Winnov WNV1 video decoder, courtesy of Konstantin Shishkov
[libav.git] / libavcodec / wnv1.c
CommitLineData
a8a15e9d
MM
1/*
2 * Winnov WNV1 codec
3 * Copyright (c) 2005 Konstantin Shishkov
4 *
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
9 *
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
14 *
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 *
19 */
20
21/**
22 * @file wnv1.c
23 * Winnov WNV1 codec.
24 */
25
26#include "avcodec.h"
27#include "common.h"
28
29
30typedef struct WNV1Context{
31 AVCodecContext *avctx;
32 AVFrame pic;
33
34 int shift;
35 /* bit buffer */
36 unsigned long bitbuf;
37 int bits;
38 uint8_t *buf;
39} WNV1Context;
40
41/* returns modified base_value */
42static inline int wnv1_get_code(WNV1Context *w, int base_value)
43{
44 int v = 0;
45
46 if (w->bits < 16) { /* need to fill bit buffer */
47 w->bitbuf |= LE_16(w->buf) << w->bits;
48 w->buf += 2;
49 w->bits += 16;
50 }
51
52 /* escape code */
53 if ((w->bitbuf & 0xFF) == 0xFF) {
54 w->bitbuf >>= 8;
55 w->bits -= 8;
56 if (w->bits < 16) { /* need to fill bit buffer */
57 w->bitbuf |= LE_16(w->buf) << w->bits;
58 w->buf += 2;
59 w->bits += 16;
60 }
61 v = w->bitbuf & (0xFF >> w->shift);
62 w->bitbuf >>= 8 - w->shift;
63 w->bits -= 8 - w->shift;
64 return v << w->shift;
65 }
66
67 /* zero code */
68 if (!(w->bitbuf & 1)) {
69 w->bitbuf >>= 1;
70 w->bits--;
71 return base_value;
72 }
73
74 /* reversed unary code and sign */
75 while (w->bits && w->bitbuf & 1) {
76 w->bitbuf >>= 1;
77 w->bits--;
78 v++;
79 }
80 w->bitbuf >>= 1;
81 w->bits--;
82 if(w->bitbuf & 1)
83 v = -v;
84 w->bitbuf >>= 1;
85 w->bits--;
86 v <<= w->shift;
87 return base_value + v;
88}
89
90static int decode_frame(AVCodecContext *avctx,
91 void *data, int *data_size,
92 uint8_t *buf, int buf_size)
93{
94 WNV1Context * const l = avctx->priv_data;
95 AVFrame * const p= (AVFrame*)&l->pic;
96 unsigned char *Y,*U,*V;
97 int i, j;
98 int prev_y = 0, prev_u = 0, prev_v = 0;
99
100 if(p->data[0])
101 avctx->release_buffer(avctx, p);
102
103 p->reference = 0;
104 if(avctx->get_buffer(avctx, p) < 0){
105 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
106 return -1;
107 }
108 p->key_frame = 1;
109
110 l->bitbuf = 0;
111 l->bits = 0;
112 l->buf = buf + 8;
113
114 if (buf[2] >> 4 == 6)
115 l->shift = 2;
116 else {
117 l->shift = 8 - (buf[2] >> 4);
118 if (l->shift > 4) {
119 av_log(avctx, AV_LOG_ERROR, "Unknown WNV1 frame header value %i, please upload file for study\n", buf[2] >> 4);
120 l->shift = 4;
121 }
122 if (l->shift < 1) {
123 av_log(avctx, AV_LOG_ERROR, "Unknown WNV1 frame header value %i, please upload file for study\n", buf[2] >> 4);
124 l->shift = 1;
125 }
126 }
127
128 Y = p->data[0];
129 U = p->data[1];
130 V = p->data[2];
131 for (j = 0; j < avctx->height; j++) {
132 for (i = 0; i < avctx->width / 2; i++) {
133 Y[i * 2] = wnv1_get_code(l, prev_y);
134 prev_u = U[i] = wnv1_get_code(l, prev_u);
135 prev_y = Y[(i * 2) + 1] = wnv1_get_code(l, Y[i * 2]);
136 prev_v = V[i] = wnv1_get_code(l, prev_v);
137 }
138 Y += p->linesize[0];
139 U += p->linesize[1];
140 V += p->linesize[2];
141 }
142
143
144 *data_size = sizeof(AVFrame);
145 *(AVFrame*)data = l->pic;
146
147 return buf_size;
148}
149
150static int decode_init(AVCodecContext *avctx){
151 WNV1Context * const l = avctx->priv_data;
152
153 l->avctx = avctx;
154 avctx->pix_fmt = PIX_FMT_YUV422P;
155
156 return 0;
157}
158
159AVCodec wnv1_decoder = {
160 "wnv1",
161 CODEC_TYPE_VIDEO,
162 CODEC_ID_WNV1,
163 sizeof(WNV1Context),
164 decode_init,
165 NULL,
166 NULL,
167 decode_frame,
168 CODEC_CAP_DR1,
169};