The French Programmer Whose C Code Stunned the World

Executable compression (LZEXE)

At age 17 Bellard wrote LZEXE, an executable‑file compressor written entirely in assembly language for DOS. The tool achieved very high compression ratios and became one of the most widely used compressors in the DOS era.

Harissa Java virtual machine

In 1996, at age 24, Bellard created Harissa, a Java virtual machine that translates Java bytecode to C source code, which is then compiled and executed. This demonstrated the ability to implement a full language runtime from scratch.

Bellard formula for π

In 1997 Bellard improved the Bailey–Borwein–Plouffe (BBP) series, producing the Bellard formula, which reduced the computational complexity of high‑precision π calculation and became the fastest known algorithm at that time.

TinyGL

Finding the Mesa implementation of OpenGL too slow for a virtual‑reality engine in 1998, Bellard wrote TinyGL, a minimal core subset of OpenGL. TinyGL is orders of magnitude smaller than Mesa and runs significantly faster on constrained hardware.

FFmpeg core libraries

Released in 2000 under the pseudonym Gérard Lantau, FFmpeg provides the libraries libavcodec and libavformat, which together support a vast number of audio‑video codecs and container formats. These libraries are used by VLC, YouTube transcoding pipelines, and countless embedded multimedia applications.

IOCCC FFT‑based primality test

Bellard won the International Obfuscated C Code Contest in 2000, 2001 and 2018. The 2000 entry implements a fast Fourier transform‑based test for the Mersenne number 2^6972593-1 in a few dozen lines of C:

int m=754974721,N,t[1<<22],a,*p,i,e=1<<22,j,s,b,c,U;