I am using Raspberry pi 4B's v3 camera to record teacher's teaching in classroom. I am using following two command to record h264 images and wav voice:
libcamera-vid -t 7200000 -o picture.h264 arecord -d 7200 -D hw:0,0 -f S32_LE -r 16000 -c 2 voice.wav
After that, I merge them into mp4 file by ffmpeg command:
ffmpeg -i picture.h264 -i voice.wav -c:v copy -c:a aac -strict experimental teacher.mp4
I made the screen shot of the video it looks like below:
How to make the whiteboard in the picture to occupy whole screen by autofocus-window and lens-position parameters?