Show HN: Overfitted a 900KB Transformer to Compress a 100MB CSV into 7MB

107 points | by spidy__ 4 days ago

23 comments

  • userbinator 1 day ago
    Fabrice Bellard may have been the first to do this, 7 years ago: https://news.ycombinator.com/item?id=27244004
    • spidy__ 1 day ago
      Yeah yeah, I just found the idea kinda interesting so wanted to implement it
      • touisteur 1 day ago
        Keep exploring and writing (please ?) ! Love seeing people explore ... even after Fabrice Bellard had a go at it.
        • spidy__ 1 day ago
          Ofcourse, am doing this just because I enjoy it.

          While we are on the discussion I have mentioned a question at the end of the discussion around an assumption am trying, can you please check it out and see if you have any suggestions?

          Would be awesome if someone can validate or help.

        • pentaphobe 1 day ago
          Hope this isnt too spicy a take, but i find it a bit disingenuous to use language that implies invention (and with no mention or citation of previous work), only to switch to dismissive language when someone notes a predecessor who you've apparently already heard of
      • SubiculumCode 1 day ago
        What do those compress to with conventional approaches? For comparison.

        I am curious. A classic machine learning ensemble approach is to overfit a collection of small models then bag them (e.g. voting) allowing the models to generalize.

        I'm sure someone's tried to overfit a bunch of transformers for compression like this, then bag them to see how well it does?

      • 7373737373 4 days ago
        What does it compress the full 1GB file to? http://prize.hutter1.net/
        • spidy__ 4 days ago
          I tried it on a enwik9 100 mb slice and was able to compress it to 20 mb + 900kb transformer so 21mb.

          I know the top submission was able to get it to 13 mb.

          Still trying some ideas to get better compression.

          • gravypod 1 day ago
            Since you know the size of the file beforehand you may be able to overfit some kind of text diffusion model instead of a transformer? May allow you to partially correct the model output using some other method and then fill in the blanks that were wrong from previous generations.
            • spidy__ 1 day ago
              Oh, sounds interesting. I hadn't considered using a diffusion model for this. My current approach generates the document byte by byte with an autoregressive transformer, so I'm curious how a diffusion model would improve memorization or reconstruction quality.

              Can you point me to something that i can read? I really wanna try this approach , diffusion model does sounds interesting for compression.

            • atiedebee 1 day ago
              Which slice? The large text compression benchmark uses enwik8 for a "smaller" input that is easily reproducible. The predictability of enwik9 can vary significantly depending on where in the file you are, as shown by Matt Mahoney https://www.mattmahoney.net/dc/textdata.html
            • purple-leafy 1 day ago
              Thanks for the link!
              • cellular 1 day ago
                Maybe everyone should compress the 1st 100MB worth of digits of pi, for an apples-to-apples comparison?

                Edit: oh wait that's too easy. Need to generate /publish random digits so everyone can use it.

                • branc116 1 day ago
                  Compressor: Output an empty file.

                  Decompressor: Take any old algorithm for finding digets of pi, find first 100M of them, print them.

                  Compression ratio of 0! :0

                  • saulpw 1 day ago
                    random digits aren't compressible though?
                    • SV_BubbleTime 1 day ago
                      Random digits are compressible though.

                      Random data does not mean it does not match a pattern in your dictionary for example.

                      • gnabgib 1 day ago
                        No.. they're not. Do you understand random (the apparent or actual lack of definite patterns or predictability[0]) or compression (reduces bits by identifying and eliminating statistical redundancy[1])?

                        [0]: https://en.wikipedia.org/wiki/Randomness

                        [1]: https://en.wikipedia.org/wiki/Data_compression

                        • gcr 1 day ago
                          I could write a program to generate the first 100MB of pi in a couple kilobytes. That certainly counts as “data compression” but isn’t useful outside this particular problem instance.
                          • echoangle 12 hours ago
                            Yeah, because the digits of pi aren’t random.
                          • IncreasePosts 1 day ago
                            Over infinite runs, you can't compress random data, but that doesn't mean any finite string of random digits is incompressible
                            • thin_carapace 1 day ago
                              by this definition, a random dataset could apparently present no patterns, while presenting non apparent patterns.
                              • ufocia 1 day ago
                                Sounds like presenting no patterns, apparently or otherwise, would be a pattern in itself.
                                • saulpw 1 day ago
                                  That's like a teenage "i am very smart" thinking. I mean sure we can look at some string of random bits and say "that looks random" but you can't just generate any old string of random bits to replace it (which would be the only 'pattern' that could be leveraged for compression here). If it's encrypted it'll also appear random, and therefore not be compressible, but you have to encode every byte exactly or the message won't be decryptable.
                    • jmspring 1 day ago
                      The model is the important part, a huffman code or adaptive huffman or other sorts of encoders would be much better on a dataset based on the model. You need the model to also decode. And on a dataset of sufficient size, embedding the model and the benefit of it's memorization of the file can be offset.

