Compression Strategy

MediaGit employs intelligent compression based on file type and size to minimize storage while maintaining performance.

Algorithms

zstd (Default)

• Speed: 100-500 MB/s compression, 500-2000 MB/s decompression
• Ratio: 2-3x for binaries, 5-10x for text
• Use: Default for all file types

brotli

• Speed: 10-50 MB/s compression, 200-400 MB/s decompression
• Ratio: 3-5x for binaries, 10-20x for text
• Use: Text and code files when size matters more than speed

delta (Zstd Dictionary Delta Encoding)

• Algorithm: Zstd dictionary compression (chunk-level delta via mediagit-versioning)
• How: Base chunk serves as a raw zstd dictionary (level 19) to compress target chunk
• Ratio: 33–83% reduction for updated files (type-dependent; validated March 2026)
• Use: Large files with incremental changes

Algorithm Selection

#![allow(unused)]
fn main() {
fn select_algorithm(path: &Path, size: u64) -> CompressionAlgorithm {
    match path.extension().and_then(|s| s.to_str()) {
        // Already compressed (store as-is)
        Some("mp4" | "mov" | "mkv" | "avi") => None,
        Some("jpg" | "jpeg" | "png" | "webp") => None,
        Some("mp3" | "aac" | "m4a") => None,

        // Lossless audio (zstd Best — uncompressed, good ratio)
        Some("flac" | "wav" | "aiff") => Zstd,

        // Text and code (brotli for better ratio)
        Some("txt" | "md" | "rs" | "py" | "js" | "ts") => Brotli,

        // Large binaries (zstd + delta)
        Some("psd" | "psb") if size > 10_MB => ZstdWithDelta,
        Some("blend") if size > 10_MB => ZstdWithDelta,
        Some("fbx" | "obj") if size > 10_MB => ZstdWithDelta,

        // Default
        _ => Zstd,
    }
}
}

Compression Levels

Fast (Level 1)

• zstd: ~150 MB/s, 2x ratio
• Use: Quick commits, local repos
• Command: mediagit config compression.level fast

Default (Level 3)

• zstd: ~100 MB/s, 2.5x ratio
• Use: Balanced performance
• Command: mediagit config compression.level default

Best (Level 19)

• zstd: ~10 MB/s, 3.5x ratio
• Use: Archival, cloud storage (bandwidth limited)
• Command: mediagit config compression.level best

Performance Benchmarks

Verified via standalone deep test suite (v0.2.6-beta.1, 2026-04-03).

Configuration

Repository-Level

# .mediagit/config.toml
[compression]
algorithm = "zstd"
level = 3        # zstd: 1 (fastest) – 22 (best compression)
min_size = 1024  # bytes; files smaller than this skip compression

Per-File Override

[compression.overrides]
"*.psd" = { algorithm = "zstd", level = 22 }
"*.txt" = { algorithm = "brotli", level = 6 }
"*.mp4" = { algorithm = "none" }

Related Documentation

• Delta Encoding
• Object Database (ODB)