The boundary-pushing compressors combine algorithms for insane results. Common algorithms include: The Burrows-Wheeler Transform and here – shuffle characters (or other bit blocks) with a predictable algorithm to increase repeated blocks which makes the source easier to compress. Decompression occurs as normal and the result is un-shuffled with the reverse transform. Note: BWT alone doesn’t … Read more
Unfortunately, such a program does not exist. To see why this is so, we need to do a bit of math. First, let’s count up how many binary strings there are of length n. Each of the bits can be either a 0 or 1, which gives us one of two choices for each of … Read more
LZ4 is built to compress fast, at hundreds of MB/s per core. It’s a fit for applications where you want compression that’s very cheap: for example, you’re trying to make a network or on-disk format more compact but can’t afford to spend a bunch of CPU time on compression. It’s in a family with, for … Read more
I am going to add a late answer to this one after spending all day trying to figure out how to get YUV 4:4:4 pixels into x264. While x264 does accept raw 4:2:0 pixels in a file, it is really quite difficult getting 4:4:4 pixels passed in. With recent versions of ffmpeg, the following works … Read more
I just released a small LZW implementation especially tailored for this very purpose as none of the existing implementations did meet my needs. Here is the home page of the project Here is a link to a demo comparing it with LZMA level 1 That’s what I’m using going forward, and I will probably try … Read more
Most generic compression algorithms work with a one-byte granularity. Let’s consider the following string: “XXXXYYYYXXXXYYYY” A Run-Length-Encoding algorithm will say: “that’s 4 ‘X’, followed by 4 ‘Y’, followed by 4 ‘X’, followed by 4 ‘Y’” A Lempel-Ziv algorithm will say: “That’s the string ‘XXXXYYYY’, followed by the same string: so let’s replace the 2nd string … Read more
As correctly answered above, using a “typical” JPEG encoder at quality 100 does not give you lossless compression. Lossless JPEG encoding exists, but it’s different in nature and seldom used. I’m just posting to say why quality 100 does not mean lossless. In JPEG compression information is mostly lost during the DCT coefficient quantization step … Read more