                      A non-general compression algorithm (model - I don't mean a distinct llm, but "modeling data") targeted at a specific dataset will always do better than a general algorithm.

                      The reason I mentioned the "encoder" doesn't matter - arithmetic coding, for the data it is presented, will beat huffman/adaptive huffman every day, but it's the model that is where the real "compression" comes into play.

                      I've implemented enough "coders" over the years, including arithmetic for both commercial and research purposes (was a student of Glen Langdon).

                      • whacked_new 1 day ago
                        Somewhat related is stavros's method to compress 500KB to something like 50 bytes https://www.stavros.io/posts/compressing-images-with-stable-...

                        main drawback is that it's not lossless ;-)

                        but this is great. I hope this actually becomes a format that wraps the weights and transformer module (maybe this can also be NAS-optimized too?). Maybe it would even work for video?

                        It's like calling gzip but instead of compression level you choose kolmogorov complexity level

                        • isoprophlex 1 day ago
                          > There are some minor kinks that need to be worked out, such as the fact that each image takes around a day to generate on mobile, but this is more than acceptable in certain domains. Website visitors, for example, are well-accustomed to such loading times, and would barely notice any difference.

                          Just amazing, wow

                          • userbinator 1 day ago
                            Maybe it would even work for video?

                            While clearly satirical, it's definitely quite thought-provoking from various angles including the basis of information, representation of data, and even copyright. It's like watching a movie, writing a book based on it, and then making another movie based on that book.

                          • Three questions:

                            1. How much was AI used to generate documentation for this project?

                            2. The 100MB CSV data sources are not provided in the repo so it doesn't seem possible to reproduce your results. The enwik9 dataset says it is a "slice" of the larger data set, and there are many NYC taxi trip record datasets that exist. Can you provide the datasets used to generate your results?

                            3. I am surprised to see performance comparisons only between your transformer and WinZIP. What were your results when comparing your transformer to more modern approaches like LZMA2 (level 9), BZIP2 and ZPAQ (max effort)?

                            • spidy__ 1 day ago
                              1. I wrote the content as what i want to mention in the documentation and just used AI to polish it so that its easy to understand, is it hard to understand the documentation right now?

                              2. Have added the link for downloading both the enwik9 slice and the nyc dataset. Apologies I forgot to add it.

                              You can get it from here - https://github.com/samyak112/pym-particles/blob/main/README....

                              3. Other than zip i tested it with zstd19, and now that you mentioned LZMA2 and BZIP2

                              I got results on enwik9 100mb slice as

                              zstd - 28mb bzip2 - 30mb lzma2 - 26mb

                              I will mention these and results from ZPAQ in the readme for both files, thanks for pointing them out!!!

                              But the thing is this neural compression approach cant be used right now, as it takes hours to compress and de compress a 100mb file so not really usable and more of a fun project.

                              • Appreciate the followup!!!

                                There were a few tells of AI based on my use of AI for personal projects, especially the end section where it says "what I tried that didn't work", I've seen Claude put sections like that in the documentation.

                                Big thanks for linking the datasets. Here's my results from ZPAQ (max effort):

                                ./zpaq.exe add archive.zpaq nyc_taxi_dataset_100mb_slice.txt -m5

                                Time: 218 seconds

                                Final size: 9.57MB

                                ./zpaq.exe add archive.zpaq enwik_9_slice_100mb.txt -m5

                                Time: 199 seconds

                                Final size: 20.46MB

                                So, your approach is comparable to ZPAQ for the wiki dataset and achieves a better compression ratio than ZPAQ with the taxi dataset. Cool!

