FFMPEG reduce fps for live h264 stream with direct copy

Question

I found different articles on changing the fps with ffmpeg but none of them is matching for my exact purposes.

There is an ffmpeg command like below:

ffmpeg -i RTSPCAMERAPRODUCEH264 -c:v copy -an -movflags +frag_keyframe+empty_moov -f mp4

This will remux my camerastream to fragmented mp4 perfectly.

Is there a way to force ffmpeg to lower the FPS to save bandwidth?

Ie camera streams 30fps, it needs 1Mbps for fmp4 (sample numbers:):

I'd like to know if it's possible to lower the FPS and get an output stream for which 500kbps (50% of original is enough) without re-encoding.

ffmpeg -r 1 -i RTSPCAMERAPRODUCEH264 -c:v copy -an -movflags +frag_keyframe+empty_moov -f mp4

and

ffmpeg -i RTSPCAMERAPRODUCEH264 -c:v copy -an -movflags +frag_keyframe+empty_moov -r 1 -f mp4

do not seem to work.

Answer 1

A temporally coded video stream (like one with H264 codec) cannot arbitrarily drop intermediate packets, so this is not possible. Only whole or trailing part of GOPs may be dropped.