ffmpeg -ss 00:23:00 -i input.mkv -frames:v 1 out1.jpg
NOTE: This extracts a single frame at the exact 23:00 time mark.
ffmpeg -i input.mp4 %02d_out.jpg -frames:v 1
NOTE: Write a single image.
ffmpeg -i input.mp4 %02d_out.jpg
NOTE: The output needs to be an image sequence pattern.
ffmpeg -i $(video_in) -vf scale=-1:$(resize_width),fps=$(FPS) $(path)/$(name)_%02d_out.jpg