# note: A compressed alpha plane with the gradient filter on top.
# expect: ok
# exercises: The two alpha stages together. Filtering and compression are
#   separate fields of the ALPH header byte and the raw cases sweep the
#   filters on their own; here the plane is decompressed first and the
#   gradient unfilter then runs over what came out, so the values in the
#   stream are differences rather than levels.
chunks VP8X ALPH VP8
alpha 1
alph_filtering 3
width 16
height 16
yac_qi 30
macroblock
coeffs y2 -20
alph_plane
transforms color_indexing
palette_colors 0x00000000 0x00000800 0x00001000
pixels 0x24 x64