FFMPEG Not Accepting Set Variable %~n1

Question

The script is to process images named Image1.png thru Image10.png. The images are resized then the resized image is converted to video with same file name with extension mp4.

Please consider the following script:

FOR %%G IN (Image*.png) DO (


ffmpeg -i %%G -vf scale=4096:-1 -y out.png

Set "FF=%~n1"
ffmpeg -loop 1 -i out.png -c:v libx264 -t 1 -crf 25 -pix_fmt yuv420p -y %FF%.mp4


del out.png
)

The result from this script is:

1. Each Image file is resized and written to file out.png in turn.
2. File out.png is deleted at the end of session.
3. The video created is MP4.mp4 which is from the last .png file being Image9.png

Why is variable %FF% which is %~n1 not being passed through FFMPEG?

Answer 1

The syntax for extracting the file-name part without extension or path for the loop variable of the FOR command is as follows:

Set FF=%%~nG

You need two percent characters inside the loop, rather than one, and the variable is G and not 1 (which is the notation for the first argument of a script).

Another problem is that you need EnableDelayedExpansion for variables to be expanded at execution time rather than at parse time.

This is my test script that demonstrates these points that you can use as a model :

%echo off
setlocal EnableDelayedExpansion
FOR %%G IN (*.png) DO (
  rem echo %%G : %%~nG
  Set FF=%%~nG
  echo !FF!
)

Answer 2

The syntax issue about Set FF=%%~nG is resolved.

But the second problem is not resolve and will be resubmitted to the group.

The script %FF%.mp4 fails to pass which is in:

ffmpeg -loop 1 -i out.png -c:v libx264 -t 1 -crf 25 -pix_fmt yuv420p -y %FF%.mp4