Since I am clumsy at English writing, I put it briefly. - The development of DVD2AVI is based on MSSG MPEG2Decode http://www.mpeg.org/MPEG/MSSG/ and adds features as follows: 1. GUI interface (gui.cpp) 2. VFAPI support (vfapi.c vfapidec.c) 3. AC3/MPA/LPCM demux (getbit.c) 4. Auto-split AVI output through RGB24/YUY2 (store.c) 5. YUY2 DirectDraw Overlay (store.c gui.cpp) 6. revised I/O routine (getbit.c getbic.h) 7. MMX-optimized motion compensation (recon.c getpic.c) 8. MMX-optimized color space conversion (store.c) 9. audio normalization (norm.c) - The author of TMPGEnc, Hiroyuki Hori, defines the spec of VFAPI (Video File API). You can find the Delphi-based VFAPI SDK on his page. http://www.yks.ne.jp/~hori/VFAPI.html - The development of VFAPI Plug-In refers to MPEG-2 VIDEO VFAPI Plug-In developed by Kazuhiro Mogi. It's helpful to C programmers. http://www.isc.meiji.ac.jp/~ee69011/mpeg2/ - MMX 32-bit iDCT is implanted from Royce