Configuration and features

Three things are configured separately: the encoder (level and parameters), the stream (what you know about one input), and the Cargo features (which codecs and adapters are compiled in). Decoder settings are covered in decompression and limits.

Choose a level first

EncoderConfig::default() uses level 3. Levels run from -131072 to 22; negative levels trade size for speed, and level 0 is an alias for 3.

use mzstd::{Compressor, EncoderConfig, Level};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let config = EncoderConfig::default().with_level(Level::try_from(19)?);
    let mut encoder = Compressor::new(config)?;
    let compressed = encoder.compress(b"configured payload")?;
    assert!(!compressed.is_empty());
    Ok(())
}

Speed and size depend on your data. The benchmark pages show both for every measured level. Serial output is byte-identical to zstd 1.5.7 at every level, so compressed sizes match the reference.

Encoder settings

EncoderConfig holds settings shared by successive frames:

Explicit parameters override the level as ZSTD_CCtx_setParameter does. Compressor::new validates parameter combinations. CParameter provides a validated parameter-by-ID interface for integrations; see OpenZL integration.

StreamConfig carries an InputSize: unknown by default, or InputSize::Exact(input.len() as u64) when the full length is known. Declared sizes are checked. Session scheduling is part of the byte-identity contract.

Explicit parameters, a checksum and long distance matching on top of a level:

use mzstd::{CompressionParams, Compressor, EncoderConfig, LdmParams, Level, LongDistanceMatching, Strategy};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let config = EncoderConfig::default()
        .with_level(Level::try_from(9)?)
        .with_checksum(true)
        .with_params(CompressionParams::default().with_window_log(24).with_strategy(Strategy::Lazy2))
        .with_long_distance_matching(LongDistanceMatching::Enabled(LdmParams::default()));
    let mut encoder = Compressor::new(config)?;
    assert!(!encoder.compress(b"tuned payload")?.is_empty());
    Ok(())
}

See dictionaries and extended formats for dictionaries, large windows, long distance matching and magicless frames.

Cargo features

The default feature set is std, compression, and decompression.

See codec features and no_std support for the gates and the checked combinations.

Not supported

• External sequence producers
• Legacy (v0.x) frames
• Byte identity with zstd’s multithreaded mode
• Dictionaries in parallel compression and the C ABI