Libav
wnv1.c
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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 "internal.h"
30 #include "mathops.h"
31 
32 
33 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 ff_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 *got_frame,
62  AVPacket *avpkt)
63 {
64  WNV1Context * const l = avctx->priv_data;
65  const uint8_t *buf = avpkt->data;
66  int buf_size = avpkt->size;
67  AVFrame * const p = data;
68  unsigned char *Y,*U,*V;
69  int i, j, ret;
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 AVERROR(ENOMEM);
82  }
83 
84  if ((ret = ff_get_buffer(avctx, p, 0)) < 0) {
85  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
86  av_free(rbuf);
87  return ret;
88  }
89  p->key_frame = 1;
90 
91  for (i = 8; i < buf_size; i++)
92  rbuf[i] = ff_reverse[buf[i]];
93  init_get_bits(&l->gb, rbuf + 8, (buf_size - 8) * 8);
94 
95  if (buf[2] >> 4 == 6)
96  l->shift = 2;
97  else {
98  l->shift = 8 - (buf[2] >> 4);
99  if (l->shift > 4) {
100  avpriv_request_sample(avctx,
101  "Unknown WNV1 frame header value %i",
102  buf[2] >> 4);
103  l->shift = 4;
104  }
105  if (l->shift < 1) {
106  avpriv_request_sample(avctx,
107  "Unknown WNV1 frame header value %i",
108  buf[2] >> 4);
109  l->shift = 1;
110  }
111  }
112 
113  Y = p->data[0];
114  U = p->data[1];
115  V = p->data[2];
116  for (j = 0; j < avctx->height; j++) {
117  for (i = 0; i < avctx->width / 2; i++) {
118  Y[i * 2] = wnv1_get_code(l, prev_y);
119  prev_u = U[i] = wnv1_get_code(l, prev_u);
120  prev_y = Y[(i * 2) + 1] = wnv1_get_code(l, Y[i * 2]);
121  prev_v = V[i] = wnv1_get_code(l, prev_v);
122  }
123  Y += p->linesize[0];
124  U += p->linesize[1];
125  V += p->linesize[2];
126  }
127 
128 
129  *got_frame = 1;
130  av_free(rbuf);
131 
132  return buf_size;
133 }
134 
136 {
137  WNV1Context * const l = avctx->priv_data;
138  static VLC_TYPE code_table[1 << CODE_VLC_BITS][2];
139 
140  l->avctx = avctx;
141  avctx->pix_fmt = AV_PIX_FMT_YUV422P;
142 
143  code_vlc.table = code_table;
144  code_vlc.table_allocated = 1 << CODE_VLC_BITS;
145  init_vlc(&code_vlc, CODE_VLC_BITS, 16,
146  &code_tab[0][1], 4, 2,
147  &code_tab[0][0], 4, 2, INIT_VLC_USE_NEW_STATIC);
148 
149  return 0;
150 }
151 
153  .name = "wnv1",
154  .long_name = NULL_IF_CONFIG_SMALL("Winnov WNV1"),
155  .type = AVMEDIA_TYPE_VIDEO,
156  .id = AV_CODEC_ID_WNV1,
157  .priv_data_size = sizeof(WNV1Context),
158  .init = decode_init,
159  .decode = decode_frame,
160  .capabilities = CODEC_CAP_DR1,
161 };