7 comments

  • wolf550e 8 minutes ago
    From status in readme in github:

    - misa77's format may change unexpectedly as it's still v0.x.y.

    - The decoder assumes that the input is a valid misa77 stream. Invalid input is UB and I offer no guarantees for whatever misa77 does in this case.

    - It's been through some local fuzzing but is not hardened, so treat it as experimental.

  • kazinator 13 minutes ago
    > It offers particularly high decompression throughput on highly compressible files.

    You know, you would expect that this is commonly observed. You'd expect, say, simple RLE (run length encoding) to be like this. It's more expensive to produce output requiring the processing of a large number of RLE opcodes that produce short sequences than one opcode that produces one long sequence.

  • scottchiefbaker 25 minutes ago
    Almost double the decompression speed, *and* a higher compression ratio than LZ4? That's very promising.

    I don't see much in your README that talks about how a developer would integrate misa into their code. I might suggest some basic code samples to help a developer integrate misa decode into their project.

    Congrats, looks like a cool project.

  • logdahl 33 minutes ago
    Nice results, I will keep a watch on this! Would be interesting to see benchmarks vs Oodle compression, I think the most similar one is Selkie?
  • bootlegbilly 1 hour ago
    this is super interesting! im excited to give this a look this afternoon, since I specifically have wanted faster throughout for decompressing maps in a game engine.
    • nonadhocproblem 20 minutes ago
      Hey, glad to hear that you found it interesting.

      misa77 primarily targets textual data (ie. byte-aligned data formats where each byte corresponds to a symbol), so I hadn't tested it on game assets much until now.

      After seeing your comment, I pulled some random assets from Pathfinder WoTR (in fact, Unity compresses them with lz4hc) and DOS2. The gains are much more modest here due to asset data being mostly floats, but level 0 performs decently nevertheless.

      Results on a map asset (WoTR):

        codec       decode      ratio    encode
        misa77 -0   4061 MB/s   61.52%   40.4 MB/s
        misa77 -1   2851 MB/s   59.04%   36.2 MB/s
        lz4         2561 MB/s   62.66%   488 MB/s
        lz4hc -12   2428 MB/s   55.53%   6.23 MB/s
      
      Results on equipment asset (WoTR):

        codec       decode      ratio    encode
        misa77 -0   4675 MB/s   54.33%   48.6 MB/s
        misa77 -1   3752 MB/s   51.96%   40.9 MB/s
        lz4         3101 MB/s   55.21%   497 MB/s
        lz4hc -12   3036 MB/s   47.62%   6.25 MB/s
      
      Results on texture asset (DOS2):

        codec       decode      ratio    encode
        misa77 -0   5546 MB/s   67.99%   47.0 MB/s
        misa77 -1   2991 MB/s   63.79%   31.5 MB/s
        lz4         3602 MB/s   68.53%   623 MB/s
        lz4hc -12   2689 MB/s   59.30%   9.01 MB/s
      
      Note: the benchmarking setup is identical to the intel x86-64 one described in the readme.
  • Sesse__ 31 minutes ago
    Interesting, but if you are not robust to corrupted/malicious data, it is really in a different class of algorithm and it is hard to compare speeds directly.

    From memory, 2505 MB/sec also sounds on the low side for LZ4 on a modern CPU?

    • nonadhocproblem 27 minutes ago
      Someone asked this on encode.su too (see my reply here: https://encode.su/threads/4514-misa77-ridiculously-fast-deco...).

      In short, my decompressor is very simple, and a naive safe version of the decompressor is only about 5% slower than the current unsafe one (and I will add this safe version in v0.3.0).

      As for the raw throughput numbers being low here, it's because Intel Turbo (frequency boost) was disabled for stability, and the CPU was running at a fixed frequency of 2.1 GHz (I've confirmed that the relative performance scales similarly even with Turbo enabled).

    • actionfromafar 19 minutes ago
      You mean some kind of error detection? LZ4 doesn't have that.
      • kzrdude 12 minutes ago
        Have defined behaviour on any input, i.e not causing security issues, memory safety issues on untrusted inputs. Lz4 has this.
  • throwaway74747 33 minutes ago
    What's the Weissman score?