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authorNiklas Söderlund <niklas.soderlund@ragnatech.se>2020-04-29 17:54:48 +0200
committerNiklas Söderlund <niklas.soderlund@ragnatech.se>2020-05-02 14:44:25 +0200
commit55d5e3e59f48ed251da5953657570c2f7c50a553 (patch)
treefc3dc59a6c0552086aab82c8e441b422e1a51fea /test/v4l2_videodevice/buffer_cache.cpp
parent58889181538a4458ba3b012f1c69a98138447a2e (diff)
qcam: Allow for a second raw stream to be configured
Allow a second stream to be configured for raw capture. This change only adds support for configuring and allocating buffers for the second stream. Later changes are needed to queue the allocated buffers to the camera when the user wishes to capture a raw frame. Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Diffstat (limited to 'test/v4l2_videodevice/buffer_cache.cpp')
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#!/usr/bin/python3
# SPDX-License-Identifier: GPL-2.0-or-later
# Copyright (C) 2022, Ideas on Board Oy
#
# Generate color space conversion table coefficients with configurable
# fixed-point precision

import argparse
import enum
import numpy as np
import sys


encodings = {
    'rec601': [
        [  0.299,          0.587,          0.114         ],
        [ -0.299 / 1.772, -0.587 / 1.772,  0.886 / 1.772 ],
        [  0.701 / 1.402, -0.587 / 1.402, -0.114 / 1.402 ]
    ],
    'rec709': [
        [  0.2126,           0.7152,           0.0722          ],
        [ -0.2126 / 1.8556, -0.7152 / 1.8556,  0.9278 / 1.8556 ],
        [  0.7874 / 1.5748, -0.7152 / 1.5748, -0.0722 / 1.5748 ]
    ],
    'rec2020': [
        [  0.2627,           0.6780,           0.0593          ],
        [ -0.2627 / 1.8814, -0.6780 / 1.8814,  0.9407 / 1.8814 ],
        [  0.7373 / 1.4746, -0.6780 / 1.4746, -0.0593 / 1.4746 ],
    ],
    'smpte240m': [
        [  0.2122,           0.7013,           0.0865          ],
        [ -0.2122 / 1.8270, -0.7013 / 1.8270,  0.9135 / 1.8270 ],
        [  0.7878 / 1.5756, -0.7013 / 1.5756, -0.0865 / 1.5756 ],
    ],
}


class Precision(object):
    def __init__(self, precision):
        if precision[0].upper() != 'Q':
            raise RuntimeError(f'Invalid precision `{precision}`')
        prec = precision[1:].split('.')
        if len(prec) != 2:
            raise RuntimeError(f'Invalid precision `{precision}`')

        self.__prec = [int(v) for v in prec]

    @property
    def integer(self):
        return self.__prec[0]

    @property
    def fractional(self):
        return self.__prec[1]

    @property
    def total(self):
        # Add 1 for the sign bit
        return self.__prec[0] + self.__prec[1] + 1


class Quantization(enum.Enum):
    FULL = 0
    LIMITED = 1


def scale_coeff(coeff, quantization, luma):
    """Scale a coefficient to the output range dictated by the quantization.

    Parameters
    ----------
    coeff : float
        The CSC matrix coefficient to scale
    quantization : Quantization
        The quantization, either FULL or LIMITED
    luma : bool
        True if the coefficient corresponds to a luma value, False otherwise
    """

    # Assume the input range is 8 bits. The output range is set by the
    # quantization and differs between luma and chrome components for limited
    # range.
    in_range = 255 - 0
    if quantization == Quantization.FULL:
        out_range = 255 - 0
    elif luma:
        out_range = 235 - 16
    else:
        out_range = 240 - 16

    return coeff * out_range / in_range


def round_array(values):
    """Round a list of signed floating point values to the closest integer while
    preserving the (rounded) value of the sum of all elements.
    """

