You can use mkvtoolnix, then go to -> output, and -> splitting -> by parts based on timestamps -> and there you can write the beginning and the end of the poart you want extract (without spaces: like 1:02:07-1:04:40, for example).
You can use this code:
ffmpeg -i [nameofthevideo] -r 10 -f image2 image-%3d.jpeg
where 10 after -r is the number of images per second. So you can change it, according to your needs.
It’s better use (one of) the following codecs for encoding
so Avidemux will be able to optizmize the CPU usage and will be much faster. And the CPU temperature will be lower.