                                Bit of a tangent but if you're curious there's an interesting writeup from a few years back that compares lossless text compression algorithms at various effort levels (speed vs compression ratio). I read it recently which prompted all of my questions

                                https://giannirosato.com/blog/post/lossless-data-comp/

                                • spidy__ 1 day ago
                                  Ohh that "what I tried that didn't work" was a section that I specifically wrote myself (and then polished with AI) because I wanted to document what are the different approaches I tried to compress more but failed.

                                  Also thanks for the reference looks like a interesting read.

                                • IncreasePosts 1 day ago
                                  These algorithms let you specify a compression level - please note in the docs which you used. The window size can also be adjusted. Zstd might default to 4, which is "goodish compression but fast"
                            • fennecbutt 9 hours ago
                              Given it's an overfitted transformer isn't is still terribly inaccurate/is liable to add random bytes here and there?
                              • spidy__ 9 hours ago
                                If I were only using a transformer that would have been true, but we use arithmetic coding alongside our transformer to fix those mistakes (layman terms). You can read about arithmetic coding, its a pretty cool topic.
                              • VorticonCmdr 1 day ago
                                Great work. Just Yesterday I thought about LLMzip and asked myself if this is something which could vastly improve HTML compression when done at Google scale and shipped with browsers. I haven't done any research though.
                                • spidy__ 1 day ago
                                  I mean neural compressors provide great compression, BUTT the issue is they are really slow like in my project it takes around 45 minutes for de compression of 100 mb so I doubt if it would be useful, also using a transformer in user's browser sounds like a heavy task.
                                • purple-leafy 1 day ago
                                  Dumb question: can you train a model to predict the next byte of ANOTHER MODEL

                                  So apply this same logic to compressing a bigger model within a smaller model

                                  I know this is absolutely regarded, but humour me please

                                  • anyg 1 day ago
                                    Not dumb at all. It's a whole field of active research - Speculative Decoding. A recent paper goes one level deeper with Speculative Speculative Decoding - https://arxiv.org/abs/2603.03251
                                    • r-w 15 hours ago
                                      Is model distillation also related?
                                      • purple-leafy 1 day ago
                                        Oh man awesome! I’m so S-M-R-T

                                        Compression is such an interesting field

                                      • userbinator 1 day ago
                                        If there's any redundancy in the model that can be compressed (parallel to how RLE is used to compress the static Huffman tree in FLATE) that's possible, but it's not necessary if the model is being trained on the input dynamically, like what Bellard's NNCP does.
                                      • rtpg 1 day ago
                                        I've had this idea of building a codec that would similarly overfit to specific images. But the codec itself would not be a fixed size transformer... instead you could just mess around with the sizing to get better quality/smaller size.

                                        So the codec would be something like: <header describing image size + transformer layer shape> <transformer data itself>

                                        I've seen experiments where people have a "fixed" pipeline but I think having something more dynamic would work quite well.

                                        • dvt 1 day ago
                                          Likely doable with metaparameter tuning (used to work on a team with data scientists that were routinely doing this in various situations). Seems like a cool idea.
                                        • tae0086 2 days ago
                                          Neat approach. Since the 900KB model ships with the compressed file, is there a file size below which the model overhead just eats the gains? Curious where the crossover is.
                                          • spidy__ 2 days ago
                                            For the model overhead to become significant enough to eat into the gains, the file size would need to be fairly small, right? I assumed nobody would use this for compressing anything below 100 MB.

                                            I tested with 100 MB files because anything larger takes a long time to evaluate. The actual target was at least 1 GB, and in that case I would use a 100 MB model (Shannon entropy rules).

                                            I also tried it on a 100 MB Photoshop file and was able to compress it down to 45 MB, whereas ZIP could only get it down to 60 MB. So yeah still not losing gains.

                                          • jxmorris12 1 day ago
                                            Lo and behold, a nice arithmetic coding implementation that wasn't written by an LLM! A sight for sore eyes – a treat, even. Looks like it was written by someone else though.

                                            Check it out: https://github.com/samyak112/pym-particles/blob/main/arithme...

                                            • spidy__ 1 day ago
                                              Ohh yeah , I took it from Project Nayuki as mentioned in the file as well, i tried to pip install it but there were some issues so just took the file and kept the copy right as it is.

                                              Its not an issue is it? I am not sure.

