xref: /third_party/ffmpeg/libavcodec/h263dsp.c (revision cabdff1a) 
1/*
2 * This file is part of FFmpeg.
3 *
4 * FFmpeg is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2.1 of the License, or (at your option) any later version.
8 *
9 * FFmpeg is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12 * Lesser General Public License for more details.
13 *
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with FFmpeg; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17 */
18
19#include <stdint.h>
20
21#include "libavutil/attributes.h"
22#include "libavutil/common.h"
23#include "config.h"
24#include "h263dsp.h"
25
26const uint8_t ff_h263_loop_filter_strength[32] = {
27    0, 1, 1, 2, 2, 3, 3,  4,  4,  4,  5,  5,  6,  6,  7, 7,
28    7, 8, 8, 8, 9, 9, 9, 10, 10, 10, 11, 11, 11, 12, 12, 12
29};
30
31static void h263_h_loop_filter_c(uint8_t *src, int stride, int qscale)
32{
33    int y;
34    const int strength = ff_h263_loop_filter_strength[qscale];
35
36    for (y = 0; y < 8; y++) {
37        int d1, d2, ad1;
38        int p0 = src[y * stride - 2];
39        int p1 = src[y * stride - 1];
40        int p2 = src[y * stride + 0];
41        int p3 = src[y * stride + 1];
42        int d  = (p0 - p3 + 4 * (p2 - p1)) / 8;
43
44        if (d < -2 * strength)
45            d1 = 0;
46        else if (d < -strength)
47            d1 = -2 * strength - d;
48        else if (d < strength)
49            d1 = d;
50        else if (d < 2 * strength)
51            d1 = 2 * strength - d;
52        else
53            d1 = 0;
54
55        p1 += d1;
56        p2 -= d1;
57        if (p1 & 256)
58            p1 = ~(p1 >> 31);
59        if (p2 & 256)
60            p2 = ~(p2 >> 31);
61
62        src[y * stride - 1] = p1;
63        src[y * stride + 0] = p2;
64
65        ad1 = FFABS(d1) >> 1;
66
67        d2 = av_clip((p0 - p3) / 4, -ad1, ad1);
68
69        src[y * stride - 2] = p0 - d2;
70        src[y * stride + 1] = p3 + d2;
71    }
72}
73
74static void h263_v_loop_filter_c(uint8_t *src, int stride, int qscale)
75{
76    int x;
77    const int strength = ff_h263_loop_filter_strength[qscale];
78
79    for (x = 0; x < 8; x++) {
80        int d1, d2, ad1;
81        int p0 = src[x - 2 * stride];
82        int p1 = src[x - 1 * stride];
83        int p2 = src[x + 0 * stride];
84        int p3 = src[x + 1 * stride];
85        int d  = (p0 - p3 + 4 * (p2 - p1)) / 8;
86
87        if (d < -2 * strength)
88            d1 = 0;
89        else if (d < -strength)
90            d1 = -2 * strength - d;
91        else if (d < strength)
92            d1 = d;
93        else if (d < 2 * strength)
94            d1 = 2 * strength - d;
95        else
96            d1 = 0;
97
98        p1 += d1;
99        p2 -= d1;
100        if (p1 & 256)
101            p1 = ~(p1 >> 31);
102        if (p2 & 256)
103            p2 = ~(p2 >> 31);
104
105        src[x - 1 * stride] = p1;
106        src[x + 0 * stride] = p2;
107
108        ad1 = FFABS(d1) >> 1;
109
110        d2 = av_clip((p0 - p3) / 4, -ad1, ad1);
111
112        src[x - 2 * stride] = p0 - d2;
113        src[x + stride]     = p3 + d2;
114    }
115}
116
117av_cold void ff_h263dsp_init(H263DSPContext *ctx)
118{
119    ctx->h263_h_loop_filter = h263_h_loop_filter_c;
120    ctx->h263_v_loop_filter = h263_v_loop_filter_c;
121
122#if ARCH_X86
123    ff_h263dsp_init_x86(ctx);
124#elif ARCH_MIPS
125    ff_h263dsp_init_mips(ctx);
126#endif
127}
128