Function try_parse_duration 

pub fn try_parse_duration(string: &str) -> Option<f64>

Example

use async_ffmpeg_sidecar::log_parser::try_parse_duration;
let line = "[info]   Duration: 00:00:05.00, start: 0.000000, bitrate: 16 kb/s, start: 0.000000, bitrate: N/A\n";
let duration = try_parse_duration(line);
assert_eq!(duration, Some(5.0));

Unknown duration

use async_ffmpeg_sidecar::log_parser::try_parse_duration;
let line = "[info]   Duration: N/A, start: 0.000000, bitrate: N/A\n";
let duration = try_parse_duration(line);
assert_eq!(duration, None);