                                            • test1072 1 day ago
                                              So has anyone tried to you know for example keep constant weights base model and just transmit the data, might be better compression
                                              • spidy__ 1 day ago
                                                I might be confused by the question, but I overfit the model on a single file and then transport the model along with the arithmetic coding file. There have been ideas where you generalize a model (constant weights) and then pass the arithmetic coding file along with it. So that way you only pass the arithmetic coding file.

                                                BUT my model size is just 900KB (for 100mb file atleast) so it is negligible

                                              • purple-leafy 3 days ago
                                                That’s so awesome! I want to try something similar. I’ve been going crazy with compression work. I reckon I can beat that prize link
                                                • spidy__ 2 days ago
                                                  Reallly?? So have you published something so far? Can i read something? Sounds like you got some interesting ideas.
                                                  • purple-leafy 2 days ago
                                                    I will be showcasing something on hackernews soon! Basically I found a way to “compress” a multiplayer game state from ~100KB+ to ~1KB

                                                    But it’s only for the game I’m building and it’s not pure compression work, I had to do some tricky things

                                                    • purple-leafy 1 day ago
                                                      And just for comparison, my absolute best compression method managed to get down to 10s of KB, but the real unlock got to the ~1KB figures. Note these numbers are ALL post-compression numbers. This is not raw data vs compressed data. The ~100KB figure IS POST COMPRESSION.

                                                      For context these numbers are for a grid based game where players can perform 4 actions per second, and the numbers I’m sharing are for 30 minutes of gameplay with anywhere from 2-1024+ players (human players) playing simultaneously

                                                      So if you do the math, my compression feat is effectively ~99% compression on naive best case. And if you compare it to the raw data, it’s closing in on an even higher number than that I haven’t done the math but the raw data is another factor of 10 greater than ~100KB so the “compression” versus raw data is ~99.9%

                                                      It sounds absolutely bullshit I know :D

                                                      But I will be posting a blog post soon once I release the game.

                                                      I do compression in quotes because it’s not a pure compression feat, the 99%+ feat is effectively being clever about what actually requires compression to achieve the same outcome

                                                      • andai 1 day ago
                                                        I was working on a multiplayer game a while ago, and one of the iterations of the netcode was "thin client" where clients just sent input, server simulated the game, and it dumped world state onto the pipe at 60hz. I didn't ship that version but I estimated a $3000 bandwidth bill with that approach!

                                                        I started looking into diffing the state, compression, etc... until I realized, wait a minute! My player movement is linear so I only need a packet for start and stop! And so I achieved near infinite efficiency improvement :)

                                                        I think the word is... a specialized solution can beat a general one.

                                                        Also, "remembering what the program actually needs to do, and just making it do that"... I de-pessimized the netcode: https://youtube.com/watch?v=pgoetgxecw8

                                                        • purple-leafy 1 day ago
                                                          $3000 bill wow!!

                                                          Clever insight :) yes a specialised solution usually wins! Good effort

                                                          Did you end up publishing your game?

                                                          • andai 22 hours ago
                                                            My game has been in development hell for several years. I've worked out most of the single-node issues and now I'm working out how to scale it to multiple nodes. (It is embarrassingly parallel, but I am embarrassingly stupid!)

                                                            Meanwhile I'm learning how to ship a trivial single player game -- I went with Pong, and it turns out polishing Pong and getting it ready for mass consumption is a surprisingly labor-intensive endeavour (yes, even with the fabled miracle machine assistants!)

                                                            But, it should probably be online by the end of July. Like, for real this time :)

                                                            What are you working on?

                                                            • purple-leafy 11 hours ago
                                                              I hope you can get around to shipping!

                                                              I’m working on a game engine/platform and my first game on the engine.

                                                              Lots of compression work so that I can fit the games into qr codes which I’m super stubborn about achieving and finally achieved for 30 minute+ games for N number of players

                                                        • spidy__ 1 day ago
                                                          Sounds interesting man, soo am a bit confused maybe but can you run this on enwik9?
                                                          • purple-leafy 1 day ago
                                                            Probably not lol, it’s very specific to PvP multiplayer games, tested on my own game. But maybe I can extract the core concept to enwiki9 but I doubt it
                                                  • totetsu 1 day ago
                                                    if first bit is 1 then decompress to a picture of my cat, else its just Huffman
                                                    • IncreasePosts 1 day ago
                                                      Isnt this what auto encoders are for?
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