VPX1

Company: reLine Extension: vpx

This a video format which starts with a 110-byte string describing what this format is and who developed it.

Header:

 110 bytes - essentially a copyright string
 4 bytes - "HEAD"
 6 bytes - do not seem to matter
 2 bytes - video width
 2 bytes - video height
 2 bytes - frames per second
 2 bytes - audio rate

Then chunks with various payload follow, some of them have explicit size, others do not:

• COLS - palette (768 bytes, no chunk size present)
• SOUN - audio data (size present)
• CODE - frame tile types, implicit size of one nibble per 8x8 block (i.e. one byte per 128 pixels)
• VIDE - frame colour values

Video coding

Frame is split into 8x8 tiles and organised in a way allowing easier decoding of down-scaled version of the stream. There are the following tile types known:

• 0 - skip
• 1 - 4x4 block scaled to 8x8
• 2 - 4x8 block scaled to 8x8, for scalability reasons all even rows are coded before odd rows
• 4 - fill block