lab-rs

Toolkit and library for reading, writing, and manipulating HTK .lab label files

.lab files are plain-text label files used by HTK and throughout speech and singing-voice tooling for phoneme/word alignments. Each line is a labelled time segment, with times in units of 100 nanoseconds:

0 2500000 sil
2500000 4200000 hh
4200000 6100000 eh
6100000 7800000 l
7800000 9200000 ow
9200000 12000000 sil

The parser handles the common subset of the HTK label format tolerantly: start and end times are optional, an optional numeric score may follow the label text, and blank lines and extra whitespace are ignored.

I tried my best not to make my code look AI-generated since that's apparently something you need to worry about nowadays. Excuse the potential lack of comments and documentation outside this README and docs.rs. And yes, I am bitter about this.

Library

cargo add lab-rs

The library has no dependencies by default. Enable the serde feature for Serialize/Deserialize on all types.

use lab_rs::LabFile;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut lab = LabFile::from_path("hello.lab")?;

    println!("{} labels", lab.len());
    lab.retain(|l| l.text != "sil");
    lab.shift_secs(0.1);
    lab.save("hello-edited.lab")?;

    Ok(())
}

LabFile dereferences to Vec<Label>, so the usual vector and slice methods work directly. It also provides helpers for looking up labels by time, shifting and scaling timestamps, merging adjacent labels, and validating a label sequence. See the documentation for the full interface.

CLI

cargo install lab-rs --features cli

This installs a lab binary that lets you do things like:

lab info hello.lab              # label count, duration, unique labels, sanity checks
lab cat hello.lab               # print with times in seconds (--raw for 100ns units)
lab convert hello.lab --to json # also: tsv, audacity, lab
lab shift hello.lab -- -0.25    # shift all times by -0.25 s (stdout, or -i for in place)
lab scale hello.lab 2.0         # stretch all times by 2x
lab merge hello.lab             # merge consecutive identical labels

License

MIT, see LICENSE.