68 lines
2.0 KiB
C
68 lines
2.0 KiB
C
/* Pixle image / PAL conversion
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*
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* (C) 2017 by Andreas Eversberg <jolly@eversberg.eu>
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* All Rights Reserved
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <math.h>
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#include <stdlib.h>
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#include "../libsample/sample.h"
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#include "image.h"
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/* render image line starting with x and end with LINE_LENGTH
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*
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* sample: pointer to samples, starting at x = 0
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* samplerate: is the sample rate in hertz
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* x: at what x to start rendering
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* line: line no. to render
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*/
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int image_gen_line(sample_t *sample, double x, double samplerate, sample_t *color_u, sample_t *color_v, int v_polarity, double line_start, double line_end, unsigned short *img, int width)
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{
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double img_x = 0;
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double step = 1.0 / samplerate;
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double img_step = (double)width / (samplerate * (line_end - line_start));
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int i = 0;
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double R, G, B, Y, U, V;
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/* skip x to line_start */
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while (x < line_start && x < line_end) {
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i++;
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x += step;
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}
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if (x >= line_end)
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return i;
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/* draw pixle into image */
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while (x < line_end) {
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R = (double)(img[(int)img_x*3+0]) / 65535.0;
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G = (double)(img[(int)img_x*3+1]) / 65535.0;
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B = (double)(img[(int)img_x*3+2]) / 65535.0;
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Y = 0.299 * R + 0.587 * G + 0.114 * B;
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U = 0.492 * (B - Y);
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V = 0.877 * (R - Y);
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sample[i] = Y;
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color_u[i] = U;
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color_v[i] = V * (double)v_polarity;
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i++;
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x += step;
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img_x += img_step;
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if ((int)img_x == width)
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break;
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}
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return i;
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}
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