    # Calculate the rounding error as the difference between the rounded sum of
    # values and the sum of rounded values. This is by definition an integer
    # (positive or negative), which indicates how many values will need to be
    # 'flipped' to the opposite rounding.
    rounded_values = [round(value) for value in values]
    sum_values = round(sum(values))
    sum_error = sum_values - sum(rounded_values)

    if sum_error == 0:
        return rounded_values

    # The next step is to distribute the error among the values, in a way that
    # will minimize the relative error introduced in individual values. We
    # extend the values list with the rounded value and original index for each
    # element, and sort by rounding error. Then we modify the elements with the
    # highest or lowest error, depending on whether the sum error is negative
    # or positive.

    values = [[value, round(value), index] for index, value in enumerate(values)]
    values.sort(key=lambda v: v[1] - v[0])

    # It could also be argued that the key for the sort order should not be the
    # absolute rouding error but the relative error, as the impact of identical
    # rounding errors will differ for coefficients with widely different values.
    # This is a topic for further research.
    #
    # values.sort(key=lambda v: (v[1] - v[0]) / abs(v[0]))

    if sum_error > 0:
        for i in range(sum_error):
            values[i][1] += 1
    else:
        for i in range(-sum_error):
            values[len(values) - i - 1][1] -= 1

    # Finally, sort back by index, make sure the total rounding error is now 0,
    # and return the rounded values.
    values.sort(key=lambda v: v[2])
    values = [value[1] for value in values]
    assert(sum(values) == sum_values)

    return values


def main(argv):

    # Parse command line arguments.
    parser = argparse.ArgumentParser(
        description='Generate color space conversion table coefficients with '
        'configurable fixed-point precision.'
    )
    parser.add_argument('--invert', '-i', action='store_true',
                        help='Invert the color space conversion (YUV -> RGB)')
    parser.add_argument('--precision', '-p', default='Q1.7',
                        help='The output fixed point precision in Q notation (sign bit excluded)')
    parser.add_argument('--quantization', '-q', choices=['full', 'limited'],
                        default='limited', help='Quantization range')
    parser.add_argument('encoding', choices=encodings.keys(), help='YCbCr encoding')
    args = parser.parse_args(argv[1:])

    try:
        precision = Precision(args.precision)
    except Exception:
        print(f'Invalid precision `{args.precision}`')
        return 1

    encoding = encodings[args.encoding]
    quantization = Quantization[args.quantization.upper()]

    # Scale and round the encoding coefficients based on the precision and
    # quantization range.
    luma = True
    scaled_coeffs = []
    for line in encoding:
        line = [scale_coeff(coeff, quantization, luma) for coeff in line]
        scaled_coeffs.append(line)
        luma = False

    if args.invert:
        scaled_coeffs = np.linalg.inv(scaled_coeffs)

    rounded_coeffs = []
    for line in scaled_coeffs:
        line = [coeff * (1 << precision.fractional) for coeff in line]
        # For the RGB to YUV conversion, use a rounding method that preserves
        # the rounded sum of each line to avoid biases and overflow, as the sum
        # of luma and chroma coefficients should be 1.0 and 0.0 respectively
        # (in full range). For the YUV to RGB conversion, there is no such
        # constraint, so use simple rounding.
        if args.invert:
            line = [round(coeff) for coeff in line]
        else:
            line = round_array(line)

        # Convert coefficients to the number of bits selected by the precision.
        # Negative values will be turned into positive integers using 2's
        # complement.
        line = [coeff & ((1 << precision.total) - 1) for coeff in line]
        rounded_coeffs.append(line)

    # Print the result as C code.
    nbits = 1 << (precision.total - 1).bit_length()
    nbytes = nbits // 4
    print(f'static const u{nbits} {"yuv2rgb" if args.invert else "rgb2yuv"}_{args.encoding}_{quantization.name.lower()}_coeffs[] = {{')

    for line in rounded_coeffs:
        line = [f'0x{coeff:0{nbytes}x}' for coeff in line]

        print(f'\t{", ".join(line)},')

    print('};')

    return 0


if __name__ == '__main__':
    sys.exit(main(sys.argv))