blind-chroma-key.c - blind - suckless command-line video editing utility
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       ---
       blind-chroma-key.c (2289B)
       ---
            1 /* See LICENSE file for copyright and license details. */
            2 #ifndef TYPE
            3 #include "common.h"
            4 
            5 USAGE("key-stream")
            6 
            7 #define FILE "blind-chroma-key.c"
            8 #include "define-functions.h"
            9 
           10 int
           11 main(int argc, char *argv[])
           12 {
           13         struct stream stream, key;
           14         void (*process)(struct stream *stream, struct stream *key);
           15 
           16         UNOFLAGS(argc != 1);
           17 
           18         eopen_stream(&stream, NULL);
           19         eopen_stream(&key, argv[0]);
           20 
           21         SELECT_PROCESS_FUNCTION(&stream);
           22         CHECK_ALPHA_CHAN(&stream);
           23         CHECK_N_CHAN(&stream, 4, 4);
           24         if (strcmp(stream.pixfmt, key.pixfmt))
           25                 eprintf("videos use incompatible pixel formats\n");
           26 
           27         if (key.width > 2 || key.height > 2 || key.width * key.height != 2)
           28                 eprintf("%s: each frame must contain exactly 2 pixels\n", key.file);
           29 
           30         fprint_stream_head(stdout, &stream);
           31         efflush(stdout, "<stdout>");
           32         process(&stream, &key);
           33         return 0;
           34 }
           35 
           36 #else
           37 
           38 static void
           39 PROCESS(struct stream *stream, struct stream *key)
           40 {
           41         size_t i, n, m = 0;
           42         TYPE x1, y1, z1, a1, a2, variance2, *keyxyza;
           43         TYPE x, y, z, d;
           44         do {
           45                 if (!m) {
           46                         m = stream->frame_size;
           47                         while (key->ptr < key->frame_size)
           48                                 if (!eread_stream(key, key->frame_size - key->ptr))
           49                                         return;
           50                         keyxyza = (TYPE *)(key->buf);
           51                         x1 = keyxyza[0];
           52                         y1 = keyxyza[1];
           53                         z1 = keyxyza[2];
           54                         a1 = keyxyza[3];
           55                         x = x1 - keyxyza[4];
           56                         y = y1 - keyxyza[5];
           57                         z = z1 - keyxyza[6];
           58                         a2 = keyxyza[7];
           59                         variance2 = x * x + y * y + z * z;
           60                         /* TODO add more formulae: https://en.wikipedia.org/wiki/Color_difference */
           61                         if (a2 > a1) {
           62                                 a1 = 1 - a1;
           63                                 a2 = 1 - a2;
           64                         }
           65                         memmove(key->buf, key->buf + key->frame_size,
           66                                 key->ptr -= key->frame_size);
           67                 }
           68                 n = MIN(stream->ptr, m) / stream->pixel_size;
           69                 for (i = 0; i < n; i++) {
           70                         x = ((TYPE *)(stream->buf))[4 * i + 0] - x1;
           71                         y = ((TYPE *)(stream->buf))[4 * i + 1] - y1;
           72                         z = ((TYPE *)(stream->buf))[4 * i + 2] - z1;
           73                         d = x * x + y * y + z * z;
           74                         if (d <= variance2) {
           75                                 if (a1 == a2)
           76                                         d = 0;
           77                                 else
           78                                         d = sqrt(d / variance2) * (a1 - a2) + a2;
           79                                 ((TYPE *)(stream->buf))[4 * i + 3] *= d;
           80                         }
           81                 }
           82                 n *= stream->pixel_size;
           83                 m -= n;
           84                 ewriteall(STDOUT_FILENO, stream->buf, n, "<stdout>");
           85                 memmove(stream->buf, stream->buf + n, stream->ptr -= n);
           86         } while (eread_stream(stream, SIZE_MAX));
           87         if (stream->ptr)
           88                 eprintf("%s: incomplete frame\n", stream->file);
           89 }
           90 
           91 #endif