FFmpeg
display.c
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1 /*
2  * Copyright (c) 2014 Vittorio Giovara <vittorio.giovara@gmail.com>
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include <stdint.h>
22 #include <string.h>
23 #include <math.h>
24 
25 #include "display.h"
26 #include "mathematics.h"
27 
28 // fixed point to double
29 #define CONV_FP(x) ((double) (x)) / (1 << 16)
30 
31 // double to fixed point
32 #define CONV_DB(x) (int32_t) ((x) * (1 << 16))
33 
34 double av_display_rotation_get(const int32_t matrix[9])
35 {
36  double rotation, scale[2];
37 
38  scale[0] = hypot(CONV_FP(matrix[0]), CONV_FP(matrix[3]));
39  scale[1] = hypot(CONV_FP(matrix[1]), CONV_FP(matrix[4]));
40 
41  if (scale[0] == 0.0 || scale[1] == 0.0)
42  return NAN;
43 
44  rotation = atan2(CONV_FP(matrix[1]) / scale[1],
45  CONV_FP(matrix[0]) / scale[0]) * 180 / M_PI;
46 
47  return -rotation;
48 }
49 
50 void av_display_rotation_set(int32_t matrix[9], double angle)
51 {
52  double radians = -angle * M_PI / 180.0f;
53  double c = cos(radians);
54  double s = sin(radians);
55 
56  memset(matrix, 0, 9 * sizeof(int32_t));
57 
58  matrix[0] = CONV_DB(c);
59  matrix[1] = CONV_DB(-s);
60  matrix[3] = CONV_DB(s);
61  matrix[4] = CONV_DB(c);
62  matrix[8] = 1 << 30;
63 }
64 
65 void av_display_matrix_flip(int32_t matrix[9], int hflip, int vflip)
66 {
67  int i;
68  const int flip[] = { 1 - 2 * (!!hflip), 1 - 2 * (!!vflip), 1 };
69 
70  if (hflip || vflip)
71  for (i = 0; i < 9; i++)
72  matrix[i] *= flip[i % 3];
73 }
void av_display_matrix_flip(int32_t matrix[9], int hflip, int vflip)
Flip the input matrix horizontally and/or vertically.
Definition: display.c:65
void av_display_rotation_set(int32_t matrix[9], double angle)
Initialize a transformation matrix describing a pure counterclockwise rotation by the specified angle...
Definition: display.c:50
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:259
static void flip(AVCodecContext *avctx, AVFrame *frame)
Definition: rawdec.c:136
Display matrix.
static av_const double hypot(double x, double y)
Definition: libm.h:366
#define NAN
Definition: mathematics.h:64
int32_t
#define s(width, name)
Definition: cbs_vp9.c:257
#define CONV_DB(x)
Definition: display.c:32
#define CONV_FP(x)
Definition: display.c:29
double av_display_rotation_get(const int32_t matrix[9])
Extract the rotation component of the transformation matrix.
Definition: display.c:34
#define M_PI
Definition: mathematics.h:52