Kostya's Boring Codec World

Recently my attention was drawn to two screen codecs. So I’ve looked a bit closer at them (I’m not going to implement them — at least now, simian audio codec is waiting) and here are the most interesting bits to me.

Dxtory codec. I don’t know if it uses prediction or not but the coding is extremely simple: read unary code (1-8 bits), if the code is 8 (escape) then read byte for a new value, otherwise retrieve value from LRU list and of course move/put the new value to the beginning of that list.
The organisation into slices and decoding for different colourspaces is trivial.

Mirillis FIC Video. This one has more complexity: it operates on 8×8 blocks. Block is coded in the following way: if the flag is present then the block is skipped, otherwise read 7 bits for the number of coefficients to decode and the coefficients (signed exp-Golomb coded). Zigzag scan, IDCT, output.

Boring.

This entry was posted on Tuesday, March 5th, 2013 at 3:45 pm and is filed under Screen Codecs. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.