame rate: %framerate% fps
  +echo Image size: %sizereport%
  +echo Position: %left% x %top%
  +echo Input: %input%
  +echo Writing to %FILENAME%
   echo CWD:
   echo   %cd%
   
  
positive.code: :: found via http://stackoverflow.com/questions/1192476/format-date-and-time-in-a-windows-batch-script
  
  @ECHO OFF
  
  :: parameters
  set framerate=25
  
  set keysecs=60
  
negative.code: ::  -video_size 1920x1200
  ::ffmpeg  -f gdigrab -r 10 -i desktop -pix_fmt yuv444p -c:v libx264 -preset:v baseline -preset:v ultrafast -tune:v stillimage -tune:v zerolatency -crf 0 %FILENAME%
  
  ffmpeg -f gdigrab -framerate %framerate% %sizeopt% -offset_x %left% -offset_y %top% -i %input% %encopts% -g %keyint% %FILENAME%
  
  