#!/bin/bash
s='frame=48612 fps= 50 q=28.0 size=  113664kB time=00:33:45.42 bitrate= 459.7kbits/s speed=2.09x    
frame=48612 fps= 50 q=28.0 size=  113664kB time=00:33:45.45 bitrate= 459.7kbits/s speed=2.09x    
frame=48613 fps= 51 q=28.0 size=  113664kB time=00:33:45.45 bitrate= 459.7kbits/s speed=2.09x    
frame=48613 fps= 50 q=28.0 size=  113664kB time=00:33:45.47 bitrate= 459.7kbits/s speed=2.09x    
frame=48613 fps= 49 q=28.0 size=  113664kB time=00:33:45.49 bitrate= 459.7kbits/s speed=2.09x    
frame=48614 fps= 50 q=28.0 size=  113664kB time=00:33:45.49 bitrate= 459.7kbits/s speed=2.09x    
frame=48614 fps= 50 q=28.0 size=  113664kB time=00:33:45.51 bitrate= 459.7kbits/s speed=2.09x    
frame=48614 fps= 51 q=28.0 size=  113664kB time=00:33:45.53 bitrate= 459.7kbits/s speed=2.09x    
frame=48615 fps= 50 q=28.0 size=  113664kB time=00:33:45.53 bitrate= 459.7kbits/s speed=2.09x    
frame=48615 fps= 50 q=28.0 size=  113664kB time=00:33:45.55 bitrate= 459.7kbits/s speed=2.09x    
frame=48615 fps= 50 q=28.0 size=  113664kB time=00:33:45.57 bitrate= 459.7kbits/s speed=2.09x    
frame=48616 fps= 52 q=25.0 size=  113664kB time=00:33:45.57 bitrate= 459.7kbits/s speed=2.09x    '
sed -nE 's/.* fps= ([0-9]+).*/\1/p' <<< "$s"