xref: /third_party/ffmpeg/libavcodec/h261.c (revision cabdff1a) 
1/*
2 * H.261 common code
3 * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
4 * Copyright (c) 2004 Maarten Daniels
5 *
6 * This file is part of FFmpeg.
7 *
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
12 *
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23/**
24 * @file
25 * H.261 codec
26 */
27
28#include "h261.h"
29#include "mpegvideo.h"
30
31#define IS_FIL(a)    ((a) & MB_TYPE_H261_FIL)
32
33static void h261_loop_filter(uint8_t *src, int stride)
34{
35    int x, y, xy, yz;
36    int temp[64];
37
38    for (x = 0; x < 8; x++) {
39        temp[x]         = 4 * src[x];
40        temp[x + 7 * 8] = 4 * src[x + 7 * stride];
41    }
42    for (y = 1; y < 7; y++) {
43        for (x = 0; x < 8; x++) {
44            xy       = y * stride + x;
45            yz       = y * 8      + x;
46            temp[yz] = src[xy - stride] + 2 * src[xy] + src[xy + stride];
47        }
48    }
49
50    for (y = 0; y < 8; y++) {
51        src[y * stride]     = (temp[y * 8]     + 2) >> 2;
52        src[y * stride + 7] = (temp[y * 8 + 7] + 2) >> 2;
53        for (x = 1; x < 7; x++) {
54            xy      = y * stride + x;
55            yz      = y * 8      + x;
56            src[xy] = (temp[yz - 1] + 2 * temp[yz] + temp[yz + 1] + 8) >> 4;
57        }
58    }
59}
60
61void ff_h261_loop_filter(MpegEncContext *s)
62{
63    H261Context *const h = s->private_ctx;
64    const int linesize   = s->linesize;
65    const int uvlinesize = s->uvlinesize;
66    uint8_t *dest_y      = s->dest[0];
67    uint8_t *dest_cb     = s->dest[1];
68    uint8_t *dest_cr     = s->dest[2];
69
70    if (!(IS_FIL(h->mtype)))
71        return;
72
73    h261_loop_filter(dest_y,                    linesize);
74    h261_loop_filter(dest_y + 8,                linesize);
75    h261_loop_filter(dest_y + 8 * linesize,     linesize);
76    h261_loop_filter(dest_y + 8 * linesize + 8, linesize);
77    h261_loop_filter(dest_cb, uvlinesize);
78    h261_loop_filter(dest_cr, uvlinesize);
79}
80