How to get bitrate of an MP3?

[truita]

I've been trying to get the bitrate of a MP3 file; so far I've tried this:

let bitrate = match (
        track.codec_params.sample_rate,
        track.codec_params.bits_per_coded_sample,
    ) {
        (Some(n), Some(b)) => n * b,
        _ => return Err("couldn't determine bitrate"),
    };

However mp3 tracks do not have bits_per_coded_sample.

Maybe I'm doing this wrong and it is in the metadata or somewhere else but I can't seem to find anything