- FOURCCs: VMnc
- Preferred container: AVI
- Company: VMware
- Samples: http://www.mplayerhq.hu/MPlayer/samples/V-codecs/VMnc/
The VMware Workstation (a commercial x86 machine emulator) can record sessions using this codec. Read the brief story behind the reverse engineering of this codec. It is suspected to be a lossless codec.
Cursory investigation details in this blog post: http://codecs.multimedia.cx/?p=9
Basically it is just a recorded session of the RFB protocol, which is used by VNC. Probably a VNC server is running on the virtual machine, while a client outside records it.
Bitstream structure (this resembles the VNC FrameBufferUpdate format), everything is big-endian ordered:
8bit message type 8bit padding 16bit number of rectangles coded
For each rectangle:
16bit x position 16bit y position 16bit coded width 16bit coded height 32bit encoding type
Encoding type might be 0 to 5 as found in the RFB Protocol specification, but current samples reveal that type 5 is the most common.
VMware adds special encoding types, abusing the whole structure. VNC ServerInitialisation is stored in the above format with encoding type set to WMVi.
8bit bits per sample 8bit depth 8bit color stored in big endian order
However, this is also signaled right in the AVI header.
There are other unknown encoding types which were not yet descrambled: