ClearVideo

• FourCCs: UCOD
• Company: Iterated Systems
• Samples: http://samples.mplayerhq.hu/V-codecs/UCOD/

ClearVideo is a video encoder ostensibly based on fractals. Alleged to be the basis of certain RealVideo codecs. Also alleged to be patented. A patent search with "iterated" as the assignee name indeed turns up over 20 patents, many of which mention "fractals" and "image compression" in the title. The same decoder core is used for VfW, QT and Real decoders.

Bitstream details

Bitreader uses 32-bit little-endian words and reads data from MSB.

At least one of the coding methods is based on DCT and works in YUV420 colourspace:

 for (all macroblocks) {
    for (i = 0; i < 6; i++)
      block_coded[i] = get_bit();
    for (i = 0; i < 6; i++) {
      if (!block_coded[i]) continue;
      idx = 0;
      while (idx < 64) {
        decode <skip, value, last> tuple
        blk[idx] = value;
        idx += skip;
        if (last)
          break;
      }
      unquantise block (with separate quantiser for DC)
      IDCT();
      put_block_clamped();
    }
 }