use mp3lame_encoder::{Builder, Id3Tag, DualPcm, FlushNoGap};

let mut mp3_encoder = Builder::new().expect("Create LAME builder");
mp3_encoder.set_num_channels(2).expect("set channels");
mp3_encoder.set_sample_rate(44_100).expect("set sample rate");
mp3_encoder.set_brate(mp3lame_encoder::Bitrate::Kbps192).expect("set brate");
mp3_encoder.set_quality(mp3lame_encoder::Quality::Best).expect("set quality");
mp3_encoder.set_id3_tag(Id3Tag {
    title: b"My title",
    artist: &[],
    album: b"My album",
    year: b"Current year",
    comment: b"Just my comment",
});
let mut mp3_encoder = mp3_encoder.build().expect("To initialize LAME encoder");

//use actual PCM data
let input = DualPcm {
    left: &[0u16, 0],
    right: &[0u16, 0],
};

let mut mp3_out_buffer = Vec::new();
mp3_out_buffer.reserve(mp3lame_encoder::max_required_buffer_size(input.left.len()));
let encoded_size = mp3_encoder.encode(input, mp3_out_buffer.spare_capacity_mut()).expect("To encode");
unsafe {
    mp3_out_buffer.set_len(mp3_out_buffer.len().wrapping_add(encoded_size));
}

let encoded_size = mp3_encoder.flush::<FlushNoGap>(mp3_out_buffer.spare_capacity_mut()).expect("to flush");
unsafe {
    mp3_out_buffer.set_len(mp3_out_buffer.len().wrapping_add(encoded_size));
}
//At this point your mp3_out_buffer should have full MP3 data, ready to be written on file system or whatever