mirror of
https://github.com/ultravideo/uvg266.git
synced 2024-12-18 03:04:06 +00:00
81b51f17d8
New implementation uses precalculated tables to look up number of reference pixels available in coded CUs. Otherwise it works just like the previous version. - NxN mostly works. Prediction appears to be almost correct but there is a slight error in the exact values, probably related to filtering.
122 lines
3.3 KiB
Python
122 lines
3.3 KiB
Python
"""This is a script that generates tables for Kvazaar HEVC encoder.
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This script is provided as reference, in case we ever need to change the tables
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or generate more similar tables.
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Because the CUs are coded in Z-order a particular index in the LCU will always
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have the same number of coded reference pixels, except if the PU is on the very
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top or left edge of the LCU.
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"""
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import numpy
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def make_z_order_table(width, coord = None, zid=0, min_width=4, result=None):
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"""Return a table with the quadtree z-order.
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Args:
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width: width of the area (LCU)
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coord: numpy.array with index 0 as x and 1 as y
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min_width: width at which the recursion is stopped
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result: numpy.array with the current table
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Returns: numpy.array with the quadtree z-order.
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"""
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if coord is None:
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coord = numpy.array([0, 0])
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if result is None:
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num_pu = width / min_width
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result = numpy.zeros((num_pu, num_pu), numpy.int16)
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offset = width / 2
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if offset >= min_width:
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# Recurse in quadtree z-order.
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offsets = map(numpy.array, [[0,0],[1,0],[0,1],[1,1]])
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for num, os in enumerate(offsets):
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num_pu = offset**2 / min_width**2
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result = make_z_order_table(offset, coord + os * offset,
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zid + num * num_pu, min_width, result)
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else:
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pu = coord / min_width
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result[pu[1]][pu[0]] = zid
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return result
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def num_lessed_zid_on_left(table, x, y):
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"""Z-order table + coord -> number of ref PUs on the left."""
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i = 0
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while True:
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if x == 0:
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return 16
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if y + i >= 16 or table[y + i][x - 1] > table[y][x]:
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return i
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i = i + 1
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def num_lessed_zid_on_top(table, x, y):
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"""Z-order table + coord -> number of ref PUs on the top."""
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i = 0
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while True:
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if y == 0:
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return 16
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if x + i >= 16 or table[y - 1][x + i] > table[y][x]:
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return i
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i = i + 1
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def matrix_to_initializer_list(table):
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"""Output a list of lists as an initializer list in C syntax.
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Args:
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table: list(list(int)) representing 2d array
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Returns:
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str
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"""
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# Convert the numbers into strings and pad them to be 2-chars wide to make
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# the table look nicer.
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str_nums = (("{0: >2}".format(x) for x in line) for line in table)
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# Get the lines with all the numbers divided by commas.
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lines = (", ".join(line) for line in str_nums)
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# Join the lines with commas and newlines in between.
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result = "{ %s }" % (" },\n{ ".join(lines))
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return result
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def main():
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zid_table = make_z_order_table(64)
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num_pu = 16
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left_table = numpy.zeros((num_pu, num_pu), numpy.int16)
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top_table = numpy.zeros((num_pu, num_pu), numpy.int16)
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for y in range(16):
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for x in range(16):
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left_table[y][x] = num_lessed_zid_on_left(zid_table, x, y)
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top_table[y][x] = num_lessed_zid_on_top(zid_table, x, y)
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print zid_table
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print left_table
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print top_table
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# Multiply by number of pixels in a PU
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left_table = left_table * 4
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top_table = top_table * 4
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print
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print "left"
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print matrix_to_initializer_list(left_table)
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print
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print "top"
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print matrix_to_initializer_list(top_table)
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print
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if __name__ == '__main__':
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main()
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