wnv1.c
Go to the documentation of this file.
1 /*
2  * Winnov WNV1 codec
3  * Copyright (c) 2005 Konstantin Shishkov
4  *
5  * This file is part of Libav.
6  *
7  * Libav is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * Libav is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
27 #include "avcodec.h"
28 #include "get_bits.h"
29 #include "libavutil/common.h"
30 
31 
32 typedef struct WNV1Context{
35 
36  int shift;
38 } WNV1Context;
39 
40 static const uint16_t code_tab[16][2]={
41 {0x1FD,9}, {0xFD,8}, {0x7D,7}, {0x3D,6}, {0x1D,5}, {0x0D,4}, {0x005,3},
42 {0x000,1},
43 {0x004,3}, {0x0C,4}, {0x1C,5}, {0x3C,6}, {0x7C,7}, {0xFC,8}, {0x1FC,9}, {0xFF,8}
44 };
45 
46 #define CODE_VLC_BITS 9
47 static VLC code_vlc;
48 
49 /* returns modified base_value */
50 static inline int wnv1_get_code(WNV1Context *w, int base_value)
51 {
52  int v = get_vlc2(&w->gb, code_vlc.table, CODE_VLC_BITS, 1);
53 
54  if(v==15)
55  return av_reverse[ get_bits(&w->gb, 8 - w->shift) ];
56  else
57  return base_value + ((v - 7)<<w->shift);
58 }
59 
60 static int decode_frame(AVCodecContext *avctx,
61  void *data, int *data_size,
62  AVPacket *avpkt)
63 {
64  const uint8_t *buf = avpkt->data;
65  int buf_size = avpkt->size;
66  WNV1Context * const l = avctx->priv_data;
67  AVFrame * const p= (AVFrame*)&l->pic;
68  unsigned char *Y,*U,*V;
69  int i, j;
70  int prev_y = 0, prev_u = 0, prev_v = 0;
71  uint8_t *rbuf;
72 
73  if (buf_size < 8) {
74  av_log(avctx, AV_LOG_ERROR, "Packet is too short\n");
75  return AVERROR_INVALIDDATA;
76  }
77 
78  rbuf = av_malloc(buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
79  if(!rbuf){
80  av_log(avctx, AV_LOG_ERROR, "Cannot allocate temporary buffer\n");
81  return -1;
82  }
83 
84  if(p->data[0])
85  avctx->release_buffer(avctx, p);
86 
87  p->reference = 0;
88  if(avctx->get_buffer(avctx, p) < 0){
89  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
90  av_free(rbuf);
91  return -1;
92  }
93  p->key_frame = 1;
94 
95  for(i=8; i<buf_size; i++)
96  rbuf[i]= av_reverse[ buf[i] ];
97  init_get_bits(&l->gb, rbuf+8, (buf_size-8)*8);
98 
99  if (buf[2] >> 4 == 6)
100  l->shift = 2;
101  else {
102  l->shift = 8 - (buf[2] >> 4);
103  if (l->shift > 4) {
104  av_log_ask_for_sample(avctx, "Unknown WNV1 frame header value %i\n",
105  buf[2] >> 4);
106  l->shift = 4;
107  }
108  if (l->shift < 1) {
109  av_log_ask_for_sample(avctx, "Unknown WNV1 frame header value %i\n",
110  buf[2] >> 4);
111  l->shift = 1;
112  }
113  }
114 
115  Y = p->data[0];
116  U = p->data[1];
117  V = p->data[2];
118  for (j = 0; j < avctx->height; j++) {
119  for (i = 0; i < avctx->width / 2; i++) {
120  Y[i * 2] = wnv1_get_code(l, prev_y);
121  prev_u = U[i] = wnv1_get_code(l, prev_u);
122  prev_y = Y[(i * 2) + 1] = wnv1_get_code(l, Y[i * 2]);
123  prev_v = V[i] = wnv1_get_code(l, prev_v);
124  }
125  Y += p->linesize[0];
126  U += p->linesize[1];
127  V += p->linesize[2];
128  }
129 
130 
131  *data_size = sizeof(AVFrame);
132  *(AVFrame*)data = l->pic;
133  av_free(rbuf);
134 
135  return buf_size;
136 }
137 
138 static av_cold int decode_init(AVCodecContext *avctx){
139  WNV1Context * const l = avctx->priv_data;
140  static VLC_TYPE code_table[1 << CODE_VLC_BITS][2];
141 
142  l->avctx = avctx;
143  avctx->pix_fmt = PIX_FMT_YUV422P;
144 
145  code_vlc.table = code_table;
146  code_vlc.table_allocated = 1 << CODE_VLC_BITS;
147  init_vlc(&code_vlc, CODE_VLC_BITS, 16,
148  &code_tab[0][1], 4, 2,
149  &code_tab[0][0], 4, 2, INIT_VLC_USE_NEW_STATIC);
150 
151  return 0;
152 }
153 
154 static av_cold int decode_end(AVCodecContext *avctx){
155  WNV1Context * const l = avctx->priv_data;
156  AVFrame *pic = &l->pic;
157 
158  if (pic->data[0])
159  avctx->release_buffer(avctx, pic);
160 
161  return 0;
162 }
163 
165  .name = "wnv1",
166  .type = AVMEDIA_TYPE_VIDEO,
167  .id = CODEC_ID_WNV1,
168  .priv_data_size = sizeof(WNV1Context),
169  .init = decode_init,
170  .close = decode_end,
171  .decode = decode_frame,
172  .capabilities = CODEC_CAP_DR1,
173  .long_name = NULL_IF_CONFIG_SMALL("Winnov WNV1"),
174 };